FAST STARTUP CONTROL CIRCUIT FOR SWITCH MODE POWER SUPPLY

摘要

A control circuit for a switch mode power supply (SMPS) includes a power switch for coupling to a primary winding of the power supply and a startup resistor coupled to an external input voltage and to a control terminal of the power switch. The control circuit also includes a controller. During startup, the controller is configured to cause the power switch to amplify a startup current from an external input voltage through the startup resistor and provide a startup power to the controller. During normal operation, the controller is configured to provide a power switch control signal to turn on and off the power switch for controlling a current flow in the primary winding and regulating an output of the power supply. The controller is configured to provide a current signal for driving an NPN power switch and to provide a voltage signal for driving an NMOS power switch.

主权项

1. A controller for a switch mode power supply (SMPS) having a power switch coupled to a primary winding for regulating an output of the power supply, wherein the controller is configured to provide a current signal for driving an NPN power switch, and the controller is also configured to provide a voltage signal for driving an NMOS power switch.