General Description
The MAX1533A/MAX1537A are dual step-down, switch mode 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. Output current sensing provides accurate current limit using a sense resistor. Alternatively, power dissipation can be reduced using lossless inductor current sensing

Features
♦ Fixed-Frequency, Current-Mode Control
♦ 40/60 Optimal Interleaving
♦ Accurate Differential Current-Sense Inputs
♦ Internal 5V and 3.3V Linear Regulators with 100mA Load Capability
♦ Auxiliary 12V or Adjustable 150mA Linear Regulator (MAX1537A Only)
♦ Dual Mode™ Feedback—3.3V/5V Fixed or Adjustable Output (Dual Mode) Voltages
♦ 200kHz/300kHz/500kHz Switching Frequency
♦ Versatile Power-Up Sequencing
♦ Adjustable Overvoltage and Undervoltage Protection
♦ 6V to 26V Input Range
♦ 2V ±0.75% Reference Output
♦ Power-Good Output
♦ Soft-Shutdown
♦ 5µA (typ) Shutdown Current

Applications
2 to 4 Li+ Cells Battery-Powered Devices
Notebook and Subnotebook Computers
PDAs and Mobile Communicators