19-1217; Rev 0; 4/97
Regulated 3.
3V Charge Pump
_______________General Description
The MAX679 step-up, regulated charge pump generates a 3.
3V ±4% output
voltage from a 1.
8V to 3.
6V input
voltage (two alkaline, NiCd, or NiMH; or one Lithium-Ion battery).
Output current is 20mA (min) from a 2.
0V input.
Only three external
capacitors are needed to build a complete DC-DC converter.
The MAX679’s switching frequency is pin selectable at 330kHz or 1MHz to allow trade-offs between lowest supply current and smallest-size
capacitors.
The logic shutdown function reduces the supply current to 5µA (max) and disconnects the load from the input.
Special soft-start circuitry prevents excessive current from...