CN116301145A - Low dropout linear voltage regulator and control circuit, chip and electronic equipment thereof - Google Patents
Low dropout linear voltage regulator and control circuit, chip and electronic equipment thereof Download PDFInfo
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Abstract
Disclosed are a low dropout linear voltage regulator, a control circuit, a chip and an electronic device thereof, the low dropout linear voltage regulator comprising a power transistor and an error amplifier, the control circuit comprising: the negative pressure protection module is used for outputting a first control signal to the control end of the power transistor to reduce the output peak current and outputting a first opening signal when the output end is short-circuited and the output voltage is detected to be reduced to be smaller than a voltage threshold value; and the overshoot protection module is connected with the reverse input end of the error amplifier, receives the first opening signal to clamp the reference voltage of the reverse input end at the clamping voltage, and adjusts the second control signal output by the error amplifier to the control end of the power transistor. When the output end of the control circuit is short-circuited and the output voltage has negative pressure, the negative pressure protection module regulates the output voltage, so that the circuit or device is prevented from being damaged due to the fact that the output voltage generates large negative pressure, the overshoot protection circuit clamps the reference voltage, and the circuit is prevented from being damaged due to large fluctuation of the output voltage.
Description
Technical Field
The application relates to the technical field of linear regulators, in particular to a low dropout linear regulator, a control circuit, a chip and electronic equipment thereof.
Background
A low dropout linear regulator (Low Dropout Regulator, LDO) converts an unstable input voltage into an adjustable dc output voltage for use as a power supply for other systems. Since the linear voltage regulator has the characteristics of simple structure, small static power consumption, small output voltage ripple, etc., the linear voltage regulator is often used for on-chip power management of a chip of a mobile consumer electronic device.
Fig. 1 shows a schematic diagram of the packaging of a low dropout linear regulator according to the prior art. As shown IN fig. 1, the conventional low dropout linear regulator includes an input pin IN, an enable pin EN, an output pin OUT, and a ground pin GND. The input pin IN is connected to the power supply voltage VCC, the enable pin EN is for receiving an enable signal, and the output pin OUT is for supplying the output voltage Vout to the subsequent load. When the enable pin EN is at a high level, the low dropout linear regulator operates normally, and when the enable pin EN is at a low level, the low dropout linear regulator turns off and the output pin OUT is pulled down to ground. Further, the low dropout linear regulator generally includes a power transistor and an error amplifier, wherein the power transistor is configured to provide an output voltage to a backward load according to a power supply voltage VCC provided at a power supply terminal. The error amplifier is used for comparing the feedback voltage obtained by sampling the output voltage with a reference voltage to obtain an error signal between the feedback voltage and the reference voltage, and adjusting the gate-source voltage drop of the power transistor according to the error signal between the feedback voltage and the reference voltage, so as to stabilize the output voltage.
In the actual use process of the low-dropout linear voltage regulator, an output end short circuit event to ground is possibly encountered, the output end short circuit event is limited by the response speed of a loop, a large undershoot peak appears on the output end voltage of a chip when short circuit occurs, and the low-dropout linear voltage regulator can have a state that the output current exceeds a set value for a long time due to the abnormal conditions such as overload and short circuit, so that the chip is seriously heated, the device is accelerated to age, even leakage phenomenon appears, and accidents are caused by control failure.
Disclosure of Invention
The application provides a low dropout linear voltage regulator and a control circuit, a chip and electronic equipment thereof, which are used for solving the problems in the prior art.
According to a first aspect of the present disclosure, there is provided a control circuit of a low dropout linear regulator including a power transistor between a power supply terminal and an output terminal, and an error amplifier connected to a control terminal of the power transistor, wherein the control circuit includes:
a negative pressure protection module for outputting a first control signal to the control terminal of the power transistor to reduce the output peak current and output a first on signal when the output terminal is short-circuited and the output voltage is detected to be reduced to be less than the voltage threshold value, and
and the overshoot protection module is connected with the reverse input end of the error amplifier and receives the first opening signal to clamp the reference voltage of the reverse input end at the clamping voltage, so that the second control signal output by the error amplifier to the control end of the power transistor is regulated to regulate the output voltage.
Optionally, the overshoot protection module includes:
the anode of the first diode is connected with the reverse input end of the error amplifier; and
a switch connected between the cathode of the first diode and the positive input terminal of the error amplifier,
the forward input end of the error amplifier receives the output voltage, the reverse input end of the error amplifier receives the reference voltage, the switch is closed to clamp the reference voltage at the clamping voltage, and the clamping voltage is the sum of the output voltage and the conduction voltage drop of the first diode.
Optionally, the switch is turned off after the output terminal is restored to a normal state from a short-circuit state.
Optionally, the overshoot protection module controls the second control signal output by the error amplifier according to the clamping voltage and the output voltage at the moment when the switch is turned off, so as to reduce the amplification of the output voltage.
Optionally, the overshoot protection module further includes: and the RC filter network is connected with the reverse input end of the error amplifier and is used for adjusting the reference voltage and gradually increasing the reference voltage from the clamping voltage after the switch is disconnected.
Optionally, the overshoot protection module is further configured to gradually increase the reference voltage via the RC filter network when the switch is in an off state, so that the error amplifier gradually increases the output voltage according to the second control signal.
Optionally, the negative pressure protection module includes:
the mirror image current source comprises a first current branch and a second current branch, wherein first ends of the first current branch and the second current branch are connected with a first voltage, and a second end of the second current branch is connected with a second voltage; and
the conduction selection module is connected between the second end of the first current branch and the output end and comprises a second diode with an anode connected with the output end and a third diode with a cathode connected with the output end,
the conduction selection module is conducted to adjust the current on the first current branch, so that the negative pressure protection module outputs different first control signals.
Optionally, the negative pressure protection module further comprises:
the logic unit is connected to the first end of the first current branch, outputs the first control signal of a low level when the second diode is conducted, outputs the first control signal of a high level when the third diode is conducted, and outputs a first turn-on signal.
Optionally, the first voltage is an input voltage of the power supply terminal, and the second voltage is set as a conduction voltage drop of the third diode.
Optionally, the power transistor is a P-type field effect transistor, the first transistor on the first current branch and the second transistor on the second current branch are both N-type field effect transistors, and the first diode, the second diode and the third diode are schottky diodes.
Optionally, the control circuit further includes:
the current limiting module is used for outputting a third control signal to the control end of the power transistor to adjust the output current to reach the current threshold when the output end is short-circuited and the output current of the power transistor is detected to exceed the current threshold, and outputting a second opening signal;
the overshoot protection module receives the second turn-on signal to clamp the reference voltage at the clamp voltage.
According to a second aspect of the present disclosure, there is provided a low dropout linear regulator comprising:
a power transistor connected between the power supply terminal and the output terminal;
a first resistor and a first capacitor connected in parallel between the output terminal and the reference ground;
the output end of the error amplifier is connected with the control end of the power transistor, the positive input end of the error amplifier receives output voltage, and the negative input end of the error amplifier receives reference voltage; and
the control circuit is used for driving the power transistor to convert the power supply voltage of the power supply terminal into output voltage.
According to a third aspect of the present disclosure, there is provided a chip comprising the control circuit described above.
According to a fourth aspect of the present disclosure, there is provided an electronic device comprising the control circuit or the chip described above.
According to the low-dropout linear voltage regulator, the control circuit, the chip and the electronic equipment thereof, the negative pressure protection module and the overshoot protection module are arranged, when the output end is short-circuited and negative output voltage is generated at the output end, the negative pressure protection module outputs a first control signal to the control end of the power transistor when detecting that the output voltage is smaller than a voltage threshold value, so that the gate-source voltage of the power transistor is reduced, the output current peak value is reduced, the circuit fault is responded quickly, and the chip burnout caused by large negative pressure of the output voltage is avoided; in addition, when the output voltage is smaller than the voltage threshold value, the negative pressure protection module outputs a first opening signal to the overshoot protection module, clamps the reference voltage at the clamping voltage, limits the second control signal output by the error amplifier at a smaller value, has a smaller adjusting range of the output voltage, and avoids the overshoot damage circuit of the output voltage after the short circuit is released, so that the fluctuation of the output voltage of the low-dropout linear voltage regulator in a short circuit state is smaller through the arrangement of the two modules, and the short circuit protection of the low-dropout linear voltage regulator is realized without generating larger negative pressure and overshoot.
Furthermore, the overshoot protection module comprises an RC filter network connected to the reverse input end of the error amplifier, and the filter network enables the reference voltage to slowly rise from the clamping voltage, so that the output voltage can be adjusted for multiple times, the output voltage is gradually increased, and the output voltage is prevented from instantaneously increasing to damage the circuit.
Further, in the mirror current source of the negative pressure protection module, one end of a current branch of the mirror current source is connected with the power supply voltage, and the other end of the current branch of the mirror current source is set to be the threshold voltage of the third diode, so that the third diode can be conducted as soon as negative pressure is generated in output voltage, a high-level first control signal is output, the output peak current is adjusted in time, fluctuation of the output voltage is small, and the circuit is protected.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.
Drawings
FIG. 1 shows a schematic diagram of a package of a low dropout linear regulator according to the prior art;
FIG. 2 is a schematic diagram showing a basic circuit configuration of a low dropout linear regulator;
FIG. 3 shows a waveform schematic of the output current and output voltage of the LDO according to FIG. 2 when the output terminal is shorted;
FIG. 4 shows a schematic block diagram of a low dropout linear regulator and its control circuit according to an embodiment of the invention;
fig. 5 shows a schematic circuit diagram of a low dropout linear regulator and its control circuit according to an embodiment of the present invention.
Detailed Description
In order that the invention may be readily understood, a more complete description of the invention will be rendered by reference to the appended drawings. Preferred embodiments of the present invention are shown in the drawings. The invention may, however, be embodied in different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Fig. 2 shows a basic circuit configuration diagram of the low dropout linear regulator.
As shown in fig. 2, the low dropout linear regulator 100 includes a power transistor M1 and an error amplifier EA, wherein the power transistor M1 is connected between a power supply terminal VCC and an output terminal, a reverse input terminal of the error amplifier EA receives a reference voltage Verf, a forward input terminal receives an output voltage Vout, and an output terminal is connected to a control terminal of the power transistor. A resistor R0 is connected between the output end and the ground GND, and two ends of the resistor R0 are connected in parallel with a capacitor C0. The power transistor M1 is configured to provide an output voltage Vout to a post-load (a resistor R0 and a capacitor C0) according to a power supply voltage VCC provided at a power supply terminal. The error amplifier EA is configured to compare the sampled output voltage Vout with the reference voltage Vref to obtain an error signal Vctrl therebetween, and adjust the gate-source voltage drop of the power transistor M1 according to the error signal Vctrl therebetween, and change the output current (or input current) Iout on the power transistor M1, so as to stabilize the output voltage Vout.
When the output current Iout is too large or too small, the circuit may not work normally, so the low dropout linear regulator is further provided with a current limiting module 110 for adjusting the current on the power transistor M1. When the LDO is in operation, an output overload or short circuit occurs, it is detected that the output current Iout of the power transistor M1 is extremely increased, and when the output current Iout is greater than the threshold current Ilimit set by the current limiting module 110, the current limiting module 110 generates the control signal Vctrl0 to control the control terminal (Gate) of the power transistor M1, so that the output current Iout is maintained at Ilimit at maximum, and the chip is protected from being burned out due to the power overload. However, the current limiting module 110 needs to detect a large current before outputting the control signal, and needs a long response time, and the output current Iout has generated an instantaneous peak large current and then gradually stabilizes at Ilimit.
Fig. 3 shows a waveform diagram of an output current and an output voltage of the low dropout linear regulator according to fig. 2 when an output terminal is short-circuited.
When the output terminal is shorted, as shown in fig. 2, it can be regarded that the output terminal is directly connected to the ground by a wire, i.e. the switch SW is closed, and the equivalent inductance of the shorted wire is L. Referring to fig. 3, when the switch SW is closed, the output terminal instantaneously touches the ground, the output current Iout of the power transistor M1 generates an instantaneously large peak current Ipk, and after the time t1, the current limiting module 110 adjusts the output current Iout to be near Ilimit. However, in this period, the circuit has generated a larger instantaneous power overload, that is, the output peak current Ipk is larger at the moment of short circuit, the loads C and L generate LC self-oscillation, so that the output voltage Vout generates a large negative pressure Vpk, and at this moment, the chip is extremely easy to burn out at the moment when the power overload is too large, so that the current limiting module 110 cannot protect the circuit. Moreover, the output voltage with larger negative pressure generated by the short circuit of the output end can also cause Latch up (Latch-up effect) to cause chip burnout; even the parasitic NPN triode channel generated by the N type device, the P type device and the P type substrate in the circuit is leaked, so that the control circuit is abnormal, the power tube M1 can be normally opened or the current limiting module 110 can work abnormally, and finally the chip is burnt.
In addition, when the switch SW is suddenly opened, i.e. the short circuit is released or the state is recovered from the short circuit state to the normal state, since the differential input of the error amplifier EA is very large (Δvref) during the short circuit, when the short circuit is suddenly released, the large control signal Vctrl may cause the output voltage Vout to generate a great overshoot, and the circuit or the chip may be damaged.
Therefore, the current limiting protection response of the control circuit of the LDO is slow, the circuit is easy to burn out due to the fact that the negative pressure of the output voltage is large during short circuit, and the overshoot problem can occur in the output voltage after the output short circuit is released, so that the LDO cannot be well protected during short circuit. Therefore, the invention provides a control circuit of a low dropout linear voltage regulator, which is used for optimizing the transient response of the circuit when the output end is short-circuited, timely adjusting the output voltage and the output current, timely and accurately protecting the circuit, and is specifically described below with reference to fig. 4-5.
Fig. 4 shows a schematic block diagram of a low dropout linear regulator and its control circuit according to an embodiment of the invention.
As shown in fig. 4, the control circuit of the LDO of the present embodiment adds a negative pressure protection module 220 and an overshoot protection module 230 on the basis of the LDO control circuit of fig. 2, that is, the control circuit of the low dropout linear regulator 200 of the present embodiment includes a current limiting module 210, a negative pressure protection module 220 and an overshoot protection module 230.
The negative pressure protection module 220 is configured to output a first control signal Vctrl1 to the control terminal of the power transistor M1 when the output terminal is shorted and the output voltage Vout is detected to be reduced to be less than the voltage threshold, so as to reduce the gate-source voltage of the power transistor M1, thereby reducing the output peak current and outputting a first on signal Vs1; the overshoot protection module 230 is connected to the inverting input terminal of the error amplifier EA, receives the first turn-on signal Vs1 to clamp the reference voltage Vref at the inverting input terminal to the clamp voltage, and adjusts the second control signal Vctrl2 output from the error amplifier EA to the control terminal of the power transistor M1; the current limiting module 210 is configured to output a third control signal Vctrl0 to the control terminal of the power transistor M1 to adjust the output current Iout to reach the current threshold when the output terminal is shorted and the output current Iout of the power transistor M1 is detected to exceed the current threshold, and output a second turn-on signal Vs2, and the overshoot protection module 230 may further receive the second turn-on signal Vs2 to clamp the reference voltage Vref at the clamp voltage. Therefore, when the LDO is shorted, the negative pressure protection module 220 can suppress the undershoot of the output voltage Vout to avoid generating a large negative voltage to damage the circuit, and the overshoot protection module 230 clamps the reference voltage Vref due to the first turn-on signal Vs1 or the second turn-on signal Vs2, so that the difference between the reference voltage and the output voltage is smaller, the output second control signal Vctrl2 is smaller, the increase of the output voltage is smaller, and the output voltage is prevented from generating a larger overshoot when the short circuit is released. The control circuit of the embodiment can stabilize the output voltage in a certain range during short circuit and short circuit release, reduce the fluctuation of the output voltage, avoid the transient change of overlarge or undersize voltage and realize the protection of LDO.
Fig. 5 shows a schematic circuit diagram of a low dropout linear regulator and its control circuit according to an embodiment of the present invention.
As shown in fig. 5, an exemplary specific circuit of the control circuit of fig. 4 is shown, and the basic circuit of the low dropout linear regulator 200 has the same structure as the circuit of fig. 2, and includes a power transistor M1 and an error amplifier EA, wherein the power transistor M1 is a P-type field effect transistor, for example, a PMOS, and a positive input terminal of the error amplifier EA receives the output voltage Vout and a negative input terminal receives the reference voltage Vref.
In this embodiment, the current limiting module 210 of the control circuit of the low dropout linear regulator 200 is connected between the power supply terminal and the control terminal of the power transistor M1, and is configured to output the third control signal Vctrl0 to the control terminal of the power transistor M1 to adjust the output current Iout to be maintained near the current threshold Ilimit and output the second turn-on signal Vs2 to the overshoot protection module 230 when the output terminal is short-circuited and the output current Iout of the power transistor M1 is detected to exceed the current threshold Ilimit.
Further, the negative pressure protection module 220 includes: a mirror current source 221, a turn-on selection module 222, and a logic unit U1. The mirror current source 221 includes a first current branch including a first current source I1 and a first transistor M3, and a second current branch including a second current source I2 and a second transistor M2, where the control terminals of the first transistor M3 and the second transistor M2 are connected, the drains of the first transistor M3 and the second transistor M2 are connected, the first transistor M3 and the second transistor M2 are N-type field effect transistors, such as NMOS, and the sizes of the first transistor M3 and the second transistor M2 are identical. The first ends of the first current branch and the second current branch are both connected to a first voltage, such as a power supply voltage VCC, and the second ends of the second current branch are connected to a second voltage VSS, which may be a ground voltage or a smaller forward voltage. The bias currents on the first current branch and the second current branch of the mirror current source 221 are I1 and I2, respectively, and i1=i2. The conduction selection module 222 is connected between the second end and the output end of the first current branch, and includes a second diode D2 with an anode connected to the output end and a third diode D3 with a cathode connected to the output end, where the second diode D2 and the third diode D3 are schottky diodes, for example, and the forward conduction voltage is 200mV. The turn-on selection module 222 turns on to adjust the current on the first current branch, so that the negative pressure protection module 220 outputs different first control signals. The logic unit U1 is connected to a first end of the first current branch, and outputs a first control signal Vctrl1 and a first turn-on signal Vs1.
Specifically, when the LDO works normally, the output voltage Vout is a forward high voltage, the second diode D2 is turned on, and the third diode D3 is turned off, so that the voltage at the point a is greater than the voltage at the point B, the current on the first current branch is less than the current on the second current branch, the point C is a logic high, and a first control signal Vctrl1 with a low level is generated through the logic unit U1; when the LDO is shorted, the output voltage Vout generates a negative voltage, and when the negative voltage exceeds a certain voltage threshold (for example, less than-200 mV), the second diode D2 is turned off, the third diode D3 is turned on, so that the voltage at the point a is smaller than the voltage at the point B, the current on the first current branch is greater than the current on the second current branch, the point C is logic low, the logic unit U1 generates the first control signal Vctrl1 with a high level, and simultaneously outputs the first turn-on signal Vs1 to the overshoot protection module 230. The control end of the power transistor M1 is pulled up by the high-level first control signal Vctrl1, the gate voltage of the power transistor M1 is rapidly increased (the gate source voltage is reduced), so that the output peak current Ipk is greatly reduced, the LC self-oscillation is restrained, the output voltage is prevented from being undershot, the output voltage is timely and rapidly adjusted, the output voltage can be quickly restrained from continuously generating large negative voltage by the first control signal as soon as the output voltage is smaller than the voltage threshold, and the chip is prevented from being burnt.
The response speed of the negative pressure protection module 220 is far faster than that of the current limiting module 210, so that the instantaneous power and the protection response time during short circuit can be reduced, the generation of large negative pressure is restrained, and the problem that the current limiting module 210 cannot respond timely to cause overheating and burning of a chip is avoided.
Further, the second voltage may be set to the ground voltage GND, and then the voltage threshold is a difference between the ground voltage and the conduction voltage drop of the third diode, that is, -200mV, and when the absolute value of the output voltage Vout decreases to be lower than the absolute value of the voltage threshold, the third diode D3 is turned on, so that an effective first control signal may be output.
In other embodiments, the second voltage VSS is set to 200mV of the conduction voltage drop of the third diode D3, so long as the output voltage Vout is less than zero or negative voltage occurs, the third diode D3 is turned on to generate an effective first control signal, so as to regulate the output voltage more timely and limit the output voltage from generating negative voltage.
Therefore, in this embodiment, by setting the second voltage to a suitable value, the maximum negative voltage in the chip can be ensured not to exceed-200 mV, and the absolute value (200 mV) of the negative voltage is smaller than the conduction voltage drop (700 mV) of the parasitic triode NPN, so that the control circuit abnormality caused by latch-up and leakage will not occur.
Further, the overshoot protection module 230 includes a first diode D1 and a switch 232 connected between the inverting input terminal and the forward input terminal of the error amplifier EA, where the anode of the first diode D1 is connected to the inverting input terminal of the error amplifier EA, the cathode is connected to the switch 232, such as a schottky diode, and the switch 232 connects the first diode D1 and the forward input terminal of the error amplifier EA when closed, so that the reference voltage Vref is clamped at a clamping voltage, which is the sum of the output voltage Vout and the conduction voltage drop of the first diode D1. When the output terminal is shorted, the current limiting module 210 outputs a second on signal Vs2 to the overshoot protection module 230, or the negative voltage protection module 220 outputs a first on signal Vs1 to the overshoot protection module 230, so that the switch 232 is closed to clamp the reference voltage Vref at the clamp voltage. At this time, due to the existence of the first diode D1, the voltage difference at the input end of the error amplifier EA is only 200mV, that is, the on voltage drop of the first diode D1, so that the second control signal Vctrl2 output by the error amplifier EA is smaller, the regulation of the output voltage Vout is smaller, and the output voltage Vout will not generate larger fluctuation. When the short circuit is released, the output voltage Vout does not generate a large overshoot due to the smaller second control signal Vctrl2, but only increases slowly and slightly, so as to avoid circuit damage caused by a large instantaneous overshoot voltage. That is, after the short circuit is released or the switch 232 is maintained in the off state in the normal state, the overshoot protection module 230 outputs the smaller second control signal Vctrl2 to the control error amplifier EA at the moment when the switch 232 is turned off, so as to reduce the amplification of the output voltage and avoid the influence of the overshoot of the output voltage on the LDO and the surrounding circuits.
In other embodiments, the overshoot protection module 230 further includes an RC filter network 231 connected to the inverting input terminal of the error amplifier EA for adjusting the reference voltage Vref and gradually increasing the reference voltage Vref from the clamp voltage after the switch 232 is opened. The RC filter network 231 comprises a resistor R1 connected to the power supply terminal and the inverting input terminal of the error amplifier EA and a capacitor C1 connected between the anode of the first diode D1 and the ground terminal, the presence of the filter network 231 can enable the reference voltage Vref to be slowly increased by the clamp voltage, and accordingly, the overshoot protection module 230 is configured to slowly adjust the reference voltage Vref via the RC filter to be gradually increased when the switch 232 is in the off state, adjust the output voltage Vout via the second control signal Vctrl2 output by the error amplifier EA whenever the reference voltage Vref is greater than the output voltage Vout, and increase the output voltage Vout, then adjust the second control signal Vctrl2 via the error amplifier EA multiple times for gradually increasing the output voltage Vout, so that both the reference voltage Vref and the output voltage Vout are gradually recovered.
The overshoot protection circuit 230 of the present embodiment may further include a bandgap reference module 233 connected between the resistor R1 and the power supply terminal VCC for converting the power supply voltage VCC into an appropriate reference voltage Vref. While switch 232 may be, for example, a complementary switch or a separate control switch, closed under the control of first and second on signals Vs1 and Vs2, and opened when the LDO circuit is in a normal state.
Therefore, when the short circuit protection is triggered by the current limiting module 210 and the negative pressure protection module 220 when the LDO is short-circuited, the switch 232 is closed so that the reference voltage Vref is pulled down to vout+200mV, that is, when the output is short-circuited or the overload is released, the differential input of the error amplifier is 200mV at maximum, the output voltage will not have larger fluctuation, and due to the existence of the RC filter network, the reference voltage Vref will slowly rise from vout+200mV to a normal value, that is, the output voltage Vout will also slowly and smoothly rise to a normal value along with the reference voltage, no overshoot will occur, and the circuit is well protected.
The embodiment also provides a low dropout linear voltage regulator, including: a power transistor M1 connected between the power supply terminal and the output terminal; a first resistor R1 and a first capacitor C1 connected in parallel between the output terminal and the reference ground; the output end of the error amplifier EA is connected with the control end of the power transistor M1, the positive input end of the error amplifier EA receives the output voltage Vout, and the negative input end of the error amplifier EA receives the reference voltage Vref; and the control circuit is used for driving the power transistor M1 to convert the power voltage of the power supply terminal into the output voltage, and the LDO and the control circuit thereof are shown in fig. 2, 4 and 5.
In summary, the low dropout linear voltage regulator and the control circuit thereof provided by the invention are provided with the negative voltage protection module and the overshoot protection module, when the output end is short-circuited to cause negative output voltage to be generated at the output end, the negative voltage protection module outputs a first control signal to the control end of the power transistor when detecting that the output voltage is smaller than a voltage threshold value, so that the output peak current is rapidly reduced, the circuit fault is rapidly responded, and the chip burnout caused by large negative voltage of the output voltage is avoided; in addition, when the output voltage is smaller than the voltage threshold value, the negative pressure protection module outputs a first opening signal to the overshoot protection module, clamps the reference voltage at the clamping voltage, limits the second control signal output by the error amplifier at a smaller value, has a smaller adjusting range of the output voltage, and avoids the overshoot damage circuit of the output voltage after the short circuit is released, so that the fluctuation of the output voltage of the low-voltage differential linear voltage stabilizer in a short circuit state is smaller through the arrangement of the two modules, and the short circuit protection of the low-voltage differential linear voltage stabilizer is realized without generating larger negative pressure and overshoot.
Correspondingly, the embodiment also provides a chip, which comprises the control circuit, wherein the chip can be an integrated chip such as a microprocessor chip or a power management chip, and the control circuit is used for adjusting the output voltage of the LDO, so that the voltage of the chip is controlled, and the chip is protected from being burnt.
Correspondingly, the embodiment also provides electronic equipment, which comprises the control circuit or the chip, wherein the control circuit or the chip can regulate the output voltage of the LDO, so that the power supply of the electronic equipment is regulated, and overshoot of the voltage or burning of the circuit with large negative pressure is avoided.
It should be noted that, the numerical values herein are only used for illustrative purposes, and in other embodiments of the present invention, other numerical values may be sampled to implement the present solution, and the present invention is not limited to this, and should be reasonably set according to practical situations.
Finally, it should be noted that: it is apparent that the above examples are only illustrative of the present invention and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.
It is also to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. The use of these terms and expressions is not meant to exclude any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications are possible and are intended to be included within the scope of the claims. Other modifications, variations, and alternatives are also possible. Accordingly, the claims should be looked to in order to cover all such equivalents.
Claims (14)
1. A control circuit of a low dropout linear regulator, the low dropout linear regulator comprising a power transistor between a power supply terminal and an output terminal, and an error amplifier connected to a control terminal of the power transistor, wherein the control circuit comprises:
a negative pressure protection module for outputting a first control signal to the control terminal of the power transistor to reduce the output peak current and output a first on signal when the output terminal is short-circuited and the output voltage is detected to be reduced to be less than the voltage threshold value, and
and the overshoot protection module is connected with the reverse input end of the error amplifier and receives the first opening signal to clamp the reference voltage of the reverse input end at the clamping voltage, so that the second control signal output by the error amplifier to the control end of the power transistor is regulated to regulate the output voltage.
2. The control circuit of claim 1, wherein the overshoot protection module comprises:
the anode of the first diode is connected with the reverse input end of the error amplifier; and
a switch connected between the cathode of the first diode and the positive input terminal of the error amplifier,
the forward input end of the error amplifier receives the output voltage, the reverse input end of the error amplifier receives the reference voltage, the switch is closed to clamp the reference voltage at the clamping voltage, and the clamping voltage is the sum of the output voltage and the conduction voltage drop of the first diode.
3. The control circuit of claim 2, wherein the switch is opened after the output has returned from the shorted state to the normal state.
4. The control circuit of claim 3, wherein the overshoot protection module controls the second control signal output by the error amplifier according to the clamp voltage and the output voltage at a timing when the switch is turned off to reduce an increase in the output voltage.
5. The control circuit of claim 3, wherein the overshoot protection module further comprises: and the RC filter network is connected with the reverse input end of the error amplifier and is used for adjusting the reference voltage and gradually increasing the reference voltage from the clamping voltage after the switch is disconnected.
6. The control circuit of claim 5, wherein the overshoot protection module is further configured to gradually increase the reference voltage via the RC filter network when the switch is in an off state to gradually increase the output voltage by the error amplifier according to the second control signal.
7. The control circuit of claim 1, wherein the negative pressure protection module comprises:
the mirror image current source comprises a first current branch and a second current branch, wherein first ends of the first current branch and the second current branch are connected with a first voltage, and a second end of the second current branch is connected with a second voltage; and
the conduction selection module is connected between the second end of the first current branch and the output end and comprises a second diode with an anode connected with the output end and a third diode with a cathode connected with the output end,
the conduction selection module is conducted to adjust the current on the first current branch, so that the negative pressure protection module outputs different first control signals.
8. The control circuit of claim 7, wherein the negative pressure protection module further comprises:
the logic unit is connected to the first end of the first current branch, outputs the first control signal of a low level when the second diode is conducted, outputs the first control signal of a high level when the third diode is conducted, and outputs a first turn-on signal.
9. The control circuit of claim 7, wherein the first voltage is an input voltage of the power supply terminal and the second voltage is set to an on-voltage drop of the third diode.
10. The control circuit of claim 7, wherein the power transistor is a P-type field effect transistor, the first transistor on the first current leg and the second transistor on the second current leg are both N-type field effect transistors, and the second diode and the third diode are both schottky diodes.
11. The control circuit of claim 1, further comprising:
the current limiting module is used for outputting a third control signal to the control end of the power transistor to adjust the output current to reach the current threshold when the output end is short-circuited and the output current of the power transistor is detected to exceed the current threshold, and outputting a second opening signal;
the overshoot protection module receives the second turn-on signal to clamp the reference voltage at the clamp voltage.
12. A low dropout linear regulator comprising:
a power transistor connected between the power supply terminal and the output terminal;
a first resistor and a first capacitor connected in parallel between the output terminal and the reference ground;
the output end of the error amplifier is connected with the control end of the power transistor, the positive input end of the error amplifier receives output voltage, and the negative input end of the error amplifier receives reference voltage; and
the control circuit of any of claims 1-11, the control circuit to drive the power transistor to convert a supply voltage of the supply terminal to an output voltage.
13. A chip comprising the control circuit of any one of claims 1-11.
14. An electronic device comprising the control circuit of any one of claims 1-11 or the chip of claim 13.
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| CN202211723007.7A CN116301145A (en) | 2022-12-30 | 2022-12-30 | Low dropout linear voltage regulator and control circuit, chip and electronic equipment thereof |
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| CN202211723007.7A CN116301145A (en) | 2022-12-30 | 2022-12-30 | Low dropout linear voltage regulator and control circuit, chip and electronic equipment thereof |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116500369A (en) * | 2023-06-28 | 2023-07-28 | 深圳安森德半导体有限公司 | Differential voltage detection method for DCDC voltage stabilizer |
| CN116544904A (en) * | 2023-07-04 | 2023-08-04 | 浙江大学 | Low-voltage difference detection anti-reverse-filling protection circuit, load switch chip and power supply system |
| CN119512304A (en) * | 2025-01-15 | 2025-02-25 | 苏州萨沙迈半导体有限公司 | Voltage regulation method and circuit |
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2022
- 2022-12-30 CN CN202211723007.7A patent/CN116301145A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116500369A (en) * | 2023-06-28 | 2023-07-28 | 深圳安森德半导体有限公司 | Differential voltage detection method for DCDC voltage stabilizer |
| CN116500369B (en) * | 2023-06-28 | 2023-09-15 | 深圳安森德半导体有限公司 | DCDC voltage stabilizer voltage detection method |
| CN116544904A (en) * | 2023-07-04 | 2023-08-04 | 浙江大学 | Low-voltage difference detection anti-reverse-filling protection circuit, load switch chip and power supply system |
| CN116544904B (en) * | 2023-07-04 | 2023-09-22 | 浙江大学 | Low voltage difference detection anti-backfeed protection circuit, load switch chip and power supply system |
| CN119512304A (en) * | 2025-01-15 | 2025-02-25 | 苏州萨沙迈半导体有限公司 | Voltage regulation method and circuit |
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