General Description

The MAX840/MAX843/MAX844 low-noise, inverting charge-pump power supplies are ideal for biasing GaAsFETs in cellular telephone transmitter amplifiers. They operate with inputs down to 2.5V.

Features

♦ Fixed -2V or Adjustable -0.5V to -9.4V Output at 4mA (MAX840)

♦ 2.5V to 10V Input Voltage Range

♦ Operate with Small Capacitors (as low as 0.22µF)

♦ 1mVp-p Output Voltage Ripple

♦ Charge-Pump Switching Frequency:

   100kHz in Normal Operation

   20kHz in Shutdown Mode (MAX844)

♦ 1µA Max Logic-Level Shutdown Over Temp. (MAX840/MAX843)

♦ Small 8-Pin SO Package

Applications

   Cellular Phones

   GaAsFET Power Amplifier Modules

   Personal Communicators, PDAs

   Wireless Data Loggers

   Continuously Adjustable GaAsFET Bias

   LCD-Bias Contrast Control

   Regulated Negative Power Supplies