The LM25149 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 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. It 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 incorporates several features to simplify compliance with various EMI standards, for example, CISPR 11 and CISPR 32 Class B requirements. Active EMI filter and dual random spread spectrum (DRSS) techniques reduce the peak harmonic EMI signature.

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