0.6-μm CMOS-Switched-Inductor Dual-Supply Hysteretic Current-Mode Buck Converter

Microsystems can sense, process, and transmit information between nodes across hospitals, factories, and homes that can save lives, energy, and money. Unfortunately, supplying power with so much embedded functionality is challenging, because while some functions can survive higher noise levels and voltages, others cannot. Power supplies must therefore satisfy several independent outputs without consuming much power or occupying much space. A switched inductor is attractive in this respect because, with only one off-chip inductor, the system can output 80%-90% of the power it draws. Regulating multiple outputs with one inductor, however, links several feedback loops and their reactions to individual and combined loads. The sacrifice for this is usually accuracy in the form of response time. The single-inductor dual-output buck converter presented here uses a hysteretic current loop for this reason: to accelerate the response of the loops used to regulate the outputs. The 0.6-μm CMOS prototype supplies 70 and 50 mA to 1.5- and 2.5-V outputs with 80%-88% power-conversion efficiency and responds to 45-65 mA load dumps within 3.8 μs to keep 1.5 V within ±5% and 2.5 V within ±7%.