MSP432E401Y: VDDA SUPPLY

balazs buglyo

Part Number: MSP432E401Y
Other Parts Discussed in Thread: REF6030, REF6033, TPS82130

Hu Guys,

Let me allow to ask something, if i want to use this processor for measuring voltage with the adc, and i want to use a ref voltage 3.0V (ref6030) with 3.3V for VDDA (ref6033).
Is a very accurate, good and stable 3.3V like REF6033 need for the VDDA or something else is enought( something with noise 5-20mV VPP at 3.3V i made the 3.3V with TPS82130 for the digital part)?
Well the truth is that i dont know power consumption of the VDDA,and i dont know is the the REF6033 is able to drive the VDDA pin.

I would like to design separate analog and digital part. i know that the 12bit is not too much , but it is good for me but i would like to best for it :)

So the question is in a nut shell.

Should i use precision power supply for vdda, if i add prec voltage ref for vrefa+ ( ref6030 ).

Thanks

UPDATED!

over 6 years ago

0 Evan Wakefield over 6 years ago

TI__Mastermind 37250 points

Balazs,

A couple things. First, you mention 3.0V for VDDA and then look to the REF6033 which generates 3.3V. Are you looking for 3.0 or 3.3V?

Regardless, the datasheet there recommends that VDDA is set to min 2.97V to max 3.63V with a typical of 3.3V. Given a 10% nominal swing in the voltage supply, supplying 3.0V to VDDA would not be smart in my opinion.

Second, and more generally what I believe your question to be, if you use the REF6033 and supply it with a voltage that is generally 3.3V, the REF6033 will clean that up and supply a clean 3.3V to your VDDA and consequently to VREFA+. I would take note of Note (1) in the image above as well if you decide to supply VDDA and VDD separately.

I would also take this into account from section 5.15.11 of the datasheet for E4

0 Evan Wakefield over 6 years ago in reply to Evan Wakefield

TI__Mastermind 37250 points

Just as an FYI, on the LaunchPad, we tie VREFA+ to VDD.

www.ti.com/.../msp-exp432e401y

You can find the schematic at the bottom of the users guide: www.ti.com/.../slau748.pdf

0 balazs buglyo over 6 years ago in reply to Evan Wakefield

Prodigy 230 points

Dear Evan,
I just updated , my question , so i hope it will be clear, couse it was a bit messy.

Balazs.

0 Evan Wakefield over 6 years ago in reply to balazs buglyo

TI__Mastermind 37250 points

Balazs,

If VDDA is the source of the ADC reference then to be accurate for conversion it must be a stable source. Alternatively a bulk cap of 1 uf and a decoupling cap of 0.1uf would be good. If Vrefa+ pin is being used then a REF6030 would work.

0 Evan Wakefield over 6 years ago in reply to Evan Wakefield

TI__Mastermind 37250 points

Balazs,

You can refer to section 4.8.1 for more information on the ADC system design guidelines as well.
www.ti.com/.../slaa770.pdf

0 balazs buglyo over 6 years ago in reply to Evan Wakefield

Prodigy 230 points

Dear Evan,

Thanks for your help.

Balazs

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MSP432E401Y: VDDA SUPPLY