General Description

The MAX768 low-noise, dual-output, regulated charge pump provides a negative output for biasing GaAsFET power amplifiers, and a positive output for powering voltage-controlled oscillators (VCOs) in wireless handsets. The outputs can also be used to power LCDs. Output ripple is less than 2mVp-p. The MAX768 is intended for use in low-voltage systems where a simple charge-pump inverter is inadequate, or where the VCO needs more range to improve its signal-to-noise ratio. The input range is 2.5V to 5.5V, enabling direct power from 1Li+ and 3-cell NiMH/NiCd batteries.

Features

♦ Dual Positive/Negative Regulated Outputs: ±5VOUT from 3VIN

♦ Output-Ready Indicator to Protect GaAsFET PAs

♦ 2.5V to 5.5V Input Voltage Range

♦ Low-Noise Output Ripple: < 2mVp-p

♦ Synchronizable Switching Frequency

♦ Uses Only Small, Low-Cost Capacitors

♦ 0.1µA Independent Shutdown Controls

♦ Adjustable Output Voltages

♦ Small 16-Pin QSOP Package

Applications

    GaAsFET Power Amp Bias

    Voltage-Controlled Oscillator (VCO) Supply

    Tuner Diode Power Supply

    Positive and Negative LCD Supply

    Cellular Phone

    PCS and Cordless Phone

    Wireless Handsets

    Wireless Handheld Computers

    Wireless PCMCIA Cards

    Modems