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 45µVRMS 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
VOUT1 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.
Applications
- Cellular Handsets
- Digital Cameras
- MP3 Players
- Smartphones and PDAs
- Wireless Local Area Networks (WLANs)
