General Description
The MAX1901/MAX1902/MAX1904 are buck-topology, step-down, switch-mode, power-supply controllers that generate logic-supply voltages in battery-powered systems. These high-performance, dual/triple-output devices include on-board power-up sequencing, power-good signaling with delay, digital soft-start, secondary winding control, low dropout circuitry, internal frequency-compensation networks, and automatic bootstrapping.
Up to 97% efficiency is achieved through synchronous rectification and Maxim’s proprietary Idle Mode™ control scheme. Efficiency is greater than 80% over a 1000:1 load-current range, which extends battery life in system suspend or standby mode. Excellent dynamic response corrects output load transients within five clock cycles. Strong 1A on-board gate drivers ensure fast external N channel MOSFET switching.

FEATUREs
♦ 97% Efficiency
♦ 4.2V to 30V Input Range
♦ 2.5V to 5.5V Dual Adjustable Outputs
♦ Selectable 3.3V and 5V Fixed or Adjustable Outputs (Dual Mode™)
♦ 12V Linear Regulator
♦ Adjustable Secondary Feedback (MAX1901/MAX1904)
♦ 5V/50mA Linear Regulator Output
♦ Precision 2.5V Reference Output
♦ Programmable Power-Up Sequencing
♦ Power-Good (RESET) Output
♦ Output Overvoltage Protection (MAX1901/MAX1902)
♦ Output Undervoltage Shutdown (MAX1901/MAX1902)
♦ 333kHz/500kHz Low-Noise, Fixed-Frequency Operation
♦ Low-Dropout, 98% Duty-Factor Operation
♦ 2.5mW Typical Quiescent Power (12V input, both SMPSs on)
♦ 4µA Typical Shutdown Current

APPLICATIONs
  Notebook and Subnotebook Computers
  PDAs and Mobile Communicators
  Desktop CPU Local DC-DC Converters