Overcurrent protection device and overcurrent protection system

Abstract

Provided are an overcurrent protection device and an overcurrent protection system which can provide time differences among the timings for executing the retry operations among a plurality of overcurrent protection devices connected to a common power supply. When a battery voltage (VBA) becomes a value equal to or lower than a threshold voltage after an FET (Q1) of an IC circuit (51-1) is turned on, all FETs (Q1) of the respective IC circuits are turned off, and a time until the battery voltage (VBA) reduces to a value lower than a threshold voltage after the turning-on of the FET (Q1) is clocked. When the time is smaller than 400 [mu]sec, the count value N is incremented. Further, turning-on of the FETs (Q1) is repeated after the lapse of the standby time (Tp) set randomly. When the count value N reaches 7, the FET (Q1) of the IC circuit (51-1) is held in the turned-off state. Accordingly, only the load-driving circuit at which the dead short occurs can be stopped and the driving of the other load-driving circuits can be continued.

Description

technical field [0001] The present invention relates to an overcurrent protection device and an overcurrent protection system. There are multiple overcurrent protection devices, and when an overcurrent flows through a load drive circuit composed of a load, an electronic switch and an electric wire, the The electronic switches of the load driving circuit are disconnected, thereby protecting the electronic switches and wires provided in the load driving circuit. Background technique [0002] For example, a load such as a light bulb or a motor mounted on a vehicle is connected to a battery through an electronic switch (for example, MOSFET), and its driving operation and stopping operation are controlled by switching the electronic switch between its on and off states. Furthermore, when a fault such as a short circuit occurs on the load, and thus an overcurrent flows through the load drive circuit, the load and the connection harness may be damaged due to heat generation. There...

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Problems solved by technology

[0003] In addition, when a dead short occurs in the load drive circuit, a counter electromotive force due to the impedance of the wiring is generated, resulting in a sharp drop in the voltage on the power supply side

Therefore, according to the method of detecting overcurrent based on the comparison result of the load current and the reference current, it may happen that when the power supply voltage drops to a voltage equal to or less than the operating range voltage of the operational amplifier, its overcurrent detection circuit itself cannot perform its function, Therefore, the electronic switch does not work properly in case of

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