Demonstration circuit 862 is a micropower regulated charge pump DC/DC converter featuring the 60mA output LTC3221 in a 2mmx2mm DFN package. It comes in three assembly versions, DC862A-A, DC862A-B and DC862A-C, featuring the LTC3221EDC-3.3 (fixed 3.3V output), the LTC3221EDC-5 (fixed 5V output) , and LTC3221EDC (adjustable output set to 3V), respectively. The demo board input voltage range depends on the IC used; for the 3.3V output DC862A-A, the input voltage range is 1.8V to 4.4V.
The LTC3221's low 8µA no-load quiescent current is even lower than the self-discharging current of many batteries. By employing a constant current to charge the output, the output ripple is low even at high input and light load, and is fairly constant over the full input voltage range.