Texas Instruments Incorporated
SEAMLESS DCM-PFM TRANSITION FOR SINGLE PULSE OPERATION IN DC-DC CONVERTERS

Abstract:

A converter operable to convert an input voltage at an input node to an output voltage at an output node coupled to a load by switching on and off a transistor at a switching frequency, the converter comprising: an error amplifier circuit having a first input coupled to a reference voltage, a second input coupled to the output node through a resistive divider, a first output operable to output a control current and a second output operable to output a current equivalent to the control current; a peak current comparator circuit having a first input coupled to the second output of the error amplifier circuit, a second input and an output, the second input is coupled to the input node through an inductor; an off-time timer circuit having an input coupled to the first output of the error amplifier circuit and an output, the off-time timer circuit operable to set the switching frequency based on the control current; and a control circuit having a first input coupled to the output of the peak current comparator circuit, a second input coupled to the output of the off-time timer circuit and an output coupled to a control terminal of the transistor.