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TMUX1209: I'm doing new SATA signal expansion card for server and want to know the propagation delay when switching from one I2C pair to another

Adam Torma
Mastermind 45340 points
Part Number: TMUX1209
Other Parts Discussed in Thread: SN74CBTLV3253,

e2e,

I'm doing a new SATA signal expansion card project for server,  I'm looking for the I2C switch solution(3 sets I2C in ,1 set I2C out) and have 2 questions to ask:

1. Both SN74CBTLV3253 & TMUX1209 are suitable for customer design , two devices are similar except SN74CBTLV3253 can use 2

                Separate OE# for 2 port , however in customer design , they will used 1 OE# for both ports.

 

 

2. Further question is , If they used TMUX1209 , what the propagation delay between (SXA)SCL /(SXB) SDA?

For example , if now is switched to 1st set I2C (SXA)SCL /(SXB) SDA as input , is there will be propagation delay between SXA & SXB

That causing the I2C clock and data out of sync at output(DA/DB)?

Customer is concerning if there’s delay between (SXA)SCL /(SXB) SDA , it may cause the issue like above.


Thank you,

Adam

  • 0
    TI__Genius 9132 points

    Hi Adam,

    Thank you for your questions on e2e - please see details below:

    1. Yes, the TMUX1209 uses one enable pin compared to the CBTLV3253 – another key difference between the two switches is the TMUX1209 supports 1.8-V compatible control inputs and Fail-safe logic

    2. Propagation Delay is the time required for a signal to pass from the input signal pin to the respective output signal pin (S to D or vice versa). The propagation delay from a switch is typically very small as the device can be equated to a wire - therefore the prop delay is heavily dependent on the load capacitance in the system as it is a combination of the device on resistance and load capacitance.

    You are  asking the difference between 1 channel to another  (SxA to SxB) that is generally the difference between the two prop delays, which we call skew. You should not expect prop delay or skew from our device to impact I2C communication.

    Thanks

    Saminah