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jefflijeff
Apr 21st, 2020, 11:00 PM
I'm going to use IRS2011 to dirve IRF250P225. I see the in the typical diagram in IRS2011 datasheet,how can I determine the capacitor and diode type in the diagram ,is there any other diagram recommended circuit for the dive IC, thank you.

4656

Emanuel
Apr 22nd, 2020, 12:31 AM
Hi and welcome to the forum.
The capacitor selection is circuit and modulation dependent. The capacitor will provide a floating power supply to the upper switch when it conducts while it will be charged when the lower switch turns on.
We have a really detailed application note about bootstrap circuit design HERE (https://www.infineon.com/dgdl/Infineon-Bootstrap_Network_Analysis-ApplicationNotes-v01_00-EN.pdf?fileId=5546d462533600a40153559692661096).
Please let us know if this answers all of your questions.
Best regards,
Emanuel

Srivatsa
Apr 22nd, 2020, 12:44 AM
Few general guidelines:

1. Capacitor on Vcc should be atleast 10 times capacitor on VB. Say Vcc cap = 10 uF, VB cap = 1 uF. This will ensure the bootstrap capacitor gets charged during transients.
2. Both Vcc and VB capacitors should be ceramic type. If electrolytic type needs to be used, add a small ceramic cap about 10 nF in parallel to the electrolytic type.
3. Both these capacitors need to be close to the gate driver IC.
4. Based on the switching frequency and duty cycle, VB cap can be of low value, 10 nF or so.
4. A small resistor, about 2.2 ohms to 10 ohms needs to be in series with the bootstrap diode.
5. A fast recovery diode or Schottky diode with low forward voltage drop and low junction capacitance is recommended. Its voltage rating should be greater than the DC link voltage.

For a deeper understanding you can review the below application notes:

https://www.infineon.com/dgdl/Infineon-Using_Monolithic_Voltage_Gate_Drivers-AN-v01_00-EN.pdf?fileId=5546d462584d1d4a01585242c11947b1

https://www.infineon.com/dgdl/Infineon-HV_Floating_MOS_Gate_Drivers-ApplicationNotes-v01_00-EN.pdf?fileId=5546d4626c1f3dc3016c47de609d140a