MAX850ESA+T

The MAX850–MAX853 are low-noise, inverting, regulated charge-pump power supplies designed for biasing GaAsFET devices, such as power-amplifier modules in cellular handsets. The applied input voltage (VIN) is first inverted to a negative voltage at NEGOUT by a capacitive charge pump. This voltage is then regulated by an internal linear regulator, and appears at OUT. The minimum (most negative) output voltage (VOUT) achievable is the inverted positive voltage, plus the 1.0V required by the post-regulator. The ripple noise induced by the charge-pump inverter is reduced by the linear regulator to 2mVp-p at VOUT for the MAX850–MAX852. In addition, the excellent AC rejection of the linear regulator attenuates noise on the incoming supply. Up to 5mA is available at OUT.

Applications

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

Key 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