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 = 100k?)

? 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