Circuitry for maintaining a substantially constant sense current to load current ratio through an electrical load driving device

Abstract

Circuitry for driving an electrical load (,) and regulating a load current (IL) therethrough includes a multiple output load driving device (,) having an input (,) receiving a gate drive signal (GD) thereat and operable to direct the load current (I,) therethrough from a collector (,) to main (,) and sense (,) outputs thereof. A control circuit is provided including an error amplifier (,) having a non-inverting input operable to receive a reference voltage and an inverting input operable to receive a sense voltage proportional to the portion of load current (I,) flowing through the sense output (,) of the load driving device (,), and producing an output based thereon to which a gate drive control circuit (,) is responsive to supply the gate drive signal (GD). A feedback capacitor (CFB) is disposed between the collector (,) of the load driving device (,) and a resistor string (R,R,RTRIM) establishing the reference voltage, and provides an AC coupling therebetween. This AC coupling compensates for oscillations in the load current (I,) during load current regulation operation and therefore provides for a stable load current (I,) during such operation. In accordance with another aspect of the present invention, the feedback capacitor (CFB) is advantageously formed with an IGBT (,) on a single monolithic integrated circuit.