CN203278623U

CN203278623U - A gate drive circuit for switching power supply or LED drive chip

Info

Publication number: CN203278623U
Application number: CN201320323484.4U
Authority: CN
Inventors: 周文质
Original assignee: CHENGDU SMET TECHNOLOGY Co Ltd
Current assignee: CHENGDU SMET TECHNOLOGY Co Ltd
Priority date: 2013-06-06
Filing date: 2013-06-06
Publication date: 2013-11-06
Anticipated expiration: 2023-06-06

Abstract

The utility model discloses a gate drive circuit for a switching power supply or an LED drive chip, comprising a high-voltage power supply, a level shift module, a NOT gate and two NMOS tubes, and the gate drive circuit also includes a comparator, an electronic switch and a PMOS tube , the positive signal input terminal of the comparator and the drain of the PMOS tube are connected to the positive terminal of the high-voltage power supply, the negative signal input terminal of the comparator inputs the reference voltage, the output terminal of the comparator is connected to the control terminal of the electronic switch, and the two terminals of the electronic switch The terminals are respectively connected to the gate of the PMOS transistor and the output terminal of the level shift module, and the source of the PMOS transistor is connected to the source of the first NMOS transistor. In the gate drive circuit described in the utility model, when the voltage of the high voltage power supply is low, the output voltage of the gate drive circuit is closer to the corresponding output voltage when the high voltage power supply is high voltage, so that the output voltage of the gate drive circuit is affected by the high voltage power supply. The impact is smaller, and the problem of half-opening of the external MOS tube is effectively avoided.

Description

A kind of grid drive circuit for Switching Power Supply or LED driving chip

Technical field

The utility model relates to a kind of drive circuit, relates in particular to a kind of grid drive circuit for Switching Power Supply or LED driving chip.

Background technology

Be used for the grid drive circuit that Switching Power Supply or LED drive chip, it is low voltage digital signal (being commonly referred to " GATE_CTRL ") to be controlled be converted to high-voltage driven signal (being commonly referred to " GATE ") in essence, and it is the on off state of external MOSFET that this high-voltage driven signal is used for controlling this circuit metal-oxide-semiconductor in addition as the grid input signal.The charging current of high-voltage driven signal (GATE) is provided by high voltage source (VCC).

Tradition grid drive circuits (being commonly referred to " DRIVER ") are made of high voltage source, level shift module (being commonly referred to " level shift "), not gate and two NMOS pipes, its operation principle is: the GATE_CTRL signal drives signal by becoming two anti-phase middle pressures after the level shift module, drives respectively two of up and down NMOS pipe.GATE_CTRL is 0 o'clock, and GATE can be pulled down to ground by the NMOS pipe of below; GATE_CTRL is 1 o'clock, and GATE can be drawn high by the NMOS pipe of top.Using two NMOS pipes rather than a PMOS pipe and a NMOS pipe, is to consider for the optimization of driving force and chip area.The GATE signal is up to one less than the clamp voltage V of VCC _GH

The defective of above-mentioned traditional grid drive circuit is: lower at VCC, but the grid drive circuit is still in when work, the high voltage V of GATE _GHCan descend.This is because the characteristic of NMOS pipe has determined that the GATE signal can not surpass VCC-Δ V _MAX, Δ V wherein _MAXBe the difference between VCC and maximum GATE signal.

Being in minimum voltage at VCC is VCC when being about to turn-off, and GATE voltage is V _GL, V _GLMuch smaller than V _GHSo, may be inadequate due to driving voltage, make external MOSFET that the risk of semi-open (be opening degree be in turn-off with fully between unlatching) be arranged, thereby cause the damage of power tube.

The utility model content

The purpose of this utility model provides a kind of grid drive circuit that is used for Switching Power Supply or LED driving chip that can effectively avoid the semi-open problem of external metal-oxide-semiconductor with regard to being in order to address the above problem.

The utility model is achieved through the following technical solutions above-mentioned purpose:

grid drive circuit for Switching Power Supply or LED driving chip described in the utility model comprises high voltage source, the level shift module, not gate and two NMOS pipes, the input input low voltage digital signal of described level shift module, the output of described level shift module is connected with the input of described not gate and the grid of the 2nd NMOS pipe respectively, the output of described not gate is connected with the grid of a NMOS pipe, the drain electrode of a described NMOS pipe be connected the high voltage source input of level shift module and all be connected with the positive pole of described high voltage source, the source electrode of described the 2nd NMOS pipe is connected with the negative pole of described high voltage source, the drain electrode of the source electrode of a described NMOS pipe and described the 2nd NMOS pipe interconnects and as the high-voltage driven signal output of described grid drive circuit, described grid drive circuit also comprises comparator, electronic switch and PMOS pipe, the positive signal input of described comparator be connected the drain electrode of PMOS pipe and all be connected with the positive pole of described high voltage source, the negative signal input input reference voltage of described comparator, the output of described comparator is connected with the control end of described electronic switch, the two ends of described electronic switch respectively with the grid of described PMOS pipe be connected the output of level shift module and be connected, the source electrode of described PMOS pipe is connected with the source electrode of a described NMOS pipe.

Comparator, electronic switch and PMOS pipe are innovation structures of the present utility model, the voltage and the reference voltage that compare high voltage source by comparator, and control the switch of PMOS pipe according to comparable situation, thereby the GATE voltage of controlling final output can be too not low, avoids having semi-open risk because driving voltage makes external MOSFET not.

Particularly, described electronic switch is triode, metal-oxide-semiconductor or insulated gate bipolar transistor, specifically decides according to demand, as long as satisfy the requirement of controlling its break-make by control end.

The beneficial effects of the utility model are:

In grid drive circuit described in the utility model, when the voltage of high voltage source hangs down, the output voltage of grid drive circuit corresponding output voltage when more being high voltage near high voltage source, so can not export too low driving voltage, thereby the output voltage that makes the grid drive circuit is subjected to the impact of high voltage source less, has effectively avoided the semi-open problem of external metal-oxide-semiconductor.

Description of drawings

Fig. 1 is the circuit diagram of traditional grid drive circuit;

Fig. 2 is the corresponding relation schematic diagram between traditional grid drive circuit output high-low voltage and high voltage source;

Fig. 3 is the circuit diagram of grid drive circuit described in the utility model;

Fig. 4 is the corresponding relation schematic diagram between grid drive circuit output high-low voltage described in the utility model and high voltage source.

Embodiment

The utility model is described in further detail below in conjunction with accompanying drawing:

as shown in Figure 3, grid drive circuit for Switching Power Supply or LED driving chip described in the utility model comprises high voltage source VCC, level shift module LV_shift(is levelshift), not gate INV, two NMOS pipes, comparator IC, electronic switch K and PMOS pipe (being the PMOS in Fig. 3), two NMOS pipes are NMOS1 and NMOS2, the input input low voltage digital signal of level shift module LV_shift, the output of the level shift module LV_shift input of NAND gate INV respectively is connected grid G 2 and is connected with NMOS2, the output of not gate INV is connected with the grid G of NMOS1 1, the drain D 1 of NMOS1 is connected the high voltage source input and all is connected with the positive pole of high voltage source VCC with level shift module LV_shift, the source S 2 of NMOS2 is connected with the negative pole of high voltage source VCC, the source S 1 of NMOS1 and the drain D 2 of NMOS2 interconnects and as the high-voltage driven signal output of grid drive circuit, its output drive signal is the GATE signal, the positive signal input of comparator IC is connected drain D and all is connected with the positive pole of high voltage source VCC with PMOS, the negative signal input input reference voltage REF of comparator IC, the output of comparator IC is connected with the control end of electronic switch K, be connected output with the grid G of PMOS respectively and be connected in the two ends of electronic switch K with level shift module LV_shift, the source S of PMOS is connected with the source S of NMOS1 1.In said structure, comparator IC, electronic switch K and the common compositional optimization circuit of PMOS DRIVER_opt.

As shown in Figure 3, electronic switch K can specifically decide according to demand for triode, metal-oxide-semiconductor or insulated gate bipolar transistor, as long as satisfy the requirement of controlling its break-make by control end.

As shown in Figure 3, the operation principle of grid drive circuit described in the utility model is as follows:

Add optimized circuit DRIVER_opt in circuit, detect the size of VCC, pass through LV_shift signal afterwards by GATE_CTRL and carry out Synchronization Control, and draw on being undertaken by the PMOS of afterbody.Can find out, optimized circuit DRIVER_opt is subjected to GATE_CTRL signal Synchronization Control, so the GATE signal is controlled is too drawn high or drag down.Therefore be all the same when being dragged down due to GATE, the situation that GATE draws high only be discussed below.

During lower than REF, comparator IC output low level makes electronic switch K conducting at VCC.Because upper trombone slide has become PMOS, draw current potential just to become VCC from VCC-Δ VMAX on GATE.

If VCC is higher than REF, comparator IC exports high level, and electronic switch K turn-offs, and the functional rehabilitation of whole grid drive circuit is with the same before.That is to say, optimized circuit DRIVER_opt only works during lower than REF at VCC.

The below carries out comparative analysis between structure to traditional grid drive circuit and grid drive circuit described in the utility model:

As shown in figures 1 and 3, traditional grid drive circuit comprises that high voltage source VCC, level shift module LV_shift(are level shift), not gate INV and two NMOS pipe; The utility model has increased optimized circuit DRIVER_opt on the basis of traditional grid drive circuit.

The below carries out comparative analysis between effect to traditional grid drive circuit and grid drive circuit described in the utility model:

As shown in Figure 2, lower at VCC in traditional grid drive circuit, but the grid drive circuit is still in when work, the high voltage V of GATE _GHCan descend also all the time less than VCC-Δ V _MAXBeing in minimum voltage at VCC is VCC when being about to turn-off, and GATE voltage is V _GL, V _GLMuch smaller than V _GHSo, may be inadequate due to driving voltage, make the external MOSFET(not shown) and the risk of semi-open (be opening degree be in turn-off with fully between unlatching) is arranged, thus cause the damage of power tube.

As shown in Figure 4, in grid drive circuit described in the utility model, if arrange appropriately, draw the minimum point of current potential can be from V on GATE _GLBecome

V _GL1=(V _GH+V _GL)/2

By following formula as can be known, V _GL1Necessarily greater than V _GLThereby, make the GATE voltage of final output can be too not low, avoid having semi-open risk because driving voltage makes external MOSFET not.

If add more optimized circuit, can make V _GL1More near V _GH, but the structure that needs is more complicated, consumes chip area also larger.In fact, avoid the semi-open of external MOSFET, an optimized circuit DRIVER_opt is enough.

Claims

1. A gate drive circuit for a switching power supply or an LED driver chip, comprising a high-voltage power supply, a level shift module, a NOT gate and two NMOS tubes, the input terminal of the level shift module inputs a low-voltage digital signal, and the The output end of the level shift module is respectively connected to the input end of the NOT gate and the grid of the second NMOS transistor, the output end of the NOT gate is connected to the grid of the first NMOS transistor, and the gate of the first NMOS transistor Both the drain and the high-voltage power input terminal of the level shifting module are connected to the positive pole of the high-voltage power supply, the source of the second NMOS transistor is connected to the negative pole of the high-voltage power supply, and the source of the first NMOS transistor is connected to the negative pole of the high-voltage power supply. The pole and the drain of the second NMOS transistor are connected to each other and serve as the high-voltage drive signal output end of the gate drive circuit; it is characterized in that it also includes a comparator, an electronic switch and a PMOS transistor, and the positive signal input of the comparator terminal and the drain of the PMOS tube are connected to the positive pole of the high-voltage power supply, the negative signal input terminal of the comparator inputs a reference voltage, and the output terminal of the comparator is connected to the control terminal of the electronic switch, so Two ends of the electronic switch are respectively connected to the gate of the PMOS transistor and the output end of the level shift module, and the source of the PMOS transistor is connected to the source of the first NMOS transistor.

2 . The gate drive circuit for switching power supply or LED driver chip according to claim 1 , wherein the electronic switch is a triode, a MOS transistor or an insulated gate bipolar transistor.