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OPA593: output pull up

Ruoxin Chang
Expert 3180 points

Part Number: OPA593

Tool/software:

Hi Teams,

When the chip has input and power, when the enable is turned off, the output end will produce such a particularly high voltage drop to zero. How to improve？

BRs,

Ruoxin

  • 0
    TI__Genius 16326 points

    Hi Ruoxin, 

    Yes, this is occurring because the output is becoming high impedance with a cap load on the output. This is also occurring just by nature of how the OPA is designed to shut off. 

    If the OPA593 was driving a load and is set to output disable, you will likely see a current spike as the load capacitance and parasitic inductance causes current to be pulled from nodes other than the OPA output. 

    The easiest way to solve this problem is with a fast acting TVS diode. I see you already have a 45V TVS installed on the board. 

    What is the amplitude of these peaks?

    Sometimes increasing the pC? capacitor can reduce the effective bandwidth of the part, and reduce some of the spiking you see. This may not perfectly solve the problem with the large shutdown transient. 

    Thanks,

    Jacob