TS5A21366: Should the GND of this part be connected to a digital ground or an analog ground and why?

sasank mallampati

Part Number: TS5A21366
Other Parts Discussed in Thread: TS5A3166

I was looking at the datasheet of TS5A21366 and there is a mention of connecting the ground to a digital ground. Why can't it be connected to an analog ground? What is the reasoning behind connecting it to a digital ground.

Regards,

Sasank.

over 4 years ago

0 Ambroise Suter over 4 years ago

TI__Expert 3820 points

Hi Sasank,

Thank you for reaching out to us.

We mention connecting it to DGND to minimize interference from signals on AGND from analog parts on the design.
You'll have to check with your design if this is necessary.

You can see our implementation the schematic of this Reference Design: https://www.ti.com/tool/TIPD188

Thank you and best regards,

Ambroise

0 sasank mallampati over 4 years ago in reply to Ambroise Suter

Prodigy 120 points

Hi Ambroise,

Thank you for the answer. I was also wondering if you had single channel SPST switch with similar on resistance as the TS5A21366. TS5A21366 is a double channel SPST switch.

Regards,

Sasank.

0 Ambroise Suter over 4 years ago in reply to sasank mallampati

TI__Expert 3820 points

Hi Sasank,

We have the TS5A3166, which is part of the same family. It has very similar specs to the 2-ch one.

If you wan't you can use our selection site to fine tune your selection: 1:1 1ch Switches

Thank you and best regards,

Ambroise

0 sasank mallampati over 4 years ago in reply to Ambroise Suter

Prodigy 120 points

Hi Ambroise,

For TS5A3166, does the digital input require a pull down resistor?

Regards,

Sasank.

0 Ambroise Suter over 4 years ago in reply to sasank mallampati

TI__Expert 3820 points

Hi Sasank,

The digital input does not require a pull down resistor if your controllers GPIO is not floating when the signal is not on high.

If the signal is floating, you should pull it to low, as you mentioned.

Best regards,

Ambroise

0 sasank mallampati over 4 years ago in reply to Ambroise Suter

Prodigy 120 points

Hi Ambroise,

Thank you for the previous answers.

I will be connecting a GPIO to the digital input of TS5A3166 using a low pass filter. So, during the startup, the capacitor in the low pass circuit will be at ground potential, acting as an effective pull down.

Also, could I know the input resistance of the digital input? I could not see it in the TS5A3166 datasheet.

Regards,

Sasank.

0 Ambroise Suter over 4 years ago in reply to sasank mallampati

TI__Expert 3820 points

Hi Sasank,

We don't have the exact input resistance of it, but it is high impedance. Can you explain what you would need the value for?

BR Ambroise

0 sasank mallampati over 4 years ago in reply to Ambroise Suter

Prodigy 120 points

Hi Ambroise,

We have connected a 25K ohm resistor between the TS5A3166 and GPIO pin of a microprocessor as a part of a low pass circuit. We wanted to make sure that the 25K ohm resistor has no effect on the input impedance of TS5A3166. Ideally, if the input impedance was 6Meg ohm, as seen in TS5A21366, the 25K ohm will not have any effect.

Since, TS5A3166 lists the digital input leakage current as 2nA when compared to TS5A21366's 0.6uA, the input impedance of TS5A3166 will be much higher than the TS5A21366.

Regards,

Sasank.

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TS5A21366: Should the GND of this part be connected to a digital ground or an analog ground and why?