Switching tube control circuit

A technology for controlling circuits and switching tubes, applied in control/regulating systems, electrical components, regulating electrical variables, etc., can solve the problems affecting system efficiency, detection errors, and the inability to detect the lowest point of voltage difference, so as to improve system efficiency, The effect of reducing switching losses

Active Publication Date: 2016-03-30
JOULWATT TECH INC LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a switching tube control circuit to solve the problem that the existing detection circuit cannot detect the lowest point of the voltage difference, which causes detection errors and affects the system efficiency.

Method used

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Examples

Experimental program
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Embodiment 1

[0028] Please refer to Figure 4 , the embodiment of the present invention discloses a switching tube control circuit, including a second inductor L2, a second freewheeling diode D2, a second switching tube Q2, a load, a differential circuit 3, a comparator 4 and a control circuit 5.

[0029] In this embodiment, the second switching transistor Q2 is a second switching MOS transistor Q2.

[0030] In this embodiment, the differential circuit 3 includes a first resistor R1 and a first capacitor C1, the two ends of the first resistor R1 are respectively connected to the output terminal of the differential circuit 3 and the zero potential, and the two ends of the first capacitor C1 are respectively connected to the second The drain of the switch MOS transistor Q2 and the output terminal of the differential circuit 3 .

[0031] In this embodiment, the first input terminal of the comparator 4 is connected to the output terminal of the differential circuit 3 , and the second input te...

Embodiment 2

[0039] Please refer to Figure 6 , the embodiment of the present invention discloses a second control circuit, including a second inductor L2, a second freewheeling diode D2, a second switching tube Q2, a differential circuit 3, a comparator 4 and a control circuit 5.

[0040] In this embodiment, the second switching transistor Q2 is a second switching MOS transistor Q2.

[0041] In this embodiment, the differential circuit 3 includes a second resistor R2 and the drain and gate parasitic capacitance Cgd of the second switch MOS transistor Q2, and the two ends of the second resistor R2 are respectively connected to the gate of the second switch MOS transistor Q2 and the zero potential . The gate of the second switch MOS transistor Q2 serves as the input terminal and the output terminal of the differential current detection circuit 3 at the same time.

[0042] In this embodiment, the first input terminal of the comparator 4 is connected to the gate of the second switching MOS ...

Embodiment 3

[0050] Please refer to Figure 7 , the embodiment of the present invention discloses a third control circuit, including a second inductor L2, a second freewheeling diode D2, a load, a second switching tube Q2, a differential circuit 3, a comparator 4 and a control circuit 5.

[0051] In this embodiment, the second switching transistor Q2 is a second switching MOS transistor Q2.

[0052] In this embodiment, the control circuit 5 includes an edge detection circuit 6 , a control drive circuit 7 , a switching transistor turn-on switch S1 and a gate pull-down MOS transistor Q3 . The input end of the edge detection circuit 6 is the input end of the control circuit 5, and the edge detection circuit 6 and the control drive circuit 7 are electrically connected in sequence; The second output terminal of the circuit 7 is connected to the gate of the gate pull-down MOS transistor Q3. The switch tube is turned on, and the two ends of the switch S1 are respectively connected to the gate o...

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PUM

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Abstract

The invention discloses a switching tube control circuit. The switching tube control circuit comprises a switching tube, a differential circuit, a comparator and a control circuit, wherein the input end of the differential circuit is connected with a drain of the switching tube, the output end of the differential circuit is connected with a first input end of the comparator and used for sampling differential current generated when the drain voltage of the switching tube changes, a second input end of the comparator inputs a voltage predetermined threshold value, the comparator is used for comparing the output voltage of the differential circuit with the voltage predetermined threshold value, the output end of the comparator outputs a switching tube control signal, the input end of the control circuit is connected with the output end of the comparator, the output end of the control circuit is connected with a grid of the switching tube, and the control circuit is used for judging whether the drain voltage of the switching tube reaches a minimum value or not according to the switching tube control signal output from the comparator, and controlling the switch-on of the switching tube when the drain voltage of the switching tube reaches the minimum value.

Description

technical field [0001] The invention relates to the field of switching power supplies, in particular to a switching tube control circuit. Background technique [0002] Insulated gate field effect transistor (MetalOxideSemiconductorFET, referred to as MOSFET, or MOS tube) is often used as a switching tube in a switching power supply circuit. The critical conduction mode is one of the working modes of the switching power supply, which occurs during the off-cycle of the MOS tube. It is hoped that the MOS tube can be turned on when the inductor current drops to zero and the drain voltage of the MOS tube is the lowest, so that the maximum Minimally reduce the instantaneous switching power consumption when the MOS tube is turned on, and improve the system efficiency. Therefore, the detection circuit needs to accurately detect the moment when the difference between the drain and source voltages of the MOS transistor is the lowest. [0003] Please refer to figure 1 , the current ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M3/157
CPCH02M3/157
Inventor 白浪黄必亮任远程周逊伟
Owner JOULWATT TECH INC LTD
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