General Description

The MAX679 step-up, regulated charge pump gener ates 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.

Features

♦ 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

Applications

Battery-Powered Applications

Miniature Equipment

Backup-Battery Boost Converters

Translators

Two-Way Pagers