Transient Response Improvement in DC-DC Converters Using Output Capacitor Current for Faster Transient Detection

Demanding high power applications, such as fast processors, and pulsed loads are requiring new levels of performance from DC/DC converters. The requirements of high slew rate of load current with minimal output voltage deviation along with high conversion efficiency, small size and low cost, are all contradicting requirements for the DC/DC converter design. Proposed is a new approach to significantly limit the voltage overshoot and undershoot during load transient and reduce the number of capacitors, without compromising on the efficiency, cost or size of the DC/DC converter. It allow to optimize the power stage efficiency for the DC operation with less concern of dynamic performance, while an additional switching circuit; that utilizes the output capacitor current to detect load transient; is activated during load step up to deliver the shortage charge to the output capacitor, and also to pull out the extra charge from the output capacitor during load step down. Therefore, lower voltage deviation is achieved during load transient. The principle of operation and experimental results are presented.