Synchronous rectifier driving circuit with low cost

Abstract

The invention discloses a synchronous rectifier driving circuit with low cost. The synchronous rectifier driving circuit comprises a synchronous rectifier tube Q3, a synchronous afterflow tube Q1, a rectifier tube grid driving circuit and an afterflow tube grid driving circuit, wherein the rectifier tube grid driving circuit comprises a triode Q4, a diode D3, a resistor R2 and a voltage-stabilizer tube D4, the afterflow tube grid driving circuit comprises a triode Q2, a diode D1, a resistor R1 and a voltage-stabilizer tube D2, the drain electrode of the rectifier tube Q3 is connected with the synonym terminal of a secondary winding of a transformer, and the drain electrode of the afterflow tube Q1 is connected with the dotted terminal of the secondary winding of the transformer. The emitter electrodes of the triodes Q4 and Q2 are respectively connected with the grids of MOSFET tubes Q3 and Q1, the base electrodes of triodes Q4 and Q2 are respectively connected with the cathodes of the voltage-stabilizer tubes D4 and D2, and the collector electrodes of the triodes Q4 and Q2 are respectively connected with the cathodes of the diodes D3 and D1. The synchronous rectifier driving circuit is formed by discrete devices, realizes the functions of special synchronous rectifying driving chips, and works with input voltages of wider scope. The design cost of the circuit is lowered.

Description

technical field [0001] The invention relates to the field of switching power supplies, in particular to a low-cost synchronous rectifier drive circuit. Background technique [0002] In order to reduce power consumption, the power supply voltage of various high-performance microprocessors is getting lower and lower, so low-voltage and high-current DC / DC converters are increasingly becoming an important research direction. Due to the large output current of the secondary, the rectification loss becomes the main factor affecting the efficiency. Traditional Schottky diodes have a large on-resistance, which cannot meet the design requirements of high-efficiency converters; and MOSFETs with low on-resistance can effectively reduce losses, which is a synchronous rectification circuit. Synchronous rectifiers can greatly improve the conversion efficiency of converters, and have been widely used in the design of low-voltage and high-current converters. Different from conventional re...

AI Technical Summary

Problems solved by technology

However, the maximum allowable voltage of the MOSFET gate-source limits the input voltage range of the converter, and the circuit must be adjusted to protect the gate for a wide range of input voltages.

Moreover, the self-driving method also has the following disadvantages: there is a dead zone, the driving waveform is poor, and the timing of the driving voltage cannot be controlled, etc.

The external driving method can make up for the shortcomings of the self-driving method and provide high-quality output driving voltage, but the use of a dedicated driver chip increases the design cost of the circuit

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