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3A, 18V, 700kHz ACOT® Synchronous Step-Down Converter

RT7275/RT7276

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The RT7275/76 are high-performance 700kHz 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 8V.

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 RT7275/76 are stable with and optimized for ceramic output capacitors.

With internal 90mΩ switches and 60mΩ synchronous rectifiers, the RT7275/76 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 RT7275 and RT7276 are each available in WDFN-10L 3x3 and PTSSOP-14 packages, with exposed thermal pads.

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
  • Not Recommended for Sink/Source Applications
Key Spec.
RT7275 RT7276
Status Active Active
Vin (min) (V) 4.5 4.5
Vin (max) (V) 18 18
Number of Outputs 1 1
Vout (min) (V) 0.765 0.765
Vout (max) (V) 8 8
Output Adj. Method Resistor Resistor
Iout (max) (A) 3 3
Current Limit (typ) (A) 4.5 4.5
Freq (typ) (kHz) 700 700
Ext Sync No No
Ron_HS (typ) (mOhm) 100;90 100;90
Ron_LS (typ) (mOhm) 60 60
Iq (typ) (mA) 0.7 0.7
Features 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 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
Package Type WDFN3x3-10;TSSOP-14(PP) WDFN3x3-10;TSSOP-14(PP)
Features
  • Fast Transient Response
  • Steady 700kHz Switching Frequency
      ► At all Load Currents (RT7275)
      ► Discontinuous Operating Mode at Light Load (RT7276)
  • 3A Output Current
  • Advanced Constant On-Time (ACOTTM) Control
  • Optimized for Ceramic Output Capacitors
  • 4.5V to 18V Input Voltage Range
  • Internal 90mΩ Switch and 60mΩ Synchronous Rectifier
  • 0.765V to 8V Adjustable Output Voltage
  • Externally-Adjustable, Pre-Biased Compatible Soft-Start
  • Cycle-by-Cycle Current Limit
  • Optional Output Discharge Function (PTSSOP-14 Only)
  • Output Over- and Under-Voltage Shut-Down
Datasheet
TitleLast UpdateShareDownload
3A, 18V, 700kHz ACOT® Synchronous Step-Down Converter2012/08/06
Technical Documents
TitleLast UpdateShareDownload
ACOT® Stability Testing2020/04/13
The Calculation of Output DC Offset for ACOT™ Control Buck Converter with Feed-forward Compensator2019/12/12
Richtek Wide Input Voltage Range DC/DC Power Solutions for Industrial, Automotive and LED lighting applications2019/12/12
ACOT™ (Advanced Constant-On Time) Synchronous Step-Down Converters2019/12/12
Comparing Buck Converter Topologies2019/12/12
Buck Converter Selection Criteria2019/12/12
Videos
TitleLast UpdateShareViews
How to estimate control loop bandwidth from the transient response time?2017/03/30 783
Introduction to Richtek's Advanced Constant On Time Buck Converters2013/05/14 55
Additional Documents
Title Last Update ShareDownload
RT7275GQW EVM kit, design consideration and FAQ 2019/03/04
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