Ultra-Low Frequency DC-DC Converters Using Switched Batteries

To address ultra-low frequency DC-DC converters, we explore the concept of the switched battery converter. It is mainly derived from the switched capacitor converter topology replacing the flying capacitors by flying batteries. The best-in- class energy density of batteries compared to inductors and capacitors reduces drastically the operating frequency at low output power delivery while maintaining low output ripple. An experimental evaluation using mm3 -scale off-the-shelf NiMH battery is described in this paper to present a first proof-of- concept of switched-battery converter. The characterized 2: 1 DC- DC converter achieves 25mW at 1.2V output voltage in 74mm
³
battery operating as low as 0.1 Hz operating frequency while maintaining less than 15 % output voltage ripple without output filtering.