The MAX8744A/MAX8745A 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 peak current-limit protection, using either an accurate sense resistor or using lossless inductor DCR current sensing. A low-noise mode maintains high light-load efficiency while keeping the switching frequency out of the audible range. An internal, fixed 5V, 100mA linear regulator powers up the MAX8744A/MAX8745A and their gate drivers, as well as external keep-alive loads. When the main PWM regulator is in regulation, an automatic bootstrap switch bypasses the internal linear regulator, providing current up to 200mA. An additional adjustable linear-regulator driver with an external pnp transistor can be used with a secondary winding to provide a 12V supply, or powered directly from the main outputs to generate low-voltage outputs as low
The MAX8744A/MAX8745A 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. These devices feature fixed-frequency operation with optimal interleaving to minimize input ripple current and include output current sensing for peak current-limit protection.
| Input Voltage Range | 6V to 26V |
|---|---|
| Switching Frequency | 200kHz/300kHz/500kHz |
| Output Voltage Reference | 2V +0.75% |
| Package Type | 32-pin, 5mm x 5mm Thin QFN |
| Operating Temperature Range | -40°C to +85°C |
The device supports an input voltage range up to a maximum of 26V.
The soft-start ramp time is 2 ms when measured from the rising edge of ON_ to full scale.
The controller offers fixed-frequency operation at 200kHz, 300kHz, or 500kHz depending on the FSEL pin setting.