Abstract: The integrable control circuit drives a semiconductor switch in a switched-mode power supply. The control circuit has a control unit for producing control pulses for the semiconductor switch based on a variable oscillator signal. A duration of the individual control pulses depends on a first control signal and on a second control signal. In addition, a measurement system produces the second control signal in dependence on a load current of the semiconductor switch. A power regulation system that receives the oscillator signal produces a third control signal and supplies the signal to the control unit. The third control signal is inversely proportional to the square root of the oscillator frequency. In this way, it is possible for the power output of the switched-mode power supply to remain constant independent of the oscillator frequency.

Abstract: An output isolated, switching power supply has a transformer with a primary and two secondaries, an electronic switch in series with the primary, a first rectifier and filter on the first secondary to provide bias power during both startup and operating modes, and a second rectifier and filter on the second secondary to provide regulated output power. A resistor-capacitor network on the primary side provide 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 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 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.

Abstract: A high efficiency flyback converter with synchronous rectifying, uses an equivalent-conducting resistor of a synchronous switch coupled with the synchronous rectifier to detect the secondary current of a transformer. Included is a logic circuit to control the duty cycle of the synchronous switch to avoid the vibration of the driving pulse. There is no inductance element, such as a current sensor, in the main power circuit loop, so that the power efficiency will be increased. The driving pulse signal drives the synchronous switch to turn on simultaneously with an output diode to reduce the component stress of the output diode, and to reduce the switching loss to promote the efficiency of the flyback converter power supply.