Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

cross mob
joynag
Level 1
Level 1
5 sign-ins First reply posted First question asked

Hello everyone,

I am using 1EDN7550B gate driver in one of my designs. My input logic is 3.3V, so I am using 33kohm, 0.1%, 0603 input resistors. Issue: as I am increasing the input voltage, one of the gate driver's output start to glitch for input voltages more than 10V.

joynag_0-1707427555022.png

Then, I changed the input logic resistors to 16Kohm, the Vgs improved.

joynag_1-1707427681125.png

I suspect this is an issue with the CMR of the gate driver? I have attached the layout of my PCB as well.

joynag_2-1707427754112.pngTop Layer

joynag_3-1707427762846.pngSecond Layer

joynag_4-1707427773736.pngThird layer

Can anyone please suggest any improvement in the design or where this error is creeping from? Any help is much appreciated!

Thanks,

Joy

0 Likes
4 Replies
Tengfei_O
Moderator
Moderator
Moderator
50 replies posted 25 replies posted 50 sign-ins

Dear customer,

Sincere gratitude is extended for your contact concerning this matter.
Assurance is given that a thorough review of the provided contents is currently underway.
The aim is to deliver a comprehensive response in the near future.
Appreciation is expressed for your understanding and patience.

Warm regards,
Tengfei

0 Likes
Tengfei_O
Moderator
Moderator
Moderator
50 replies posted 25 replies posted 50 sign-ins

Dear Joynag,

I hope this message finds you well.
Could you please provide more details about your situation?

1. What voltage have you adapted on VDD?

2. What frequencies have you used?

3. Do the glitching waveforms happened continuously or repeatedly?

4. Could you measure the voltage between the input+ pin and the input- pin?

Best regards,
Tengfei

0 Likes
joynag
Level 1
Level 1
5 sign-ins First reply posted First question asked

Hi,

1. VDD = 12V

2. The converter is running in DCM. Switching frequency is around 70kHz.

3. Glitching waveforms are continuous. Its not random.

4. The differential voltage between In+ and In- pins is very small due to the presence of 33kohm input resistors and 2kohm internal resistance of the Gate driver. Before reducing the Rin to 16kohm, the differential input was clean. And after reducing Rin it is still clean. Its the output of the gate driver which is glitching.

Thanks,

Joy

0 Likes
Tengfei_O
Moderator
Moderator
Moderator
50 replies posted 25 replies posted 50 sign-ins

Dear Joy,

Thank you for using the "Developer Community."
There are a few aspects of your design that you may need to reconsider:

1. You may want to refer to the recommended layout in the application note. For your convenience, the link to the AN is provided below. The design layout which was shown in Figure 20 should be suitable for your case.
https://www.infineon.com/dgdl/Infineon-EiceDRIVER_1EDN_TDI_1EDNx550-ApplicationNotes-v02_00-EN.pdf?f...

2. According to Equation 1, as shown in AN page 12, this equation represents how to set an optimized value of Rin(+,-) for an input PWM signal.
You have mentioned that the output waveforms have been improved with Rin(+,-)=16K ohm instead of 33K ohm. A higher value of the k factor was obtained in this case, according to Equation 1. This suggests that a strong AC voltage shift between the driver ground and the controller ground might exist.
Please measure the voltage between the "IN+" pin and the "GND" pin to confirm the issue.

Best regards,
Tengfei

0 Likes