#374 VoltageReference/LT1019
Exploring the LT1019 precision reference, tested with an Arduino as an external voltage reference.
Notes
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.
Code
The LT1019.ino sketch drives the demo.
It uses the Adafruit-PCD8544 Library to drive the 5110 display with hardware SPI.
Construction
