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SN74AUC2G53: SN74AUC2G53 break-before-make time

user5182412
Prodigy 90 points
Part Number: SN74AUC2G53
Other Parts Discussed in Thread: TMUX1219, SN74AUC2G66

HI team,

I am using the SN74AUC2G53 . I can not find the break-before-make  parameter in the datasheet .  As many other switch give the break-before-make number  there , like  74LVC1G3157, and they have similiar circuit inside, is there anything missing for SN74AUC2G53 ?

Best Regards,

James

  • 0
    TI__Mastermind 23653 points

    Hey James,

    The SN74AUC2G53 doesn't specify this spec in the datasheet so TI can't guarantee that there won't be any cross conduction between the channel that being turned off and the new channel being turned on. However, this device does have a enable pin (INH) that can be utilized to perform the function similarly. You can use this to isolate both inputs during the switching. Here, your timing limitations will depend on enable and disable times (ten and tdis).

    Depending on the voltage range you're working with, you could also select another 2:1 switch that has this break-before-make such as the TMUX1219 whose supply can run down as low as 1.08V. 

    Thanks,
    Rami

  • 0 in reply to Rami Mooti1
    Prodigy 90 points

    Hi, Rami,

    Many thanks!

    I need the fast switch time (10ns), so the minimal break-before-make time is important for my application.There seems no other part can work on that switch frequency (100Mhz), right?

    Best Regards,

    James

  • +1 in reply to user5182412
    TI__Mastermind 23653 points

    Hey James,

    I couldn't identify a single channel SPDT (2:1) that would meet the 10ns requirement on switching time. The TMUX1219 has break-before-make sub 10ns (8ns) but the switching time between channels (transition time) is a a little higher (12ns) so not quite where you want it to be.  Note that this is pretty dependent on the load (RL and CL). Transition time is a measure of the time required for the switch output to settle to 10% of the final value (90% on rising edges, 10% on falling) so what the load is will really impact this. The break before make may meet your requirements but whether it settles in time will depend on the load. We have this tested with a 200ohms and 15pF load and the voltage across the switch at 3V. So there is a chance that the TMUX1219 could work and it may be worth your time to get your hands on one and test it with your system requirements to see the results since it's so close. 

    Another option would be 2 SPST (1:1) switches and tie one end of the I/O's together. The SN74AUC2G66 is a two channel single chip solution you can implement that has faster switching time that can be utilized to meet your requirements. There will be some extra off capacitance since you're shorting two I/O's for this but there seems to be some room to budge here with the switching time. You will lose some performance in terms of frequency here though which may not be so impactful on your system, depending on the frequency and supply you're working with on the actual signal being passed through. 

    Thanks,
    Rami

  • 0 in reply to Rami Mooti1
    Prodigy 90 points

    Hi, Rami,

    Many thanks!  I will try as your advice。

    Best Regards,

    James