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Synchronous rectification control method, synchronous rectification control circuit and switch-type voltage regulator

A synchronous rectification and control circuit technology, which is applied in the electronic field, can solve the problems of precision influence and performance reduction of synchronous rectification circuit, etc.

Active Publication Date: 2014-01-08
SILERGY SEMICON TECH (HANGZHOU) CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the comparator in practical applications has an input offset voltage, such as 0.03V (volts), when the on-resistance of the rectifier switch is very small, its on-voltage drop may be lower than the offset voltage of the comparator. Therefore, the zero-crossing detection The accuracy of the synchronous rectification circuit will be greatly affected, thereby reducing the performance of the synchronous rectification circuit

Method used

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  • Synchronous rectification control method, synchronous rectification control circuit and switch-type voltage regulator
  • Synchronous rectification control method, synchronous rectification control circuit and switch-type voltage regulator
  • Synchronous rectification control method, synchronous rectification control circuit and switch-type voltage regulator

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Embodiment 1

[0064] In a synchronous rectification circuit (usually part of a switching voltage regulator), there is a rectifying switch connected to an inductor. In order to eliminate output filter circulating current, reduce magnetic loss and switching loss, and prevent backflow current, it is necessary to control the synchronous rectification circuit to work in the inductor current discontinuous mode, that is, DCM (Discontinuous Conduction Mode) mode, so in order to ensure the above-mentioned The overall performance of the synchronous rectification circuit needs to control and turn off the rectification switch tube when the inductor current is zero.

[0065] It should be noted that the synchronous rectification circuit includes but not limited to a BOOST structure circuit, a BUCK structure circuit and a BOOST-BUCK structure circuit. Among them, the rectifier circuit with BOOST structure is also called step-up rectifier circuit, the rectifier circuit with BUCK structure is also called st...

Embodiment 2

[0086] The basic working principle of this embodiment is the same as that of the first embodiment, and the difference between it and the first embodiment is that this embodiment provides a preferred implementation manner for updating the count value.

[0087] In this embodiment, a count value is set or updated when the rectifier switch tube is turned on; a shutdown enable signal is generated after a time delay corresponding to the count value is executed; according to the shutdown enable signal controlling to turn off the rectifier switch tube, and judging the drain-source voltage V when the rectifier switch tube is turned off DS with a preset reference voltage V ref size relationship. In specific implementation, the above process is the same as that in Embodiment 1, and will not be repeated here.

[0088] Further, in this embodiment, according to the drain-source voltage V DS with the reference voltage V ref The size relationship of , generating a comparison signal for up...

Embodiment 3

[0102] The embodiment of the present invention also provides a synchronous rectification control circuit, which is used to control the rectification switch tube in the synchronous rectification circuit.

[0103] Specifically, this embodiment takes a synchronous rectification circuit with a BOOST structure as an example to illustrate the working principle of a synchronous rectification control circuit provided by the present invention. It should be noted that the synchronous rectification circuit provided by the present invention may include but not limited to a BOOST structure circuit, a BUCK structure circuit and a BOOST-BUCK structure circuit.

[0104] see image 3 , is a schematic structural diagram of a synchronous rectification control circuit provided in Embodiment 3 of the present invention.

[0105] The synchronous rectification control circuit provided in this embodiment is used to control the rectification switch MOSFET in the synchronous rectification circuit, incl...

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Abstract

The invention discloses a synchronous rectification control method which comprises the following steps: when a rectification switching tube is turned on, setting or updating a count value; after executing time delay corresponding to the count value, generating a turn-off enable signal; according to the turn-off enable signal, controlling to turn off the rectification switching tube and judging a size relation between a drain-source voltage of the rectification switching tube and a preset reference voltage; and according to the size relation between the drain-source voltage of the rectification switching tube and the preset reference voltage, generating a comparison signal for updating the count value. The invention also provides a synchronous rectification control circuit and a switch-type voltage regulator applying the same. The synchronous rectification control circuit and the switch-type voltage regulator have the advantages of high accuracy, flexibility for regulation, low switching loss and improvement on conversion efficiency of a system.

Description

technical field [0001] The invention relates to the field of electronic technology, in particular to a synchronous rectification control method, a control circuit and a switch-type voltage regulator. Background technique [0002] In the synchronous rectification circuit, in order to obtain a switching power supply with superior performance, the synchronous rectification switching tube should be controlled to be turned off when the inductor current is zero, that is, try to make the switching power supply work in the inductor current discontinuous mode (Discontinuous Conduction Mode, referred to as DCM) mode. In DCM mode, it is necessary to control the rectifier switching tube to turn off when the inductor current is zero, so the switching power supply can eliminate the output filter loop current, reduce the magnetic loss and switching loss, and prevent back-feeding current, thereby improving reliability. [0003] In order to achieve the above purpose, it is usually necessary...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M3/156H02M3/157
CPCH02M3/1588Y02B70/10
Inventor 陈君王珏
Owner SILERGY SEMICON TECH (HANGZHOU) CO LTD