1. Products
  2. Power Management
  3. Switching Regulators
  4. Step-Down (Buck) Regulators
  5. External Power Switch Buck Controllers
  6. ADP1821


Features and Benefits

  • Wide power-input voltage range: 1 V to 24 V
  • Chip supply voltage range: 3.7 V to 5.5 V
  • Wide output voltage range: 0.6 V to 85% of input voltage
  • 1% accuracy, 0.6 V reference voltage
  • All N-channel MOSFET design for low cost
  • Fixed-frequency operation 300 kHz, 600 kHz, or synchronized operation up to 1.2 MHz
  • No current sense resistor required
  • Power-good output
  • Programmable soft start with reverse current protection
  • Soft start, thermal overload, current-limit protection
  • Undervoltage lockout
  • 10 μA shutdown supply current

Product Details

The ADP1821 is a versatile and inexpensive, synchronous, pulse-width-modulated (PWM), voltage-mode, step-down controller. It drives an all N-channel power stage to regulate an output voltage as low as 0.6 V. The ADP1821 can be configured to provide output voltages from 0.6 V to 85% of the input voltage and is sized to handle large MOSFETs for point-of-load regulators.

The ADP1821 is well suited for a wide range of high power applications, such as DSP and processor core power in telecommunications, medical imaging, high performance servers, and industrial applications. It operates from a 3.7 V to 5.5 V supply with a power input voltage ranging from 1.0 V to 24 V.

The ADP1821 operates at a pin-selectable, fixed switching frequency of either 300 kHz or 600 kHz, minimizing external component size and cost. For noise sensitive applications, it can be synchronized to an external clock to achieve switching frequencies between 300 kHz and 1.2 MHz. The ADP1821 includes soft start protection to limit the inrush current from the input supply during startup, reverse current protection during soft start for precharged outputs, as well as a unique adjustable lossless current-limit scheme utilizing external MOSFET sensing.

The ADP1821 operates over the –40°C to +125°C junction temperature range and is available in a 16-lead QSOP.


  • Telecommunications and networking systems
  • Set-top boxes
  • Printers
  • Servers
  • Medical imaging systems
  • Microprocessor and DSP core power supplies
  • Mobile communication base stations

Product Lifecycle icon-recommended Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Evaluation Kits (1)

Tools & Simulations

Design Tool

ADP182x Buck Designer Tool

Microsoft Excel download tool from ADIsimPower to generate a power supply design complete with a schematic, bill of materials, and performance specifications.

Design Resources

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.

Part Number Material Declaration Reliability Data Pin/Package Drawing CAD Symbols, Footprints & 3D Models
ADP1821ARQZ-R7 Material Declaration Reliability Data 16-Lead QSOP
Wafer Fabrication Data

PCN-PDN Information

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Sample & Buy

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Buy Now Pricing

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List Pricing

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Evaluation Boards

Pricing displayed is based on 1-piece.

Up to two boards can be purchased through Analog.com. To order more than two, please purchase through one of our listed distributors.

Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.