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Project Notes

#152 LD1117 Regulator

Test an LD1117 3.3V linear regulator

The Build


The LD1117 is a low drop fixed and adjustable voltage regulator, available from a number of manufacturers including UTC and ST. Parts are available for a range of output voltages, including: 1.2V, 1.5V, 1.8V, 2.5V, 2.85V, 3.0V, 3.3V, 3.6V, 5.0V, and ADJ.

The component I have is marked: UTC LD1117AL 33D010HT5

Although I can’t find a datasheet that matches these markings exactly, I figure:

  • A = 1A
  • L = lead free
  • 33 = 3.3V
  • D? = pin out is (from left front): Vin, Ground, Vout

Note that the LD1117A by ST has a different pin configuration for the TO220 package. From pin 1 left front: Ground, Vout, Vin.

Some DMM measurements, with a 10kΩ output load:

Vin Iin Vout Iout Pin:Pout
5.10V 2.47mA 3.30V 329µA 12.6mW : 1.09mW

The inefficiency of a linear regulator is clear to see - we’re dissipating 11.51mW in the 1117, far more power than is actually delivered to the load. But they’re convenient!



The Schematic

The Build

Credits and References

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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.