Control circuit for a primary controlled switching power supply with increased accuracy of voltage regulation and primary controlled switched mode power supply

摘要

The circuit has a control output (B) connected with a control input of a primary transistor of a primary controlled switching power supply. A pin (U) is connected with a primary auxiliary winding of a transformer for detecting an auxiliary voltage. The auxiliary voltage is induced depending on a secondary output voltage. An error amplifier (202) compares the detected auxiliary voltage with a reference voltage (Vref2), and amplifies a difference between the detected auxiliary voltage and reference voltage. A feedback branch feeds back output signals of the error amplifier to the pin. An independent claim is also included for a method for controlling a primary switch.