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Original question:

ISO5852S: Desat level shift

ISO5852S: How to measure the Desaturation protection current value？

JiaNg L
Prodigy 10 points
Part Number: ISO5852S

Dear sir,

We use ISO5852S to drive our IGBT and refer to this circuit schematic diagram：

https://www.ti.com.cn/cn/lit/pdf/tidrpj3

Now I want to measure the value of the de saturation protection current (Ichg) in the actual circuit, so how should I measure it?

Can the measured current value reach the ideal 500uA?

  • +1
    TI__Expert 5093 points

    Hi Jiang,

    Thanks for the interesting question. Ichg is the blanking-capacitor charge current which is mentioned in the datasheet as shown below:

    Since this current is internal and comes from a current source it is usually constant with the minimal variance as shown in the datasheet.

    If you measure the current flowing through the capacitor (using multimeter or other methods like C.dv/dt), it should be very close to the value/range mentioned in the datasheet.

    Hope this helps.

    Best,

    Pratik

  • 0 in reply to Pratik Adibatla
    Prodigy 10 points

    Thank you, Pratik.

    I have another question about desaturation protection.How do I make desaturation protection active in this circuit, or what action should I use to trigger protection?Is it possible to apply a voltage of 9V directly to the DESAT pin?

  • 0 in reply to JiaNg L
    Prodigy 10 points

    Or disconnect the resistors connected in series to the DESAT pins?

  • +1 in reply to JiaNg L
    TI__Expert 5093 points

    Hi JiaNg,

    If the purpose is to test the DESAT circuit protection, I believe you can apply 9V or higher directly at the DESAT pin and test it.

    Hope this helps!

    Best,

    Pratik