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ISO5451: ISO5451 gate driver

Bipin Patil
Intellectual 870 points
Part Number: ISO5451
Other Parts Discussed in Thread: UCC21750

Tool/software:

I have designed the gate driver using ISO5451 attached is the schematic for 1 channel.

Please clarify my following queries.

 

VCE-FAULT(TH) as per datasheet is as follows.

VCE-FAULT(TH) = 9 V – n × VF (where n is the number of DESAT diodes).

But my requirement for VCE-FAULT(TH) is 3.6V

So I have connected 1 nos STTH112A diode and 1 Nos BZT52C4V3-7-F 4.3V zener

with the above mentioned components my equation becomes

VCE-FAULT(TH) = 9 V – 1.1(Diode)-4.3(Zener)=3.6V

Is this correct?

For increasing the gate driver sink and source currents I have used booster transistors

PHPT60410PYX and PHPT60410NYX

My VCC2 and VEE2 is +15V and -8V respectively.

And gate resistor is 3.4 Ohms.

My operating PWM frequency is 4 Khz.

 

 

I will be using the gate driver circuit to run SKM200GB12T4 and SKM400GB12T4 IGBTs

Please suggest if any changes are required.
  • 0
    TI__Expert 4590 points

    Hi Bipin, 

    I do not see a schematic attached. Could you try to attach again? 

    Regarding your questions - 

    1. Yes, you can use a Zener diode to adjust the DESAT threshold. We also always recommend a current-limiting resistor around 1kOhm in the path of DESAT to dampen any potential noise that might couple into DESAT pin, so I would encourage you to add that. Another good thing about the current limiting resistor is that it can help to adjust DESAT detection threshold as well, since the HV diode might have a different forward voltage than expected due to the small forward current. Thus, the current limiting resistor can help you with quickly changing the detection threshold in the prototype system. 

    2. The booster circuit works. I would also suggest looking into UCC217xx (for example, UCC21750) since it has higher current source/sink capabilities, so you might not need the booster stage. 

    Thank you,, 

    Vivian