3-CH, 18V, Synchronous Step-Down Converter


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The RT7273 features three synchronous wide input range high efficiency Buck converters. The converters are designed to simplify its application while giving the designer the option to optimize their usage according to the target application.

The converters can operate in 5V, 9V or 12V systems and have integrated power transistors. The output voltage can be set externally using a resistor divider to any value between 0.8V and the input supply minus 1V. Each converter features an enable pin that allows a delayed start-up for sequencing purposes, a soft-start pin that allows adjustable soft-start time by choosing the soft-start capacitor, and a current limit pin (RLIMx) to adjust current limit by selecting an external resistor. The COMP pin allows optimizing transient versus dc accuracy response with a simple RC compensation.

The switching frequency of the converters can either be set with an external resistor connected to ROSC pin or be synchronized to an external clock connected to SYNC pin if needed. The switching converters are designed to operate from 300kHz to 2.2MHz. The converters operate with 180° phase between CH 1 and CH 2, CH 3 (CH 2 and CH 3 ran in phase) to minimize the input filter requirements.

The RT7273 also features a low power mode enabled by an external signal, which allows for a reduction on the input power supplied to the system when the host processor is in stand-by (low activity) mode.


  • Set Top Boxes
  • Blu-ray DVD
  • DVR
  • DTV
  • Car Audio/Video
  • Security Camera
Key Spec.
Status Active
Vin (min) (V) 4.5
Vin (max) (V) 18
Number of Outputs 3
Vout (min) (V) 0.8
Vout (max) (V) 17
Output Adj. Method Resistor
Iout (max) (A) 2.5;2.5;3.5
Current Limit (typ) (A) 4;4;5
Freq (typ) (kHz) 500
Freq (min) (kHz) 300
Freq (max) (kHz) 2200
Ext Sync Yes
Ron_HS (typ) (mOhm) 95
Ron_LS (typ) (mOhm) 50
Iq (typ) (mA) 20
Features Adjustable Current Limit;Adjustable Frequency;Adjustable Soft-Start;Current Mode Control;Cycle-by-Cycle Current Limit;Enable Input;External Synchronization;Force PWM;Internal Compensation;Power Good;Stable with Ceramic Capacitor;UVP
Package Type WQFN6x6-40
  • Wide Input Supply Voltage Range : 4.5V to 18V
  • Output Range : 0.8V to (VIN - 1V)
  • Fully Integrated Triple-Buck
    ► Maximum Current 3.5A/2.5A/2.5A
    ► Continuous Operation 3A/2A/2A
  • High Efficiency
  • Switching Frequency
    ► 300kHz to 2.2MHz Set by External Resistor
  • External Synchronization Pin for Oscillator
  • External Enable/Sequencing Pins
  • Adjustable Cycle-By-Cycle Current Limit Set by External Resistor
  • Soft-Start
  • Current Mode Control with Simple Compensation Circuit
  • Power Good Indicator
  • Discontinuous Operating Mode at Light Load when LOWP = High
  • RoHS Compliant and Halogen Free
TitleLast UpdateShareDownload
3-CH, 18V, Synchronous Step-Down Converter2012/11/22
Technical Documents
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Richtek Selection Guide [Oct., 2020]2020/12/30
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How to estimate control loop bandwidth from the transient response time?2017/03/30 1363
Evaluation Boards
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3-CH, 18V, 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
RT7273GQWWQFN6x6-402500 Not available Buy from Distributor