The LM25149-Q1 is a switching controller that features all of the functions necessary to implement a high-efficiency synchronous buck power supply operating over a wide input voltage range from 3.5 V to 42 V. The LM25149-Q1 is configured to provide a fixed 3.3-V, 5-V, or 12-V output, or an adjustable output between 0.8 V to 36 V. This easy-to-use controller integrates high-side and low-side MOSFET gate drivers capable of sourcing and sinking peak currents of 2.2 A and 3.2 A, respectively. Adaptive dead-time control is designed to minimize body diode conduction during switching transitions.

Current-mode control using a shunt resistor or inductor DCR current sensing provides inherent line feedforward, cycle-by-cycle peak current limiting, and easy loop compensation. Current-mode control using a shunt resistor or inductor DCR current sensing also supports a wide duty cycle range for high input voltage and low-dropout applications as well as application requiring a high step-down conversion ratio (for example, 10-to-1). The oscillator frequency is user-programmable between 100 kHz to 2.2 MHz, and the frequency can be synchronized as high as 2.5 MHz by applying an external clock to the PFM/SYNC pin.

An external bias supply can be connected to VCCX to maximize efficiency in high input voltage applications. A user-selectable diode emulation feature enables discontinuous conduction mode (DCM) operation to further improve efficiency and reduce power dissipation during light-load conditions. Fault protection features include current limiting, thermal shutdown, UVLO, and remote shutdown capability.

The LM25149-Q1 incorporates several features to simplify compliance with various EMI standards, for example, CISPR 25 Class 5 automotive EMI requirements. Active EMI filter and dual random spread spectrum (DRSS) techniques reduce the peak harmonic EMI signature.

The LM25149-Q1 is provided in a 24-pin VQFN package with a wettable flank pinout and an exposed pad to aid in thermal dissipation.