AFE5832LP: The pins for the segmentation of analog ground and digital ground

Kangwei Wang

Part Number: AFE5832LP

Dear engineers,

We use AFE5832LP for the design.
We want to divide the ground into two different grounds: AVSS (analog ground) and DVSS (digital ground) for better performance.
But we are confused about which type of ground the pins belong to.

In the pdf file, we can find the pin and its "Rail reference". The questions are：

1. If the "Rail reference" is only about “AVDD”, it means that these pins will be associated with the AVSS (analog ground) and wired on the AVSS (analog ground)？ The pins use the AVSS (analog ground) as the reference point?
Such as the "INPx", "INMx", "TGC_SLOPE", "ADC_CLKP", "TGC_UP_DN" and so on.

2. If the "Rail reference" is about “AVDD”and "DVDD", which ground are these pins wired on? and which ground to use as the reference point?
Such as the "SDOUT", "SCLK", "SDIN", "RESET", "PDN_GBL" and so on.

3. If the "Rail reference" is only about “DVDD”, it means that these pins will be associated with the DVSS (digital ground) and wired on the DVSS (digital ground)？ The pins use the DVSS (digital ground) as the reference point?
Such as the "SEN", "TX_TRIG ", "DOUTPx" and so on.

Thanks for your help.

over 1 year ago

+1 Shabbir Amjhera Wala over 1 year ago

TI__Expert 4711 points

Hi,

Kangwei Wang said:
1. If the "Rail reference" is only about “AVDD”, it means that these pins will be associated with the AVSS (analog ground) and wired on the AVSS (analog ground)？ The pins use the AVSS (analog ground) as the reference point?
Such as the "INPx", "INMx", "TGC_SLOPE", "ADC_CLKP", "TGC_UP_DN" and so on.

You can refer all of these signals to referred to AVDD to ground AVSS.

Kangwei Wang said:
2. If the "Rail reference" is about “AVDD”and "DVDD", which ground are these pins wired on? and which ground to use as the reference point?
Such as the "SDOUT", "SCLK", "SDIN", "RESET", "PDN_GBL" and so on

These pins are going to both VCA and ADC die. You can refer to AVSS for simplicity.

Kangwei Wang said:
3. If the "Rail reference" is only about “DVDD”, it means that these pins will be associated with the DVSS (digital ground) and wired on the DVSS (digital ground)？ The pins use the DVSS (digital ground) as the reference point?
Such as the "SEN", "TX_TRIG ", "DOUTPx" and so on.

Yes correct. But you can refer SEN, TX_TRIG to AVSS and all the SOUTP/Mx pins to DVSS.

We recommend ground separation only if user choose demod operation in our device. Since AFE5832LP doesnt support demod then ground separation is not must.

Regards,

Shabbir

0 Kangwei Wang over 1 year ago in reply to Shabbir Amjhera Wala

Prodigy 40 points

Dear, Shabbir

Thanks for your help. I have one more question.

There are digital devices on my system, and the reason for the ground plane separation is because the noise is too high for the single ground. Is it better to split the ground plane? Or is it ineffective? Or even worse?

+1 Shabbir Amjhera Wala over 1 year ago in reply to Kangwei Wang

TI__Expert 4711 points

I think instead of separating analog and digital ground of AFE, you can consider having an AFE ground (Analog and digital) on one common ground and have digital IC referred to separated ground. That might be more easier for layout and noise separation.

Thanks!