The LM5166 is a compact,easy-to-use, 3-V to 65-V, ultra-low IQ synchronous buck converter with highefficiency over wide input voltage and load current ranges. With integrated high-side and low-sidepower MOSFETs, up to 500 mA of output current can be delivered at fixed output voltages of 3.3 V or5 V, or an adjustable output. The converter is designed to simplify implementation while providingoptions 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 nearlyconstant operating frequency. Both control schemes do not require loop compensation while providingexcellent line and load transient response and short PWM on-time for large step-down conversionratios.
The high-side P-channel MOSFET can operate at 100% duty cycle for lowest dropout voltageand does not require a bootstrap capacitor for gate drive. Also, the current limit setpoint isadjustable to optimize inductor selection for a particular load current requirement. Selectable andadjustable start-up timing options include minimum delay (no soft start), internally fixed (900µs), and externally programmable soft start using a capacitor. An open-drain PGOOD indicator can beused for sequencing, fault reporting, and output voltage monitoring. The LM5166 is available in a 10-pin VSONpackage with 0.5-mm pin pitch.