Maxim Introduces First Step-Down DC-DC Converter

The MAX8655 synchronous-PWM buck regulator operates from a 4.5V to 25V input and generates an output voltage adjustable from 0.7V to 5.5V at loads up to 25A. Integrated power MOSFETs provide a small footprint, ease of layout, and reduced EMI. Removing the board trace inductances ensures the highest efficiency at high frequency.

The MAX8655 uses peak current-mode control architecture with an adjustable (200kHz to 1MHz), constant-switching frequency, which is externally synchronizable. The MAX8655's adjustable current limit uses the inductor's DC resistance to improve efficiency or an external sense resistor for higher accuracy. Foldback type current limit is available to reduce the power dissipation under severe-overload or short-circuit conditions. A reference input is provided for use with a high-accuracy external reference or for DDR and tracking applications.

Monotonic startup provides safe starting into a prebiased output, where traditional step-down regulators discharge the output capacitor during soft-start, creating a negative voltage at the output and possibly damaging the load.

A 180° out-of-phase synchronization output is available for synchronizing with another MAX8655.

An enable input is provided for on/off control and to facilitate output sequencing. Output-voltage sensing for programmable overvoltage protection is provided and is independent of the feedback network to further enhance the output overvoltage protection.

Overall, the MAX8655 provides enough flexibility for the experienced user, as well as simplicity and ease of use for non-power-supply engineers.