TMUX1136: Simulation Model

Hi Massimiliano,

Before I get into the passive modeling tips on a mux - I would like to point you to the TMUX1119 (As we have PSpice / TINA spice models for it). The results won't be perfect but both devices are from the same low voltage precision family - the biggest difference is the TMUX1119 is only 1 channel - but its impact on the signal is very similar to the TMUX1136 and will probably give a better approximation than a passive model - at least for room temperature -(so if you go above 25C it will give a baseline but it won't be super accurate) with all that being said I think the TMUX1119 model + a higher temp passive model can get a decent approximation of how to expect the device to work in the system. 

that being said you are correct - for quick general channel impact simulations to help get some boundary condition approximations you can use a simple model.

On your second question, C_ON is the effective capacitance of the switch (when closed) from input/output to ground. This means the C_ON of 20pF for the TMUX1136 only needs to be added once as you have shown in option 1.

However a passive model using option 2 is a better passive model - but the capacitances won't both be 20pF. The S side of the device (S pins) will have a capacitance to ground of CS_Off - which for the TMUX1136 at VDD = 3.3V is 6pF. (I am assuming 3.3V supply due to the resistance being worst case for the +85C range.). The other side would be CD_OFF + C_Switch - which isn't spec'd for the TMUX1136 directly but can be found by C_ON - (CS_OFF) = CD_OFF + C_SWITCH (this approximation holds for many of our switches but not all - but for the TMUX1136 this approximation is ok) So  either of the following models would be okay (Assuming 3.3V supply at -40C to 85C range":

If you have any other questions please let me know!

Best,

Parker Dodson