General Description

The MAX1958/MAX1959 power amplifier (PA) power-management ICs (PMICs) integrate an 800mA, dynamically adjustable step-down converter, a 5mA Rail-to-Rail® operational amplifier (op amp), and a precision temperature sensor to power a heterojunction bipolar transistor (HBT) PA in W-CDMA and N-CDMA cell phones.

Features

♦ Step-Down Converter

    Dynamically Adjustable Output Voltage from

    0.75V to 3.4V (MAX1958)

    Dynamically Adjustable Output Voltage from

    1V to 3.6V (MAX1959)

    800mA Guaranteed Output Current

    130mV IC Dropout at 600mA Load

    Low Quiescent Current

        190µA (typ) in Skip Mode (MAX1958)

        3mA (typ) in PWM Mode

        0.1µA (typ) in Shutdown Mode

    1MHz Fixed-Frequency PWM operation

    16 to 100 Duty-Cycle Operation

No External Schottky Diode Required Soft-Start

♦ Operational Amplifier

    5mA Rail-to-Rail Output

    Active Discharge in Shutdown

    800kHz Gain-Bandwidth Product

    120dB Open-Loop Voltage Gain (RL = 100kΩ)

♦ Temperature Sensor

    Accurate Sensor -11.7mV/°C Slope

    -40°C to +125°C-Rated Temperature Range

♦ 20-Pin Thin QFN (5mm ✕ 5mm), 0.8mm Height (max)

Applications

    W-CDMA and N-CDMA Cellular Phones

    Wireless PDAs and Modems