SparkFun BabyBuck Regulator Breakout - 5V (AP63357)

The SparkFun 5V BabyBuck Regulator Breakout features the AP63357 from Diodes Inc., a 3.5A synchronous buck converter with a wide input voltage range of 3.8V to 32V. The fully integrated 74mΩ high-side power MOSFET/40mΩ low-side power MOSFET provides a high-efficiency step-down DC/DC conversion.

The BabyBuck regulator is a minimalistic version of our buck regulator boards. This board is configured to provide a regulated 5V output (from a 6 to 32V input voltage range) and features a high-voltage EN (enable) control pin that is rated up to 32V. On the back of the board, a small copper pad is available to dissipate excess heat with a heat sink. With only four PTH pins for connecting input and output power, everything fits on a mere 0.63in. x 0.52in. board layout.

Check out the SparkFun Buck Regulator Breakout - 5V (AP63357), for the larger, full-feature version of this board.

Note: While the AP63357 is rated up to a 3.5A output, users should expect a 3A maximum with our boards due to thermal constraints. The boards can output 3.5A but would require a sufficient amount of active cooling.

BabyBuck Board:

  • 0.63" x 0.52" PCB layout
  • Four 0.1" spaced PTH pins
    • VIN - Power In (6V to 32V)
    • GND - Common Ground
    • VOUT - Power Out (Regulated 5V)
    • EN - Enable (Pull high to enable the power output)
  • 0.5" x 0.6" Plated copper pad (for heat sinks)


  • VIN 3.8V to 32V
  • 3.5A Continuous Output Current
  • 0.8V ± 1% Reference Voltage
  • 22µA Low Quiescent Current (Pulse Frequency Modulation)
  • 450kHz Switching Frequency
  • Supports Pulse Frequency Modulation (PFM)
    • Up to 86% Efficiency at 5mA Light Load
  • Proprietary Gate Driver Design for Best EMI Reduction
  • Frequency Spread Spectrum (FSS) to Reduce EMI
  • Low-Dropout (LDO) Mode
  • Power Good Indicator with 5MΩ Internal Pull-up
  • Precision Enable Threshold to Adjust UVLO
  • Protection Circuitry
    • Undervoltage Lockout (UVLO)
    • Output Undervoltage Protection (UVP)
    • Cycle-by-Cycle Peak Current Limit
    • Thermal Shutdown

SparkFun BabyBuck Regulator Breakout - 5V (AP63357) Product Help and Resources

Core Skill: Soldering

This skill defines how difficult the soldering is on a particular product. It might be a couple simple solder joints, or require special reflow tools.

1 Soldering

Skill Level: Noob - Some basic soldering is required, but it is limited to a just a few pins, basic through-hole soldering, and couple (if any) polarized components. A basic soldering iron is all you should need.
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Core Skill: Programming

If a board needs code or communicates somehow, you're going to need to know how to program or interface with it. The programming skill is all about communication and code.

2 Programming

Skill Level: Rookie - You will need a better fundamental understand of what code is, and how it works. You will be using beginner-level software and development tools like Arduino. You will be dealing directly with code, but numerous examples and libraries are available. Sensors or shields will communicate with serial or TTL.
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Core Skill: Electrical Prototyping

If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.

3 Electrical Prototyping

Skill Level: Competent - You will be required to reference a datasheet or schematic to know how to use a component. Your knowledge of a datasheet will only require basic features like power requirements, pinouts, or communications type. Also, you may need a power supply that?s greater than 12V or more than 1A worth of current.
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Looking for answers to technical questions?

We welcome your comments and suggestions below. However, if you are looking for solutions to technical questions please see our Technical Assistance page.

  • JoyMonkey / about a year ago / 1

    Could this baby handle 2A continuous output (using a 24V battery as source) without additional cooling?

    • santaimpersonator / about a year ago / 1

      As specified in the hookup guide:

      "Without a heat sink or active cooling, we recommend users not load the boards with more than 1.5A."

Customer Reviews

3.5 out of 5

Based on 2 ratings:

Currently viewing all customer reviews.

Painful to implement.

It has no screw holes (which I knew from the picture), and the recommended heatsink takes up the whole bottom so you can't even try to hold down the edges. The lack of a jumper for the Enable pin is even more irritating on this one than on the full-size version because there aren't extra pads to short together.

Works great, always plan for the the unexpected

I accidentally blew up my SparkFun Buck Regulator Breakout - 5V (AP63357), fortunately I bought this at the same time. I put on a heatsink and then soldered it on my breadboard using right angle pins to mount it vertically. It doesn't take up too much space and works great. I am going to buy more.