View max679 datasheet:

19-1217; Rev 0; 4/97 Regulated 3.3V Charge Pump _______________General Description ____________________________Features The MAX679 step-up, regulated charge pump gener- Regulated 3.3V ±4% Output ates a 3.3V ±4% output voltage from a 1.8V to 3.6V Ultra-Small: input voltage (two alkaline, NiCd, or NiMH; or one 1.1mm-High, 8-Pin µMAX Package Lithium-Ion battery). Output current is 20mA (min) from a 2.0V input. Only three external capacitors are needed No Inductors Required to build a complete DC-DC converter. Up to 1MHz Operation The MAX679’s switching frequency is pin selectable at (small external components) 330kHz or 1MHz to allow trade-offs between lowest supply current and smallest-size capacitors. The logic Fits into 0.05 in.2 shutdown function reduces the suppl