TPS2211A schematic discussion

The datasheet recommends the following for the power supply inputs:

To increase the noise immunity of the TPS2211A, the power supply inputs should be bypassed with a 4.7-µF, or larger, electrolytic or tantalum capacitor paralleled by a 0.1-µF ceramic capacitor.

Other than that the schematic looks fine.

Hi Eric,
Thanks for your support!
So if I don't use 12V input (pin 9 of IC) I can let pin9 and pin10 floating as NC(no connection)?
Thanks!

Jefer

Hi Eric,
Do you have any idea about how to implement pin9 (12V) and pin10 if I don't use 12V input?
Thanks!

Jefer

I would suggest connecting the 12V input to GND if it is not used. For the AVPP output, it can be left floating but I would recommend also adding a 0.1uF ceramic capacitor to GND for some additional ESD protection if you have the room on the board.

Hi Eric,
It seems your suggestion which conflict with application information of datasheet.(see page 14 of datasheet).
Datasheet mentioned "Do not ground the 12-V switch inputs when the 12-V input is not used."
So.. how should I implement it if I don't use 12V input?
Thanks!

Jefer

Thanks for pointing this out. I wasn't aware of that.

Please follow the datasheet guidance over my suggestions.

Hi Eric,
Okay.
It just mentioned do not connect it to ground when not use 12V, but how should I implement it? floating ? or others?
Thanks!

Jefer

Hi Jefer,

The apps/system engineer for this device left TI in ~2005. I will try to find someone else who is familiar with this device and the scenario you describe, but It may take a week or so as this device is very old (2000 timeframe). You may have to use your best engineering judgement (ie, leave floating with or without a capacitor attached or connect a large resistor to ground to help control the voltage level without hard grounding) or breadboard the circuit and run various tests. Unfortunately, I could not find an available EVM for this device (or device family) or I would run the lab tests for you.

If this biz opportunity is significant, can you request more design support through your local sales office? The product line could then assign a resource to build/design a test board to help with the application circuit.

Jefer,

I was able to find some more information about this case. In Figure 25, Note A also mentions not to connect unused switch inputs to ground as you pointed out. Note A also points out why this is (back-gate diode of the internal MOSFET).

What is not mentioned in the datasheet is that the unused output can be connected to the highest used input voltage. Or it could be left open and not connected. For your case, you could either leave pin 9 open or connect it to pins 5/6.

Hi Eric,
Okay.
Thanks for your answer.

Jefer