3A Peak, 18V, 500kHz, ACOT™ Step-Down Converter


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The RT6233A/B is a high-efficiency, monolithic synchronous step-down DC/DC converter that can deliver up to 3A peak output current from a 4.5V to 18V input supply. The RT6233A/B adopts ACOT architecture to allow the transient response to be improved and keep in constant frequency. Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. Fault conditions also include output under voltage protection, output over current protection, and thermal shutdown.


  • Set-Top Boxes
  • Portable TVs
  • Access Point Routers
  • DSL Modems
  • LCD TVs
Key Spec.
RT6233A RT6233B
Status Active Active
Vin (min) (V) 4.5 4.5
Vin (max) (V) 18 18
Number of Outputs 1 1
Vout (min) (V) 0.8 0.8
Vout (max) (V) 5 5
Output Adj. Method Resistor Resistor
Iout (max) (A) 3 3
Current Limit (typ) (A) 3.8 3.8
Freq (typ) (kHz) 500 500
Ext Sync No No
Ron_HS (typ) (mOhm) 195 195
Ron_LS (typ) (mOhm) 105 105
Iq (typ) (mA) 0.5 0.5
Features ACOT Control;Adjustable Soft-Start;Cycle-by-Cycle Current Limit;Enable Input;Fast Transient Response;Internal Compensation;OCP;OVP;PSM;Power Good;Stable with Ceramic Capacitor;UVP ACOT Control;Adjustable Soft-Start;Cycle-by-Cycle Current Limit;Enable Input;Fast Transient Response;Force PWM;Internal Compensation;OCP;OVP;Power Good;Stable with Ceramic Capacitor;UVP
Package Type WDFN2x3-8 WDFN2x3-8
  • Integrated 195mΩ/105mΩ MOSFETs
  • 4.5V to 18V Supply Voltage Range
  • 500kHz Switching Frequency
  • ACOT Control
  • 0.8V ± 1.5% Voltage Reference
  • Adjustable Soft-Start
  • Power Good Indicator
  • Monotonic Start-Up into Pre-biased Outputs
  • Input Under-Voltage Lockout
  • Over-Current Protection and Hiccup
TitleLast UpdateShareDownload
3A Peak, 18V, 500kHz, ACOT™ Step-Down Converter2015/04/29
Technical Documents
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ACOT™ Stability Testing2019/03/18
ACOT™ (Advanced Constant-On Time) Synchronous Step-Down Converters2018/11/15
Richtek Wide Input Voltage Range DC/DC Power Solutions for Industrial, Automotive and LED lighting applications2018/11/01
Comparing Buck Converter Topologies2018/09/20
Buck Converter Selection Criteria2016/08/04
The Calculation of Output DC Offset for ACOT™ Control Buck Converter with Feed-forward Compensator2016/07/07
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How to estimate control loop bandwidth from the transient response time?2017/03/30 586
Reference Design
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Richtek Load Transient Tool2019/01/09