PROTECTED HIGH-SIDE OUTPUT

Publishing Venue

Motorola

Related People

Abstract

The purpose of this circuit is to drive a grounded load from a microprocessor output port. There are several features: the VBAT supply can vary between 6 to 24 volts, the circuit is designed to drive an unclamped inductive load, and the circuit is self-pro- tected from the load being shorted to ground.

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MOTOROLA INC. Technical Developments Volume 13 July 1991

PROTECTED HIGH-SIDE OUTPUT

by Guy Griffin

  The purpose of this circuit is to drive a grounded load from a microprocessor output port. There are several features: the VBAT supply can vary between 6 to 24 volts, the circuit is designed to drive an unclamped inductive load, and the circuit is self-pro- tected from the load being shorted to ground.

The circuit is inverting from input to output, and is turned on and off by the transition of the input signal.

The sensed output voltage is fed back to a comparator. If the output voltage drops below a certain threshold, set by R5 and R6, the comparator will turn off the out- put MOSFET. The input must then make a high to low transition to reset (turn on) the output. Dl and D2 are there to protect the comparator inputs from over and under voltage conditions. R7 maintains that, under low VBAT conditions, the output stays on when it is supposed to.

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