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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

About LEAP#374 Voltage Reference
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LEAP is my personal collection of electronics projects, 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 (IMHO!).

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