摘要 |
An output isolated, switching power supply (100) has a transformer (73) with a primary (91) and two secondaries (92, 93), and electronic switch (75) in series with the primary, a first rectifier (87) and filter (88) on the first secondary (93) to provide bias power during both startup and operating modes, and a second rectifier (80) and filter (82) on the second secondary (92) to provide regulated output power. A resistor-capacitor network (78, 74) on the primary side provides an initial operating condition, such as a single control pulse, to the electronic switch which causes sufficient energy to be transferred through the first secondary to supply sufficient startup energy to operate a current control integrated circuit (89) on the secondary side in a staged fashion. After the initial operating condition, the current control integrated circuit generates and applies a control signal to the electronic switch through an isolation circuit (77) to cause the electronic switch to turn on and off in controlled fashion in order to deliver regulated power to the output of the supply. The low voltage, secondary side, current control integrated circuit provides a further aspect of the present invention. |