ADC10040: Recommendation for Vref

Massimiliano De Cristofaro

Expert 6640 points

Part Number: ADC10040
Other Parts Discussed in Thread: ADC10D040

Hi team,

one of my customers would like to use this device with an external Vref =1V.

Divider from 2.5V with 1.5k/1k with a bypass capacitor of 0.1uF.

Do you see any issue in this condition?

Any recommendation for Vref?

Thanks a lot in advance.

Best regards,
Massimiliano De Cristofaro
TI Staff Field Application Engineer - WEU

over 5 years ago

0 Jim Brinkhurst1 over 5 years ago

TI__Mastermind 44430 points

Hi Massimiliano
We should have a more detailed response to your question later today.
Best regards,
Jim B

0 dBrock over 5 years ago

TI__Genius 12780 points

Hi Massimiliano,

It might be ok, but it depends on how much noise is riding along. If the voltage reference is not precise or noisy, it could effect the ADCs reference level and this code cause unexpected results. Code = V_in * (2^N/Vref) so you can see that if Vref fluctuates, it can cause problems.

This article/series goes into further detail about voltage references with respect to ADCs.

www.ti.com/.../slyt331.pdf Part 1
www.ti.com/.../slyt339.pdf Part 2
www.ti.com/.../slyt355.pdf Part 3 (most useful analysis, in my opinion)

TI's power management portfolio has some good options for references. Here is a small/cost effective part that can provide 1V output.

www.ti.com/.../TLV713P

Best Regards,

Dan

0 Massimiliano De Cristofaro over 5 years ago in reply to dBrock

TI__Expert 6640 points

Hi Dan,

thanks for your very detailed feedback.

I am going to send it to the customer.

However the VRef selection of 1V comes from the evaluation board documentation that it is still present on the web. See attached.

Specifically:

Could you please comment that based on what it is written in the datasheet (Vref=1.2V)?

Thanks a lot in advance.

Best regards,

Massimiliano.

adc10d040man.pdf

0 dBrock over 5 years ago in reply to Massimiliano De Cristofaro

TI__Genius 12780 points

Hi Massimiliano,

Are you wanting to know the suggested Vref for the ADC10040 or the ADC10D040? These ADCs have different requirements for Vref, so I would stick with what the datasheet has stated for the ADC10040 (Vref = 1.2V). It may be possible to drive a lower Vref, but this is not stated anywhere in the datasheet.

As you pointed out, it appears that the ADC10D040 is more flexible with the Vref, so this may be a better option if your customer requires more room with the Vref.

Best Regards,

Dan

0 Massimiliano De Cristofaro over 5 years ago in reply to dBrock

TI__Expert 6640 points

Hi Dan,

sorry, my fault. Customer is using both devices and I merged them.

Thanks a lot for your support, highly appreciated.

Best regards,
Massimiliano.

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ADC10040: Recommendation for Vref