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 Nchannel MOSFET switching.
These devices feature a logic-controlled and synchronizable, fixed-frequency, pulse-width modulation (PWM) operating mode. This reduces noise and RF interference
in sensitive mobile communications and pen-entry applications. Asserting the SKIP pin enables fixed-frequency mode, for lowest noise under all load conditions.
The MAX1901/MAX1902/MAX1904 include two PWM regulators, adjustable from 2.5V to 5.5V with fixed 5.0V and 3.3V modes. All these devices include secondary feedback regulation, and the MAX1902 contains a 12V/120mA linear regulator. The MAX1901/MAX1904 include a secondary feedback input (SECFB), plus a control pin (STEER) that selects which PWM (3.3V or 5V) receives the secondary feedback signal. SECFB provides a method for adjusting the secondary winding voltage regulation point with an external resistor divider, and is intended to aid in creating auxiliary voltages other than fixed 12V.
The MAX1901/MAX1902 contain internal output overvoltage and undervoltage protection features.

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

Package included:

• 1 x MAX1902EA1 500kHz Multi-Output, Low-Noise Power-Supply Controllers