MAX1958 Datasheet | Maxim Integrated

Description Features o Step-Down Converter Dynamically Adjustable Output Voltage from 0.75V to 3.4V (MAX1958) Dynamically Adjustable Output Voltage from 1V to 3.6V (MAX1959) 800m A Guaranteed Output Current 130m V IC Dropout at 600m A Load Low Quiescent Current 190µA (typ) in Skip Mode (MAX1958) 3m A (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 o Operational Amplifier 5m A Rail-to-Rail Output Active Discharge in Shutdown 800k Hz Gain-Bandwidth Product 120d B Open-Loop Voltage Gain (RL = 100kΩ) o Temperature Sensor Accurate Sensor -11.7m V/°C Slope -40°C to +125°C-Rated Temperature Range o 20-Pin Thin QFN (5mm ✕ 5mm), 0.8mm Height (max) MAX1958/MAX1959 The MAX1958/MAX1959 power amplifier (PA) powermanagement ICs (PMICs) integrate an 800m A, dynamically adjustable step-down converter, a 5m A 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. The high-efficiency, pulse-width modulated (PWM), DCto-DC buck converter is optimized to provide a guaranteed output current of 800m A. The output voltage is dynamically controlled to produce any fixed-output voltage in the range of 0.75V to 3.4V (MAX1958) or 1V to 3.6V (MAX1959), with settling time less than 30µs for a full-scale change in voltage and current. The 1MHz PWM switching frequency allows the use of small external ponents while pulse-skip mode reduces quiescent current to 190µA with light loads. The converter utilizes a low on-resistance internal MOSFET switch and synchronous rectifier to maximize efficiency and minimize external ponent count. The 100% duty-cycle operation allows for an IC dropout voltage of only 130m V (typ) at 600m A load. The micropower op amp is used to provide bias to the HBT PA to maximize efficiency. The amplifier features active discharge in shutdown for full PA bias...