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