General Description
The MAX850–MAX853 low-noise, inverting, charge pump power supplies are ideal for biasing GaAsFETs in cellular telephone transmitter amplifiers.
The MAX850–MAX852 offer both preset (-4.1V) and adjustable (-0.5V to -9.0V) output voltages. The MAX853 uses an external positive control voltage to set the negative output voltage. Input voltage range for all four devices is 4.5V to 10V. Output current is 5mA.
An internal linear regulator reduces the output voltage ripple to 2mVp-p. With a well-filtered control voltage (VCTRL), the MAX853 achieves typical output ripple of less than 1mVp-p. Supply current is 3mA max, and shutdown current is less than 1µA max over temperature (5µA max for MAX851).

Features
♦ Fixed -4.1V or Adjustable -0.5V to -9V Output at 5mA
♦ 4.5V to 10V Input Voltage Range
♦ 2mVp-p Output Voltage Ripple (MAX850–MAX852)
   1mVp-p Output Voltage Ripple (MAX853)
♦ 100kHz Charge-Pump Switching Frequency
   (MAX850/MAX851/MAX853)
♦ External Synchronizing Clock Input (MAX852)
♦ Logic-Level Shutdown Mode: 1µA Max Over Temperature (MAX850/MAX852/MAX853)
♦ Low Cost, 8-Pin SO Package

Applications
  Cellular Phones
  Negative Regulated Power Supplies
  Personal Communicators, PDAs
  Wireless Data Loggers
  Continuously Adjustable GaAsFET Bias
  LCD-Bias Contrast Control