MSP432P401R: Analog and Digital Ground

Colin Adema

Part Number: MSP432P401R

Hello!

I'm designing a system that will use an MSP432 and will have both analog and digital circuitry on the PCB. The MSP432 will be sending music data from an SD card to an external DAC to then be output to a speaker using an AB amp. There will be other components in the design, but a majority of the analog is the amp. I was planning on using a star ground to connect analog and digital ground planes at a point close to the DAC.

I was wondering if since the MSP432 isn't inherently performing any analog function, I could just tie AVSS and DVSS to the digital ground plane rather than connect AVSS to the analog plane without causing any issues. The reason I would prefer to connect AVSS to the digital ground plane is because the MSP432 isn't going to sit close to the border of the 2 ground planes, so the analog ground plane would have to jut out into the digital plane in order to encompass AVSS.

Please let me know if this is viable or not, thank you!

Best,

Colin

over 6 years ago

0 Matt Calvo over 6 years ago

TI__Genius 14930 points

Hey Colin,

Great question!

In terms of the MCU, TI recommends separated grounds with a single-point connection for noise isolation from digital-to-analog circuits and for better on-chip analog accuracy. Now, if you are saying that you don't necessarily care for the highest possible analog accuracy on-chip then I don't see an issue with tying the AVSS and DVSS to the digital ground plane.

You can refer to the datasheet for all of the stipulations associated with AVSS and how it should be treated. Either way, make sure you have decoupling and bulk caps as shown in Section 7.1.1: