Hi everyone,
I'am driving two mosfet in half bridge configration with 38R RL load and 300V DC Link,
Gate drive resistances for two of them;
Ron=7,5R,
Roff=10R,

When I turned on to high side mosfet around 100us, The Vgs voltage is ringing for high side mosfet. Its a little bit normal and I think I can figure it out with changing Rg.. but my question is that While turning on and turning off high side mosfet, I also observed Vgs ringing in low side mosfet ?
I added turn on and turn off scope pictures,
Is it normal ? What is the reason of that ring ?
Yellow: Vds(around 300V)
Blue: Current passing through RL load,
Purple: Low Side Vgs,
Green: High Side Vgs,

Thank you,

 

No dead time insertion between phases ?

And ringing clearly inductive effects, layout, wiring to driver/bridge ?
Size of Rg.....Ringing ~ 40 nS period, 25 Mhz

https://www.google.com/url?sa=t&rct.../slpa010.pdf&usg=AOvVaw20xdEYMc8l6XpTnAIioCqn

https://electronics.stackexchange.c...and-drain-ringing-on-a-highside-mosfet-driver

https://www.google.com/url?sa=t&rct.../AN-9005.pdf&usg=AOvVaw21Q5qUYBKDz-qIyUbpOJid

Regards, Dana.

 

No dead time insertion between phases ?

And ringing clearly inductive effects, layout, wiring to driver/bridge ?
Size of Rg.....Ringing ~ 40 nS period, 25 Mhz

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwj-hP6hjZnbAhVG1IMKHfn7AekQFggnMAA&url=http://www.ti.com/lit/an/slpa010/slpa010.pdf&usg=AOvVaw20xdEYMc8l6XpTnAIioCqn

https://electronics.stackexchange.c...and-drain-ringing-on-a-highside-mosfet-driver

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0ahUKEwj-hP6hjZnbAhVG1IMKHfn7AekQFghSMAU&url=https://www.fairchildsemi.com/application-notes/AN/AN-9005.pdf&usg=AOvVaw21Q5qUYBKDz-qIyUbpOJid

Regards, Dana.

No dead time insertion between phases ?

And ringing clearly inductive effects, layout, wiring to driver/bridge ?
Size of Rg.....Ringing ~ 40 nS period, 25 Mhz

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwj-hP6hjZnbAhVG1IMKHfn7AekQFggnMAA&url=http://www.ti.com/lit/an/slpa010/slpa010.pdf&usg=AOvVaw20xdEYMc8l6XpTnAIioCqn

https://electronics.stackexchange.c...and-drain-ringing-on-a-highside-mosfet-driver

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0ahUKEwj-hP6hjZnbAhVG1IMKHfn7AekQFghSMAU&url=https://www.fairchildsemi.com/application-notes/AN/AN-9005.pdf&usg=AOvVaw21Q5qUYBKDz-qIyUbpOJid

Regards, Dana.

Hi Dana,

I have dead time but I just applied one pulse to high side mosfet. For lower mosfet I did not applied any pulses.(Always OFF)
Also I have Zener clamp, 10k resistor(Parallel to source pin) and Ferrite bead(30R at 100mHz) at gate.

I measured directly from mosfet pins by isolated probe ( Maybe I can improve my measurement methods) and If you checked the Vds voltage, there is no much ringing as Vgs.

Maybe I should change ferrite bead ? any suggestions ?

 

What does board layout look like ?

https://www.google.com/search?q=mosfet+driver+psb+layout&ie=utf-8&oe=utf-8&client=firefox-b-1-ab

Using scope on infinite persistence what is Pk-Pk noise on supply rail ?

Scope probing big consideration.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwiA_ab6q5nbAhVl34MKHf-LCYwQFghHMAE&url=http://www.tek.com/dl/Probing%2520Techniques%2520for%2520Accurate%2520Voltage%2520Measurements%252051W_60161_1_HR_Letter.pdf&usg=AOvVaw3XaJCZZ-E_Hwo_t4Swz2ez

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&cad=rja&uact=8&ved=0ahUKEwiA_ab6q5nbAhVl34MKHf-LCYwQFgiAATAH&url=http://web.mit.edu/6.101/www/reference/ABCprobes_s.pdf&usg=AOvVaw3jqTqjxTe5xhU8dQaIF70U

Bypassing crucial on driver, not all Cs are equal, look carefully at datasheets and
C technology -

Regards, Dana.

 

Slantoner are you still working on this?

 

Slantoner are you still working on this?

yes ?