CN202978734U

CN202978734U - Flyback synchronous rectification switching power supply

Info

Publication number: CN202978734U
Application number: CN 201220179741
Authority: CN
Inventors: 邓世国
Original assignee: DONGGUAN LIDE ELECTRONIC Co Ltd
Current assignee: DONGGUAN LIDE ELECTRONIC Co Ltd
Priority date: 2012-04-25
Filing date: 2012-04-25
Publication date: 2013-06-05
Anticipated expiration: 2022-04-25

Abstract

The utility model discloses a flyback synchronous rectification switching power supply, comprising a primary winding L7, a secondary winding L6, a synchronous rectification circuit, a drive circuit, a detection circuit and a control circuit. The drive circuit comprises auxiliary windings L2 to L4, a rectifier diode D9, a filtering capacitor C30, a filtering capacitor C33, a PNP type transistor Q14, a field effect transistor Q15, a resistor R90, a diode D15 and a diode D16. The synchronous rectification circuit comprises a metal-oxide-semiconductor field effect transistor Q3, a metal-oxide-semiconductor field effect transistor Q4, a resistor R69, a resistor R72, a resistor R96 and a resistor R97. The detection circuit comprises a detection winding CT1, a resistor R65, a capacitor C31, a diode D8, a diode D10, a resistor R67, a resistor R66 and a resistor R68. A discrete device is employed to establish the drive circuit of an effect transistor MOSFET to drive the effect transistor MOSFET of the synchronous rectification circuit, the larger of an output current is, the higher degree the efficiency is raised at, the efficiency of the power supply is raised, zero load power consumption is minimized, material cost is reduced, and the flyback synchronous rectification switching power supply is suitable for a low-voltage heavy current output circuit.

Description

A kind of inverse-excitation type synchronous rectifying Switching Power Supply

Technical field

The utility model relates to switch power technology field, particularly a kind of inverse-excitation type synchronous rectifying Switching Power Supply that is applicable to High-current output.

Background technology

In recent years, along with the development of electronic technology, make the operating voltage of circuit more and more lower, electric current is increasing.Low voltage operating is conducive to reduce the overall power consumption of circuit, but has also proposed a new difficult problem to Power Management Design.The loss of Switching Power Supply mainly is comprised of 3 parts: the loss of power switch pipe, the loss of high frequency transformer, the loss of output rectifying tube.In the situation that low-voltage, High-current output, the conduction voltage drop of rectifier diode is higher, and the loss of output rectifying tube is particularly outstanding.Fast recovery diode (FRD) or Ultrafast recovery diode (SRD) can reach 1.0～1.2V, even adopt the Schottky diode (SBD) of low pressure drop, and the pressure drop that also can produce about 0.6V, this just causes rectifier loss to increase, and power-efficient reduces.At present notebook computer generally adopts the even supply power voltage of 1.8V or 1.5V of 3.3V, and the electric current that consumes can reach 20A.This moment, the rectifier loss of Ultrafast recovery diode approached even over 50% of output power of power supply.Even employing Schottky diode, the loss on rectifying tube also can reach (18%～40%) PO, account for more than 60% of power supply total losses.Therefore, traditional diode rectifier circuit can't satisfy the needs of realizing low-voltage, high-current switch high efficiency of power supply and small size, becomes the bottleneck that restriction DC/DC converter is raised the efficiency.

Existing Switching Power Supply is all to adopt special-purpose pulsewidth integrated manipulator, " novel switched power supply practical technique " the 62nd and 63 page of Switching Power Supply of introducing-application pulsewidth integrated manipulator UC3842 in the Electronic Industry Press for example, it is the integrated circuit that applied current is controlled (Current Mode Control) PWM.The deficiency of its existence is: 1, need special-purpose pulsewidth integrated manipulator, cost of manufacture is high; 2, need larger start and ongoing operation electric current; 3, the peripheral components requirement is more, is unfavorable for miniature.

Summary of the invention

The utility model proposes for the shortcoming that overcomes above prior art existence, and its technical problem that solves is to provide the inverse-excitation type synchronous rectifying Switching Power Supply of a kind of low cost, energy consumption.

For this reason, the utility model provides a kind of inverse-excitation type synchronous rectifying Switching Power Supply, comprise armature winding L7, secondary winding L6, circuit of synchronous rectification, drive circuit, testing circuit, control circuit, secondary winding L6 is connected with drive circuit, the circuit of synchronous rectification input is connected with drive circuit, circuit of synchronous rectification output connects secondary winding L6, and testing circuit is located at secondary winding L6 output and drive circuit forms the loop, it is characterized in that:

Described drive circuit comprises auxiliary winding L 2-L4, rectifier diode D9, filter capacitor C30, filter capacitor C33, PNP transistor Q14, field effect transistor Q15, resistance R 85, resistance R 90, diode D15 and diode D16, and wherein auxiliary group of winding L 2-L4, rectifier diode D9, filter capacitor C30 and filter capacitor C33 form a basic rectifying and wave-filtering circuit to whole drive circuitry use.

Described circuit of synchronous rectification comprises metal-oxide half field effect transistor Q3, metal-oxide half field effect transistor Q4, resistance R 69, resistance R 72, resistance R 96, resistance R 97, circuit of synchronous rectification of the present utility model has used the extremely low metal-oxide half field effect transistor Q3(power MOSFET of resistance) replace the circuit of synchronous rectification that rectifier diode D9 and special-purpose pulsewidth integrated manipulator form and can reduce rectifier loss, greatly improve the efficient of DC/DC converter and do not have the dead band voltage that is caused by Schottky barrier voltage.Power MOSFET belongs to voltage-controlled device, and its voltage-current characteristic when conducting is linear.

Described testing circuit comprises detection winding CT1, resistance R 65, capacitor C 31, diode D8, diode D10, resistance R 67, resistance R 66 and resistance R 68, and testing circuit can finish prerequisite for switching signal in switch periods.

Described control circuit comprises diode D11, diode D14, voltage-stabiliser tube ZD3, resistance R 63, resistance R 70, resistance R 71, resistance R 73, resistance R 77, resistance R 78, capacitor C 63, NPN transistor Q11.

Described auxiliary winding L 2-L4 superposition on secondary winding L6, the end of the negative pole contact resistance R77 of rectifier diode D9, the emitter of PNP transistor Q14 and the anode of diode D14; The collector electrode of PNP transistor Q14 is connected to the end of negative electrode, resistance R 85 and resistance R 90 of the D utmost point, diode D15 and the diode D16 of field effect transistor Q15; The other end of the anode of diode D15 and diode D16, resistance R 85 and resistance R 90 is connected to the metal-oxide half field effect transistor Q3 of circuit of synchronous rectification, the G utmost point of metal-oxide half field effect transistor Q4; The base stage of PNP transistor Q14 is connected to an end of the other end, capacitor C 36 and the resistance R 78 of resistance R 77; The other end of capacitor C 36 and resistance R 78 is connected to the negative electrode of voltage-stabiliser tube ZD3; The anodic bonding of voltage-stabiliser tube ZD3 is to an end, the negative electrode of diode D11 and the collector electrode of NPN transistor Q11 of the G utmost point, resistance R 71 and the resistance R 73 of field effect transistor Q15; The other end of resistance R 73 is connected to the negative electrode of diode D14; The other end of resistance R 71 and resistance R 70 are serially connected and are connected to output cathode; The anodic bonding of diode D11 is to the base stage of NPN transistor Q11, an end of resistance R 63; The other end of resistance R 63 is connected to an end of resistance R 66, resistance R 67 and resistance R 68 and the negative electrode of diode D8 and diode D10.

The beneficial effects of the utility model are: the effect transistor MOSFET that drives circuit of synchronous rectification by the drive circuit that builds an effect transistor MOSFET with discrete device, what efficient improved when output current is larger is more, can improve the efficient of power supply, reduce the no-load power consumption energy, reduce material cost.

Description of drawings

Fig. 1 is inverse-excitation type synchronous rectifying switching power circuit figure described in the utility model.

Embodiment

Below in conjunction with accompanying drawing, embodiment of the present utility model is described in further detail.

As shown in Figure 1, the below omits basic circuit is described and just describes around the utility model innovative point.a kind of inverse-excitation type synchronous rectifying Switching Power Supply, include armature winding L7, secondary winding L6, circuit of synchronous rectification, drive circuit, testing circuit, secondary winding L6 is connected with drive circuit, the circuit of synchronous rectification input is connected with drive circuit, circuit of synchronous rectification output connects secondary winding L6, testing circuit is located at secondary winding L6 output and drive circuit forms the loop, described drive circuit comprises auxiliary winding L 2-L4, rectifier diode D9, filter capacitor C30, filter capacitor C33, PNP transistor Q14, field effect transistor Q15, resistance R 85, resistance R 90, diode D15 and diode D16, circuit of synchronous rectification comprises metal-oxide half field effect transistor Q3, metal-oxide half field effect transistor Q4, resistance R 69, resistance R 72, resistance R 96, resistance R 97, testing circuit comprises detection winding CT1, resistance R 65, capacitor C 31, diode D8, diode D10, resistance R 67, resistance R 66 and resistance R 68.

The inverse-excitation type synchronous rectifying Switching Power Supply course of work described in the utility model is as follows:

auxiliary group of winding L 2-L4 and rectifier diode D9, filter capacitor C30, filter capacitor C33 forms a basic rectifying and wave-filtering circuit and uses to whole drive circuitry, when output is when providing energy by transformer secondary output winding L 6 to output, detect the output current that winding CT1 can detect main winding, it detects winding CT1 can be via diode D8, diode D10, resistance R 66, resistance R 67, resistance R 68 forms a closed-loop path, in resistance R 66, resistance R 67, produce a voltage on resistance R 68, this voltage can pass through resistance R 63 driving N PN transistor npn npn Q11, make the G utmost point of field effect transistor Q15 become electronegative potential, the voltage that this time, auxiliary winding produced can be by resistance R 77, resistance R 78 and voltage-stabiliser tube ZD3 dividing potential drop, PNP transistor Q14 is opened make the voltage of auxiliary winding generation can drive synchronous rectification MOSFET.

when transformer secondary output winding L 6 to the current reduction to of output output low value the time, detect winding CT1 in resistance R 66, resistance R 67, the voltage that produces on resistance R 68 with deficiency so that NPN transistor Q11 is open-minded, NPN transistor Q11 enters cut-off state, the voltage that this time, auxiliary winding produced can arrive via diode D14 and resistance R 73 the G utmost point of field effect transistor Q15, make field effect transistor Q15 enter conducting state, simultaneously because resistance R 77, the voltage difference at this serial circuit of resistance R 78 and voltage-stabiliser tube ZD3 two ends is large not and make PNP transistor Q14 enter into cut-off state, synchronous rectification MOSFET will can not get any driving voltage and safety shutdown in this time, this moment, the electric current of transformer secondary output winding L 6 outputs was very little, will continue to power to output by the parasitic diode of MOSFET inside.

Claims

1. inverse-excitation type synchronous rectifying Switching Power Supply, comprise armature winding L7, secondary winding L6, circuit of synchronous rectification, drive circuit, testing circuit, control circuit, secondary winding L6 is connected with drive circuit, the circuit of synchronous rectification input is connected with drive circuit, circuit of synchronous rectification output connects secondary winding L6, testing circuit is located at secondary winding L6 output and drive circuit forms the loop, it is characterized in that:

Described drive circuit comprises auxiliary winding L 2-L4, rectifier diode D9, filter capacitor C30, filter capacitor C33, PNP transistor Q14, field effect transistor Q15, resistance R 85, resistance R 90, diode D15 and diode D16;

Described circuit of synchronous rectification comprises metal-oxide half field effect transistor Q3, metal-oxide half field effect transistor Q4, resistance R 69, resistance R 72, resistance R 96 and resistance R 97;

Described testing circuit comprises detection winding CT1, resistance R 65, capacitor C 31, diode D8, diode D10, resistance R 67, resistance R 66 and resistance R 68;

Described control circuit comprises diode D11, diode D14, voltage-stabiliser tube ZD3, resistance R 63, resistance R 70, resistance R 71, resistance R 73, resistance R 77, resistance R 78, capacitor C 63, NPN transistor Q11;