A Fully Autonomous 1.2A Auxiliary Buck DC-DC Converter for Fast Transient Load-on-Demand

A fully autonomous auxiliary buck converter for supplying transient load current is proposed in this paper. When connected in parallel with the existing converter, the auxiliary converter can support load transients as fast as 1A/10ns hence relaxing the bandwidth and output capacitor requirements of the main converter. The proposed auxiliary buck converter can be either integrated on-chip with the main dc-dc converter or used with a standalone converter. A built-in always ON low quiescent current transient detector predicts the load transient in the output and automatically enables/disables the auxiliary converter whenever demanded by the system load. Designed and fabricated in 180nm CMOS process for maximum output current of 1.2A at input supply of 1.8V, the converter uses only 56nH inductor and consumes 15μA quiescent current. Measurement results of the prototype chip show more than 5x improvement in the transient response when connected in parallel with TI's TPS6206x-Q1 buck converter without requiring a large output capacitor.