LM98640 14-Bit ADC

James Becker18

If the band-gap reference output, VREFBG, is overdriven with an external voltage source, how or what does that affect in the performance of the ADC? For instance, if 0.833V is driven into this pin, what should be expected to change?

Thanks,

Jim Becker

Raytheon Space Systems

El Segundo, CA

310 647-8373

over 8 years ago

0 Kirby Kruckmeyer96848 over 8 years ago

TI__Genius 17035 points

Hi Jim,
We have not characterized this and cannot provide guidance on what it would do.
What are you looking to acheive by doing this?

0 James Becker18 over 8 years ago in reply to Kirby Kruckmeyer96848

Prodigy 120 points

Kirby,
I have an existing design that has had +1.22V, +0.63V, and now +0.83V applied to the VREFBG pin. I assume, the original designer of the circuit wanted a more accurate reference voltage, but unfortunately, he has retired and there is no documentation explaining why the voltages are anything but +1.22V. Should I assume, if an external voltage is used to overdrive the internal source, then it must be +1.22V?
Thanks,
Jim Becker
Raytheon SAS

0 Kirby Kruckmeyer96848 over 8 years ago in reply to James Becker18

TI__Genius 17035 points

Jim,

the VREGBG pin can be overdriven with other voltage levels, TI just has not characterized it and cannot provide guidance on it.

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LM98640 14-Bit ADC