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OPA454 - E/D and E/D Com pin , Status flag pin

Ryuji
Guru 20090 points
Other Parts Discussed in Thread: OPA454

Hello,
 
Could you please kindly let me know about below issue of OPA454 ?
 
supply voltage is +/- 7V.
-------
(1)
In the datasheet P.20, we can't froat pins both of E/D and E/D com.
Is my understanding correct ?
 
(2)
If E/D Com pin is connected to V- pin, can I open the E/D pin ?
 
(3)
If we don't use status flag pin, can I open the status flag pin?
 
I understood this pin is open drain.
But could I have your confirmation ?
-------
 
Best Regards,
Ryuji Asaka
 
 
  • 0
    Guru 20090 points
    Hello,

    Sorry for bothering you.
    But could I have the answer of my questions please ?
     
    If need more information for reply , please let me know.
     
    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    Guru 21975 points

    Ryuji,

    1.  It is possible to leave these pins disconnected but they may possibly be disturbed by capacitive coupling from nearby signals.

    2.  If E/D com is connected to V-, it will not be affected by capacitive coupling from nearby signals. This does not change the possibility of coupling to the E/D pin. It could still be be sensitive to capacitive coupling.

    3. If you do not use the status flag it can be left disconnected. The status flag is an open-drain output.

    Regards, Bruce

  • 0 in reply to Bruce Trump
    Guru 20090 points
    Hello Bruce san,
     
    Thank you for the reply.
    I understood that about status pin can be left disconnected.
    I would like to know about E/D and E/D pins processing for pins disconnected.
     
    (1)
    Concerning, E/D and E/D pins , could you please kindly let me know the best approach for pins disconnected ?
     
    (2)
    In the datasheet  P20 , E/D pin is pulled up to 50V(V+) by 1Mohm and Ip is 50uA for pins disconnected.
    I understood that  any Ip(uA) need for stability operation when E/D and E/D pins were disconnected.
    Could you please kindly let me know the current value of Ip for stability operation?  
    Is 50uA necessary?
    Supply voltage is +/- 7V.
     
    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    Guru 21975 points

    Ryuji,

    I recommend that you connect the E/D com terminal to the V- supply terminal.

    Connect at 30pF capacitor from E/D to E/D com. Then no pullup resistor is required.

    Regards, Bruce.

  • 0 in reply to Bruce Trump
    Guru 20090 points
    Hello Bruce san,
     
    Thank you for the information.
    I understood the recommended circuit as attached file.
    If my understanding is incorrect please let me know.
     
    Best Regards,
    Ryuji Asaka
     
  • 0 in reply to Ryuji
    Guru 21975 points

    Ryuji,

    Yes, the circuit you attached is correct.

    Regards, Bruce.

  • 0 in reply to Bruce Trump
    Guru 20090 points

    Hello Bruce,

    Thank you for the checking.
     
    Best Regards,
    Ryuji Asaka