5A, 18V, 700kHz ACOTTM Synchronous Step-Down Converter with VID Control


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The RT6203B is an adaptive on-time mode synchronous Buck converter. The main control loop of the RT6203B uses an adaptive on-time mode control which provides a very fast transient response with no external components. The RT6203B operates from 4.5V to 18V VIN input. After the initial power-up, the output voltage can be changed by codes sent into the IC via an I2C compatible VID control bus. There are special codes which can be used to program current limit level and thermal shutdown level. Shutdown and startup can be also programmed by special codes. The device also features an adjustable soft-start time. Output voltage is adjustable by resistor divider through the FB pin between 0.8V to 8V.


  • 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.
Status Active
Vin (min) (V) 4.5
Vin (max) (V) 18
Number of Outputs 1
Vout (min) (V) 0.72
Vout (max) (V) 8
Output Adj. Method Digital;Resistor
Iout (max) (A) 5
Current Limit (typ) (A) 7
Freq (typ) (kHz) 700
Ext Sync No
Ron_HS (typ) (mOhm) 60
Ron_LS (typ) (mOhm) 30
Iq (typ) (mA) 0.55
Features ACOT Control;Adjustable Current Limit;Adjustable Soft-Start;Built-in Bootstrap Switch;Cycle-by-Cycle Current Limit;Enable Input;Fast Transient Response;I2C;OCP;OTP;OVP;PSM;Power Good;Stable with Ceramic Capacitor;UVP
Package Type WQFN4x4-20
  • VID Control Range Via I2C Compatitable Interface : 0.72V to 1.48V in 10mV Steps
  • Adjustable Current Limit
  • Adjustable Thermal Shutdown
  • Fast Transient Response
  • Adjustable Output Voltage from 0.8V to 8V
  • Steady 700kHz Switching Frequency
  • Optimized for All Ceramic Capacitors
  • Externally-Adjustable, Pre-Biased Compatible Soft-Start
  • Input Under-Voltage Lockout
  • Output Over- and Under-Voltage Protection
  • Power Good Output
  • Thermal Shutdown
  • RoHS Compliant and Halogen Free
TitleLast UpdateShareDownload
5A, 18V, 700kHz ACOTTM Synchronous Step-Down Converter with VID Control2016/11/09
Technical Documents
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Richtek Selection Guide [Oct., 2021]2022/09/03
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How to estimate control loop bandwidth from the transient response time?2017/03/30 1570
Reference Design
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Richtek Load Transient Tool2022/07/25