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# Voltage Reference Generator | ||
# AD5791/AD5781 Voltage Reference Generator | ||
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 | ||
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## Introduction | ||
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This full open source precision voltage reference generator consists of LM399 as reference and AD5781/5791 DAC. | ||
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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. | ||
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## Highlights | ||
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- 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. | ||
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## Hardware | ||
LM399 | ||
Statistic method for ref boost up. | ||
AD5791 - the 2-bit 1ppm INL DAC | ||
STM32F030 as the controller | ||
USB isolated UART input | ||
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Main reference: LM399 with statistic resistors booted up to 10V | ||
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DAC: AD5791/AD5781 | ||
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ADT7420: internal temperature monitor(can be omitted) | ||
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Display: 10 digits segments LED display | ||
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MainController: STM32F030 | ||
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USB to isolated UART for remote control | ||
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Encoder for manual control | ||
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## Gallery | ||
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 | ||
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 | ||
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 | ||
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 | ||
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 | ||
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 | ||
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## Test Result | ||
TBD | ||
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1. INL | ||
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2. Temp-drift | ||
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3. TBD | ||
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