Connections to VDDC TM4C1290NCPDT

Marcie Dobyns

Other Parts Discussed in Thread: TM4C1294KCPDT

I am working on a conversion of a LM3S9B92 to a TM4C1290CPDT (or possibly a TM4C1294KCPDT).

The previous design connected the LDO output to an ADC input. The new part(s) don't have an LDO output, instead the pin description says to connect the two VDDC pins together with decoupling capacitors.

Can I still hook these to the ADC to measure the VDDC voltage?

Thanks!

over 11 years ago

0 Amit Ashara over 11 years ago

TI__Guru**** 244440 points

Hello Marcie,

On the TM4C129 parts the VDDC is the internal LDO output. You can still hook it up to the ADC Pins. Do make sure that there is not a large current required by your custom design (except for the ADC Sampling)

Regards

Amit

0 Marcie Dobyns over 11 years ago in reply to Amit Ashara

Prodigy 40 points

Thanks!

I'm thinking a resistor in series between this and the ADC would be prudent so the output doesn't accidentally get shorted to GND or PWR. What kind of current is tolerable for these pins?

0 Amit Ashara over 11 years ago in reply to Marcie Dobyns

TI__Guru**** 244440 points

Hello Marcie,

The important thing is that the IO for ADC is not configured as a Digital Output at any time. By Default it will be an input pad. So do make sure that the only configuration is that for ADC

The second important thing is that by adding a resistance of 1K (as an example), you can protect the circuit to a basic extent, However it would delay the charging of the ADC Sampling Cap, so you may have to play with the Sample and Hold control in the ADC Controller to fine tune the conversion accuracy to the time it takes for the conversion

Regards

Amit

0 Marcie Dobyns over 11 years ago in reply to Amit Ashara

Prodigy 40 points

Excellent! Thanks for your help!

0 cb1_mobile over 11 years ago in reply to Marcie Dobyns

Guru 117855 points

Ms. Dobyns,

Enjoyed your posts. (well introduced, detailed and responsive - good job)

On a historical note - if your Dad is named Bob - and an EE - it's likely we went to engineering school (in NYC) together... (few rainy seasons past...he was a neat & good guy...)

0 Marcie Dobyns over 11 years ago in reply to cb1_mobile

Prodigy 40 points

Nope, his name is Ken. Apparently there are more Dobyns' out there than I realized. :)

Thanks again!

0 cb1_mobile over 11 years ago in reply to Marcie Dobyns

Guru 117855 points

Oh well - continue to wish you/Ken well. (anyway)

Bob used to tell us his Mom would ask (once a week, at least) "How do we spell that?" (Dobyns)

Confess I stole that line (my name has all of 4 letters) always gets laughs... Ciao...

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Connections to VDDC TM4C1290NCPDT