CN100421347C - Semi-bridge type converter circuit for driving double N-MOS by using push-pull control chip - Google Patents

Abstract

The invention relates to a half-bridge type converter circuit for driving double N-MOS by using a push-pull control chip, which can be connected with a driving circuit in a common half-bridge type converter circuit, namely, the push-pull control chip can be used for controlling the half-bridge type converter circuit, and comprises the following components: a push-pull control chip with two output ends; the driving circuit is provided with two input ends and two output ends, and the two input ends are connected with the two output ends of the push-pull control chip and are controlled by the push-pull control chip; and a half-bridge switch component, which is composed of a first N-channel field effect transistor and a second N-channel field effect transistor, wherein each N-channel field effect transistor is provided with a control end, the control ends are connected with the two output ends of the driving circuit, and are used for switching the direct current power supply into the alternating current power supply and transmitting the alternating current power supply to the primary side end of the transformer through the driving of the driving circuit.

Description

Utilizing push-pull control chip to drive double N-MOS half-bridge converter circuit

technical field

The invention relates to a half-bridge commutation circuit driven by a push-pull control chip, in particular to a half-bridge switch component composed of two N-channel field-effect transistors that can be controlled by a push-pull type, thereby A converter circuit that drives a load.

Background technique

The power supply (Power Supply) of the TFT panel backlight mainly uses the inverter circuit (Inverter Circuit) to achieve energy conversion and drive the light emission of the cold cathode fluorescent lamp (CCFL). The common inverter circuit (Inverter Circuit) is different due to the circuit topology. Generally, there are half-bridge commutation circuits, full-bridge commutation circuits and push-pull commutation circuits, etc., which are commutation circuits that convert direct current into alternating current.

Please refer to FIG. 1 , which is a schematic diagram of a common push-pull commutation circuit driving a load. The double voltage transformer T1 divides the circuit into a primary-side pre-stage circuit 101 and a secondary-side post-stage circuit 102. The primary side 101 includes : a DC power supply Vcc, a first switch Q1, a second switch Q2, etc., the secondary side 102 includes: at least one capacitor (C1, C2, C3), a load (Load), at least one diode (D1, D2) etc. Furthermore, a push-pull control chip 103 is connected between the primary side 101 and the secondary side 102 . In conjunction with Figure 2, it is a schematic diagram of the output signal of a common push-pull control chip and the output waveform of the load terminal. The push-pull control chip 103 outputs a first control signal a and a second control signal b, wherein the first control signal a and the second control signal b respectively control the switching of the first switch Q1 and the second switch Q2 of the primary side 101 Work, and at the same time, according to the voltage of the DC power supply Vcc, it is used to provide energy and convert the voltage of the DC power supply Vcc to the secondary side 102 through the transformer T1 to drive the load (Load). The output voltage waveform of the secondary side of the transformer T1 c shows the voltage waveform at point C, as shown in Figure 2, the secondary side output voltage waveform c is the AC voltage waveform.

In the above description, the push-pull control chip 103 is a chip produced by LINFINITY (MICEOSEMI), whose models are LX1686 and LX1691 series, or a chip produced by Micro international Limited company, whose model is 02-9RR series, and Beyond The chips produced by Innovation Technology Company are BIT3494 and BIT3193 series.

Please refer to FIG. 3 , which is a schematic diagram of a common half-bridge converter circuit driving a load circuit. The transformer T2 divides the circuit into a front-stage circuit 201 on the primary side and a rear-stage circuit 202 on the secondary side. The primary side 201 includes: a DC power supply Vcc, two electronic switches (Q1, Q2), and a half-bridge control chip TL494 , two capacitors ( C1 , C2 ) and an isolation transformer Tr, etc., the secondary side 202 includes: a load (Load). In conjunction with Figure 4, it is a schematic diagram of the output control signal and AC power voltage waveform of a common half-bridge control chip. The half-bridge control chip TK494 outputs control signals D1-D2 from two output terminals D1 and D2 to control the switching work of the two electronic switches Q1 and Q2 respectively through the isolation transformer Tr. The switching operation of the two electronic switches Q1 and Q2 transmits the electric energy stored in the capacitors C1 and C2 to the primary terminal T21 of the transformer T2 respectively through a connecting capacitor C3 to form an AC power source ac. The voltage of the capacitors C1 and C2 is half the voltage Vcc/2 of the DC power supply Vcc. The AC power ac is used to provide energy to the transformer T2, and through the transformer T2, the AC power is boosted and converted to the secondary side 202 for driving a load (Load).

In the above description, if the inverter circuit used is a half-bridge inverter circuit, it needs to be controlled by a half-bridge control chip to work, and if it is a push-pull inverter circuit, it needs to be matched with a push-pull control The chip controls are required to work. Therefore, it lacks flexibility and commonality in practice. Furthermore, the use of the inverter circuit (Inverter Circuit) is often limited to the control chip, and the inverter circuit (Inverter Circuit) is subject to the above description, so that the control chip cannot be shared and purchased in a unified manner, or it needs to be matched more complex circuits.

Contents of the invention

In view of this, the present invention provides a half-bridge commutation circuit using a push-pull control chip to drive double N-MOS, which utilizes a drive circuit, respectively connected to the output end of the push-pull control chip and the two N-channels The switching work of the half-bridge switching component composed of field effect transistors.

The invention utilizes a push-pull control chip to drive a double N-MOS half-bridge commutation circuit, and a driving circuit is connected between two N-channel field effect transistors and the control chip of a common half-bridge commutation circuit. Moreover, the control chip is replaced by a push-pull type control chip, and then controls the switching operation of the two N-channel field effect transistors.

The present invention provides a half-bridge commutation circuit driven by a push-pull control chip to drive double N-MOS, which is connected to the primary side of a transformer to convert a DC power supply into an AC power supply, including a push-pull The pull-type control chip is provided with two output terminals; a driving circuit is provided with two input terminals and two output terminals, and the two input terminals are connected to the two output terminals of the push-pull control chip respectively, and receive the The control of the push-pull control chip, the drive circuit includes: a high-frequency transformer, which has a first input terminal, a second input terminal, a first output terminal and a second output terminal, and the first input terminal is passed through an RC The series circuit is connected to an output terminal of the push-pull control chip, and the second input terminal is connected to the reference terminal, and the first output terminal is connected to the control terminal of the first N-channel field effect transistor through a first resistor, The second output end is connected to the primary side end of the transformer, and a second resistor is connected to the other output end of the push-pull control chip and the control end of the second N-channel field effect transistor; and a diode is used connected in parallel to the second resistor; and a half-bridge switch component, which is composed of a first N-channel field effect transistor and a second N-channel field effect transistor, and each N-channel field effect transistor is provided with a control terminal, And respectively connected to the two output ends of the drive circuit, driven by the drive circuit, to switch the DC power to the AC power and transmit it to the primary side of the transformer.

As explained above, the present invention uses a push-pull control chip to drive a half-bridge commutation circuit of double N-MOS. The driving circuit can be used to receive the control signal of the push-pull control chip, and then control the half-bridge The switching work of the half-bridge switch component composed of two N-channel field effect transistors in the commutation circuit.

In this way, the present invention uses a push-pull control chip to drive a dual N-MOS half-bridge commutation circuit. A drive circuit can be connected to a common half-bridge commutation circuit, and the push-pull control chip can be used for control. It is more flexible in practice and will not be limited by the control chip. Moreover, the industry can simultaneously control the push-pull commutation circuit and the half-bridge commutation circuit only by using the push-pull control chip.

In order to further understand the features and technical content of the present invention, please refer to the detailed description and accompanying drawings of the present invention. However, the accompanying drawings are provided for reference and illustration only, and are not intended to limit the present invention.

Description of drawings

Fig. 1 is a schematic circuit diagram of a load driven by a common push-pull commutation circuit;

Figure 2 is a schematic diagram of the output control signal of a common push-pull control chip and the output voltage waveform at the load end;

Fig. 3 is a schematic circuit diagram of a load driven by a common half-bridge converter circuit;

Figure 4 is a schematic diagram of the output control signal and AC power voltage waveform of a common half-bridge control chip;

Fig. 5 is a schematic circuit diagram of the present invention;

Fig. 6 is another schematic circuit diagram of the present invention;

Fig. 7 is another schematic circuit diagram of the present invention;

Fig. 8 is a schematic diagram of another circuit of the present invention;

FIG. 9 is a schematic diagram of the output signal and AC power voltage waveform of the push-pull control chip of the present invention.

Wherein, the reference numerals explain:

101 Pre-stage circuit 102 Post-stage circuit 103 Push-pull control chip

T1 Transformer

a first control signal b second control signal c secondary side output voltage waveform of transformer T1

201 pre-stage circuit 202 post-stage circuit T2 transformer

TL494 half-bridge control chip

D1-D2 output control signal Q1 control signal Q2 control signal

AC power supply

103 push-pull control chip 302 half-bridge switch assembly 304 drive circuit

T2 transformer Gnd reference terminal

a first control signal b second control signal ac voltage waveform

Detailed ways

Please refer to Figure 5, which is a schematic circuit diagram of the present invention, wherein the present invention uses a push-pull control chip to drive a double N-MOS half-bridge commutation circuit, which is connected to the primary side of a transformer T2 to convert a DC The power supply Vcc is converted into an alternating current power supply AC, and the alternating current power supply AC passes through the transformer T2 to provide the energy required for the load to work. In the above description, the peak-to-peak value of the alternating current power supply AC is the direct current power supply Vcc.

Referring again to Fig. 5, the present invention utilizes a push-pull control chip to drive a double N-MOS half-bridge commutation circuit, including: a push-pull control chip 103, a drive circuit 304, a half-bridge switch assembly 302 and two Capacitors (C2, C3). Wherein, the push-pull control chip 103 is provided with two output terminals A and B for outputting control signals. The driving circuit 304 has two input terminals and two output terminals, the two input terminals are connected to the two output terminals A and B of the push-pull control chip 103, and are controlled by the push-pull control chip. The half-bridge switch element 302 is composed of two N-channel field effect transistors Q1 and Q2, and each N-channel field effect transistor is provided with a control terminal G, and these control terminals G are respectively connected to the two output terminals of the driving circuit 304 , and is driven by the driving circuit 304 to switch the DC power Vcc into the AC power AC and transmit it to the primary side of the transformer T2.

Referring to Fig. 5 again, the drains (D) of the two N-channel field effect transistors Q1 and Q2 are connected to the primary side of the transformer T2, and the individual sources (S) are respectively connected to a DC power supply terminal Vcc and A reference terminal Gnd. The other secondary side of the transformer T2 is connected to the reference terminal Gnd through the capacitor C3, and connected to the DC power supply Vcc through the capacitor C2. Meanwhile, the control terminals G of the two N-channel field effect transistors Q1 and Q2 are respectively connected to the output terminals of the driving circuit 304 . In the above description, the two N-channel field effect transistors Q1 and Q2 are connected to form the half-bridge switch component 302 . Moreover, the two N-channel field effect transistors Q1 and Q2 form a positive half-cycle drive or a negative half-cycle drive, and the positive half-cycle drive and the negative half-cycle drive form the AC power supply AC at the primary side terminal T21 of the transformer T2.

Referring again to Fig. 5, a drive circuit 304 is used to drive two N-channel field effect transistors Q1, Q2, and the drive circuit 304 is connected to an output terminal A of the push-pull control chip 103 through an RC series circuit 3040, the RC The other end of the series circuit 3040 is connected to a first input terminal 1 of a high-frequency transformer Tr, a second input terminal 2 of the high-frequency transformer Tr is connected to the reference terminal Gnd, and a second input terminal of the high-frequency transformer Tr 2 connected to the reference terminal Gnd, a first output terminal 3 of the high-frequency transformer Tr, connected to the control terminal G of the first N-channel field effect transistor through a first resistor R2, and a second output terminal of the high-frequency transformer Tr The terminal 4 is connected to the primary side terminal T21 of the transformer T2. In the above, the first input terminal 1 and the first output terminal 3 are in the same phase. At the same time, the first output terminal 3 and the second output terminal 4 of the high-frequency transformer Tr are connected with a damping resistor R4, which is used to prevent the ringing phenomenon generated when the transformer Tr is driven, causing the N-channel field effect transistor Q1's burnt. Furthermore, the drive circuit 304 uses a second resistor R3 to connect the other output terminal B of the push-pull control chip 103 with the control terminal G of the second N-channel field effect transistor, and a diode D, and connected in parallel. on the second resistor R3.

Please refer to FIG. 6 , FIG. 7 and FIG. 8 , these circuit diagrams are schematic circuit diagrams of other embodiments of the present invention. The difference between these schematic circuit diagrams and FIG. 5 lies in the placement positions of the capacitors C2 and C3. The circuit shown in Figure 6 uses only capacitor C3, the circuit shown in Figure 7 uses only capacitor C2, and the circuit shown in Figure 6 uses capacitor C4. In the above description, the capacitors C2 and C3 are used to temporarily store the power of the DC power supply terminal Vcc and provide the power to the transformer T2. Please cooperate with FIG. 5 and refer to FIG. 9 , which is a schematic diagram of the output signal and AC power voltage waveform of the push-pull control chip of the present invention. As shown in Figure 9, the output terminal A of the push-pull control chip 103 outputs a first control signal a, and the output terminal B outputs a second control signal b, such as the chip produced by Beyond Innovation Technology, whose model is BIT3105 and other series Clock pulses for POUT1 and POUT2. The voltage waveform ac of the AC power supply AC can be obtained at the terminal T21 of the primary side of the transformer T2, and its peak-to-peak value is the DC power supply Vcc.

Referring to FIG. 5 , referring to FIG. 9 , at time t1-t2, the first control signal a is at a high potential, and the second control signal b is at a low potential. The first control signal a is transmitted to the first input terminal 1 of the high-frequency transformer Tr through the RC series circuit 3040. Due to the polarity relationship of the high-frequency transformer Tr, the first output terminal 3 of the high-frequency transformer Tr senses and outputs a high potential at this time. to the control terminal G of the first N-channel field effect transistor Q1, and drive the first N-channel field effect transistor Q1 to conduct (ON). The second control signal b is transmitted to the control terminal G of the second N-channel field effect transistor Q2 through the second resistor R3 for controlling the transistor switch Q3 to be turned off (OFF). At this time, the first N-channel field effect transistor Q1 is in the ON state, and the second N-channel field effect transistor Q2 is in the OFF state, so that the electric energy stored in the capacitor C2 can be transmitted to the primary side of the transformer T2 terminal, and the voltage waveform ac available at terminal T21 is positive DC power supply +Vcc/2. In the above description, the two N-channel field effect transistors Q1 and Q2 are driven in a positive half cycle.

Referring to FIG. 5 , referring to FIG. 9 , at time t2-t3, the first control signal a drops from a high potential to a low potential, and the second control signal b remains low. At this time, the first input terminal 1 transmitted to the high-frequency transformer Tr is a low potential. Due to the polarity relationship of the high-frequency transformer Tr, the first output terminal 3 of the high-frequency transformer Tr senses and outputs a low potential to the first high-frequency transformer Tr. The control terminal G of the N-channel field effect transistor Q1 is used to control the first N-channel field effect transistor Q1 to be turned off (OFF). It can be seen from the above description that at the time t2-t3, the two N-channel field effect transistors Q1 and Q2 are both in the OFF state. At this time, the primary side of the transformer T2 forms an open circuit, so that the energy stored in the transformer T2 can be discharged, and the energy discharge state is reached. Therefore, at this time, the voltage waveform ac obtained at the terminal T21 of the primary side of the transformer T2 is zero potential.

Cooperate with Fig. 5 again, refer to Fig. 9, the present invention utilizes the push-pull type control chip to drive the double N-MOS half-bridge commutation circuit work and the voltage waveform ac obtained by the T21 end point of the primary side end of the transformer T2, which is at time t5-t6 Time returns to the waveform at time t1-t2. As described above, an alternating current power supply AC is formed to provide energy, and its peak value is a direct current power supply Vcc. At the same time, the AC power source AC is boosted and converted to the secondary side of the transformer T2 to provide energy to the load (Load).

As mentioned above, the present invention uses a push-pull control chip to drive a dual N-MOS half-bridge commutation circuit, and can connect a drive circuit 304 to a common half-bridge commutation circuit, and can also be used with a push-pull control chip 103, it is practically more flexible and will not be limited by the control chip. Moreover, the industry only needs to use the push-pull control chip 103 to simultaneously control the push-pull commutation circuit and the half-bridge commutation circuit.

The above descriptions are only the best specific embodiments of the present invention, and the features of the present invention are not limited thereto. Any changes or modifications obvious to those skilled in the art can be included in the patent scope of the present invention.

Claims (5)

1. semi bridge type inversion circuit that utilizes the push-pull type control chip to drive two N-MOS is connected in a side of a transformer, in order to a DC power supply is converted to an AC power, includes:

A push-pull type control chip is provided with two outputs;

A drive circuit is provided with two inputs and two outputs, and these two inputs are connected to two outputs of this push-pull type control chip, accept the control of this push-pull type control chip; And

A semi bridge type switch module, form by one the one N channel fet and one the 2nd N channel fet, each N channel fet all is provided with a control end, and be connected to two outputs of this drive circuit, driving by this drive circuit, in order to this DC power supply is switched to this AC power, and be sent to a side of this transformer.

2. the semi bridge type inversion circuit that utilizes the push-pull type control chip to drive two N-MOS as claimed in claim 1 is characterized in that, these two N channel fet are formed a positive half cycle driving or a negative half period drives.

3. the semi bridge type inversion circuit that utilizes the push-pull type control chip to drive two N-MOS as claimed in claim 1, it is characterized in that, the drain electrode of the one N channel fet and the 2nd N channel fet is connected to side of this transformer, and the source terminal of these two N channel fet is connected respectively to a dc power supply terminal and a reference edge.

4. the semi bridge type inversion circuit that utilizes the push-pull type control chip to drive two N-MOS as claimed in claim 1 is characterized in that this drive circuit includes:

A high frequency transformer, have first input end, second input, first output and second output, the first input end of high frequency transformer is connected to an output of this push-pull type control chip by a RC series circuit, and second input of high frequency transformer is connected to a reference edge, first output of high frequency transformer, be connected to the control end of a N channel fet by one first resistance, second output of high frequency transformer is connected to a side of this transformer;

One second resistor is connected in another output of this push-pull type control chip and the control end of the 2nd N channel fet;

A damping resistance is connected to first output of high frequency transformer and second output of high frequency transformer;

A diode is connected to this second resistor.

5. the circuit that utilizes the push-pull type control chip to drive the semi-bridge converter device as claimed in claim 4, it is characterized in that, the cathode terminal of this diode is connected to another output of this push-pull type control chip, and anode tap is connected to the control end of the 2nd N channel fet.

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