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OPA818: Simulation model capacitance

Marvn Arcangel
Genius 12575 points
Part Number: OPA818

Hi Team,

A customer is using the spice model of this device and found something interesting:

As per the image above, the C_C34 has a value of 1F which seems unrealistically large.
Could you please check whether this is indeed the correct value or whether there is an error in the SPICE model?

Thanks in advance

Regards,

Marvin

  • 0
    Guru 140200 points

    Hi Marvin,

    this need not necessarily to be a mistake. This could be an universal model also being used for many other OPAmps. And C_C34 may sit at a place where the concrete value doesn't play any role for the OPA818. Think of a "disabled part" of the model or think of C_C34 being short circuited by a zero Ohm bridge. C_C34 could also be a switch to turn something in the model on or off: C_C34 = 1 -> "ON", C_C34 = 0 -> "OFF", or vice versa.

    Kai

  • 0
    TI__Mastermind 22924 points

    Hello Marvin,

    I will ask my team about the model; I wanted to add to Kai's response that some circuits require large component values in SPICE simulations to assist with simulation convergence.  C_C34 may be a necessity for other operable functions of the amplifier to perform as intended.  

    If I find there to be more information to share, I will update you here.

    Best,

    Alec