AT73C237_14 Datasheet, PDF (1/33 Pages) ATMEL Corporation – Applications: GPS Modules, WLAN Devices, Wireless Modules

Features
• LDO1: 2.75V (Default) and 1.8V (Programmable by TWI), 70 mA Linear Very Low Drop
Out Regulator with High PSRR and Low Noise.
• LDO2: 1.8V (Default) and 1.5V (Programmable by TWI), 70 mA Linear Low Drop Out
Regulator with High PSRR and Low Noise.
• LDO3: 1.8V (Default) and 1.5V or 1.2V (Programmable by TWI), 70 mA Linear Low Drop
Out Regulator with high PSRR and Low noise.
• LDO4: 1.8V, 2mA Linear Low Drop Out Regulator with Very Low Quiescent Current, +/-
100 mV Adjustable.
• Main Supply Rail from 2.8V to 5.5V
• Independent Auxiliary Supply for LDO4 Backup Section, 2.8V to 5.5V
• Internal State Machine for Startup and Delayed Reset Generation
• Additional External Reset Input
• Two Wire Interface for Independent Power Up/Power Down and Output Voltage
Programming for Each LDO.
• LDOs Voltage Customization Possible on Request
• Available in 3 x 3 x 0.9 mm 16-pin QFN Package
• Applications: GPS Modules, WLAN Devices, Wireless Modules.
Power
Management
and Analog
Companions
(PMAAC)
1. Description
The AT73C237 is a four-channel Power Supply Power Management Unit (PMU) avail-
able in a small outline QFN 3 x 3mm package. It is a fully integrated, attractively
priced, combined Power Management device for wireless modules, GPS and WLAN
devices. It integrates 4X Linear Low Drop Out Regulators, three of which (LDO1, 2, 3)
provide high-accuracy RF performance and 1X (LDO4) with very low quiescent cur-
rent, that can be supplied by an external backup battery (VDD4) on a separate rail. An
internal Low Power Bandgap (LPBG) requiring no external capacitor for decoupling, is
used as reference voltage for LDO4 and starts when VDD4 is present. LDO4 regu-
lates its output voltage with extremely low quiescent current, maximizing the lifetime of
the backup battery.
An Internal State Machine manages the startup of the other LDOs. An economic High
Precision Bandgap (HPBG) provides highly accurate, low noise voltage reference to
LDOs 1, 2, 3 while operating in switching mode to optimize the quiescent current.
The AT73C237 features a Two-wire Interface (TWI) to increase the efficiency of the
system by disabling individually each LDO when not needed.
AT73C237
4-channel
Power
Management for
Wireless
Modules
6362A–PMAAC–01-Jul-08