Control circuit for switched current regulator - uses comparator acting as pulse width modulator for controlling transistor switch element.

摘要

The switched current regulator acting as a constant current source in PCM appts. has a control circuit provided by a comparator (22), controlling the switch element (18) via a coupling capacitor (20). The inverting input of the comparator (22) is supplied with a sawtooth voltage (b) obtained from a clock signal (a), its non-inverting input receiving a regulating voltage (c), obtained from a current measuring element (9) inserted in the current circuit of the switch element (18) via an amplifier. Pref. the switch element (18) is provided by a bipolar transistor or a FET, the comparator (22) acting as a pulse width modulator. ADVANTAGE - Loss-free control of switch element and reduced output filter.