External offset trim of TLC07X and TLC08X op amps

Jim McGarvey

Intellectual 460 points

Other Parts Discussed in Thread: TLC070, TLC081

When using an external offset trim pot on these ICs, which supply should the pot wiper connect to?

The data sheets are inconsistent...

TLC07X data sheet: Wiper to VDD- (What's that??)

TLC08X data sheet: Wiper to VDD (Positive supply)

Application Report SLOA045 "Nulling offset voltage.." refers to TLC070 and shows wiper to VEE/GND (Negative supply)

over 12 years ago

0 John Caldwell over 12 years ago

TI__Genius 12325 points

Hi Jim,

I'm checking into this issue for you and will update this thread once we have the official answer. However, right now it looks like both the TLC07x and TLC08x would have the potentiometer wiper connected to the negative supply (or Ground if configured for single supply) for offset nulling.

0 Jim McGarvey over 12 years ago in reply to John Caldwell

Intellectual 460 points

Thanks. I just received some TLC081's and tried the offset null to both pos and neg supplies. The neg supply works correctly.

0 John Caldwell over 12 years ago in reply to Jim McGarvey

TI__Genius 12325 points

Good to hear! I was able to double check the internal schematic of both parts at the very end of last week and confirmed that the trim should go to the negative supply. good luck with your project and please let us know if there is anything else we can help with.

0 Jim McGarvey over 12 years ago in reply to John Caldwell

Intellectual 460 points

Thanks!

I suggest the data sheets be corrected ;-)

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External offset trim of TLC07X and TLC08X op amps