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ADUM4135 Sat function

Hi Sir

I use the Adum4135 for IGBT in inverter application & found the P10 is too sensitive for IGBT Protect

how to adjust the R&C value as the red circle

Can I shut down the Pin 10 function which keep the IC work correct ?


  • Hello,

    The Rblank is an optional pull-up resistor that can effectively increase the current source Cblank sees. This will increase the charge rate of the blanking capacitor. In most cases, you can leave Rblank out. The internal current source is approximately 500 µA, but if you are in a large noise environment, and want to increase Cblank's size while keeping the same detection time, adding an Rblank can achieve this. The charging current added will act like an RC circuit, but a quick estimation is to know the charge current will be increased by VDD2/Rblank when Cblank is discharged.

    If you want to disable the Desat function, the best way is to short the DESAT pin to GND2.


  • One more question, what Cblank are you using? A value of around 100pF to 300 pF is typical, and without an Rblank results in a blanking time of around 2 to 6 µs.

  • i haver a similar question, is seems that the desat threshold is switched voltage dependent in my application  

    The resistors are used to increase the detected voltage.  The current limit changes from about 7A at 400V to 17A at 100V.  The switching edge is about 10nS 400V.    Do I need to change the diode or resistors?  I have seen various values in evals boards but not found any description of how to dimension this.

  • Hallo Nignogs,

    I am not sure if you had a reply via Email etc before. If not, sorry for delay.

    DESAT Threshold is fixed inside the gate driver.
    The external components and/or factors (e.g. temperature of diode, MOSFET/IGBT) can affect the voltages in your system, and changing node voltage on Pin10. Thus the threshold voltage is reached differently.