3A, 18V, 650kHz, ACOT® Synchronous Step-Down Converter


Update Alert Share

The RT2853A/B are high-performance 650kHz 3A step-down 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 complicated external compensation, 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 fast-response 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 RT2853A/B are stable with and optimized for ceramic output capacitors.

With internal 110mΩ switches and 30mΩ synchronous rectifiers, the RT2853A/B display excellent efficiency and good behavior across a range of applications, especially for low output voltages and low duty cycles. Cycle-by-cycle current limit, input under-voltage lock-out, externally-adjustable soft-start, output under- and over-voltage protection, and thermal shutdown provide safe and smooth operation in all operating conditions.

The RT2853A and RT2853B are each available in WQFN-16L 3x3 package, with exposed thermal pads.


  • Industrial and Commercial Low Power Systems
  • Computer Peripherals
  • LCD Monitors and TVs
  • Point of Load Regulation for High-Performance DSPs, FPGAs, and ASICs
TitleLast UpdateShareDownload
3A, 18V, 650kHz, ACOT® Synchronous Step-Down Converter2015/04/29
Technical Documents
TitleLast UpdateShareDownload
ACOT™ (Advanced Constant-On Time) Synchronous Step-Down Converters2020/12/30
Richtek Selection Guide [Oct., 2020]2020/12/30
ACOT® Stability Testing2020/04/13
The Calculation of Output DC Offset for ACOT™ Control Buck Converter with Feed-forward Compensator2019/12/12
Comparing Buck Converter Topologies2019/12/12
Buck Converter Selection Criteria2019/12/12
TitleLast UpdateShareViews
How to estimate control loop bandwidth from the transient response time?2017/03/30 1379
Introduction to Richtek's Advanced Constant On Time Buck Converters2013/05/14 84
Design Tool
TitleLast UpdateShare
Richtek Designer™ Web Simulation Tool : RT2853AHGQW2020/09/23
Richtek Designer™ Web Simulation Tool : RT2853ALGQW2020/09/23
Richtek Designer™ Web Simulation Tool : RT2853BHGQW2020/09/23
Richtek Designer™ Web Simulation Tool : RT2853BLGQW2020/09/23
Part NumberPackage TypePackage Qty.Free SampleBuy From Authorized Distributor
RT2853AHGQWWQFN3x3-161500 Not available Buy from Distributor
RT2853ALGQWWQFN3x3-161500 Not available Buy from Distributor
RT2853BHGQWWQFN3x3-161500 Not available Buy from Distributor
RT2853BLGQWWQFN3x3-161500 Not available Buy from Distributor