RT2855B Datasheet | Richtek

® RT2855A/B 4A, 18V, 650k Hz, ACOT® Synchronous Step-Down Converter General Description The RT2855A/B are high-performance 650k Hz 4A stepdown regulators with internal power switches and synchronous rectifiers. They feature quick transient response using their Advanced Constant On-Time (ACOT®) control architecture that provides stable operation with small ceramic output capacitors and without plicated external pensation, among other benefits. The input voltage range is from 4.5V to 18V and the output is adjustable from 0.765V to 7V. The proprietary ACOT®control improves upon other fastresponse constant on-time architectures, achieving nearly constant switching frequency over line, load, and output voltage ranges. Since there is no internal clock, response to transients is nearly instantaneous and inductor current can ramp quickly to maintain output regulation without large bulk output capacitance. The RT2855A/B are stable with and optimized for ceramic output capacitors With internal 70mΩ switches and 30mΩ synchronous rectifiers, the RT2855A/B display excellent efficiency and good behavior across a range of applications, especially for low output voltages and low duty cycles. Cycle-bycycle current limit, input under-voltage lock-out, externallyadjustable soft-start, output under- and over-voltage protection, and thermal shutdown provide safe and smooth operation in all operating conditions. The RT2855A and RT2855B are each available in WQFN-16L 3x3 package, with exposed thermal pads. The RT2855B switches continuously even at light loads to avoid low-frequency interference while the RT2855A Features a power-saving discontinuous operating mode at light loads. Features - Fast Transient Response - Steady 650k Hz Switching Frequency at all Load Current (RT2855B) - Discontinuous operating mode at Light Load (RT2855A) - 4A Output Current - Advanced Constant On-Time (ACOT®) Control - Optimized for Ceramic Output Capacitors - 4.5V to 18V Input Voltage Range - Internal...