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Project Notes

#374 VoltageReference/LT1019

Exploring the LT1019 precision reference, tested with an Arduino as an external voltage reference.



The Linear Technology LT1019 precision reference is available in four voltages: 2.5V, 4.5V, 5V and 10V. I am using a 2.5V LT1019-2.5 in a DIP8 package.

Stabilising the Reference Output

The datasheet recommends for the best transient load response to add a bypass RC filter on the output:

  • 2-5Ω + 2µF tantalum

Although my test setup is not really prone to such transient issues, I’ve added the bypass but with 2x10Ω resistors in parallel and a 2.2µF electrolytic.

As expected, the voltage reference performs just fine, expecially within the 10-bit resolution of of the ATmega328.

Test Circuit

In this example, the LT1019 is used to provide a 2.5V reference for an Arduino (AREF). This requires the external reference to be enabled analogReference(EXTERNAL)

A voltage divider comprising a 10kΩ pot in series with a 10kΩ resistor across the 5V supply provides a test input with a range of roughly 0 to 2.5V. This test signal is read on the Ardunio A0 analog input.

Since AREF is enabled (analogReference(EXTERNAL)), analog readings are all with respect the the 2.5V reference voltage.

A Nokia 5110 display provides a realtime reading of the analog input and the derived voltage reading.


The LT1019.ino sketch drives the demo.

It uses the Adafruit-PCD8544 Library to drive the 5110 display with hardware SPI.





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.