Demonstration circuit 903 is a step-up/step-down charge pump dc-dc converter. It comes with two assembly versions, DC903A-A and DC903A-B featuring the 150mA output current LTC3240-3.3 (3.3V output) and LTC3240-2.5 (2.5V output) respectively, each in a tiny 2mm x 2mm DFN package. The DC903A-A and DC903A-B operate with an input voltage from 1.8V to 5.5V.
When using the DC903A-A, the output current can reach up to 150mA when the input voltage is above 2.5V. The maximum output current of the DC903A-B is 60mA with a 1.8V input voltage. The DC903A optimizes the output efficiency by operating in the LDO step-down mode during the time the input is higher than the output voltage. When the input voltage drops low enough, The LTC3240 automatically switches to charge-pump doubling mode to extend system run-time. Built-in soft-start limits inrush current at turn-on, and short-circuit current limit/thermal protection help the part survive a continuous short-circuit.
Additionally, the DC903A features Automatic Burst Mode operation at light load to achieve low supply current (65µA, no load).