General Description

The MAX1549 dual pulse-width modulation (PWM) stepdown controller provides the high efficiency, excellent transient response, and high DC-output accuracy necessary for generating low-voltage chipset and RAM power supplies in notebook computers. The controller employs a fixed-frequency, current-mode PWM architecture that does not require complex compensation. The MAX1549 also interleaves the dual step-down regulators, minimizing the input capacitor requirements.

Features

? Interleaved, Fixed-Frequency, Current-Mode Control Architecture

? 1 VOUT Accuracy Over Line and Load

? Main Output (OUT1)

??? 0.5V to 2.0V Adjustable Output

??? External Reference Input for Dynamically

??? Selectable Output Voltages

??? Four Digitally Selectable Output Voltages

??? Power-Good and Fault Blanking During

??? Transitions

? Second Output (OUT2) 2.5V/1.8V Fixed or 0.5V to 2.7V Adjustable Output

? Accurate Differential Current-Sense Inputs

? 100kHz/200kHz/300kHz/400kHz Selectable Switching Frequency

? Output Overvoltage/Undervoltage Protection

? Soft-Start and Soft-Shutdown

? Drives Large Synchronous-Rectifier FETs

? 2V ±0.6 Reference Output

? Separate Enable Inputs with Accurate Threshold Voltages

? Separate Power-Good Window Comparators

Applications

??? Notebook Computers

??? Dynamically Adjustable Chipset Supplies

??? Video/GPU Core Supplies

??? DDR Memory Termination

??? CPU Core or VCC Supplies

??? Fixed Chipset/RAM Supplies

??? Active Termination Buses