Grounding unused Vcc pin

[Cicada]

Hi

I have a compound device with an Avalanche Photodiode (3 external pins) and a separate RDT-based temperature measurement with I2C interface (4 pins: Vcc, GND, clock, data). I do not want to use the temperature measurement function at the moment. I plan to ground the clock. Data should probably be connected to ground through a 10k resistor, but does it make sense to ground Vcc? If so, should it be shorted to ground or connected through a resistor?

Or should Vcc be left floating?

Thanks
Cicada.

[TomS_]

If the temperature sensor is completely separate from the photo diode and they don't share any power or logic connections, I would just leave all of the temperature sensor pins unconnected. It doesn't make sense to ground the VCC pin, and if the device is unpowered then the other pins don't need to be grounded either, just as if you were holding a chip in free air (it will do nothing and can't misbehave without power.)

If the photo diode section is relying on power from the same pins that also power the temperature sensor, then pull up or down the unused temperature sensor pins as makes most sense for their function. For I2C I'd pull up as that is the idle state from an I2C bus.

[Cicada]

If the temperature sensor is completely separate from the photo diode and they don't share any power or logic connections, I would just leave all of the temperature sensor pins unconnected. It doesn't make sense to ground the VCC pin, and if the device is unpowered then the other pins don't need to be grounded either, just as if you were holding a chip in free air (it will do nothing and can't misbehave without power.)

If the photo diode section is relying on power from the same pins that also power the temperature sensor, then pull up or down the unused temperature sensor pins as makes most sense for their function. For I2C I'd pull up as that is the idle state from an I2C bus.

Your thoughts is my thoughts exactly. The I2C temperature device is completely separate. I just had to check since someone less knowledgeable of electronics involved in the project asked that they be grounded. A physicist; so not completely oblivious to the field of electronics. So I just had to check myself.
Thanks