TMUX1511: Unused inputs on TMUX1511

Saminah C

Part Number: TMUX1511
Other Parts Discussed in Thread: SN74HC4066

Hi,

I am replacing the SN74HC4066 with the TMUX1511 switch but since I am using only 1 of the 4 channels, should I ground the source of the 3 unused channels? The SEL control inputs have weak 6Mohm pull downs to prevent the switch from turning on, but if these inputs are still actually CMOS, should they be grounded if unused (i.e. S2, S3, S4)?

Thanks

over 4 years ago

0 Jon Alejandro over 4 years ago

TI__Prodigy 547 points

Hi Saminah,

All CMOS inputs must be terminated at either Vcc or Ground. The inputs of a CMOS device have high-impedance. These terminations can be through a resistor (for example, a 10kohm pull-up resistor to Vcc or a 1kohm pull-down resistor to ground), or they can be directly connected.

Thanks,
Jon

0 Frank Dyer over 4 years ago in reply to Jon Alejandro

Prodigy 60 points

And since the drains work as inputs as well, should the 3 unused drains be terminated as well?

0 Jon Alejandro over 4 years ago in reply to Frank Dyer

TI__Prodigy 547 points

Frank,

Switch signal input/output pins may be left floating. In high speed applications, best practice is to terminate these unused pins to GND. You can see some commentary on this in the e2e switches FAQ page.

Thanks,
Jon

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TMUX1511: Unused inputs on TMUX1511