Simple and reliable pre-bias load starting circuit

Abstract

The utility model discloses a simple and reliable pre-bias load starting circuit for a direct current (DC) converter, consisting of a switching tube Q1, a transistor Q2, a resistor R1 and a resistor R2 and a capacitor C1 and a capacitor C2, a diode D1 and a DC power VCC. The circuit utilizes the current control characteristic of the transistor Q2 to detect the voltage difference of the input voltage and the output pre-bias load voltage of the converter, and controls the turnon and turnoff of the switching tube Q1 according to the voltage difference, thus realizing soft start of the pre-bias load circuit. Simultaneously, the optimization of the pre-bias load starting circuit can be realized by selecting the parameters of R1, C1, R2 and C2 reasonably. The pre-bias load starting circuit can effectively solve the problems of output voltage waveform overshooting, restarting and even damaging module and the like occurring in the starting process of the output pre-bias voltage, and can be widely applied to the starting circuit that is used for the DC converter and has the pre-bias load.

Description

technical field [0001] The invention relates to a direct current to direct current (DC-DC) converter, and is especially suitable for a starting circuit of a direct current converter with a pre-biased load. Background technique [0002] Pre-biased soft-start is one of the main functions of DC converters. It can prevent a single DC converter from discharging the capacitance on a single node of a multi-power pre-biased load during the start-up process, causing node voltage instability or start-up voltage oscillation, and even damage to devices. Therefore, it is widely used in single-node multi-power systems such as redundant power systems, parallel power modules, and battery backup power buses. [0003] At present, various power supply companies and IC design companies have proposed many practical and effective top-bias start-up circuits according to different actual application conditions. Although these circuit structures are different, their working principles can be rough...

AI Technical Summary

Problems solved by technology

Although these chips introduced by IC suppliers have the function of pre-bias voltage startup, these chips are used in non-isolated converters and require a separate auxiliary power supply, which is costly

[0004] The patent (publication number CN101313263A) proposes a pre-bias circuit for synchronous rectification power converters, and the patent (publication number CN1665114A) proposes a starting circuit suitable for converters with pre-biased loads. These two starting circuits The schemes are all developed based on the first working principle. Although the circuit can quickly increase the voltage on the output terminal of the converter and avoid any voltage or current leakage from the output terminal during start-up, its circuit topology is relatively complicated, so the circuit high cost

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