Soft start and soft shutoff circuit for Buck converters

A soft-start and soft-shutdown technology, applied in the electronic field, can solve problems such as battery internal resistance, heat generation, system circuit system abnormalities, etc., and achieve the effect of preventing surge current

Inactive Publication Date: 2016-08-31
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It is possible to damage the switch tube and other components, resulting in abnormalities in the system circuit system
In addition, in practical applications, most of the power sources of portable electronic products are batteries. Due to problems such as internal resistance and heat generation, the batteries may be burned if a large current flows instantaneously.

Method used

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  • Soft start and soft shutoff circuit for Buck converters
  • Soft start and soft shutoff circuit for Buck converters
  • Soft start and soft shutoff circuit for Buck converters

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Embodiment Construction

[0011] Below in conjunction with accompanying drawing, describe technical scheme of the present invention in detail:

[0012] In order to eliminate the surge current in the start-up phase, the present invention uses the slope voltage VSS_OUT to compare with VFB in the soft-start phase to realize the output soft-start. In the soft turn-off stage, the output voltage drops slowly to turn off the chip slowly. The present invention will be described in detail below in conjunction with the accompanying drawings.

[0013] The specific circuit structure diagram of the soft start / soft shutdown of the present invention is as follows: Figure 4 As shown, where I1 is the constant charging current of the soft-start / soft-off module, which is used to generate a stable slope VSS_OUT; I2 is the constant discharge current of the soft-start / soft-off module (after EN is turned off), so that VSS_OUT slowly decreases until The chip is turned off, and the soft shutdown is completed; I3 is also a c...

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Abstract

The invention belongs to the technical field of electronics, and relates to a soft start and soft shutoff circuit for Buck converters. According to the circuit of the invention, during system powering-on, an SS-end soft start capacitor CSS is charged by a current source to generate a slowly rising slope voltage VSS_OUT, VSS_OUT is compared with a feedback voltage VFB to make VFB rise slowly with VSS_OUT, so that the output voltage rises slowly, and surge current and output voltage overshoot are avoided. The beneficial effects are as follows: a soft start/soft shutoff circuit for Buck converters is provided, and in the soft start stage, slow rise of the output voltage is ensured, and surge current is prevented; and in the soft shutoff stage, the output voltage drops slowly to shut off a chip slowly.

Description

technical field [0001] The invention belongs to the field of electronic technology and relates to a soft start and soft turn off circuit for a Buck converter. Background technique [0002] With the wide application of portable electronic products in the fields of communications, computers and consumer electronics, the demand for power management ICs continues to rise. The DC-DC switching power supply is widely used due to its advantages of wide input voltage range, large output current, small quiescent current, and wide output load range. The switching power supply is to drive the switch by converting the error signal into a duty cycle control signal. If the DC-DC switching power supply does not have soft-start protection, in the start-up phase, the error amplifier is in an unbalanced state, and the PWM output duty cycle of the power tube drive signal reaches 100%. After the power tube is turned on, a large surge current will be generated to charge the output capacitor. I...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M1/34H02M1/36
CPCH02M1/34H02M1/36H02M3/155
Inventor 明鑫李要何烨王卓张波
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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