7
\$\begingroup\$

How do the electrical characteristics of an ADC typically degrade over lifetime?

And is there a way to do a somewhat realistic worst-case estimate for that before doing aging tests over a big batch?

Example data, probably for begin of life, taken from the PIC16(L)F1855/75 data sheet is: ANALOG-TO-DIGITAL CONVERTER (ADC) ACCURACY SPECIFICATIONS from the PIC16(L)F1855/75 data sheet

There are also application notes available what can be compensated away and what is remaining, for the case one does not already know.

However, I never see any information about degradation due to aging.

Also no information how much the characteristics worst-case change over the operational temperature range.

\$\endgroup\$
14
  • 1
    \$\begingroup\$ Lifetime of an ADC may be several decades, how should a manufacturer get information about degrading of the ADC in only a few years? \$\endgroup\$
    – Uwe
    Jul 20, 2022 at 16:47
  • 2
    \$\begingroup\$ Consult thru buyer with OEM for reliability and design validation test reports. There may be Vref and offset vs T data. Also noise is a factor for DNL and linearity \$\endgroup\$
    – Tony Stewart EE75
    Jul 20, 2022 at 17:00
  • 3
    \$\begingroup\$ @Uwe Via accelerated aging tests, as usually done for assembled PCBAs at least for safety relevant applications. \$\endgroup\$
    – Torsten Knodt
    Jul 20, 2022 at 18:34
  • 1
    \$\begingroup\$ If it’s crucial that the ADC perform to a certain spec over time try one of my tricks: connect a stable and fully qualified reference to one of the ADC inputs and use that to measure the ADC performance. You may need several to get an idea of linearity and the like. \$\endgroup\$
    – Bryan
    Jul 20, 2022 at 18:35
  • 3
    \$\begingroup\$ Indeed, as @Uwe says, external ADCs often run circles around integrated ones. Even when you have these peripherals provided, it sometimes pays to use external ones (e.g.: faster; better accuracy or noise; more bits; more flexible supply/reference; onboard gain/buffer stages; wider temp range; etc.). \$\endgroup\$
    – Tim Williams
    Jul 21, 2022 at 2:27

2 Answers 2

Reset to default
8
\$\begingroup\$

I'm not aware of any ADCs that degrade, nor what mechanisms would lead to such (while meeting abs. max. ratings). (But then, ADCs are usually super-secret sauce, and I'm hardly expert in VLSI to begin with.) This is a question for the manufacturer, not random people from the internet.

This may be relevant: http://ww1.microchip.com/downloads/en/DeviceDoc/00000169J.pdf

Offhand, the only indications I know of, regarding reliability, are made explicit: to wit, I've been using the AVR64DA64 lately, and errata show a lower than expected Flash lifetime (100k --> 10k erase cycles), and "The offset of the DAC output buffer can drift over lifetime if the device is powered with the DAC output buffer disabled". No such notes about the ADC.

If you need guaranteed device lifetime, expect to pay for it. Perhaps you can obtain some MIL/aerospace rated parts with more extensive testing, proven operation, and a paper trail to prove it? I'm sure an FAE can help figure something out.

\$\endgroup\$
6
\$\begingroup\$

It'll either cost real money to get parts where this is known, or you can use some intrinsically accurate self-calibration process. A ramp from an integrator is an excellent way to check ADCs for static linearity errors. As far as scaling goes - try for ratiometric operation if at all possible, then you only deal with resistor drift, if any.

The best way to "deal" with such problems is to design them out.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.