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Gate Driver ICs Forum Discussions

kagarwal37
Level 2
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Hi,

I'm designing a gate driver to drive 2 600 V CoolMOS P7 MOSFETs (P/N: IPAW60R180P7SXKSA1) in a half-bridge configuration, where one of the switches is a high side switch and the other is a low side switch. The only modification is that I want to switch both MOSFETs at the same time (both switches on high side and low side are on or off at the same time).

Based on some initial research, I have found that the EiceDriver 2EDF7275K gate driver IC would be ideal for my application, because it seems like this can be configured as a high-side and low-side driver through it's dual channels. I have a few questions regarding this application as follows:

Q1. Since this is an isolated gate driver IC, can I use two separate isolated power supplies for Channels A and B instead of a bootstrap circuit to drive both the low side and high side switch simultaneously? (To elaborate: I would connect each isolated power supply across V_ddA - GNDA and V_ddb - GNDB, respectively)

Q2. If the answer to Q1 is yes, does the power supply need to be rated to provide the initial peak source current? For example, if I'm trying to drive the MOSFET with a peak source current of 6A, this must come from the isolated power supply right? But, this is leading to significant over-sizing of the supply. Could I please get some advice to manage this?

Q3. If the answer to Q1 is yes, how can I design the resistor that is recommended to be connected on the output power supply pin? Is this just for current limiting purposes?

I'm relatively new to gate driver design and would greatly appreciate any guidance on the above questions.

Thank you very much,

Sincerely,
Kartavya Agarwal.

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Jingwei
Moderator
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Moderator

Hi Agarwal,

As you said, R71 is for current limiting. I saw some other applications also not using this resistor. From my point of view, a 10R resistor will be good for this application. 

Thanks and BR,

Steven

View solution in original post

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Jingwei
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Moderator

Hi Agarwal,

thanks for using Infineon Community.

At first, may i ask the detail about using 2 CoolMOS as Half bridge, and why you want to switch the two mosfet at the same time? Is that still half bridge?

Best regards,

Steven

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kagarwal37
Level 2
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Level 2

Hi Steven,

Apologies for the confusing terminology, it is not technically a half bridge but the placement of the MOSFET in the schematic is like a half bridge (one switch on high side on top of low side switch). I want to switch them at the same time because I'm using these switches on the primary side of a 2-switch forward converter which requires the high side and low side switch to be on or off at the same time. So I would use the dual channel gate driver IC as a high side and low side driver. Does this clarify the confusion?

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Jingwei
Moderator
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Moderator

Hi Agarwal,

yes it is clear now. For Q1, yes. If you go through the datasheet of gate driver, you can find the truth table of this driver. If two inputs are high, normally you can get two high outputs. For Q2, you can put capacitors between VDDA and GNDA, also for VDDB and GNDB to store some energy from power supply to maintain enough voltage. For Q3, Rg calculation is most important part of gate driver design. It can effect tdon, tdoff, dudt, didt, EMI, losses, peak current, voltage spike. I attached a AN to show how to select Rg. https://www.infineon.com/dgdl/Infineon-EiceDRIVER-Gate_resistor_for_power_devices-ApplicationNotes-v...

If you have further questions, reply behind this.

 

Best regards,

Steven

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kagarwal37
Level 2
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Level 2

Hi Steven,

Thank you very much for the detailed answers. Just a quick follow up on Q3, I did not mean the gate resistor design (Rg). I was referring to the resistor between the power supply and Vdd_A. This resistor is also labelled as R71 in Fig. 4 in the following application note:

https://www.infineon.com/dgdl/Infineon-GateDriverICs_EiceDRIVER_2EDi_Using_the_EiceDRIVER_2EDi_famil...

Would you be able to provide clarification on Q3 from the above post with respect to this resistor? Apologies for the confusion.

Sincerely,
Kartavya Agarwal.

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Jingwei
Moderator
Moderator 100 sign-ins 50 replies posted 25 solutions authored
Moderator

Hi Agarwal,

As you said, R71 is for current limiting. I saw some other applications also not using this resistor. From my point of view, a 10R resistor will be good for this application. 

Thanks and BR,

Steven

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