TMUX1104: The ground pin connection of analog mux

Xiang Maverick

Part Number: TMUX1104

Should the ground pin of analog mux be connected to digital ground or analog ground?

I think it should be connected to DGND, because DGND is the reference for the control pins which are digital signal. Although analog signal is in the main signal path, the ground pins has no relation with the main signal path.

over 4 years ago

0 Saminah C over 4 years ago

TI__Genius 9132 points

Hi Maverick,

Thanks for using e2e. You'll have to check what works best for your design .

The TMUX1104 datasheet specifies Ground with 0V reference.

It means 0V connection of a power supply is connected to the system ground. So 0V point is same as ground.

If you connect GND pin to DGND, it can minimize interference from signals on AGND from analog parts on the design.

However, since the digital signals are static, the GND pin of the MUX should be connected to the Analog Ground.

Regards

Saminah

0 Xiang Maverick over 4 years ago in reply to Saminah C

Intellectual 750 points

If the control pins are not static, but rather switching all the time. The ground pin should be connected to AGND or DGND?

What is the function of GND in mux? Is it used as the reference for digital signal?

0 Clemens Ladisch over 4 years ago in reply to Xiang Maverick

Guru 286310 points

Yes, GND is the reference for the digital inputs. If you want to keep the switching noise away from the analog signals, connect it to DGND.

0 Xiang Maverick over 4 years ago in reply to Clemens Ladisch

Intellectual 750 points

"If you connect GND pin to DGND, it can minimize interference from signals on AGND from analog parts on the design. "

What you really what to express is ""If you connect GND pin to DGND, it can minimize interference from signals on DGND to analog parts on the design. "?

0 Xiang Maverick over 4 years ago in reply to Clemens Ladisch

Intellectual 750 points

Can I connect the ground pin of MUX to DGND all the time? Is there any problem in doing that? I think the ground of MUX has no relation with the analog signal path. Is it correct?

0 Saminah C over 4 years ago in reply to Xiang Maverick

TI__Genius 9132 points

Hi Maverick,

If the digital control signals are switching, the switching noise can cause interference to analog signals, so in that case, connect GND pin of mux to DGND, otherwise connect it on analog ground for simplicity.

Regards

Saminah

0 Xiang Maverick over 4 years ago in reply to Saminah C

Intellectual 750 points

Thank you

"otherwise connect it on analog ground for simplicity."

I think connect it to DGND is also simple. From the point of view of theory and performance,should I always connect it to DGND?

0 Saminah C over 4 years ago in reply to Xiang Maverick

TI__Genius 9132 points

Hi Maverick,,

This is going to be really depending upon your system. Any switching current from the TMUX11xx device will go through GND, so if there is a significant amount of switching in your system it might be better to connect this to DGND. But noise on the GND pin can also couple to S/D pins of the device.

Regards

Saminah

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TMUX1104: The ground pin connection of analog mux