Patent ID: 9124184
Filing Date: 2015-09-01
Classification: H02M

Abstract:
1. A control circuit for a DC/DC converter comprising a transformer and a switching transistor arranged on a current path of a primary winding of the transformer, the control circuit comprising: a detection terminal configured to be connected to one end of an external detection resistor arranged on the current path of the primary winding such that the other end of the detection resistor is grounded; a feedback terminal configured to receive a feedback voltage that corresponds to an output voltage of the DC/DC converter; a pulse modulator configured to generate a pulse signal having a duty ratio that is adjusted such that the output voltage of the DC/DC converter approaches a target value, and to switch the pulse signal to an off level that corresponds to an off state of the switching transistor according to a detection voltage that develops at the detection terminal; a driver configured to perform switching of the switching transistor according to the pulse signal; and a short-circuit detection circuit configured to generate a short-circuit detection signal which is asserted when the detection voltage is lower than a short-circuit detection threshold voltage after a judgment time elapses after the pulse signal is switched to an on level that corresponds to an on state of the switching transistor, wherein, when the short-circuit detection signal is asserted, the pulse modulator is configured to switch the pulse signal to the off level.