SN74CB3Q3257: EMMC5.1 scenario

Part Number: SN74CB3Q3257

Hi

My customer tends to adopt SN74CB3Q3257 for EMMC5.1 scenario which is bidirectional 400MHz. Please help with below questions.

1.Is SN74CB3Q3257 ok for this scenario?

2. Customer needs to cascade 2 pieces SN74CB3Q3257 for this scenario, is it ok?

Regards

David

2 Replies

  • David,

    The SN74CB3Q3257 is a bi-directional switch which will support signals up to 500MHz. If you cascade these devices your signal will occur the parasitic on state series resistance and on state parallel capacitance each stage it passes through the switch.  The SN74CB3Q3257 has about ~3dB loss at 400MHz and if you place two of them in series you will have ~6dB loss due to the switch parasitic.   You will need to calculate the signal integrity your system can withstand including the transmitter, receiver, switch losses, trace and layout losses, etc. to fully understand if your system will handle these losses.   

    Why do you need to cascade the switches?  Do you have a diagram?  maybe there is a different part that can give you the same function.

    Have you looked at our new TMUX136 device?   It will not have much loss at 400MHz.

    Thank you,

    Adam

  • In reply to Adam Torma:

    David,

    Were you able to find the device you needed? I'm going to close this thread. If you have additional question replying to this post will reopen the ticket or you may start a new thread.

    Thank you,
    Adam