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I've an IC where there is no mention of what to do with the SPI pins when it is unused.

In that case, can I connect the SPI pins to GND, only pulling up the Chip select pin?

Please confirm

Datasheet.

Also, it doesn't mention on what to do with the unused WAKE and INH pins.

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    Duplicate of [In a 74HC14 Schmitt trigger IC, unused inputs/outpus](https://electronics.stackexchange.com/questions/174016/in-a-74hc14-schmitt-trigger-ic-unused-inputs-outpus) – CL. Nov 30 '22 at 08:54
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    Only unused inputs should be grounded but not unused outputs. – Uwe Nov 30 '22 at 08:57
  • Could you please tell me how that answers my question? I am not sure. The pin buffers of SPI pins in the datasheet are not mentioned as CMOS buffer logic type. They could also be TTL, right? In that case, what is the difference between TTL and CMOS inputs? –  Nov 30 '22 at 08:57
  • Also, in that answer, it is mentioned as, "their states being determined by whether the inputs are terminated to the positive or negative rail." How does the output depend on the input ? –  Nov 30 '22 at 09:02
  • You are looking at a product brief. It is not the data sheet which likely contains the information you need. The brief does say what you can do with the INH pin. – Justme Nov 30 '22 at 09:12
  • It one another place (Referred a similar TI part), it is mentioned as the INH can be High-Z or can be HIGH. If I connect the INH pin to a pull-down resistor, during High-Z, the INH will be low (due to pull-down) and during high, the value will be high, am i right @Justme –  Nov 30 '22 at 09:21

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Yes, you can tie them to GND (through resistor) if you want to without damageing the device. Weather you should or not is an other question.

Pay attention to the table in page 14. There is a note for the SDO pin that says:

"This pin also provides configuration strap functions during a hardware reset".

The DS states on page 12:

"Configuration straps allow various features of the device to be automatically configured to user defined values. Configuration straps are identified by an underlined symbol name and are latched upon Power-On Reset (POR) and pin reset (RESET_N). Configuration straps include internal pull-up/pull-down resistors in order to prevent the signal from floating when unconnected."

From here, it is for you to decide what straping options to use.

Regarding the wake part. I assume that you need the wake in pulled high even if you dont use it. For the wake out, you can pull it to GND with ~10k Ohm.

T Andersen
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  • Could you please tell why I need to pull the WAKE IN high when I am not using it? –  Nov 30 '22 at 09:19
  • @Newbie I wrote that I asume so, because the opposite of wake is sleep. I dont think you have any interest in a sleeping device that cannot wake up. – T Andersen Nov 30 '22 at 09:31