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