MAX679

Regulated 3.3V Charge Pump

Compact, Inductorless, Low-Profile 3.3V Backup Supply Fits in 0.075 Sq. Inch

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Overview

Regulated 3.3V ±4% Output
Ultra-Small: 1.1mm-High, 8-Pin µMAX Package
No Inductors Required
Up to 1MHz Operation (small external components)
Fits into 0.05 in.²
Up to 85% Efficiency
1.8V to 3.6V Input Voltage Range
50µA Quiescent Supply Current
1µA Shutdown Current
Only three small capacitors required

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 being drawn from the battery during start-up. This DC-DC converter requires no inductors and has low EMI. It is available in the ultra-small µMAX® package, which is only 1.11mm high and half the area of an 8-pin SO.

Applications