12A, 18V, 500kHz, ACOT® Synchronous Step-Down Converter


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The RT6242A/B is a synchronous step-down converter with Advanced Constant On-Time (ACOT®) mode control. The ACOT® provides a very fast transient response with few external components. The low impedance internal MOSFET supports high efficiency operation with wide input voltage range from 4.5V to 18V. The proprietary circuit of the RT6242A/B enables to support all ceramic capacitors. The output voltage can be adjustable between 0.7V and 8V. The soft-start is adjustable by an external capacitor.


  • Industrial and Commercial Low Power Systems
  • Computer Peripherals
  • LCD Monitors and TVs
  • Green Electronics/Appliances
  • Point of Load Regulation for High-Performance DSPs, FPGAs, and ASICs
Key Spec.
RT6242A RT6242B
Status Active Active
Vin (min) (V) 4.5 4.5
Vin (max) (V) 18 18
Number of Outputs 1 1
Vout (min) (V) 0.7 0.7
Vout (max) (V) 8 8
Output Adj. Method Resistor Resistor
Iout (max) (A) 12 12
Current Limit (typ) (A) 16 16
Freq (typ) (kHz) 500 500
Freq (min) (kHz) 300 300
Freq (max) (kHz) 700 700
Ext Sync No No
Ron_HS (typ) (mOhm) 12 12
Ron_LS (typ) (mOhm) 5.4 5.4
Iq (typ) (mA) 0.8 0.8
Features ACOT Control;Adjustable Current Limit;Adjustable Frequency;Adjustable Soft-Start;Cycle-by-Cycle Current Limit;Enable Input;Fast Transient Response;OTP;OVP;PSM;Power Good;Stable with Ceramic Capacitor;UVP ACOT Control;Adjustable Current Limit;Adjustable Frequency;Adjustable Soft-Start;Cycle-by-Cycle Current Limit;Enable Input;Fast Transient Response;Force PWM;OTP;OVP;Power Good;Stable with Ceramic Capacitor;UVP
Package Type UQFN3x3-16J(FC) UQFN3x3-16J(FC)
  • 4.5V to 18V Input Voltage Range
  • 12A Output Current
  • 12mΩ Internal High-Side N-MOSFET and 5.4mΩ Internal Low-Side N-MOSFET
  • Advanced Constant On-Time Control
  • Fast Transient Response
  • Support All Ceramic Capacitors
  • Up to 95% Efficiency
  • Adjustable Switching Frequency from 300kHz to 700kHz
  • Adjustable Output Voltage from 0.7V to 8V
  • Adjustable Soft-Start
  • Pre-bias Start-Up
  • Adjustable Current Limit from 6A to 16A
  • Cycle-by-Cycle Over Current Protection
  • Power Good Output
  • Input Under-Voltage Lockout
  • Hiccup Mode Under-Voltage Protection
  • Thermal Shutdown Protection
TitleLast UpdateShareDownload
12A, 18V, 500kHz, ACOT® Synchronous Step-Down Converter2015/09/15
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
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How to estimate control loop bandwidth from the transient response time?2017/03/30 1379
Evaluation Boards
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12A, 18V, 500kHz, ACOT™ Synchronous Step-Down Converter2021/01/21
Reference Design
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Richtek Load Transient Tool2021/01/21
Part NumberPackage TypePackage Qty.Free SampleBuy From Authorized Distributor
RT6242AHGQUFUQFN3x3-16J(FC)1500 Not available Buy from Distributor
RT6242BHGQUFUQFN3x3-16J(FC)1500 Request Buy from Distributor