Load control apparatus

摘要

A load control apparatus is provided in which a circuit of detecting an overcurrent can be correctly operated even if a first capacitor (C1) for noise measures is disposed. Since a second capacitor (C2) is provided between a gate and a drain of an FET (T1), when the voltage (V1) of a point (P1) decreases, a part of the gate current of the FET (T1) bypasses the FET (T1) and flows to the capacitor (C2), and the amount of charge supplied to the gate of the FET (T1) decreases. Therefore, the increase of the drain current of the FET (T1) can be suppressed and a sudden change of the voltage (V1) can be prevented. As a result, the voltage (V1) can be prevented from decreasing to such a degree that the comparator (CMP1) cannot operate, and the comparator (CMP1) can be prevented from malfunctioning.

主权项

1. A load control apparatus that controls a drive and a stop of a load by switching on and off a field effect transistor which is provided between a DC power supply and the load, wherein
a drain electrode of the field effect transistor is connected to a plus electrode of the DC power supply via a power supply line, and a source electrode of the field effect transistor is connected to one end of the load via a load line, and the other end of the load is connected to a minus electrode of the DC power supply, the load control apparatus comprising: a comparing unit that is configured to detect an overcurrent by comparing a reference voltage based on a drain voltage of the field effect transistor and a source voltage of the field effect transistor; a control unit that is configured to output a drive signal to a gate electrode of the field effect transistor when the load is to be driven, and also to stop output of the drive signal when the overcurrent is detected by the comparing unit; a first capacitor that is provided between the drain electrode of the field effect transistor and the minus electrode of the DC power supply; and a second capacitor that is provided between the gate electrode and the drain electrode of the field effect transistor.