CN109031089B - Synchronous rectification chip, automatic detection circuit and automatic detection method for power supply of synchronous rectification chip - Google Patents
Synchronous rectification chip, automatic detection circuit and automatic detection method for power supply of synchronous rectification chip Download PDFInfo
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- CN109031089B CN109031089B CN201810609732.9A CN201810609732A CN109031089B CN 109031089 B CN109031089 B CN 109031089B CN 201810609732 A CN201810609732 A CN 201810609732A CN 109031089 B CN109031089 B CN 109031089B
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G—PHYSICS
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Abstract
The invention belongs to the technical field of circuit detection, and provides an automatic detection circuit applied to external power supply of a synchronous rectification chip, the synchronous rectification chip and an automatic detection method of external power supply of the synchronous rectification chip; the automatic detection circuit includes: the device comprises a pulse power supply module, a first voltage detection module, a pull-down current module and a power supply mode judgment module; when the driving signal is in a first level state, the pulse power supply module transmits VD pulses to the VCC power supply pin; the first voltage detection module generates a first voltage detection signal according to the difference value between the voltage of the VCC power supply pin and a first reference voltage; when the VCC power supply pin is connected with the pull-down current, the power supply mode judging module judges the power supply mode of the synchronous rectification chip according to the descending or ascending condition of the voltage of the VCC power supply pin; the invention can solve the problem that the synchronous rectification chip in the traditional technology can not automatically detect which external power supply connection mode is adopted by the synchronous rectification chip.
Description
Technical Field
The invention belongs to the technical field of circuit detection, and particularly relates to an automatic detection circuit applied to external power supply of a synchronous rectification chip, the synchronous rectification chip and an automatic detection method of external power supply of the synchronous rectification chip.
Background
Because the synchronous rectification chip can play a good role in the design of electronic circuits, technicians have applied the synchronous rectification chip to various electronic devices, such as mobile phones, notebook computers and the like; the synchronous rectification chip comprises a VD power input pin and a VCC power pin, and in the traditional circuit topology structure, when the synchronous rectification chip is applied to the synchronous rectification circuit, the synchronous rectification chip can output pulse voltage to the VCC power pin through the VD power input pin, and power supply is realized to the VCC power pin through the pulse voltage; the VCC power supply pin of the synchronous rectification chip can be directly externally connected with an external power supply, and the external power supply can directly supply power to the VCC power supply pin.
Therefore, in the traditional external power supply mode of the synchronous rectification chip, two external power supply modes exist on the VCC power supply pin of the synchronous rectification chip, if different external power supply connection modes are adopted by the synchronous rectification chip, the power supply connected to the VCC power supply pin of the synchronous rectification chip is also different, and correspondingly, different power components are required to be externally connected to the VCC power supply pin of the synchronous rectification chip; however, in practical application, when a technician applies the synchronous rectification chip to the synchronous rectification circuit, the synchronous rectification chip cannot automatically detect what external power supply mode is adopted by the synchronous rectification chip at the moment, so that the compatibility of the synchronous rectification chip is reduced, and the synchronous rectification chip cannot be universally applied to rectification circuits of different types.
Disclosure of Invention
The invention provides an automatic detection circuit applied to external power supply of a synchronous rectification chip, the synchronous rectification chip and an automatic detection method of external power supply of the synchronous rectification chip, and aims to solve the problems that the synchronous rectification chip in the prior art cannot automatically detect what external power supply connection mode is adopted by the synchronous rectification chip, and therefore compatibility and practicality are low.
The first aspect of the present invention provides an automatic detection circuit applied to external power supply of a synchronous rectification chip, the synchronous rectification chip comprising: VCC power pin and be used for inserting VD power input pin of VD pulse, automatic detection circuit includes:
The pulse power supply module is connected between the VD power supply input pin and the VCC power supply pin and is configured to supply power to the VCC power supply pin through the VD pulse when the accessed driving signal is in a first level state;
The first voltage detection module is connected with the VCC power pin, is configured to detect the voltage of the VCC power pin and generates a first voltage detection signal according to the difference value of the voltage of the VCC power pin and a first reference voltage; wherein the first voltage detection signal is in a first level state when the voltage of the VCC power supply pin is greater than or equal to the first reference voltage;
A pull-down current module connected to the first voltage detection module and the VCC power supply pin and configured to output a pull-down current to the VCC power supply pin according to when the first voltage detection signal is in a first level state;
The power supply mode judging module is electrically connected with the pulse power supply module, is coupled with the first voltage detecting module and the pull-down current module, is configured to generate the driving signal, and judges whether the synchronous rectification chip is in a first power supply mode or a second power supply mode according to the falling or rising condition of the voltage of the VCC power supply pin when the VCC power supply pin is connected with the pull-down current; and when the first voltage detection signal is in a first level state, the driving signal is in a second level state.
A second aspect of the present invention provides a synchronous rectification chip, wherein the synchronous rectification chip includes: VCC power pin, VD power input pin, ground pin and rectification signal output pin, synchronous rectification chip still includes the automatic detection circuit that is applied to synchronous rectification chip external power supply as described above.
The third aspect of the present invention provides an automatic detection method for external power supply of a synchronous rectification chip, the synchronous rectification chip comprising: VCC power pin and be used for inserting VD power input pin of VD pulse, the automated inspection method includes:
when a driving signal in a first level state is accessed, power is supplied to the VCC power supply pin through the VD pulse;
Detecting the voltage of the VCC power pin, and generating a first voltage detection signal according to the difference value of the voltage of the VCC power pin and a first reference voltage; wherein the first voltage detection signal is in a first level state when the voltage of the VCC power supply pin is greater than or equal to the first reference voltage;
Outputting a pull-down current to the VCC power supply pin when the first voltage detecting signal is in a first level state;
When the VCC power supply pin is connected with the pull-down current, judging whether the synchronous rectification chip is in a first power supply mode or a second power supply mode according to the voltage drop or rise condition of the VCC power supply pin; and when the first voltage detection signal is in a first level state, the driving signal is in a second level state.
In the automatic detection circuit applied to the external power supply of the synchronous rectification chip, when the driving signal is in the first level state, the pulse power supply module transmits VD pulses to the VCC power supply pin so as to realize the initial power supply of the VCC power supply pin; with the continuous transmission of VD pulses to the VCC power supply pin by the pulse power supply module, the voltage of the VCC power supply pin rises, the first voltage detection signal jumps to a first level state, the driving signal jumps to a second level state, at the moment, the pulse power supply module stops outputting the VD pulses to the VCC power supply pin, and the pull-down current module transmits pull-down current to the VCC power supply pin, the pull-down current has the effects of inhibiting and reducing the voltage of the VCC power supply pin, and the power supply mode judging module can judge whether the synchronous rectification chip is in a power supply mode according to the rising or falling condition of the voltage of the VCC power supply pin so as to realize automatic detection and identification of external power supply connection of the synchronous rectification chip; therefore, the problem that the synchronous rectification chip in the traditional technology cannot automatically detect what external power supply connection mode is adopted, so that the compatibility is low is solved.
Drawings
FIG. 1 is a schematic diagram of an external power supply connection structure of a synchronous rectification chip provided by an embodiment of the present invention in different power supply modes;
FIG. 2 is a block diagram of an automatic detection circuit applied to external power supply of a synchronous rectification chip according to an embodiment of the present invention;
FIG. 3 is a block diagram of another automatic detection circuit applied to external power supply of a synchronous rectification chip according to an embodiment of the present invention;
FIG. 4 is a circuit configuration diagram of an automatic detection circuit applied to external power supply of a synchronous rectification chip according to an embodiment of the present invention;
FIG. 5 is a waveform diagram of signals in the automatic detection circuit in the first power mode according to the embodiment of the present invention;
FIG. 6 is a waveform diagram of signals in the automatic detection circuit in the second power mode according to the embodiment of the present invention;
FIG. 7 is a block diagram of a synchronous rectification chip according to an embodiment of the present invention;
Fig. 8 is a specific flowchart of an automatic detection method for external power supply of a synchronous rectification chip according to an embodiment of the present invention.
Detailed Description
The synchronous rectification chip is used as a common functional chip in the traditional technology and can be applied to various rectification circuits; the related technicians successively develop various types of rectifying chips, such as DK5V45R25, IR1166S, SOT, 23-5, SOT23-6, etc.; the synchronous rectification chip comprises rectification chips of all types in the traditional technology; although the rectification chips of different types in the traditional technology have certain difference in the functions and structures of pins, the synchronous rectification chips of all types necessarily comprise VCC power supply pins and VD power supply input pins, and in the power-on process of the synchronous rectification chips, the VCC power supply pins of the synchronous rectification chips necessarily need to be connected with electric energy so that the synchronous rectification chips can realize normal circuit functions; therefore, the automatic detection circuit disclosed by the invention can be suitable for synchronous rectification chips of all types, and realizes automatic detection of an external power supply connection mode of the synchronous rectification chips.
According to the basic electronic general knowledge in the technical field, the synchronous rectification chip comprises a VCC power supply pin and a VD power supply input pin, when the synchronous rectification chip is applied to the synchronous rectification circuit, the VCC power supply pin of the synchronous rectification chip has a charging process, but in the practical application process, because the external power supply connection structures of the synchronous rectification chip are not the same, the VCC power supply pin needs to be externally connected with different electronic components in different power supply modes, and fig. 1 shows a schematic diagram of the external power supply connection structure of the synchronous rectification chip 200 in different power supply modes; in fig. 1 (a), the VCC power input pin of the synchronous rectification chip 200 is directly connected with the secondary winding of the transformer, and since the secondary winding of the transformer can output stable electric energy in the operation process of the synchronous rectification circuit, the VCC power input pin of the synchronous rectification chip 200 can directly access external electric energy to realize rapid self-charging, and in the external power supply connection mode shown in fig. 1 (a), the VCC power input pin of the synchronous rectification chip 200 is directly connected with an external power source without any external auxiliary power component, so that the electric energy loss is reduced, and the application cost of the synchronous rectification chip 200 is reduced, but in fig. 1 (c), the external power supply connection mode of the chip in fig. 1 (a) cannot be suitable for all application occasions, for example, since the ground pin 500 of the synchronous rectification chip 200 is directly connected with the secondary winding of the transformer, the ground pin 500 of the synchronous rectification chip 200 is directly connected with electric energy, and at this moment, the VCC power pin 300 of the synchronous rectification chip 200 cannot be directly connected with the secondary winding of the transformer, so that the VCC power pin 300 of the synchronous rectification chip 200 is directly connected with the external power source.
In fig. 1 (b) and fig. 1 (c), since the VD power input pin 400 of the synchronous rectification chip 200 is directly connected to the secondary winding of the transformer, VD pulses can be connected to the VD power input pin 400, and power can be supplied to the VCC power pin 300 through the VD pulses, in the power supply mode of fig. 1 (b) and fig. 1 (c), the VCC power pin 300 of the synchronous rectification chip 200 is not directly connected to an external power supply, the VCC power pin 300 is connected to an external power supply circuit through a decoupling capacitor 600, and at this time, the VCC power pin 300 of the synchronous rectification chip 200 is connected to electric energy through VD pulses, so as to realize self charging; in the external power supply connection modes shown in fig. 1 (b) and 1 (c), the synchronous rectification chip 200 can be applied to synchronous rectification circuits of different types, and has strong compatibility and wide application range; however, in the external power supply connection manner shown in fig. 1 (b) and fig. 1 (c), since the VCC power pin 300 of the synchronous rectification chip 200 needs to be externally connected with a decoupling capacitor 600, the manufacturing cost of the synchronous rectification circuit is increased, and the power consumption of the synchronous rectification chip 200 is larger; therefore, in the rectifying circuit design and manufacturing process, a technician can adopt different external power supply connection modes for the synchronous rectifying chip 200 according to actual needs, such as fig. 1 (a), fig. 1 (b) and fig. 1 (c), but when the synchronous rectifying chip 200 adopts different external power supply connection modes, the synchronous rectifying chip 200 cannot automatically detect what power supply mode the VCC power supply pin 300 adopts at this time, which further results in reduced compatibility of the synchronous rectifying chip 200.
Fig. 2 illustrates a block structure of the automatic detection circuit 100 applied to external power supply of the synchronous rectification chip 200 according to an embodiment of the present invention, for convenience of explanation, only a portion related to the embodiment of the present invention is illustrated, and as illustrated in fig. 2, the automatic detection circuit 100 is used for automatically detecting and identifying an external power supply connection mode of the synchronous rectification chip 200, and as described above, the synchronous rectification chip 200 includes a VCC power supply pin 300 and a VD power supply input pin 400; specifically, referring to fig. 1, a schematic structural diagram of a synchronous rectification chip in an embodiment of the present invention may refer to fig. 1, when the synchronous rectification chip is applied in an electronic circuit, a VD power input pin 400 is continuously connected to a VD pulse, and power may be provided to a VCC power pin 300 through the VD pulse, where the VD pulse has a specific frequency and period; when the VCC power supply pin 300 of the synchronous rectification chip reaches a stable operating voltage through initial charging, the synchronous rectification chip can be in a normal operating state.
The automatic detection circuit 100 includes: a pulse power supply module 10, a first voltage detection module 20, a pull-down current module 30, and a power supply mode judgment module 40; the pulse power supply module 10 is connected between the VD power supply input pin 400 and the VCC power supply pin 300, and the pulse power supply module 10 is connected to the driving signal DisableVD, when the driving signal DisableVD is in the first level state, the pulse power supply module 10 supplies power to the VCC power supply pin 300 through VD pulses, specifically, the on or off state of the pulse power supply module 10 can be controlled through the driving signal DisableVD, and only when the driving signal DisableVD is in the first level state, the pulse power supply module 10 is turned on, the VD power supply input pin 400 transmits VD pulses to the VCC power supply pin 300, and further supplies power to the VCC power supply pin 300; conversely, if the driving signal DisableVD is in the second level state, the pulse power module 10 is turned off, and the VD power input pin 400 does not transmit the VD pulse to the VCC power pin 300; it should be noted that, the driving signal DisableVD may be in a high level state or a low level state, which is not limited thereto, and those skilled in the art may specifically set the first level state of the driving signal DisableVD according to the specific application circuit of the synchronous rectification chip; in the embodiment of the present invention, the first level state of the driving signal DisableVD is a low level state, that is, the VD power input pin 400 transmits the VD pulse to the VCC power pin 300 only when the driving signal DisableVD is a low level state.
The first voltage detection module 20 is connected with the VCC power supply pin 300, the first voltage detection module 20 detects the voltage of the VCC power supply pin 300, and the first voltage detection module 20 generates a first voltage detection signal D1 according to the difference between the voltage of the VCC power supply pin 300 and a first reference voltage, and the magnitude relation between the voltage of the VCC power supply pin 300 and the first reference voltage is measured by the level state of the first voltage detection signal D1, wherein when the voltage of the VCC power supply pin 300 is greater than the first reference voltage, the first voltage detection signal D1 is in the first level state; if the voltage of the VCC power supply pin 300 is less than or equal to the first reference voltage, the first voltage detection signal D1 is in the second level state; it should be noted that, the first reference voltage is a system intrinsic parameter of the first voltage detection module 20, and the amplitude of the first reference voltage is determined by the circuit structure of the first voltage detection module 20; the first voltage detection signal D1 may be in a high level state or a low level state, which is not limited herein, and a person skilled in the art may set the level state of the first voltage detection signal D1 according to actual needs; in the embodiment of the present invention, the first voltage detection signal D1 is in a first level state and refers to a high level state, i.e., d1=1, and the first voltage detection signal D1 is in a second level state and refers to a low level state, i.e., d1=0.
The pull-down current module 30 is connected to the first voltage detection module 20 and the VCC power supply pin 300, the first voltage detection module 20 transmits a first voltage detection signal D1 to the pull-down current module 30, and when the first voltage detection signal D1 is in a first level state, the pull-down current module 30 outputs a pull-down current to the VCC power supply pin 300, wherein the pull-down current is used to decrease the voltage of the VCC power supply pin 300; specifically, in combination with the above discussion, the first voltage detection module 20 detects the voltage of the VCC power supply pin 300, if the voltage of the VCC power supply pin 300 is greater than the first reference voltage, the first voltage detection signal D1 is in the first level state, and at this time, the VCC power supply pin 300 is connected to the pull-down current, and the voltage of the VCC power supply pin 300 can be reduced by a certain amplitude through the pull-down current, where the amplitude of the pull-down current is set in advance, and is more than 20 milliamperes; therefore, only when the voltage of the VCC power pin 300 is greater than the first reference voltage, the pull-down current module 30 transmits the pull-down current to the VCC power pin 300, if the VCC power pin 300 adopts different power supply modes, such as fig. 1 (a), fig. 1 (b) and fig. 1 (c), in different power supply modes, when the VCC power pin 300 accesses the pull-down current, the voltage change condition of the VCC power pin 300 is different, so that the voltage rising or falling condition of the VCC power pin 300 can be used to determine what power supply mode the VCC power pin 300 specifically adopts.
The power supply mode judging module 40 is electrically connected with the pulse power supply module 10, and the power supply mode judging module 40 is coupled with the first voltage detecting module 20 and the pull-down current module 30, the power supply mode judging module 40 generates a driving signal DisableVD, and the on or off of the pulse power supply module 10 is controlled through the level state of the driving signal DisableVD; specifically, when the first voltage detection signal D1 is in the first level state, the driving signal DisableVD is in the second level state, and at this time, the pulse power supply module 10 is disconnected, and the VCC power supply pin 300 is not connected to the VD pulse; conversely, when the first voltage detection signal D1 is in the second level state, the driving signal DisableVD is in the first level state, and the VCC power supply pin 300 is connected to the VD pulse, so that the power is supplied to the VCC power supply pin 300 through the VD pulse; further, according to the module structure of the automatic detection circuit 100, when the voltage of the VCC power supply pin 300 is greater than the first reference voltage, the first voltage detection signal D1 is in the first level state, and the driving signal DisableVD is in the second level state, while the synchronous rectification chip is continuously connected to the VD pulse through the VD power input pin 400, since the pulse power supply module 10 is disconnected at this time, the VCC power supply pin 300 is not connected to the VD pulse, the pull-down current module 30 transmits the pull-down current to the VCC power supply pin 300 at this time, and the power supply mode determining module 40 determines whether the synchronous rectification chip is in the first power supply mode or the second power supply mode according to the condition that the voltage of the VCC power supply pin 300 drops or rises when the pull-down current is connected; the synchronous rectification chip can adopt different external power supply connection modes; when the VCC power supply pin 300 is connected to the pull-down current, the voltage of the VCC power supply pin 300 varies within a certain period of time, so that the synchronous rectification chip can be accurately determined to be in the first power supply mode or the second power supply mode according to the voltage drop or the voltage rise of the VCC power supply pin 300 when the VCC power supply pin 300 is connected to the pull-down current.
It should be noted that, in the embodiment of the present invention, the first power supply mode refers to that the VCC power supply pin 300 of the synchronous rectification chip supplies power through VD pulses, and at this time, the VCC power supply pin 300 needs to be connected to a power supply loop in the synchronous rectification circuit through a decoupling capacitor, and the VCC power supply pin 300 is not directly connected to an external power supply, as shown in fig. 1 (b) and fig. 1 (c); the second power supply mode refers to that the VCC power supply pin 300 of the synchronous rectification chip is directly connected to the power supply loop in the synchronous rectification circuit, and at this time, the VCC power supply pin 300 can be directly connected to an external power supply, as shown in fig. 1 (a).
In a preferred embodiment, in the power supply mode determining module 40, the power supply mode determining module 40 generates and outputs the mode determining signal ModeDone, and the power supply mode determining module determines that the power supply mode is determined by the level state of the mode determining signal ModeDone: the automatic detection circuit 100 completes the power supply mode determination process for the synchronous rectification chip.
In the embodiment of the present invention, if the first voltage detection signal D1 is in the first level state, the driving signal DisableVD jumps to the second level state, at this time, the pulse power supply module 10 is disconnected, the VCC power supply pin 300 stops accessing the VD pulse, and the pull-down current module 30 transmits the pull-down current to the VCC power supply pin 300, and since the pull-down current has the function of suppressing and reducing the voltage of the VCC power supply pin 300, the power supply mode determining module 40 may determine whether the synchronous rectification chip is in the first power supply mode or the second power supply mode according to the condition that the voltage of the VCC power supply pin 300 drops or rises when accessing the pull-down current.
Referring to fig. 1 and fig. 2, in the circuit structure of the automatic detection circuit 100, when the first voltage detection module 20 detects that the voltage of the VCC power supply pin 300 is greater than the first reference voltage, the first voltage detection signal D1 is in the first level state, the driving signal DisableVD jumps to the second level state, and the pull-down current module 30 transmits the pull-down current to the VCC power supply pin 300, so that when the VCC power supply pin 300 is connected to the pull-down current, two change states exist, specifically:
If the voltage of the VCC power pin 300 drops below the first preset value and can maintain N VD pulse periods, then the voltage of the VCC power pin 300 can be reduced by pulling down the current, and the voltage of the VCC power pin 300 after the voltage reduction can be kept below the first preset value all the time in N VD pulse periods, which indicates that the VCC power pin 300 is not directly connected to the external power source, that is, the VCC power pin 300 is powered by VD pulses, and at this time, the VCC power pin 300 of the synchronous rectification chip is connected to the power supply loop of the circuit through a decoupling capacitor, as shown in fig. 1 (b) and fig. 1 (c); therefore, if the voltage of the VCC power pin 300 drops below the first preset value and can maintain N VD pulse periods when the VCC power pin 300 is connected to the pull-down current, the power supply mode determining module 40 can determine that the synchronous rectification chip is in the first power supply mode accordingly.
Conversely, if the voltage of the VCC power pin 300 does not drop below the first preset value after M VD pulse periods when the VCC power pin 300 is connected to the pull-down current, or the voltage of the VCC power pin 300 rises above the second preset value after M VD pulse periods, where the second preset value is greater than the first reference voltage, this indicates that: the VCC power pin 300 is connected with a pull-down current, which cannot lower the voltage of the VCC power pin 300; that is, the VCC power supply pin 300 is not supplied by VD pulses, but is directly supplied by an external power supply, and the VCC power supply pin 300 is directly connected to a power supply loop of the circuit, as shown in fig. 1 (a); therefore, if the voltage of the VCC power pin 300 is not lowered below the first preset value after M VD pulse periods, or the voltage of the VCC power pin 300 is raised above the second preset value after M VD pulse periods, the power supply mode determining module 40 may determine that the synchronous rectification chip is in the second power supply mode accordingly.
It should be noted that, N and M are positive integers set in advance to be greater than or equal to 1, and because each VD pulse has a specific period, the value of N or the value of M is determined according to the specific circuit structure of the synchronous rectification chip; the first preset value and the second preset value are preset in advance, and simultaneously meet the following conditions: the first preset value is smaller than the first reference voltage, and the second preset value is larger than the first reference voltage; therefore, the automatic detection circuit 100 can accurately judge the external power supply connection mode of the synchronous rectification chip, and detection errors are avoided.
As a preferred implementation manner, fig. 3 illustrates another module structure of the automatic detection circuit 100 applied to external power supply of the synchronous rectification chip according to the embodiment of the present invention, compared to the module structure of the automatic detection circuit 100 illustrated in fig. 2, the automatic detection circuit 100 in fig. 3 further includes a second voltage detection module 50 and a pulse detection counting module 60, where the second voltage detection module 50 is connected to the power supply mode judgment module 40 and the VCC power supply pin 300, the second voltage detection module 50 detects the voltage of the VCC power supply pin 300, and the second voltage detection module 50 generates a second voltage detection signal D2 according to the difference between the voltage of the VCC power supply pin 300 and the second reference voltage, where the second reference voltage is greater than the first reference voltage; it should be noted that, the second reference voltage is set in advance, and a related technician can set the magnitude of the second reference voltage according to the specific model of the synchronous rectification chip; the power supply mode determining module 40 may determine whether the synchronous rectification chip is in the second power supply mode according to the second voltage detection signal D2.
In order to illustrate the function implemented by the second voltage detection module 50, the following describes, by way of a specific example, the operation principle of the second voltage detection module 50, and in combination with the embodiment of the automatic detection circuit 100 shown in fig. 2, in the module structure of the automatic detection circuit 100 shown in fig. 2, the power supply mode determining module 40 may determine whether the synchronous rectification chip is in the first power supply mode (as shown in fig. 1 (b) and fig. 1 (c)) or the second power supply mode (as shown in fig. 1 (a)) according to the falling or rising condition of the voltage of the VCC power supply pin 300 in the period of the preset VD pulse; in the module structure of the automatic detection circuit 100 shown in fig. 3, when the VCC power pin 300 is connected to the pull-down current, if the voltage of the VCC power pin 300 increases from the first reference voltage to the second reference voltage within the time t1, and the time t1 is less than the period of the preset VD pulse, this will be described as follows: although the VCC power supply pin 300 is connected to the pull-down current, the pull-down current does not decrease the voltage of the VCC power supply pin 300 and the voltage of the VCC power supply pin 300 rises to the second reference voltage in a shorter time (t 1 time), in which case it can be derived that the VCC power supply pin 300 of the synchronous rectification chip is directly connected to the external power supply without connecting the power through the VD pulse, and the synchronous rectification chip is in the second power supply mode.
Therefore, in the module structure of the automatic detection circuit 100 shown in fig. 3, the power supply mode determination module 40 may determine from the faster detection of the second voltage detection signal D2 by detecting the voltage of the VCC power supply pin 300 by the second voltage detection module 50: whether the synchronous rectification chip is in a second power supply mode or not; therefore, the automatic detection circuit 100 has higher detection efficiency for the external power supply connection mode of the synchronous rectification chip.
As shown in fig. 3, the pulse detection and counting module 60 is connected to the VD power input pin 400 and the power supply mode judging module 40, and the pulse detection and counting module 60 detects the number of VD pulses, and when the synchronous rectification chip is connected to an external power source, the VD pulses are continuously connected to the VD power input pin, so that the pulse detection and counting module 60 can detect the number of VD pulses connected to the VD power input pin in real time.
As an alternative implementation manner, fig. 4 shows a circuit structure of an automatic detection circuit 100 applied to external power supply of a synchronous rectification chip according to an embodiment of the present invention, and as shown in fig. 4, a pulse detection counting module 60 includes: a first resistor 601, a first diode 602, a first buffer 603, a first register 604, a second register 606, a third register 607, a fourth register 608, a fifth register 609, a sixth register 610, and a first inverter 605.
Wherein the first end of the first resistor 601 is connected to the VD power input pin 400, and the VD power input pin 400 transmits VD pulses to the pulse detecting and counting module 60, the cathode of the first diode 602 and the second end of the first resistor 601 are commonly connected to the input end of the first buffer 603, wherein the first buffer 603 has the function of buffering and coordinating VD pulses in the pulse detecting and counting module 60, the anode of the first diode 602 is grounded GND, the clock signal input end Clk of the first register 604 and the clock signal input end Clk of the third register 607 are commonly connected to the output end of the first buffer 603, the trigger signal input end D of the second register 606 is connected to the VCC power pin 300, the clock signal input end Clk of the second register 606 is connected to the output end of the first inverter 605, the input terminal Reset of the first inverter 605, the Reset signal input terminal Reset of the third register 607, the Reset signal input terminal Reset of the fifth register 609 and the Reset signal input terminal Reset of the sixth register 610 are commonly connected to the first voltage detection module 20 and the pull-down current module 30, the Reset signal input terminal Reset of the first register 604 and the Reset signal input terminal Reset of the fourth register 608 are commonly connected to the forward signal output terminal Q of the second register 606, the trigger signal input terminal D of the first register 604 and the clock signal input terminal Clk of the fourth register 608 are commonly connected to the reverse signal output terminal QZ of the first register 604, the forward signal output terminal Q of the fourth register 608 is commonly connected to the power supply mode determination module 40, the trigger signal input terminal D of the third register 607 and the clock signal input terminal Clk of the fifth register 609 are commonly connected to the reverse signal output terminal QZ of the third register, the trigger signal input terminal D of the fifth register 609 and the clock signal input terminal Clk of the sixth register 610 are commonly connected to the reverse signal output terminal QZ of the fifth register 609, the trigger signal input terminal D of the sixth register 610 is connected to the VCC power supply pin 300, and the forward signal output terminal Q of the sixth register 610 is connected to the power supply mode judging module 40.
As shown in fig. 4, the pulse power supply module 10 includes: a charge pump circuit 101, a first CMOS transistor 102, and a second diode 103; the voltage input of the charge pump circuit 101 is connected to the power supply mode determining module 40, and is used for accessing a driving signal DisableVD, the voltage output of the charge pump circuit 101 is connected to the gate of the first CMOS transistor 102, the drain of the first CMOS transistor 102 is connected to the VD power input pin 400, the source of the first CMOS transistor is connected to the anode of the second diode 103, and the cathode of the second diode 103 is connected to the VCC power pin 300.
It should be noted that, the charge pump circuit 101 is a circuit structure existing in the art, and a person skilled in the art may apply the charge pump circuit in the conventional art to the pulse power supply module 10, and the charge pump circuit has the functions of storing electric energy and outputting constant voltage according to the basic circuit structure of the charge pump circuit in the conventional art; therefore, when the charge pump circuit 101 is connected to the driving signal DisableVD, the charge pump circuit 101 outputs different constant voltages according to the level state of the driving signal DisableVD, and the constant voltages are used for controlling the on/off between the drain and the source of the first CMOS transistor 102; specifically, when the driving signal DisableVD is in the first level state, the charge pump circuit 101 outputs a constant voltage to the gate of the first CMOS transistor 102 according to the driving signal DisableVD, so that the first CMOS transistor 102 is turned on, and at this time, the VD pulse connected through the VD power input pin 400 sequentially passes through the first CMOS transistor 102 and the second diode 103 to reach the VCC power pin 300, and further, the power is supplied to the VCC power pin 300 through the VD pulse.
As shown in fig. 4, the first voltage detection module 20 includes: a second CMOS transistor 203, a third CMOS transistor 204, a second inverter 202, and a second resistor 201; the first end of the second resistor 201 and the gate of the second CMOS transistor 203 are connected to the VCC power pin 300, the drain of the second CMOS transistor 203 and the second end of the second resistor 201 are commonly connected to the input end of the second inverter 202, the output end of the second inverter 202 is connected to the pull-down current module 30 and the pulse detection count module 60, the source of the second CMOS transistor 203 and the drain of the third CMOS transistor 204 are commonly connected to the gate of the third CMOS transistor 204, and the source of the third CMOS transistor 204 is grounded GND.
As shown in fig. 5, the pull-down current module 30 includes: a fourth CMOS transistor 302, a fifth CMOS transistor 303, a sixth CMOS transistor 304, a reference current source 305, and a third inverter 301; the input end of the third inverter 301 is connected to the first voltage detection module 20 and the pulse detection counting module 60, the output end of the third inverter 301 is connected to the gate of the fourth CMOS transistor 302, the drain of the sixth CMOS transistor 304 is connected to the VCC power pin 300, the drain of the fourth CMOS transistor 302, the gate of the fifth CMOS transistor 303, the gate of the sixth CMOS transistor 304, and the drain of the fifth CMOS transistor 303 are commonly connected to one end of the reference current source 305, the other end of the reference current source 305 is connected to the VCC power pin 300 for transmitting a pull-down current to the VCC power pin 300, wherein the reference current source 305 can output a constant current, and the source of the fourth CMOS transistor 302, the source of the fifth CMOS transistor 303, and the source of the sixth CMOS transistor 304 are commonly connected to the ground GND.
As shown in fig. 6, the power supply mode judgment module 40 includes: a seventh register 401, a first or gate 402, and a second or gate 403; the trigger signal input end D of the seventh register 401 is connected to the pulse detection counting module 60, the forward signal output end of the seventh register 401 is connected to the first input end of the first or gate 402, the second input end of the first or gate 402 is connected to the pulse detection counting module 60, the first input end of the second or gate 403 is connected to the pulse detection counting module 60, the output end of the second or gate 403 is a mode judgment signal output end of the automatic detection circuit 100, the mode judgment signal ModeDone can be output through the mode judgment signal output end, and the second input end of the second or gate 403 and the output end of the first or gate 402 are commonly connected to the pulse power supply module 10, so as to transmit the driving signal DisableVD to the pulse power supply module 10, and the on or off of the pulse power supply module 10 can be controlled through the driving signal DisableVD.
As shown in fig. 4, the second voltage detection module 50 includes: a third resistor 501, a fourth resistor 502, and a comparator 503; the first end of the third resistor 501 is connected to the VCC power pin 300, the second end of the third resistor 501 and the first end of the fourth resistor 502 are commonly connected to the non-inverting input end of the comparator 503, the second end of the fourth resistor 502 is grounded GND, the inverting input end of the comparator 503 is connected to the second reference voltage Vref, and the output end of the comparator 503 is connected to the power supply mode judging module 40; since the second voltage detection module 50 includes the comparator 60, when the non-inverting input terminal and the inverting input terminal of the comparator 60 are connected to the voltages of the second reference voltage Vref and the VCC power pin 300, the output terminal of the comparator 60 may transmit the second voltage detection signal D2 to the power supply mode determination module 40 after comparing the voltages of the second reference voltage Vref and the VCC power pin 300, and the magnitude relationship between the voltages of the second reference voltage Vref and the VCC power pin 300 is measured by the level state of the second voltage detection signal D2.
In order to better explain the working principle of the automatic detection circuit 100 in the embodiment of the present invention, referring to fig. 1 to fig. 4, the following specific example is used to describe the steps of determining the external power supply connection mode of the automatic detection circuit 100 to the synchronous rectification chip, where the specific steps are as follows:
1) If the VCC of the synchronous rectification chip is powered by VD pulse (namely, corresponding to the accompanying drawings of FIG. 1 (b) and FIG. 1 (c)); when the synchronous rectification chip starts to operate, the VD power input pin 400 transmits VD pulses to the VCC power pin 300, and the VCC power pin 300 continuously rises, wherein fig. 5 shows a waveform diagram of each signal in the automatic detection circuit 100 in the first power supply mode; as shown in fig. 5, when the voltage of the VCC power pin 300 reaches the first reference voltage, for example, the first reference voltage is 2V, the driving signal DisableVD jumps from the first level state (low level state) to the second level state (high level state), at this time, the VD power input pin 400 does not transmit the VD pulse to the VCC power pin 300, and the first voltage detection signal D1 jumps from the second level state (low level state) to the first level state (high level state), the pull-down current module 30 transmits the pull-down current (20 milliamp) to the VCC power pin 300, since the VCC of the synchronous rectification chip is supplied with the VD pulse, the voltage of the VCC power pin 300 is reduced due to the pull-down current being connected, and when the voltage of the VCC power pin 300 is reduced to the fixed value (1.8V), in this example, the pull-down current module 30 does not transmit the pull-down current to the VCC power pin 300, and if the voltage of the VCC power pin 300 remains below the first preset value for a plurality of periods of VD pulses, the VCC power supply module 40 can determine that the VCC mode. At this time, the VCC power pin 300 of the synchronous rectification chip adopts the first power supply mode (as shown in fig. 1 (b) and fig. 1 (c)), so that the automatic detection circuit 100 performs automatic detection of the external power supply connection mode of the synchronous rectification chip, and the mode determination signal ModeDone transitions from the low level to the high level.
2) If the VCC power pin 300 of the synchronous rectification chip is directly connected to an external power supply to achieve power supply (i.e., corresponding to fig. 1 (a)), fig. 6 shows a waveform diagram of each signal in the automatic detection circuit 100 in the second power supply mode, and referring to the operation process of the automatic detection circuit 100 in the first power supply mode of the synchronous rectification chip in fig. 5; in the second power supply mode shown in fig. 6, when the pull-down current module 30 transmits the pull-down current to the VCC power supply pin 300, the voltage of the VCC power supply pin 300 does not always keep decreasing due to the pull-down current, and even the voltage of the VCC power supply pin 300 always increases; therefore, when the VCC power supply pin 300 is connected to the pull-down current, the voltage of the VCC power supply pin 300 does not drop below the first preset value (1.8V) after the period of the plurality of VD pulses, whereas the voltage of the VCC power supply pin 300 is always raised until the voltage is above the second preset value (3V); therefore, the power supply mode judging module 40 can judge the external connection mode of the synchronous rectification chip according to the change condition of the voltage of the VCC power pin 300 after the pull-down current is connected, so as to realize the automatic detection process of the power supply mode of the synchronous rectification chip.
Fig. 7 shows a circuit structure of a synchronous rectification chip 70 according to an embodiment of the present invention, wherein the synchronous rectification chip 70 includes: the VCC power pin 300, the VD power input pin 400, the ground pin 500, the rectified signal output pin 700, and the automatic detection circuit 100 applied to external power supply of the synchronous rectification chip as described above, according to the above discussion, when the synchronous rectification chip 70 is applied to the synchronous rectification circuit, the automatic detection circuit 100 can automatically detect the external power supply connection mode of the synchronous rectification chip 70 to implement the charging process of the synchronous rectification chip 70, so that the synchronous rectification chip 70 can normally output the rectified signal through the rectified signal output pin 700, and the synchronous rectification circuit implements the corresponding power conversion function.
Specifically, as shown in fig. 7, the synchronous rectification chip 70 further includes: the synchronous rectification circuit comprises a turn-off judging unit 701, a turn-on judging unit 702, a first NOR gate 703, a second NOR gate 704 and a second buffer 705, wherein the turn-off judging unit 701 and the turn-on judging unit 702 are used as internal circuit functional modules of the synchronous rectification chip 70, the turn-off judging unit 701 can generate a turn-off signal, the turn-on judging unit 702 generates a turn-on signal, the turn-off signal and the turn-on signal jointly form a rectification signal of the synchronous rectification chip 70, when a rectification signal output pin 700 of the synchronous rectification chip 70 outputs the turn-on signal or the turn-off signal, the turn-on signal can enable a power supply loop of the rectification circuit to be turned on, and when the turn-off signal can turn off the power supply loop of the rectification circuit, and further whether the synchronous rectification circuit outputs constant voltage can be controlled through the turn-on signal and the turn-off signal.
It should be noted that, in the embodiment of the present invention, the turn-off determining unit 701 and the turn-on determining unit 702 are all existing circuit structures in the conventional technology in the field; the on/off signal generating circuits commonly used in the conventional technology can be adopted by those skilled in the art to realize the circuit functions of the off determination unit 701 and the on determination unit 702, for example, the off determination unit 701 and the on determination unit 702 can be logic gates in the conventional technology.
As shown in fig. 7, in the automatic detection circuit 100, the pulse power supply module 10, the first voltage detection module 20 and the pull-down current module 30 are commonly connected to the VCC power supply pin 300 of the synchronous rectification chip 70, and the pulse power supply module 10 is connected to the VD power supply input pin 400; the functions and the internal circuit structures of the respective circuit modules (including the pulse power supply module 10, the first voltage detection module 20, etc.) in the automatic detection circuit 100 in fig. 7 may be referred to the embodiments in fig. 2 to 4, and will not be described herein.
The input end of the turn-off judging unit 701 and the input end of the turn-on judging unit 702 are commonly connected to the VD power input pin 400, the output end of the turn-off judging unit 701 is connected to the first input end of the first nor gate 703, the second input end of the first nor gate 703 is connected to the output end of the second nor gate 704, the first input end of the second nor gate 704 and the output end of the first nor gate 703 are commonly connected to the input end of the second buffer 705, and the second buffer 705 has the functions of data buffering and synchronous transmission for the turn-on signal and the turn-off signal; the second input end of the second nor gate 704 is connected to the output end of the conduction determination unit 702, the output end of the second buffer 705 is connected to the rectified signal output pin 700, and the synchronous rectification chip 70 can output a rectified signal through the rectified signal output pin 700 so as to control the rectification circuit to be in different working states.
In the circuit structure of the synchronous rectification chip 70 shown in fig. 7, as described above, the automatic detection circuit 10 can automatically detect the external power supply connection mode of the synchronous rectification chip 70 applied in the synchronous rectification circuit, so that compared with the synchronous rectification chip in the conventional technology, the synchronous rectification chip 70 in the embodiment of the invention has better compatibility, wider application range and better user experience.
Fig. 8 shows a specific flow of an automatic detection method for external power supply of a synchronous rectification chip, where the synchronous rectification chip includes a VCC power supply pin 300 and a VD power supply input pin 400, where the VD power supply input pin 400 can be connected to a VD pulse, and power can be supplied to the VCC power supply pin 300 through the VD pulse; it should be noted that the automatic detection method in fig. 8 corresponds to the automatic detection circuit 100 in fig. 2, so, regarding the detailed implementation of each step in the automatic detection method in fig. 8, a person skilled in the art may refer to an example of the automatic detection circuit 100 in fig. 2, where only the steps related to the example of the present invention are shown, and specifically, the automatic detection method includes the following steps:
Step S801: when the driving signal DisableVD in the first level state is accessed, power is supplied to the VCC power supply pin 300 through VD pulses.
Step S802: detecting the voltage of the VCC power pin 300 and generating a first voltage detection signal D1 according to the difference between the voltage of the VCC power pin 300 and a first reference voltage; wherein the first voltage detection signal D1 is in a first level state when the voltage of the VCC power supply pin 300 is greater than or equal to the first reference voltage.
Step S803: when the first voltage detection signal D1 is in the first level state, a pull-down current is output to the VCC power supply pin 300;
Step S804: when the VCC power pin 300 is connected with a pull-down current, judging whether the synchronous rectification chip is in a first power supply mode or a second power supply mode according to the voltage drop or rise condition of the VCC power pin 300; when the first voltage detection signal D1 is in the first level state, the driving signal DisableVD is in the second level state.
In step S804, it is determined whether the synchronous rectification chip is in the first power supply mode or the second power supply mode according to the voltage drop or rise condition of the VCC power supply pin 300, specifically:
When the voltage of the VCC power supply pin 300 drops below a first preset value and can maintain N VD pulse periods, determining that the synchronous rectification chip is in the first power supply mode; when the voltage of the VCC power supply pin 300 does not decrease below the first preset value after M VD pulse periods, or increases above the second preset value after M VD pulse periods, determining that the synchronous rectification chip is in the second power supply mode; wherein both said N and said M are positive integers greater than or equal to 1. Therefore, in the automatic detection method shown in fig. 8, the synchronous rectification chip can automatically detect the external power supply connection mode, so that the method has extremely strong compatibility and adaptability; it is to be noted that, in this document, numbers such as plural and plural each refer to a number greater than 1; relational terms such as first and second are used solely to distinguish one entity from another entity; further, herein, "greater than," "less than," "exceeding," and the like are understood to not include the present number; "above", "below", "within" and the like are understood to include this number.
Claims (7)
1. An automatic detection circuit for external power supply of a synchronous rectification chip, the synchronous rectification chip comprising: VCC power pin and be used for inserting VD power input pin of VD pulse, its characterized in that, automatic detection circuit includes:
The pulse power supply module is connected between the VD power supply input pin and the VCC power supply pin and is configured to supply power to the VCC power supply pin through the VD pulse when the accessed driving signal is in a first level state;
The first voltage detection module is connected with the VCC power pin, is configured to detect the voltage of the VCC power pin and generates a first voltage detection signal according to the difference value of the voltage of the VCC power pin and a first reference voltage; wherein the first voltage detection signal is in a first level state when the voltage of the VCC power supply pin is greater than or equal to the first reference voltage;
A pull-down current module connected to the first voltage detection module and the VCC power supply pin and configured to output a pull-down current to the VCC power supply pin according to when the first voltage detection signal is in a first level state;
The power supply mode judging module is electrically connected with the pulse power supply module, is coupled with the first voltage detecting module and the pull-down current module, is configured to generate the driving signal, and judges whether the synchronous rectification chip is in a first power supply mode or a second power supply mode according to the falling or rising condition of the voltage of the VCC power supply pin when the VCC power supply pin is connected with the pull-down current; wherein, the driving signal is in a second level state when the first voltage detection signal is in a first level state;
the power supply mode judging module determines that the synchronous rectification chip is in a first power supply mode when the voltage of the VCC power supply pin is reduced to be lower than a first preset value and N VD pulse periods can be maintained;
The power supply mode judging module determines that the synchronous rectification chip is in a second power supply mode according to the fact that the voltage of the VCC power supply pin is not reduced to be below a first preset value after M VD pulse periods or is increased to be above a second preset value after M VD pulse periods;
wherein said N and said M are both positive integers greater than or equal to 1;
the automatic detection circuit further includes: the pulse detection and counting module is connected with the VD power supply input pin and the power supply mode judging module and is configured to detect the number of the VD pulses;
The first power supply mode is that a power supply pin of the synchronous rectification chip supplies power through the VD pulse, and at the moment, the power supply pin is required to be connected with a power supply loop in the synchronous rectification circuit through a decoupling capacitor and is not directly connected with an external power supply; the second power supply mode refers to that a power supply pin of the synchronous rectification chip is directly connected with a power supply loop in the synchronous rectification circuit, and at the moment, the power supply pin can be directly connected with an external power supply;
The pulse detection counting module comprises: a first resistor, a first diode, a first buffer, a first register, a second register, a third register, a fourth register, a fifth register, a sixth register and a first inverter;
Wherein a first end of the first resistor is connected with the VD power supply input pin, a cathode of the first diode and a second end of the first resistor are connected with an input end of the first buffer, an anode of the first diode is grounded, a clock signal input end of the first register and a clock signal input end of the third register are connected with an output end of the first buffer, a trigger signal input end of the second register is connected with the VCC power supply pin, a clock signal input end of the second register is connected with an output end of the first inverter, an input end of the first inverter, a reset signal input end of the third register, a reset signal input end of the fifth register and a reset signal input end of the sixth register are connected with the first voltage detection module and the pull-down current module, the reset signal input end of the first register and the reset signal input end of the fourth register are connected with the forward signal output end of the second register, the trigger signal input end of the first register and the clock signal input end of the fourth register are connected with the reverse signal output end of the first register, the forward signal output end of the fourth register is connected with the power supply mode judging module, the trigger signal input end of the third register and the clock signal input end of the fifth register are connected with the reverse signal output end of the third register, the trigger signal input end of the fifth register and the clock signal input end of the sixth register are connected with the reverse signal output end of the fifth register, the trigger signal input end of the sixth register is connected with the VCC power supply pin, and the positive signal output end of the sixth register is connected with the power supply mode judging module.
2. The automatic detection circuit of claim 1, further comprising:
The second voltage detection module is connected with the power supply mode judging module and the VCC power supply pin, is configured to detect the voltage of the VCC power supply pin and generates a second voltage detection signal according to the difference value between the voltage of the VCC power supply pin and a second reference voltage; wherein the second reference voltage is greater than the first reference voltage.
3. The automatic detection circuit of claim 1, wherein the pulsed power supply module comprises: a charge pump circuit, a first CMOS transistor, and a second diode; the voltage input end of the charge pump circuit is connected with the power supply mode judging module, the voltage output end of the charge pump circuit is connected with the grid electrode of the first CMOS tube, the drain electrode of the first CMOS tube is connected with the VD power supply input pin, the source electrode of the first CMOS tube is connected with the anode of the second diode, and the cathode of the second diode is connected with the VCC power supply pin.
4. A synchronous rectification chip, wherein the synchronous rectification chip comprises: VCC power supply pin, VD power supply input pin, ground pin and rectified signal output pin, wherein the synchronous rectification chip further comprises an automatic detection circuit according to any one of claims 1-3 applied to external power supply of the synchronous rectification chip.
5. The synchronous rectification chip of claim 4, further comprising: the device comprises a turn-off judging unit configured to generate a turn-off signal, a turn-on judging unit configured to generate a turn-on signal, a first NOR gate, a second NOR gate and a second buffer;
In the automatic detection circuit, the pulse power supply module, the first voltage detection module and the pull-down current module are commonly connected to the VCC power supply pin, and the pulse power supply module is connected to the VD power supply input pin;
the input end of the turn-off judging unit and the input end of the turn-on judging unit are connected with the VD power input pin, the output end of the turn-off judging unit is connected with the first input end of the first NOR gate, the second input end of the first NOR gate is connected with the output end of the second NOR gate, the first input end of the second NOR gate and the output end of the first NOR gate are connected with the input end of the second buffer, the second input end of the second NOR gate is connected with the output end of the turn-on judging unit, and the output end of the second buffer is connected with the rectifying signal output pin.
6. An automatic detection method for external power supply of synchronous rectification chip based on the automatic detection circuit for external power supply of synchronous rectification chip as claimed in claim 1, wherein the synchronous rectification chip comprises: VCC power pin and be used for inserting VD power input pin of VD pulse, its characterized in that, automatic detection method includes:
when a driving signal in a first level state is accessed, power is supplied to the VCC power supply pin through the VD pulse;
Detecting the voltage of the VCC power pin, and generating a first voltage detection signal according to the difference value of the voltage of the VCC power pin and a first reference voltage; wherein the first voltage detection signal is in a first level state when the voltage of the VCC power supply pin is greater than or equal to the first reference voltage;
Outputting a pull-down current to the VCC power supply pin when the first voltage detecting signal is in a first level state;
When the VCC power supply pin is connected with the pull-down current, judging whether the synchronous rectification chip is in a first power supply mode or a second power supply mode according to the voltage drop or rise condition of the VCC power supply pin; and when the first voltage detection signal is in a first level state, the driving signal is in a second level state.
7. The automatic detection method according to claim 6, wherein the synchronous rectification chip is judged to be in a first power supply mode or a second power supply mode according to a voltage drop or a voltage rise condition of the VCC power supply pin, specifically:
When the voltage of the VCC power supply pin is reduced to be lower than a first preset value and N VD pulse periods can be maintained, determining that the synchronous rectification chip is in a first power supply mode;
When the voltage of the VCC power supply pin is not reduced below a first preset value after M VD pulse periods or is increased above a second preset value after M VD pulse periods, determining that the synchronous rectification chip is in a second power supply mode;
wherein both said N and said M are positive integers greater than or equal to 1.
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| CN112327145B (en) * | 2021-01-04 | 2021-05-18 | 北京紫光青藤微系统有限公司 | Measurement circuit for measuring chip through IO pin |
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