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8A, 18V, 500kHz, ACOTTM Synchronous Step-Down Converter

RT6238A/RT6238B

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The RT6238A/B is a high-performance 500kHz, 8A step-down regulator with internal power switches and synchronous rectifiers. It features quick transient response using its Advanced Constant On-Time (ACOTTM) 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 0.7V to 8V. The proprietary ACOTTM 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 RT6238A/B is stable with and optimized for ceramic output capacitors. With internal 35mΩ switches and 14mΩ synchronous rectifiers, the RT6238A/B displays excellent efficiency and good behavior across a range of applications, especially for low output voltages and low duty cycles. Cycle-by-cycle current limit provides protection against shorted outputs, input under-voltage lockout, externally-adjustable soft-start, output under- and over-voltage protection, and thermal shutdown provide safe and smooth operation in all operating conditions. The RT6238A/B is available in the UQFN-14L 2x3 (FC) package, with exposed thermal pad.

Applications

  • 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
  • Networked Communication
Key Spec.
RT6238A RT6238B
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) 8 8
Current Limit (typ) (A) 11 11
Freq (typ) (kHz) 500 500
Ext Sync No No
Ron_HS (typ) (mOhm) 35 35
Ron_LS (typ) (mOhm) 14 14
Iq (typ) (mA) 0.6 0.6
Features ACOT Control;Adjustable Soft-Start;Cycle-by-Cycle Current Limit;Enable Input;Fast Transient Response;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;OCP;OVP;Power Good;Stable with Ceramic Capacitor;UVP
Package Type UQFN2x3-14(FC) UQFN2x3-14(FC)
Features
  • Fast Transient Response
  • Advanced Constant On-Time (ACOTTM) Control
  • 4.5V to 18V Input Voltage Range
  • Adjustable Output Voltage from 0.7V to 8V
  • 8A Output Current
  • 35mΩ Internal High-Side N-MOSFET and 14mΩ Internal Low-Side N-MOSFET
  • Steady 500kHz Switching Frequency
  • Up to 95% Efficiency
  • Optimized for All Ceramic Capacitors
  • Externally-Adjustable, Pre-Biased Compatible Soft-Start
  • Cycle-by-Cycle Current Limit
  • Input Under-Voltage Lockout
  • Output Over- and Under-Voltage Protection
  • Power Good Output
  • Thermal Shutdown
Datasheet
TitleLast UpdateShareDownload
8A, 18V, 500kHz, ACOTTM Synchronous Step-Down Converter2015/03/18
Technical Documents
TitleLast UpdateShareDownload
ACOT™ Stability Testing2019/03/18
ACOT™ (Advanced Constant-On Time) Synchronous Step-Down Converters2018/11/15
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
Videos
TitleLast UpdateShareViews
How to estimate control loop bandwidth from the transient response time?2017/03/30 619
Evaluation Boards
TitleLast UpdateShareDownload
8A, 18V, 500kHz, ACOT™ Synchronous Step-Down Converter2018/11/08
Reference Design
TitleLast UpdateShareDownload
Richtek Load Transient Tool2019/01/09
Part NumberPackage TypePackage Qty.Free SampleBuy From Authorized Distributor
RT6238AHGQUFUQFN2x3-14(FC)1500 Not available Buy from Distributor
RT6238ALGQUFUQFN2x3-14(FC)1500 Not available Buy from Distributor
RT6238BHGQUFUQFN2x3-14(FC)1500 Request Buy from Distributor
RT6238BLGQUFUQFN2x3-14(FC)1500 Not available Buy from Distributor
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