TIDA-010019: Leakage current of diodes

Kurumi Hasegawa

Expert 7661 points

Part Number: TIDA-010019

Hi team,

The reference design has diodes on TC’s signal line, for protection.

Would the leakage current of those diodes flow into the ADC input? If yes, would it affect the ADC’s performance?

Best regards,

Kurumi

over 4 years ago

+1 Steffen Graf70 over 4 years ago

TI__Intellectual 1365 points

Hi Kurumi,

you are right, the leakage current of the diodes could impact the performance of the system. To reduce this as much as possible, a low leakage diode is chosen here. The BAV199 in the design is specified with a typical leakage of only 3 pA, which is much less than the input current of the ADC (with PGA, typical 1 nA).

Best regards,

Steffen

0 Kurumi Hasegawa over 4 years ago in reply to Steffen Graf70

TI__Expert 7661 points

Hi Steffen,

Thank you for the reply. I understand the diode needs to have lower leakage current compare with the ADC.

However, as far as I checked, BAV199 has max 5.0nA and typ ~0.5nA leakage current. Am I missing something? Or, BAV199 in the design was somehow modified to have lower leakage current?

I'd appreciate it if you could provide recommended diode.

Best regards,

Kurumi

+1 Steffen Graf70 over 4 years ago in reply to Kurumi Hasegawa

TI__Intellectual 1365 points

Hi Kurumi,

it seems different manufacturer specify this a little bit different. If you look at the diode from Nexperia, they have in the table: 3 - 80 nA at 75 V, but specify 3 pA typical. But still 0.5 nA does not cause a significant error and you are far away from 75 V, so the current will be much lower.

Best regards,

Steffen

0 Kurumi Hasegawa over 4 years ago in reply to Steffen Graf70

TI__Expert 7661 points

Hi Steffen,

I understand, thank you so much for your help!

Best regards,

Kurumi

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TIDA-010019: Leakage current of diodes