Switch mode power converter with overshoot and undershoot transient control circuits

A switch mode power converter (SMPC) comprising:

• a control circuit configured for controlling overshoot and/or undershoot of the output voltage of the SMPC in response to very large and rapid load current transient, wherein the control circuit comprises:
• at least one load variation detector connected for sensing a large and rapid increase or decrease in load current at an output of the SMPC comprising:
• a first input terminal connected for receiving a feedback signal indicative of an output voltage of the SMPC,
• a second input terminal is connected for receiving a variation limit threshold reference voltage,
• a comparator for comparing the feedback signal with the variation limit threshold reference voltage to determine that a large, rapid load current increase or decrease has occurred and generates a panic voltage when the feedback signal exceeds the variation limit threshold reference voltage, and
• an output terminal connected to receive the panic voltage from the comparator for communication to a switch stage of the SMPC such that when the feedback signal has exceeded the variation limit threshold reference voltage, the panic voltage commands the switch stage to activate for sourcing current through or sinking current from a filter stage of the SMPC and thus to or from the load circuit to compensate to the large, rapid load current variation;
• and
• a slope detector connected for receiving the feedback signal and the target reference voltage and configured for creating a slope signal indicative of a slope of the output voltage determined from the difference of the feedback signal and a target reference voltage and configured for determining when the slope of the output voltage changes polarity and generating a slope polarity signal for activating the switch stage for preventing an overshoot or undershoot of the output voltage of the SMPC once the large and rapid current transient has been compensated.

A method for operating a switch mode power converter (SMPC) comprises the steps of:

• monitoring for a very large, rapid load current increase or decrease in a load current flowing from an output terminal of the SMPC;
• determining a type of very large, rapid load current increase or decrease, when the very large, rapid load current increase or decrease in a load current occurs;
• comparing an amplitude of an output voltage of the SMPC with an undershoot threshold voltage;
• when the very large, rapid load current increase or decrease is an increase in the load current;
• activating a switching stage of the SMPC for supplying current to the load circuit, when the output is lesser than undershoot threshold voltage;
• comparing an amplitude of an output voltage of the SMPC with an overshoot threshold voltage;
• when the very large, rapid load current increase or decrease is a decrease in the load current;
• activating a switching stage of the SMPC for sinking current from the load circuit, when the output is greater than overshoot threshold voltage;
• monitoring a polarity of the slope of a change in the output voltage during the very large, rapid load current increase or decrease;
• evaluating the change in the slope for determining that a change in polarity of the slope of the change in the output voltage has occurred;
• deactivating the first switch in the switch stage to stop additional current from flowing to the load circuit to prevent an overshoot, when the changes in polarity of the slope of the change in the output voltage is from negative to positive;
• deactivating the second switch in the switch stage to stop additional current from flowing from load circuit to prevent an undershoot, when the changes in polarity of the slope of the change in the output voltage is from positive to negative;
• and
• activating a normal pulse width modulation operation of the SMPC.