General Description

The MAX8744/MAX8745 are dual step-down, switchmode, power-supply (SMPS) controllers with synchronous rectification, intended for main 5V/3.3V power generation in battery-powered systems. Fixed-frequency operation with optimal interleaving minimizes input ripple current from the lowest input voltages up to the 26V maximum input. Optimal 40/60 interleaving allows the input voltage to go down to 8.3V before duty-cycle overlap occurs, compared to 180° out-of-phase regulators where the duty-cycle overlap occurs when the input drops below 10V.

Features

♦ Fixed-Frequency, Current-Mode Control

♦ 40/60 Optimal Interleaving

♦ Internal BST Switches

♦ Internal 5V, 100mA Linear Regulator

♦ Auxiliary Linear-Regulator Driver (12V or Adjustable Down to 1V)

♦ Dual Mode™ Feedback—3.3V/5V Fixed or Adjustable Output Voltages

♦ 200kHz/300kHz/500kHz Switching Frequency

♦ Undervoltage and Thermal-Fault Protection

♦ Overvoltage-Fault Protection (MAX8744 Only)

♦ 6V to 26V Input Range

♦ 2V ±0.75 Reference Output

♦ Independent Enable Inputs and Power-Good Outputs

♦ Soft-Start and Soft-Shutdown (Voltage Ramp)

♦ 8µA (typ) Shutdown Current

Applications

    Main Power Supplies

    2 to 4 Li+ Cell Battery-Powered Devices

    Notebook and Subnotebook Computers

    PDAs and Mobile Communicators