| 摘要 |
Improved control circuitry for pulse-width-modulated power supplies is described that includes a pulse generator for generating a train of trigger pulses at a predetermined repetition frequency, a signal source for generating a reference voltage and a comparator for comparing the power supply output voltage to the reference voltage and generating a first state of a switching control signal in response to each trigger pulse from the pulse generator and a second state of the switching control signal when the magnitude of the power supply output voltage is equal to the magnitude of the reference voltage. The first state of the switching control signal enables switching transistors of the switching power supply, and the second state of the switching control signal disables the switching transistors. The comparator also includes circuitry for reducing the magnitude of the reference voltage when the switching control signal has the second state. Thus, once the switching transistors are disabled by the second state of the switching control signal, the magnitude of the reference voltage is reduced by a predetermined amount so that the switching transistors cannot be re-enabled until the next trigger pulse from the pulse generator causes the switching control signal to change states.
|
