KIT_DRIVER_2EDS8265H

[DHO]

Hello, my goal is to use two KIT_DRIVER_2EDS8265H to build a h-bridge that runs at 250V.

MOSFET IPA60R280CFD7 with RG, SOURCE = 51 Ω and RG, SINK = 43 Ω, like in the demo application.

After running a few seconds always, the high side fet dies because of a huge GS voltage on HS gate.

Setup: jumper BS_EN connected, DRAIN_HS --> 30V, SOURCE_HS connect to DRAIN_LS, SOURCE_LS connect to GND

VCCB-1 --> 12V, VCCB-2 --> GND. Scope picture is VCCA-2, nothing else connected.

Any idea what I can do?

[Abhilash_P]

Hi,

    Thank you for posting on the Infineon community.

Please follow the below steps to debug this issue,

1. If you want to turn-on or turn-off the MOSFET, you must integrate the board in a proper circuit.
2. We cannot apply directly the voltage (e.g 400 V) across the MOSFET through the banana connectors on the board .
3. We must limit the input current from the DC source generator by adding an inductance.
4. By this you will be creating a freewheeling path for the current when MOSFET is turned off.
5. The values 51 and 42 ohms are designed for a specific MOSFET part and not the Mosfet that you are intended to use.
6. Please use the gate resistor calculation formulas given in the guide.
   
7. Before connecting the MOSFETs', please check the waveforms by shorting the drain to source pins as explained in the guide. By this you will get to know if the issue is with the kit or with the specific mosfet.
8. The rise and fall times due to the selected gate resistor has to be b=observed before connecting the MOSFET. This has to match with the selected mosfet. 
9. Which SLDO mode jumper settings is used?
10. If your upper MOSFET is getting damaged with high voltage, then this might be due to the high value of bootstrap capacitor. After few charge times, high charge must have accumulated in the capacitor (due to higher duty cycle and high capacitance) leading to high voltage being seen on the gate terminal of the High side mosfet.
11. Please go thought section 9.3 in this Application note to cross verify the bootstrap capacitance value based on your application.

Regards,
Abhilash P

[DHO]

1. If you want to turn-on or turn-off the MOSFET, you must integrate the board in a proper circuit.
2. We cannot apply directly the voltage (e.g 400 V) across the MOSFET through the banana connectors on the board .  

   Ok but before I will try demo board and a few volts and amperes should be possible. Or is there any daughter board I can connect?

3. We must limit the input current from the DC source generator by adding an inductance.
4. By this you will be creating a freewheeling path for the current when MOSFET is turned off. 

   Not sure what you mean here. How can I create a freewheeling path? I don’t want to add an inductor. I just want to switch a load on and off.

5. The values 51 and 42 ohms are designed for a specific MOSFET part and not the Mosfet that you are intended to use.
6. Please use the gate resistor calculation formulas given in the guide.
   

   Hmm I understand this resistor values as a good starting point in the quick start guide. But if this is wrong which value you recommend for this FET? (see attachments QuickStartGuideP31)

7. Before connecting the MOSFETs', please check the waveforms by shorting the drain to source pins as explained in the guide. By this you will get to know if the issue is with the kit or with the specific mosfet.
8. The rise and fall times due to the selected gate resistor has to be b=observed before connecting the MOSFET. This has to match with the selected mosfet. 

   I did this and I think it sould be fine.

9. Which SLDO mode jumper settings is used?

   R30=0, SLDO jumper on Pin1 and Pin2, 3V3 on VCCI

10. If your upper MOSFET is getting damaged with high voltage, then this might be due to the high value of bootstrap capacitor. After few charge times, high charge must have accumulated in the capacitor (due to higher duty cycle and high capacitance) leading to high voltage being seen on the gate terminal of the High side mosfet.

    Yes, I think this is the main problem. Please see scope2 picture. I only connect a resistor between LS drain and 30V. As you can see turn off LS has a huge voltage which will destroy over the bootstrap HS mosfet. So how can I avoid this?

11. Please go thought section 9.3 in this Application note to cross verify the bootstrap capacitance value based on your application.

    Ok I will increase this capacitor because 100n for C10 is maybe a little to less.

Regards, David

[Abhilash_P · Accepted solution]

Hi,

   Please find below my comments,

1. If you want to turn-on or turn-off the MOSFET, you must integrate the board in a proper circuit.
2. We cannot apply directly the voltage (e.g 400 V) across the MOSFET through the banana connectors on the board .  
   David: Ok but before I will try demo board and a few volts and amperes should be possible. Or is there any daughter board I can connect?

             Abhilash: You can use the demo board without the MOSFET or testing this.

3. We must limit the input current from the DC source generator by adding an inductance.
4. By this you will be creating a freewheeling path for the current when MOSFET is turned off. 
   David: Not sure what you mean here. How can I create a freewheeling path? I don’t want to add an inductor. I just want to switch a load on and off.

             Abhilash: During turn OFF, you must create a freewheeling path for the MOSFET.

5. The values 51 and 42 ohms are designed for a specific MOSFET part and not the Mosfet that you are intended to use.
6. Please use the gate resistor calculation formulas given in the guide.            

                        David: Hmm I understand this resistor values as a good starting point in the quick start guide. But if                            this is wrong which value you recommend for this FET? (see attachments QuickStartGuideP31)

7. Before connecting the MOSFETs', please check the waveforms by shorting the drain to source pins as explained in the guide. By this you will get to know if the issue is with the kit or with the specific mosfet.
8. The rise and fall times due to the selected gate resistor has to be b=observed before connecting the MOSFET. This has to match with the selected mosfet. 
   David: I did this and I think it should be fine.

            Abhilash: Okay. You can once cross verify.

9. Which SLDO mode jumper settings is used?
   David: R30=0, SLDO jumper on Pin1 and Pin2, 3V3 on VCCI

             Abhilash: Okay

10. If your upper MOSFET is getting damaged with high voltage, then this might be due to the high value of bootstrap capacitor. After few charge times, high charge must have accumulated in the capacitor (due to higher duty cycle and high capacitance) leading to high voltage being seen on the gate terminal of the High side mosfet.
    David: Yes, I think this is the main problem. Please see scope2 picture. I only connect a resistor between LS drain and 30V. As you can see turn off LS has a huge voltage which will destroy over the bootstrap HS Mosfet. So how can I avoid this?

             Abhilash: Make sure you have isolated the power supplies of the gate driver and the main bus                              power. If there is high voltage spike during turn OFF, gate resistance in the turn OFF has to be                                 increased.

11. Please go thought section 9.3 in this Application note to cross verify the bootstrap capacitance value based on your application.
    David: Ok I will increase this capacitor because 100n for C10 is maybe a little to less

             Abhilash: You can do this provided the charging and discharging time constants are matching with               the MOSFET parameters.

Regards,
Abhilash P

[DHO]

Hmm I don't think it is an turn OFF fet problem. Please see pictures V1 all fine, V2 show this high voltage. For testing I use two isolated 12V for Vcca and Vccb, so high side stay alive....