P5V0REF - Githubissues

sinara-hw / Thermostat_EEM

Thermostat with 4 TEC and 8 sensor channels in EEM form factor

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P5V0REF #7

Closed jordens closed 3 years ago

jordens commented 3 years ago

Do we need P5V0REF?

The DACs don't need to be extremely accurate. They are in-loop and relative to the somewhat unstable MAX Vref.
The CPU ADC reference is as inaccurate as the resistors/buffer.
The P5V0A seems clean and has enough power

jordens commented 3 years ago

Maybe it's much better to have a 3V reference for the DAC VREF and the CPU VREF+. Then there would be no need for the IC10 buffer, the R54/R70 divider (remove R70 only, R54 is a reconstruction filter) and the R88/R87 divider. CPU ADC accuracy would be improved. Drive IC5 VDD from P5V0A with a bit of resistance to isolate it (like the ADCs).

gkasprow commented 3 years ago

Good idea. I don't remember what was the rationale behind supplying the DAC REF from 5V. The DAC performance is not critical here.