The RT5701 is a Peak-Current Mode Pulse-Width-Modulated (PWM) step-down DC/DC converter with I2C control interface. Capable of delivering 4A continuing output current over a wide input voltage range from 2.5V to 5.5V, the RT5701 is ideally suited for Automotive Infotainment applications for low-voltage outputs to Micro controllers and ASICs in Navigation, Information Display, and Audio systems, Video systems and other battery operated systems requiring very low Shutdown current and Quiescent current consumption.

Internal synchronous rectifier with low RDS(ON) dramatically reduces conduction loss at PWM mode. No external Schottky barrier diode is required in practical application. The RT5701 enters low-dropout mode when normal PWM cannot provide regulated output voltage by continuously turning on the upper P-MOSFET. The RT5701 enters shut-down mode and consumes less than 5μA when the EN pin is pulled low. The switching ripple is easily smoothed-out by small package filtering elements due to a fixed operation frequency of 3MHz. This along with small TSSOP-14 (Exposed Pad) package provides small PCB area applications.

The RT5701 also includes Dynamic Voltage Scaling (DVS) for system low power applications.

The I2C interface let the RT5701 controllable flexibly to select VOUT voltage level, peak current limit level, PWM control mode, and so on. Other features include soft-start, auto discharge, lower internal reference voltage, over-temperature, and over-current protection.


  • Automotive Infotainment Systems
  • Microprocessor and DSP Core Supply
  • Industrial-Grade Point-of-Load
  • Cellular Telephones
  • Personal Information Appliances
  • Wireless and DSL Modems
  • MP3 Players
  • Portable Instruments
Key Spec.
Status Active
Vin (min) (V) 2.5
Vin (max) (V) 5.5
Number of Outputs 1
Vout (min) (V) 0.303125
Vout (max) (V) 5.5
Output Adj. Method Digital
Iout (max) (A) 4
Current Limit (typ) (A) 6.2
Freq (typ) (kHz) 3000
Freq (min) (kHz) 2700
Freq (max) (kHz) 3300
Ext Sync No
Ron_HS (typ) (mOhm) 40
Ron_LS (typ) (mOhm) 20
Interface I2C
Features 100% Duty Cycle;AEC-Q100;Adjustable Current Limit;Current Mode Control;Cycle-by-Cycle Current Limit;Enable Input;I2C;Internal Compensation;OCP;OTP;Power Good;SCP;Selectable (PSM or PWM);Stable with Ceramic Capacitor;UVP;Voltage Mode Control
Package Type TSSOP-14(PP)
  • 2.5V to 5.5V Input Range
  • Output Range from 0.3V to 5.5V
    ► Bank 0 : 0.3V to 0.7V
    ► Bank 1 : 0.6V to 1.4V
    ► Bank 2 : 1.2V to 2.8V
    ► Bank 3 : 2.4V to 5.5V
    ► The Default Value is 1.2V (VSEL = High) and 1.15V (VSEL = Low)
  • 4A Continuing Output Current
  • Support DVS in the Same Bank
    ► VOUT Adjusting Range (max, min) is Settable
  • High Efficiency
    ► 83% at 5V→1.2V with 1.5A Load
  • 3MHz Fixed-Frequency PWM Operation
    ► Auto-PSM/PWM or Force-PWM Selectable
  • Support Remote Ground Sensing for Accurate Output Voltage
  • Dedicated Hardware Pin to Immediately Switch Nominal Output Voltage Setting
  • Output Discharging when Turning Off
  • Over-Current Protection
    ► OC Level Settable
  • Available in AEC-Q100 Grade 2 Qualified (105°C)
  • Over-Temperature Protection
  • Integrated Soft-Start Function
  • Enabling Control by Enable Pin and I2C Register Setting by Software
  • I2C Interface
    ► I2C Communication allowed Even in Off-State
    (EN = L)
    ► Support Fast Mode (400kbps)
    ► Registers Setting Retained in Off-State (EN = L)
  • RoHS Compliant and Halogen Free
TitleLast UpdateDownload
3MHz 4A High Efficiency Step-Down Converter with I2C Interface2014/12/29
Reference Design
TitleLast UpdateDownload
Richtek Load Transient Tool2022/07/25