• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Subscribers 32 subscribers
  • Views 624 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ISO7640FM, ISO7140FCC for Virtex6 LVCMOS 25 isolation

Ryuji
Guru 20090 points
Other Parts Discussed in Thread: ISO7640FM, ISO7240M, ISO7140FCC
Hello,
 
Our customer want to use Digital Isolator for Virtex6 LVCMOS 25 I/O.
Please see the below url page 39 as Virtex6 LVCMOS 25 DC level.
http://www.xilinx.com/support/documentation/user_guides/ug361.pdf
 
LVCMOS 25 VOH=Vcco-0.4V(min), VOL=0.4V(max), Vcco=2.5V(typ).
I introduced ISO7240M, ISO7640FM and ISO7140FCC to our customer then our customer has some questions.
Could you please kindly let me know about below questions?
 
(1)
I think that ISO7240M can't use for Virtex6 LVCMOS25 I/Odue to VIH(min) is 0.7*Vcc.
ISO7240M Vcc(min) is 3.3V.
But, ISO7640FM and ISO7140FCC can use for Virtex6 LVCMOS25 I/O due to these device's VIH(min) is 2.0V
Is my understanding correct ?

(2)
Our customer use below two Vcc conditions.
But there is not electrical characteristics.

 <a>Vcc1=2.7V、Vcc2=5.0V
 <b>Vcc1=5.0V、Vcc2=2.7V
 
Can we use ISO7640FM and ISO7140FCC with these conditions?
If yes, should we refer which electrical characteristics?

Best Regards,
Ryuji Asaka
  • 0
    TI__Genius 14015 points

    Hi Ryuji,

    (1) You are correct, the ISO7240M will not work because the levels don't match, but the ISO7640FM and ISO7140FCC will work.

    (2) For electrical characteristics, I would refer to the worst case supplies, which would be Vcc1 and Vcc2 = 2.7V for everything but current, which would be the Vcc1 and Vcc2 = 5V case. The actual performance will be slightly better, but that is a conservative approach.

    Thanks,
    Jason Blackman 

  • 0 in reply to Jason Blackman
    Guru 20090 points
    Hello Jason san,
     
    Thank you for your prompt reply.
    Let me check one thing about (2).
     
    Is "Current" meaning Supply current ?
    Or all of current specification ?
     
    Best Regards,
    Ryuji Asaka
     
     
  • 0 in reply to Ryuji
    TI__Genius 14015 points

    Hi Ryuji,

    Sorry, yes I meant supply current.

    Thanks,
    Jason Blackman 

  • 0 in reply to Jason Blackman
    Guru 20090 points
    Hello Jason san,
     
    Thank you for the checking.
    I undertstood that ISO7640FM and ISO7140FCC with Vcc1=2.7V and Vcc2=5.0V, Vcc1=5.0V and Vcc2=2.7V.
    But there isn't specification of above conditions.
     
    Are there any reason ?
     
    Sorry for bothering you but,
    I want to confirm that we can use both items with above Vcc conditions without any difficulty for confirmation.
     
    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Genius 14015 points

    Hi Ryuji,

    You absolutely can use any combination of Vcc1 and Vcc2 as long as each Vcc is within the recommended range of 2.7V to 5.5V. Digital isolators have level shifting inherently. 

    The reason we don't call out separate electrical information for each supply voltage combination is that it becomes cumbersome to read the datasheet. There would be 9 separate electrical characteristics tables if every case was listed. 

    I hope this helps answer your questions.

    Thanks!
    Jason Blackman