TMUX1574: May both SPI interfaces are running @ 3.3V Logic level but the VDD of TMUX1574 VDD is 5V

Hi Cheney_Sun,

The TMUX1574 operates at consistent thresholds for it's logic, this is why it is 1.8V compatible. I've attached the logic levels from pg. 6 of the TMUX1574 datasheet below (VDD range shown here: 1.5V-5.5V) :

For the TMUX1574 to register a logic high, the minimum voltage on the select pin, with reference to ground, is 1.2V; while the maximum voltage on the select pin  to register a logic low is 0.45V. So as long as the MCU at 3.3V has a VOH >= 1.2V and a VOL <= 0.45V you shouldn't have issues with the application. 

For more information on logic levels in our MUX's as well as 1.8V logic compatibility please see our Precision Lab Video here and an App Note on 1.8V logic here.

Best Regards,

Parker Dodson

The SEL and EN pins are 1.8 V logic compatible, so they will work.

The four data channels can handle analog signals, so 3.3 V will work. (The TMUX1574 actually allows anything between 0 V and 10 V.)

Hi Clemes Ladisch:

                               Thank you for your reply.Your answer is different with above Parker Dodson's answer.Which one is right?TKS~

BR 

Cheney_Sun 

Hi Parker Dodson:

                               Thank you for your reply.Your answer is different with below Clemens Ladisch's answer.Which one is right?TKS~

BR 

Cheney_Sun 

Both answers say "yes", with varying levels of detail. Nothing in them is contradictory; both are right.

To allow us to remove any misunderstandings: which point do you think is different?