TMUX1204: multiplexer take over 1ms to discharge the output on S pins when enable input is turned off

When the switches are disabled, the pins are disconnected, so any capacitance on the output will hold its voltage.

The test circuit has a strong pull-down resistor (see figure 12).

Hi Karthick,

What Clemens mentioned is this picture.

For multiplexers the timing characteristics  like Toff and Ton are (load dependent) the RL and CL in the picture above.

And the measurements in the datasheet are dependent on those values

For this device our team test Toff and Ton with a RL = 200 Ω, CL = 15 pF, but in your system maybe you are using a bigger load than we use during testing.

If you are using a bigger load then, the timing characteristics of your system will be slower than the datasheet.( The Rc time constant of your system is likely larger in your system because of your load.)

Having a bigger load makes your discharge time slower.

Please let me know if you have any additional questions

Regards,

Kameron

Hi Karthick,

I think this is more of a system design question.

But let me try to help.

In addition adding a strong pulldown resistor on the control pins( like enable and selects)  may help or hurt your application.

For example 

If the MUX is active when Enable is High( Which the 1204 is) . A strong pulldown may cause the driver to need to work harder and slowing down the TON, However the pulldown  help TOFF.

But with this idea  you are only affecting the propagation delay of the Enable pin which is very small, I don't think this will make a big difference in TON/TOFF

A idea you could try is to  add a "bleeder switch and strong pull down resistor" in parallel with your load to help discharge the load faster when the TMUX1204 is disabled.

The switch would need to have opposite logic of the TMUX1204.

So the TMUX1204 is active high, you would use a active low switch.

The TS5A3167 or TMUX1102 are two ideas to me.

This is just a idea and think this is more of system design idea maybe you can look into 

Please let me know if any other assistance is needed.

Regards,

Kameron

If you require the three inactive signals to be at ground, then it might make sense to remove the pull-down resistors, and to replace the TMUX1204 with a four-channel 2:1 switch like the TMUX1574 to connect the four signals to either the input or to GND.