Switching power source with a digital control circuit to maintain a constant DC output signal

摘要

PCT No. PCT/JP97/02172 Sec. 371 Date Jul. 13, 1998 Sec. 102(e) Date Jul. 13, 1998 PCT Filed Jun. 24, 1997 PCT Pub. No. WO97/50165 PCT Pub. Date Dec. 31, 1997A switching power source having a digital control system is provided. The switching power source includes a switching circuit 40 for switching an input power, an output circuit 50 for converting the switching output into a DC output, and a digital control 70. The digital control 70 is adapted to receive an output voltage analog signal AS1 and an output current analog signal AS2, and to convert the signals AS1 and AS2 into digital signals. It further functions to calculate, based on the digital signals, a command value for determining at least one of the switching frequency and the on or off time of the main switch 42. The operation of the main switch 42 is controlled in accordance with the command value. Information on power source input voltage or load terminal voltage is obtained through an assumption based on the signals AS1 and AS2.