SYNCHRONOUS VCC GENERATOR FOR SWITCHING VOLTAGE REGULATOR

摘要

A capacitor is charged synchronously with the beginning of an ON portion of a pulse width modulated (PWM) signal to generate a voltage across the capacitor using charging current sourced from an inductor on a primary side of a transformer. The voltage is supplied as a supply voltage to control circuitry in an integrated circuit used to generate the pulse width modulated signal. The charging is stopped when either the charging current goes above a predetermined charging current level or when the capacitor voltage goes above a predetermined capacitor voltage.