The RT6273A/B is a simple, easy-to-use, 3A synchronous step-down DC-DC converter with an input supply voltage range of 4.5V to 17V. The device possesses an accurate reference voltage and integrates low RDS(ON) power MOSFETs to achieve high efficiency.

The RT6273A/B adopts Advanced Constant On-Time (ACOT®) control architecture to provide an ultrafast transient response with few external components and to operate in nearly constant switching frequency over the line, load, and output voltage range. The RT6273A operates in automatic PSM that maintains high efficiency during light load operation. The RT6273B operates in Forced PWM that helps meet tight voltage regulation accuracy requirements.

The RT6273A/B senses both FETs current for a robust over-current protection (OCP). The device features cycle-by-cycle current limit protection to prevent the device from the catastrophic damage in output short circuit, over-current or inductor saturation conditions. A built-in soft-start function prevents inrush current during start-up. The device also includes input under-voltage lockout, output under-voltage protection, and over-temperature protection (OTP) to provide safe and smooth operation in all operating conditions.


  • Set-Top Boxes
  • LCD TVs
  • Home Networking Devices
  • Surveillance
  • General Purpose
Key Spec.
RT6273A RT6273B
Status Active Active
Vin (min) (V) 4.5 4.5
Vin (max) (V) 17 17
Number of Outputs 1 1
Vout (min) (V) 0.765 0.765
Vout (max) (V) 7 7
Output Adj. Method Resistor Resistor
Iout (max) (A) 3 3
Current Limit (typ) (A) 4.2 4.2
Freq (typ) (kHz) 1400 1400
Ext Sync No No
Ron_HS (typ) (mOhm) 95 95
Ron_LS (typ) (mOhm) 50 50
Iq (typ) (mA) 0.28 0.28
Features ACOT Control;COT Control;Cycle-by-Cycle Current Limit;Enable Input;Fast Transient Response;OCP;OTP;PSM;SCP;Stable with Ceramic Capacitor;UVP ACOT Control;COT Control;Cycle-by-Cycle Current Limit;Enable Input;Fast Transient Response;Force PWM;OCP;OTP;SCP;Stable with Ceramic Capacitor;UVP
Package Type TSOT-26(FC);SOT-563(FC) TSOT-26(FC);SOT-563(FC)
  • 3A Converter Integrated 95mΩ and 50mΩ FETs
  • Continuous Current
    ► TSOT-23-6 (FC) : 3A
    ► SOT-563 (FC) : 2A
  • Input Supply Voltage Range : 4.5V to 17V
  • Output Voltage Range : 0.765V to 7V
  • Advanced Constant On-Time (ACOT®) Control
    ► Ultrafast Transient Response
    ► Optimized for Low-ESR Ceramic Output Capacitors
  • High Accuracy Feedback Reference Voltage : Typ. ± 1%
  • Optional for Operation Modes :
    ► RT6273A : Power Saving Mode (PSM)
    ► RT6273B : Forced PWM Mode
  • Fixed Switching Frequency : 1.4MHz
  • Enable Control and Internally Fixed Soft-Start with typ. 1ms
  • Input Under-Voltage Lockout (UVLO)
  • Protection Function
    ► Output Under-Voltage Protection (UVP) with Hiccup Mode
    ► High- / Low-side MOSFET OCP and OTP Function
  • RoHS Compliant and Halogen Free
TitleLast UpdateDownload
17V Input, 3A, ACOT® Buck Converter with Both FETs OC Protection2019/10/04
Technical Documents
TitleItem TypeLast UpdateDownload
Richtek Product Selection Guide [Jan., 2024] Selection Guide2024/01/18
Richtek Featured Product Tree [Aug., 2023] Selection Guide2023/08/07
Reference Design
TitleLast UpdateDownload
Richtek Load Transient Tool2022/07/25
Part NumberPackage TypePackage Qty.Free SampleBuy From Authorized Distributor
RT6273BHGJ6FTSOT-26(FC)3000 Request Buy from Distributor