Apparatus for sensing the presence of an inductive load driven by a pulse width modulated signal

摘要

A circuit (60) for sensing the presence of an inductive load that is particularly applicable to sensing when a solenoid is being driven by a pulse width modulation (PWM) signal (62). The circuit (62) includes a high side connected transistor (68) having an output driving a load, with the transistor driven by a PWM signal (62). A circulating diode (70) is coupled to the driving output of the transistor (68). The circuit (60) further comprises an operational amplifier (op amp) circuit (66) that is coupled to the circulating diode (70) and operates as an inverting operational amplifier (op amp). The op amp circuit (66) charges a first capacitor (64) when the transistor (68) releases driving an inductive load.