Constant current circuit of DC converter

A technology of DC converter and constant current, which is applied in the direction of conversion of DC power input to DC power output, output power conversion devices, instruments, etc. It can solve the problems of pull-down tube process and temperature deviation, and affect the accuracy of limiting current, so as to improve Response time, precise effect of limiting current

Inactive Publication Date: 2013-10-02
SHANGHAI XINDI INFORMATION TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] 1. There is a certain process and temperature deviation in the threshold of the pull-down tube itself,

Method used

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  • Constant current circuit of DC converter
  • Constant current circuit of DC converter

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Example Embodiment

[0014] The present invention will be further described below in conjunction with embodiments and drawings.

[0015] Reference figure 1 As shown, a constant current circuit of a DC converter is shown in the part enclosed by the dashed frame, and includes an operational amplifier 20, a pull-down tube 10 and a bias voltage generating circuit 30. The output terminal of the error release device in the DC converter is the first node, which connects the drain of the pull-down tube 10 and the non-inverting input terminal of the operational amplifier 20, and the gate of the pull-down tube 10 is connected to the operational amplifier 20. At the output end, the source of the pull-down tube 10 is grounded. The output terminal of the bias voltage generating circuit 3 is connected to the inverting input terminal of the operational amplifier 20, and the input terminal of the bias voltage generating circuit 3 is connected to the input terminal of the driving circuit in the DC converter.

[0016...

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PUM

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Abstract

The invention relates to a constant current circuit of a DC converter. The constant current circuit comprises an operational amplifier, a lower pull tube and a bias voltage generating circuit. An output end of an error amplifier in the DC converter is a first node and connected with a drain electrode of the lower pull tube and a non-inverting input end of the operational amplifier, a grid electrode of the lower pull tube is connected with an output end of the operational amplifier, and a source electrode of the lower pull tube is grounded; and an output end of the bias voltage generating circuit is connected to an inverting input end of the operational amplifier, and an input end of the bias voltage generating circuit is connected to an input end of a driving circuit in the DC converter. The constant current circuit provided by the invention is more accurate in limiting the current and faster in response speed. When voltage of the first node is smaller than the bias voltage, the lower pull tube is closed; and when the voltage of the first node rises to a bias voltage value, the operational amplifier suppresses the voltage of the first node to the bias voltage. The bias voltage generating circuit is additionally arranged, and the bias voltage outputted by the bias voltage generating circuit equals to the sum of a fixed voltage and a voltage related to output clock of the driving circuit, thereby enabling a switch to limit the current to maintain constant.

Description

technical field [0001] This invention relates to integrated circuit design, in particular to a constant current limiting circuit for use in DC converters (BUCK). Background technique [0002] The working loop of the DC converter in the prior art includes a sawtooth wave generating circuit, a voltage conversion circuit with a BLCK structure, an output voltage feedback circuit and a switch current limiting circuit. The slope of the sawtooth wave is added by two parts: the first part is a fixed slope, which is provided by an integrated component other than the converter; the slope of the second part is proportional to the switch current, and is obtained by the switch current detection circuit from the NMOS connected to the input voltage. Obtained on the drain of the switching tube. The output voltage of the conversion circuit generates a feedback voltage through the feedback network, which is connected to the negative input terminal of the error amplifier, and the output termi...

Claims

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Application Information

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IPC IPC(8): H02M3/156
Inventor 肖国庆
Owner SHANGHAI XINDI INFORMATION TECH
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