Integrated soft=start pulse width modulation power supply circuit

摘要

The circuit includes a comparison voltage signal generator (10) whose output (V1) rises with a predetermined slope and varies in response to a feedback signal during the normal operation. There is a soft-start and external synchronisation signal input section (20) whose output (V2) rises with a gentler slope and is overlaid with the external sync signal (V3). The superimposed signal level is compared (30) with a reference voltage (VREF2) to generate (40) a triangular wave at a lower frequency, during soft-start operation, and at the external sync frequency in normal operation. The pulse width modulation signal from the modulator (50) is proportional to the comparison voltage signal level.