thermal design

[sbourdeauducq]

I think it's reasonable to assume temperature of air supplied to microTCA chassis is stable to +/- 2 C.

Also from discussion in Warsaw... I'll close #13.

• [ ] is it possible to achieve 1 LSB stability for both ADC and DAC?
  • [ ] is 1 LSB accuracy needed board-to-board?
• [ ] regarding on-board DC calibration
  • use heavy low-pass; sigma-delta DAC on motherboard, 16 single-ended inputs
  • SPI interface
  • [x] how many channels are needed? (temperature, voltage measurements)
  • [x] allocate several pins (how many?) on 40-pin header #40 for routing to calibration ADC @gkasprow
  • I want to add 4 ADC pins per mezzanine. They can be used as differential or single ended. Can be used for offset, gain or temperature measurement.
• [ ] analog component temperature coefficients (DACs, ADCs, amplifiers, attenuators)
• [x] are voltage references needed?
  • yes,I want to use 0.25ppm LTC6655
• [x] power supply noise rejection of components -- should this go on another Issue?
  • this is standard engineering task but if you feel that some discussion is needed then go on

[gkasprow]

We had a discussion in Warsaw about it. Certainly the DACs will be cooled by MTCA fans and some crate-wide temperature regulation is possible. The idea is to place additional 24bit ADC connected to the DAC (or mezzanine) outputs so on-line compensation will be performed. We will compensate for gain and offset changes. The ADC will be connected to dedicated pins of mezzanine connector so the DAC driver offset can be compensated as well. We will use AD7194 for this purpose with external ppm reference.

[jordens]

@jbqubit please don't be sloppy and keep the top comment up to date. Move text if necessary.

[jordens]

@jbqubit @gkasprow could you then mark those tasks as done or re-raise them where appropriate? Also, who should resolve/answer the tasks that need handling?

[dhslichter]

Temperature monitoring can also be performed on mezzanines by using ADT7420, which contains conversion and I2C hardware, thus freeing slow ADC lines for e.g. monitoring of I/Q modulator drift or amplifier gain drift.