INA240: NC pin status

pelletier frederic

Part Number: INA240

Hello team,

I've seen an update from the datasheet SBOS662B (october 2017) to SBOS662C (december 2021) which the NC pin can be let floating.

SBOS662B picture

SBOS662C picture

In previous topic, the NC pin must be connected to ground to reduce noise, then why the new datasheet version can let floating ? An HW update of your chip has been done for SBOS662C ?

If yes, can you send me the first component batch identification which include this update please ?

Regards,

over 2 years ago

0 Levi DV over 2 years ago

TI__Expert 8525 points

Hello,

The change in the datasheet was simply a clarification, there is no change to the device itself. The functionality of the device shouldn't be significantly impacted by leaving the pin floating.

Let me know if you have any more questions,

Levi DeVries

0 pelletier frederic over 2 years ago

Prodigy 10 points

Thanks for your answer.

When you says "shouldn't be significantly impacted by leaving the pin floating.", can you clarify please ? It is more noises on the output ? an lower accuracy ? An instability of the component ? other ?

Thanks,

0 Levi DV over 2 years ago in reply to pelletier frederic

TI__Expert 8525 points

Hello,

I have seen your post and will get beak to you tomorrow as I am travelling today.

Thank you for your patience,

Levi DeVries

0 Levi DV over 2 years ago in reply to pelletier frederic

TI__Expert 8525 points

Hello, thank you for your patience.

The NC pin is used for testing the chip during manufacture, but it is also (weakly) pulled low internally. We generally recommend grounding the pin to avoid coupling to nearby PCB traces. Putting the device in test mode accidentally is unlikely.

Levi DeVries

0 pelletier frederic over 2 years ago in reply to Levi DV

Prodigy 10 points

Hello,

Can you give me the value of the internal pull down and the minimal voltage activation threshold of the testing function please ?

Regards,

+1 Levi DV over 2 years ago in reply to pelletier frederic

TI__Expert 8525 points

Hello,

The testing function is not activated by reaching a certain voltage threshold, activating test mode from a disconnected nc pin requires a specific input sequence be coupled into the nc pin, so it is not likely that the device would enter test mode unintentionally. The internal values of the device, including the internal pull down resistor, are proprietary information.

Let me know if you have any other questions,

Levi DeVries

0 pelletier frederic over 2 years ago in reply to Levi DV

Prodigy 10 points

Hello,

Thanks for this answer.

If we suppose that the test mode occurs when my electornic board is operationnal, which is the behavior of the INA240 ? Erroneous on pin OUT is possible ? pin OUT is clamped ?

0 Levi DV over 2 years ago in reply to pelletier frederic

TI__Expert 8525 points

Hello,

Entering test mode accidently is unlikely even if you directly coupled the NC pin to a noise source. Entering test mode accidently with nothing attached to the NC pin is probably unlikely enough you won't need to worry about it.

If you enter test mode unintentionally the output would be invalid.

Levi DeVries

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INA240: NC pin status