Texas Instruments' LM5166 is a compact, easy-to-use, 3 V to 65 V, ultra-low I_Q synchronous buck converter with high efficiency over wide input voltage and load current ranges. With integrated high-side and low-side power MOSFETs, up to 500 mA of output current can be delivered at fixed output voltages of 3.3 V or 5 V, or an adjustable output. The converter is designed to simplify implementation while providing options to optimize the performance for the target application. Pulse frequency modulation (PFM) mode is selected for optimal light-load efficiency or constant on-time (COT) control for nearly constant operating frequency. Neither control scheme require loop compensation while still providing excellent line-and-load transient response and short PWM on-time for large step-down conversion ratios.

The high-side P-channel MOSFET can operate at 100% duty cycle for lowest dropout voltage and does not require a bootstrap capacitor for gate drive. Also, the current limit set point is adjustable to optimize inductor selection for a particular output current requirement. Selectable/adjustable startup timing options include minimum delay (no soft-start), internally fixed (900 μs), and externally programmable soft-start via an external capacitor. An open-drain PGOOD indicator can be used for sequencing and output voltage monitoring. The LM5166 is available in a VSON-10 package with 0.5 mm pin pitch.