Diodes Incorporated
U QFN4040 16 SWP

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Back to Buck Converter


3.8V to 60V Input, 3A Low IQ Synchronous Buck Converter

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The AP66300 is an adjustable switching frequency internal compensated synchronous DC-DC buck converter with a default internal frequency of 500kHz. The device fully integrates a 120mΩ high-side power MOSFET and a 55mΩ low-side power MOSFET to provide high-efficiency step-down DC-DC conversion.

The AP66300 enables continuous load current of up to 3A with efficiency as high as 95% in enhanced biased.

The AP66300 features current mode control operation, which enables easy loop stabilization supporting wide range of output capacitive loads.

The AP66300 simplifies board layout and reduces space requirements with its high level of integration and minimal need for external components, making it ideal for distributed power architectures.

The AP66300 is available in a standard Green U-QFN4040-16/SWP (Type UXB) package.


  • VIN8 to 60V
  • 3A Continuous Output Current
  • VOUT Adjustable from 0.8V to 50V
  • Enhanced Efficiency Mode with Bias
  • Adjustable Switching Frequency. 500kHz Default Frequency
  • Start-up with Pre-biased Output
  • External Soft-Start with Tracking – Sequential, Ratiometric, or Absolute. Default Internal Soft-Start of 2ms
  • Enable Pin with 5% tolerance
  • Soft Discharge
  • ±5% Power Good Detection with Internal Pull-up Resistor
  • Overvoltage Protection & Undervoltage Protection
  • Overcurrent Protection (OCP) with Hiccup
  • Thermal Protection
  • Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
  • Halogen and Antimony Free. “Green” Device (Note 3)
  • For automotive applications requiring specific change control (i.e. parts qualified to AEC-Q100/101/104/200, PPAP capable, and manufactured in IATF 16949 certified facilities), please contact us or your local Diodes representative. https://www.diodes.com/quality/product-definitions/


  • General-purpose point-of-load DC/DC power conversions
  • Telecommunications
  • Distributed power systems
  • Home audios
  • Consumer electronics
  • Network systems
  • FPGA, DSP, and ASIC supplies
  • Green electronics

Product Specifications

Product Parameters

Compliance(Only Automotive supports PPAP) Standard
Type Buck
Minimum Input Voltage (V) 3.8
Maximum Input Voltage (V) 60
Output Current (A) 3
Minimum Output Voltage (V) 0.8
Maximum Output Voltage (V) 50
Quiescent Current Typ (µA) 43
Shutdown Current Typ (µA) 2.2
Frequency Typ (kHz) 300/500/2500
HS RDS(ON) (mΩ) 120
LS RDS(ON) (mΩ) 55
Features Enhanced Efficiency Mode with Bias, Adjustable Switching Frequency, 500kHz Default Frequency, Start-up with Pre-biased Output, External Soft-Start with Tracking – Sequential, Ratiometric, or Absolute, Default Internal Soft-Start of 1.7ms, Enable Pin with 5

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