Maxim Integrated MAX881REUB

Description
The MAX881R is a low-noise, inverting power supply designed for biasing GaAsFET power amplifiers in portable wireless applications. It consists of a charge-pump inverter followed by a negative linear regulator. The input voltage range is 2.5V to 5.5V. The output can be set to any voltage from -0.5V to (-VIN 0.6V) using two resistors, or it can be preset to -2.0V. The output can deliver up to 4mA and is filtered to 1mVp-p ripple and noise by the internal linear regulator.
The MAX881R also features a power-OK (POK) output that signals when the negative voltage is within 7.5% of its setpoint. This signal can be routed to a microcontroller or directly to a switch at the GaAsFET drain to protect the GaAsFET by preventing power from being applied to its drain until it is properly biased.
The MAX881R is available in a 10-pin μMAX package.

Features
1mVp-p output voltage ripple and noise
Power-OK signal to control GaAsFET drain switch
0.05μA logic-controlled shutdown
1ms guaranteed startup
2.5V to 5.5V input
-0.5V to (-VIN 0.6V) output at up to 4mA
Operates with one 4.7µF and three 0.22μF capacitors (no inductors needed)

Applications
Cell phones
PCS phones
Wireless modems
Two-way pagers
PHS phones
Mobile radios
Wireless handsets
Wireless computers