Patent ID: 8339113

Claim:
A switch mode power supply (SMPS) controller using hysteretic control in combination with pulse-width modulation (PWM) control, said controller comprising: a hysteretic control circuit having a first input coupled to a reference voltage, a second input coupled to a feedback voltage representing a load side output voltage of a switch mode power supply (SMPS), a first output for controlling a high side hysteretic demand, and a second output for controlling a low side hysteretic disable; a PWM error generator having a third input coupled to the reference voltage, a fourth input coupled to the feedback voltage, a fifth input coupled to a current sense circuit, and a third output for controlling PWM demand; and a power circuit driver having a high side (HS) power control output, and a low side (LS) power control output, the HS and LS power control outputs are adapted to drive power switches of a switch mode power supply (SMPS), the third output of the PWM error generator is coupled to the power circuit driver for control thereof, and the first and second outputs of the hysteretic control circuit are coupled to the power circuit driver for further control thereof; the PWM error generator third output controls the power circuit driver to make the feedback voltage substantially equal to the reference voltage unless a difference between the feedback voltage and the reference voltage is greater than at least a predetermined value, wherein if the feedback voltage is greater than the reference voltage by at least the predetermined hysteretic value, then the hysteretic control circuit forces the HS and LS power control outputs to an off-state, if the feedback voltage is less than the reference voltage by at least the predetermined hysteretic value, then the hysteretic control circuit turns on the HS power control output and turns off the LS power control output, and otherwise the PWM error generator controls the HS and LS power control outputs so as to force the difference between the reference voltage and the feedback voltage to substantially zero over a certain time period.