LMH6882: Connection of NC pins?

Val Valeriy

Part Number: LMH6882

Hello folks!

I have a question about connection of NC pins in LMH6882. Functions of this pins are absent in table named "Pin Functions" in datasheet. Is this pins are not connected internally?
In LMH6882 EVAL BOARD this pins connects to capacitors 0.1uF.

Could anyone explane me the point of this connection?

What is the effect of connecting capacitors 0.1uF to this pins?

Why is there no description of these pins in the datasheet?

Best regards, Val

over 4 years ago

0 SimaJalaleddine over 4 years ago

TI__Mastermind 23445 points

Hello Val,

The NC pins are the No connect pins. They are physical pins, but are not connected internally. It is common to leave these pins floating. The capacitors at the digital pins are DC coupling capacitors or known as decoupling capacitors which block AC signals.

Thank you,

Sima

0 Val Valeriy over 4 years ago in reply to SimaJalaleddine

Intellectual 430 points

Hello, thank you for your reply.
Why in LMH6882 EVAL BOARD pins 36, 33, 31 and 28 are connected to capacitors C3, C14, C18, C19? And why pin 32 is connect to V+ through resistor R40?
These pins are NC in datasheet.

0 SimaJalaleddine over 4 years ago in reply to Val Valeriy

TI__Mastermind 23445 points

Hello Val,

I will have to look into the discrepancy between the two layouts. I should have an update for you by the end of this week.

Thank you,

Sima

0 kai klaas69 over 4 years ago in reply to SimaJalaleddine

Guru 140200 points

Hi Sima,

interesting is that the discussed pins are not labeled as "NC" in the EVAL board, but as "DC1A", "DC2A", a.s.o. As if it was a different chip or a LMH6882 with a different internal circuit.

Kai

0 SimaJalaleddine over 4 years ago in reply to kai klaas69

TI__Mastermind 23445 points

Hello Kai and Val,

Kai is correct; turns out the EVM was designed to support other chips that used those pins. The LMH6882 does not use these pins, and they can be left floating. This was from an older post answered by Loren: https://e2e.ti.com/support/amplifiers/f/14/t/386239.

Thank you,

Sima

0 Val Valeriy over 4 years ago in reply to SimaJalaleddine

Intellectual 430 points

Thank you Sima.

Best regards, Val.

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LMH6882: Connection of NC pins?