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Hello,
In the infineon 22kw inverter reference design, there are resistors in series with Vcc and Vee (R129 and R33) of the low side gatedrivers . Can someone explain the reason why we need the resistors on the low side alone.
Thank you
Solved! Go to Solution.
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Hi,
I have checked the schematic and here is my answer for the resistor usage.
1) No, the resistor will not come in gate path because, the capacitor (C40,C39) will supply the peak current needed by the gate capacitor. So, VCC2 pin done come in path when it comes to charging to of gate capacitor and hence, 10ohm resistor will also not come in gate picture.
PFA find the attachment for more clarity.
Similarly, during discharge, the path will be from OUT- to VEE2 pin to bottom or lower side switch emitter and hence no additional resistor comes in picture except actual gate resistor put and internal resistor.
2) The resistor is used only in lower side switches to limit the average charge current of the capacitor (C39, C40) which provides the peak current) because they are getting supplied from same supply unlike in top switch where every switch has separate supply.
Please refer supply section in schematic to understand more.
I hope you understood.
BR,
AZIZ
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Hi,
Thank you for posting at Infineon community.
I will get back to you in some time.
BR,
AZIZ
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Hi,
The resistor R129 and R33 are current limiting resistors. In order to not drain the supply beyond its rating, these low value resistors are used.
BR,
AZIZ
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But why are these resistors used only in low side gate drivers and ignored in the high side. And does these resistors add up to the gate resistance ?
Thank you
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Hi,
Ya sure I will reply for that, but can you please share the name of the reference design or link to check once, whether it has any specific requirements.
BR,
AZIZ
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REF-22K-GPD-INV-EASY3B - Infineon Technologies
link fr the ref design
schematic in the inverter power board
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Hi,
I have checked the schematic and here is my answer for the resistor usage.
1) No, the resistor will not come in gate path because, the capacitor (C40,C39) will supply the peak current needed by the gate capacitor. So, VCC2 pin done come in path when it comes to charging to of gate capacitor and hence, 10ohm resistor will also not come in gate picture.
PFA find the attachment for more clarity.
Similarly, during discharge, the path will be from OUT- to VEE2 pin to bottom or lower side switch emitter and hence no additional resistor comes in picture except actual gate resistor put and internal resistor.
2) The resistor is used only in lower side switches to limit the average charge current of the capacitor (C39, C40) which provides the peak current) because they are getting supplied from same supply unlike in top switch where every switch has separate supply.
Please refer supply section in schematic to understand more.
I hope you understood.
BR,
AZIZ