Maxim Integrated MAX1534ETE

Description
The MAX1534 is a high-efficiency, triple-output power supply designed for keep-alive voltage rails. It consists of a 500mA buck regulator with an internal 0.5Ω PMOS, followed by two low-voltage linear regulators. The buck regulator steps down the battery or wall adapter supply rail to a fixed 5V or an adjustable output voltage. The linear regulators provide two independent preset output voltages of 3.3V and 1.8V, or adjustable output voltages.
The buck regulator utilizes a peak current-limit, pulse-frequency modulation (PFM) architecture for high light-load efficiency. High switching frequencies (up to 200kHz) allow the use of small surface-mount inductors and output capacitors. Operation to 100% duty cycle minimizes dropout voltage (250mV at 500mA).
The low-dropout linear regulators use an internal P-channel metal-oxide (PMOS) pass transistor to minimize supply current and deliver up to 160mA each of continuous current.
The MAX1534 includes a power-OK (POK) signal that indicates all outputs are in regulation. The 4% accurate threshold of the SHDN input permits its use as a low-battery detector.

Features
One switching and two linear regulators
Switching regulator:
4.5V to 24V input voltage range
Over 95% efficiency
Up to 500mA output current
Up to 200kHz switching frequency
Fixed 5V or adjustable output voltage
Internal 0.5Ω PMOS switch
100% maximum duty cycle for low-dropout operation
Two low-dropout linear regulators:
Up to 160mA output current (each)
3.3V/Adj output voltage for OUT1
1.8V/Adj output voltage for OUT2
±1.5% accurate output voltage
24% accurate shutdown for low battery detection
Thermal shutdown protection
POK output
1mW typical standby power

Applications
Notebook and sub-notebook computers
Wake-On LAN
2 to 4 Li cells battery-powered devices
Hand-held devices
Keep-alive supplies
Standby supplies