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DC/DC transducer synchronous rectification clamping position driving circuit

A drive circuit, synchronous rectification technology, applied in the direction of converting DC power input to DC power output, instruments, electrical components, etc., can solve the problems of Q5 failure, Q5 and Q4 failure, etc., to simplify the circuit, improve reliability, and reduce costs. Effect

Active Publication Date: 2009-04-01
ASTEC POWER SUPPLY (SHENZHEN) CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the above circuit can clamp the positive drive level of the switch tube Q4 to the Vp voltage, since the gate potential of the forward clamp switch tube Q5 is equal to the Vp voltage during the entire switching cycle, when the pole of the third winding W3 When the characteristic change is positive at the top and negative at the bottom, the gate-source voltage of Q5 is equal to Vp+|Vn|, so it will exceed its maximum gate-source breakdown voltage in some input voltage regions, causing Q5 to fail
At the same time, when the input voltage of the converter is high and the polarity of the third winding W3 changes from positive to negative, the negative driving voltage |Vn| may also be greater than the maximum negative gate-source breakdown voltage of Q5 and Q4, so that Q5 and Q4 failure

Method used

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  • DC/DC transducer synchronous rectification clamping position driving circuit
  • DC/DC transducer synchronous rectification clamping position driving circuit
  • DC/DC transducer synchronous rectification clamping position driving circuit

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Such as figure 2 As shown, the transformer T1 includes two secondary windings connected in series: the second winding W2 as the secondary main winding and the third winding W3 as the secondary freewheeling tube driving winding. The opposite end of the second winding W2 is connected to the same end of the third winding W3. The drain of the rectifier switch Q3 is connected to the opposite terminal of the second winding W2, its gate is connected to the same terminal of the second winding W2 through the first resistor R1, and its source is connected to the source of the freewheeling switch Q4. The drain of the freewheeling switch tube Q4 is connected to the terminal with the same name of the second winding W2 on the secondary side of the transformer T1. The anode of the first diode D1 is connected to the opposite terminal of the third winding W3 on the secondary side of the transformer T1, and its cathode is connected to the drain of the forward clamping switch Q5. The s...

Embodiment 2

[0037] Such as Figure 4 As shown, the circuit of this embodiment is based on the circuit of the first embodiment, adding a resistor for adjusting the switching speed of Q6. The second resistor R2 is connected in series between the gate of the negative clamping switch Q6 and the opposite terminal of the secondary winding W3 of the transformer T1. The second resistor R2 plays the role of adjusting the discharge speed of the freewheeling tube Q4, which is beneficial to improving the efficiency of the converter and improving the gate-source driving waveform of Q6.

Embodiment 3

[0039] Such as Figure 5 As shown, compared with the first embodiment, the circuit of this embodiment has one more fourth winding W4 connected in series with the second winding W2 and the third winding W3, and the opposite end of the fourth winding W4 is connected to the second winding W2. The end of the same name is connected. In addition, the source of the rectifier switch Q3 is connected to the same terminal of the second winding W2, its gate is connected to the same terminal of the fourth winding W4, and its drain is connected to the drain of the freewheeling switch Q4.

[0040] The drain of the freewheeling switch Q4 is coupled to the terminal with the same name of the secondary winding W2 of the transformer T1 through the rectifying switch Q3, and its source is connected to the terminal with the same name of the secondary winding W2 of the transformer T1. The anode of the first diode D1 is connected to the opposite terminal of the third winding W3 on the secondary side ...

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PUM

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Abstract

The invention relates to a clamp drive circuit in the synchronous commutation of DC / DC converter including a transformer, a commutation switch tube and a continuous switch tube, in which, the source and drain of the continuous switch are connected with the source of the commutation switch tube and the side winding of the transformer connected with the drain of the commutation switch tube and the circuit also includes a negative clamping drive circuit for counter-discharge for the grating-source of the commutation switch tube or continuous switch tube for clamping the grating to a low level.

Description

[technical field] [0001] The invention relates to a synchronous rectification technology, in particular to a clamp driving circuit in a DC / DC converter synchronous rectification. [Background technique] [0002] Synchronous rectification is the key technology of low-voltage high-current DC / DC converter. On the secondary side of the DC / DC converter, a synchronous rectification MOS transistor (MOSFET) is used to replace the Schottky diode for rectification, which can greatly reduce the conduction loss of the rectification. However, the gate of the synchronous rectification MOS transistor needs a corresponding drive circuit with higher requirements: since the gate oxide layer of the synchronous rectifier is composed of an extremely thin SiO2 layer, if the gate-source voltage Vgs (including negative gate-source negative bias) exceeds its maximum gate-source breakdown voltage, the device may fail permanently. The driving circuit of the synchronous rectifier mostly adopts the pow...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M3/135
Inventor 何建军向志强
Owner ASTEC POWER SUPPLY (SHENZHEN) CO LTD