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