Patent ID: 7098632

Claim:
A controller in a voltage mode buck converter for implementing a mode switch function and an over-current protection by a multifunction pin, the controller comprising: a driver responsive to a first control signal for generating a first drive signal and a second drive signal for switching a high side switch and a low side switch connected in series by a phase node to generate an output voltage; a CCM/DCM control circuit for generating the first control signal; a multiplexer for generating a second control signal and a third control signal from the second drive signal; an over-current sense circuit controlled by the second control signal for sensing a voltage on the multifunction pin to thereby generate an over-current signal for signaling the CCM/DCM control circuit; and a CCM/DCM sense circuit controlled by the third control signal for sensing the voltage on the multifunction pin and the output voltage to thereby generate a CCM mode switch signal for the CCM/DCM control circuit to switch the converter between a CCM mode and a DCM mode; wherein the multifunction pin and phase node has a phase resistor connected therebetween for generating a voltage drop between the multifunction pin and phase node when a current flowing therethrough.