Dual Step-Down DC-DC Power-Management ICs for Portable Devices

Active: In Production.

The MAX8621Y/MAX8621Z power-management integrated circuits (PMICs) are designed for a variety of portable devices including cellular handsets. These PMICs include two high-efficiency step-down DC-DC converters, four low-dropout linear regulators (LDOs) with pin-programmable capability, one open-drain driver, a 60ms (typ) reset timer, and power-on/off control logic. These devices offer high efficiency with a no-load supply current of 160µA, and their small thin QFN 4mm x 4mm package makes them ideal for portable devices.

The step-down DC-DC converters utilize a proprietary 4MHz hysteretic-PWM control scheme that allows for ultra-small external components. Internal synchronous rectification improves efficiency and eliminates the external Schottky diode that is required in conventional step-down converters. The output voltage is adjustable from 0.6V to 3.3V. The output current is guaranteed up to 500mA.

The four LDOs offer low 45µV_RMS output noise and low dropout of only 100mV at 100mA. OUT1 and OUT2 deliver 300mA (min) of continuous output current. OUT3 and OUT4 deliver 150mA (min) of continuous output current. The output voltages are pin selectable by SEL1 and SEL2 for flexibility. The MAX8621Y/MAX8621Z offer different sets of LDO output voltages.

A microprocessor reset output (active-low RESET) monitors OUT1 and warns the system of impending power loss, allowing safe shutdown. Active-low RESET asserts during power-up, power-down, shutdown, and fault conditions where V_OUT1 is below its regulation voltage.

A 200mA driver output is provided to control LED backlighting or provide an open-drain connection for resistors such as in feedback networks.

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