AD5791/AD5781 Voltage Reference Generator
Introduction
This full open source precision voltage reference generator consists of LM399 as reference and AD5781/5791 DAC.
Resistors used to convert LM399 voltage to 10V is ten 0805 resistors with specification of 20ppm/C. The tested temperature coefficient is around 5ppm/C under 0~60 degree C. The whole device is around 3ppm/C.
Highlights
- Cheap. Both AD5781 and LM399 can be reached with pretty low prices, and 20ppm/C resistors are super cheap.
- Full open source. This repo consists of all the sources(links) include hardware to replicate.
- Portable. Palm-sized device with 220V as main supply.
Hardware
Main reference: LM399 with statistic resistors booted up to 10V
DAC: AD5791/AD5781
ADT7420: internal temperature monitor(can be omitted)
Display: 10 digits segments LED display
MainController: STM32F030
USB to isolated UART for remote control
Encoder for manual control
Gallery
Test Result
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INL
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Temp-drift
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TBD