CN101834515B

CN101834515B - Zero voltage switching circuit suitable for drive circuit of switch power supply power tube

Info

Publication number: CN101834515B
Application number: CN201010186467A
Authority: CN
Inventors: 蔡曙江; 许海峰; 皮常明; 李文宏
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2010-05-27
Filing date: 2010-05-27
Publication date: 2012-10-17
Anticipated expiration: 2030-05-27
Also published as: CN101834515A

Abstract

The invention belongs to the technical field of integrated circuits, in particular to a zero voltage switching circuit suitable for a drive circuit of a switch power supply power tube. The circuit comprises a comparator, a switch tube, a control logic of the switch tube, and a D trigger with an asynchronous low-level reset terminal. The comparator detects whether a signal is reduced to zero; if the signal is reduced to zero, the comparator sends a rising edge signal to the D trigger; and then the D trigger outputs a starting signal. The switch tube and the control logic thereof can close the comparator at an unessential time so as to save power consumption. The asynchronous low-level reset function of the D trigger makes the zero voltage switching circuit not affect the closing process of the power tube. The zero voltage switching circuit of the invention has the advantages of simple structure, low energy consumption and reliable function, and is suitable for the drive circuit of the switch power supply power tube.

Description

A kind of Zero voltage switching circuit that is applicable to drive circuit of switch power supply power tube

Technical field

The invention belongs to technical field of integrated circuits, be specifically related to a kind of Zero voltage switching circuit that is applicable to drive circuit of switch power supply power tube.

Background technology

In recent years little, the use of electronic product is more and more extensive, and electric energy has become current main energy and utilized form.Rationally effectively utilize the common focus that electric energy (perhaps being called power management) becomes various electronic application field.In order to improve utilization rate of electrical, both need improve the efficient of electric power system (power circuit), also need improve the efficient that receives electric system.For lower-powered consumer electronics product, portable, battery powered electronic product especially, the efficient height of power circuit is bigger for the overall system efficiency influence.The power consumption that as far as possible reduces power circuit self has excellent application value and realistic meaning.

Switching Power Supply is as a kind of common circuit construction of electric power; From external power source, obtain power with interrupted mode, and the power that obtains temporarily is stored in the inner energy storage device (inductance, electric capacity); After then power being redistributed in time, output in the load continuously.Therefore, the acquisition process of power separates with output procedure to a certain extent.Have benefited from this separation, in the ideal case, Switching Power Supply is loss-free on mechanism.This also makes Switching Power Supply can have high efficiency advantage.

Under actual conditions, the power tube switching network in the Switching Power Supply has bigger parasitic capacitance (resistance) because device size is bigger.These parasitic capacitances (resistance) make and when switching power tube, need spend many power consumptions.When one of them opens N type power tube exactly, the conducting power consumption that possibly exist.If when N type power tube drain terminal voltage is non-vanishing, open power tube, then will there be drain terminal voltage and leakage current simultaneously, will have some energy dissipations this moment on one's body N type power tube.For fear of this dissipation, can, N type power tube drain terminal voltage open power tube when reducing to zero, and will not exist the conducting power consumption this moment.This process is called zero voltage switching.The circuit of accomplishing this function is called Zero voltage switching circuit.Zero voltage switching circuit can improve switch power efficiency effectively, has also become the necessary component of high-performance power tube drive circuit.

Summary of the invention

Little the object of the invention is to propose a kind of Zero voltage switching circuit (ZVS, Zero-Voltage Switching) that is applicable to drive circuit of switch power supply power tube, drives to realize the high-performance power tube, improves the efficient of Switching Power Supply.

Switch power supply power tube and drive circuit sketch map thereof are as shown in Figure 1.The buffer chain (1.2) that ZVS circuit (1.1) is positioned at N type power tube before.It can realize the zero voltage switching of N type power tube.Specifically, when needs were opened N type power tube, ZVS circuit tracing N type power tube drain terminal voltage Vx after it reduces to zero, opened N type power tube again.When needs are closed N type power tube, close N type power tube immediately.

The Zero voltage switching circuit that is applicable to drive circuit of switch power supply power tube that the present invention proposes; By comparator (2.2; 2.3), switching tube Ms and control logic thereof (2.1) and a d type flip flop (2.4) that has asynchronous low level reset terminal are formed, and physical circuit is as shown in Figure 2.Comparator adopts metal-oxide-semiconductor source end as input, can realize zero balancing, adopts push-pull configuration can have bigger gain, connects a two-stage chain of inverters then, helps to draw rapidly comparative result, and with this result of high-low level form output.Between power supply and comparator, add switching tube Ms and control logic, in order to the operating time of comparator to be set, only when opening N type power tube, open comparator, comparator then is in closed condition At All Other Times, to save power consumption.When needs are opened N type power tube Mn, when comparator reduces to zero at N type power tube Mn drain terminal voltage Vx, send the rising edge signal, d type flip flop and then output start signal to d type flip flop.When needs were closed N type power tube Mn, asynchronous low level reset terminal made d type flip flop export shutdown signal immediately.This makes the ZVS circuit not influence the pass closed procedure of N type power tube.

Zero voltage switching circuit of the present invention is simple in structure, and is low in energy consumption, and reliable in function is applicable to the drive circuit of switch power supply power tube.

Description of drawings

Fig. 1. switch power supply power tube and drive circuit sketch map thereof.

Fig. 2 .ZVS circuit diagram.

Fig. 3. when opening N type power tube Mn, the main node signal waveforms.

Fig. 4. when closing N type power tube Mn, the main node signal waveforms.

Embodiment

Below in conjunction with accompanying drawing the present invention is further explained.

When needs were opened N type power tube Mn, signal Vdrv was a high level by low transition.Signal VGp is a high level by low transition subsequently, and P type power tube is closed.At this moment, Vdrv is a high level, and VGn is a low level, switching tube Ms control logic output low level, and switching tube Ms is in open mode, and comparator is also in running order.Simultaneously, signal Vx is begun to reduce gradually by high level.When Vx reduced to zero, comparator output was high level by low transition, after the shaping of two-stage chain of inverters, to d type flip flop output rising edge signal.Because the rising edge signal inserts the clock end of d type flip flop, so trigger will be exported D end data, i.e. high level.Signal Vdrvn is a high level by low transition, and signal VGn is a high level by low transition subsequently, and N type power tube begins to open.And the output of switching tube Ms control logic is high level by low transition, and switching tube Ms gets into closed condition, and comparator also gets into closed condition.It is thus clear that the ZVS circuit is guaranteed when drain terminal voltage Vx is zero, to open N type power tube, and comparator is only in that to open moment in running order, and all the other times all are in closed condition.When opening N type power tube Mn, the main node signal waveform is as shown in Figure 3.

When needs were closed N type power tube Mn, signal Vdrv was a low level by the high level saltus step.Signal VGp is a low level by the high level saltus step subsequently, and P type power tube is opened.Because Vdrv is connected on the asynchronous low level reset terminal of d type flip flop, trigger will be reset, and promptly Vdrvn is a low level by the high level saltus step, and VGn is a low level by the high level saltus step subsequently, and N type power tube is closed.In this process, switching tube Ms control logic is exported high level all the time, and switching tube Ms is in closed condition, and comparator also is in closed condition.It is thus clear that the ZVS circuit does not influence the pass closed procedure of N type power tube.When closing N type power tube Mn, the main node signal waveform is as shown in Figure 4.

Claims

1. Zero voltage switching circuit that is applicable to Switching Power Supply N type power tube drive circuit is characterized in that: by comparator (2.2,2.3), switching tube and control logic thereof (2.1) and a d type flip flop (2.4) that has asynchronous low level reset terminal are formed; Said comparator adopts metal-oxide-semiconductor source end as input, and to realize zero balancing, comparator adopts push-pull configuration, and connects into a two-stage chain of inverters, and comparator is with high-low level form output comparative result; Between power supply and comparator, add switching tube and control logic thereof, in order to the operating time of comparator to be set, only when opening N type power tube, open comparator, comparator then is in closed condition At All Other Times; When needs are opened N type power tube, when comparator reduces to zero at N type power tube drain terminal voltage Vx, send the rising edge signal, d type flip flop and then output start signal to d type flip flop; When needs were closed N type power tube, asynchronous low level reset terminal made d type flip flop export shutdown signal immediately.