GENERAL DESCRIPTION
The MAX1533A/MAX1537A 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. Output current sensing provides accurate current limit using a sense resistor. Alternatively, power dissipation can be reduced using lossless inductor current sensing. Internal 5V and 3.3V linear regulators power the MAX1533A/MAX1537A and their gate drivers, as well as external keep-alive loads, up to a total of 100mA. When the main PWM regulators are in regulation, automatic bootstrap switches bypass the internal linear regulators, providing currents up to 200mA from each linear output.
Maxim Integrated
