Inrush current limiter

Abstract

The invention discloses an inrush current limiter in a power supply, comprising a resistor, a field effect transistor and a gate driver. In a startup moment of the power supply, the gate driver does not start the field effect transistor so that an inrush current passes by the resistor and the resistance is limited to a safety value; and in a steady state of the power supply, the field effect transistor is already started by the gate driver so that a steady state current passes by the field effect transistor and the power dissipation is reduced by the field effect transistor to a minimum.

Description

technical field [0001] The present invention discloses an inrush current limiter in a power supply, which utilizes a resistor to limit the inrush current and a field effect transistor to conduct the steady state current. Background technique [0002] When the power supply is turned on, the current flowing into the power supply is called inrush current. In order to protect the power supply from being damaged by the inrush current, an inrush current limiter is usually used to limit the inrush current to a safe value. [0003] The circuit diagrams of the existing high-side inrush current limiter (high-side inrush current limiter) and low-voltage side inrush current limiter (low-side inrush current limiter) implemented by thermistor are shown in Figure 1a and Figure 1b , where the bridge rectifier BD is used to rectify the AC sine wave input voltage into a DC sine wave input voltage; the thermistor R with a negative temperature coefficient (negative temperaturecoefficient) T...

AI Technical Summary

Problems solved by technology

However, practical thermistors cannot satisfy both requirements of an ideal thermistor

That is, practical thermistors cannot simultaneously reduce inrush current and power dissipation

To make matters worse, R initial Decrease with increasing temperature will result in increases with increasing temperature

In other words, if the power supply is turned on at high temperature, the thermistor cannot fully perform the function of the inrush current limiter

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