4A, 1MHz, Synchronous Step-Down Converter


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The RT8078A is a high efficiency synchronous, step-down DC/DC converter. It's input voltage range from 2.7V to 5.5V that provides an adjustable regulated output voltage from 0.6V to VIN while delivering up to 4A of output current. The internal synchronous low on-resistance power switches increase efficiency and eliminate the need for an external Schottky diode. The switching frequency is fixed internally at 1MHz. The 100% duty cycle provides low dropout operation, hence extending battery life in portable systems. Current mode operation with internal compensation allows the transient response to be optimized over a wide range of loads and output capacitors. The RT8078A is operated in PWM mode to achieve high efficiency for a wide load range. The RT8078A is available in WDFN-10L 3x3 and SOP-8 (Exposed Pad) packages.


  • Portable Instruments
  • Battery Powered Equipment
  • Notebook Computers
  • Distributed Power Systems
  • IP Phones
  • Digital Cameras
Key Spec.
Status Active
Vin (min) (V) 2.7
Vin (max) (V) 5.5
Number of Outputs 1
Vout (min) (V) 0.6
Vout (max) (V) 5.5
Output Adj. Method Resistor
Iout (max) (A) 4
Current Limit (typ) (A) 4.4
Freq (typ) (kHz) 1000
Ext Sync No
Ron_HS (typ) (mOhm) 69
Ron_LS (typ) (mOhm) 49
Iq (typ) (mA) 0.11
Features 100% Duty Cycle;Current Mode Control;Enable Input;Fast Transient Response;Internal Compensation;OCP;Power Good;Stable with Ceramic Capacitor;UVP
Package Type WDFN3x3-10
  • High Efficiency : Up to 95%
  • Fixed Frequency : 1MHz
  • No Schottky Diode Required
  • Internal Compensation
  • 0.6V Reference Allows Low Output Voltage
  • PWM Mode Operation
  • Low Dropout Operation : 100% Duty Cycle
  • RoHS Compliant and Halogen Free
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4A, 1MHz, Synchronous Step-Down Converter2015/04/29
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4A, 1MHz, Synchronous Step-Down Converter 2015/05/19
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 1378
Reference Design
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Richtek Load Transient Tool2021/01/21