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TMUX6221: Power OFF state , Latch protection on Sx and Dx

eytan dahan
Prodigy 80 points
Part Number: TMUX6221
Other Parts Discussed in Thread: TMUX6222, , TMUX7436F

Tool/software:

Hey ,

We are currently using the TMUX6222 for the Termination setting on CAN and RS485 bus.

Our design is as below: When VIN is 12V

1. Can you advise/confirm the OFF state of the IC ( VIN =0) ?

a. For TMUX6222  , Sx and DX are disconnected.

b. For TMUX6221 , Sx and DX are shorted.

2. As we may have a situation that voltage on the BUS can be present when VIN is off , meaning VSx and VDx > VDD , we have an additional diode on the VIN for latch protection.

  • 0
    Guru 316440 points

    These devices need power to enable the switch. For both 6221 and 6222, when VIN = 0, then Sx and Dx are disconnected. Also, the I/O pins are diode-clamped to the supply rails, so you are not allowed to apply voltages to these pins while the switch is unpowered.

    To allow bus voltages without power, you need a switch with the "powered-off protection" feature like the TMUX7436F.

  • 0 in reply to Clemens Ladisch
    Prodigy 80 points

    Many thanks for the very quick response Slight smile

    Look that this one is also not match our need  , seems we may have voltages on both side of the IC (Sx and DX) side and here its look that the protection is applied only on the Sx side

  • 0 in reply to eytan dahan
    TI__Genius 17665 points

    Hello Eytan,

    Yes, the TMUX7436F has only protection on the source side. 

    Depending on the voltage levels and frequency you want to pass through the mux the TMUX4827 might work.  

    It has powered off protection on both sides, but can only pass signals up to +-12V and the bandwidth is 72MHz.

    Thanks,

    Nir