DRV8353: What is "MOSFET drain sense pin voltage slew rate"?

Eggsy Pang

Expert 4985 points

Part Number: DRV8353
Other Parts Discussed in Thread: DRV8323R, DRV8350R, DRV8323, DRV832X

Hi team,

I have two questions as below.

Question 1:

My customer used DRV8323R and now plan to use DRV8350R.

And they found some difference in the datasheet.

In 7.1, we can see the spec "MOSFET drain sense pin voltage slew rate".

May I know what MOSFET drain sense pin voltage slew rate is?

Question 2:

DRV8323R's High-side gate drive pin voltage with respect to SHx is 13.5V but DRV8350R's is 16V.

Low side gate drive is also different.

They don't want to change to MOSFET. Their MOSFET Vgs on =10V.

May I know if this will have some impact?

And the gate voltage is bigger, what will it happen?

Thanks!

over 4 years ago

0 Adam Sidelsky over 4 years ago

TI__Guru 61380 points

Eggsy,

The "MOSFET drain sense pin voltage slew rate" concerns the VDRAIN pin. This pin should not slew at 2V/uS or higher.

You are considering the MAX limit of the gate drive voltage, not the actual voltage level itself. Please check section 7.5, GATE DRIVERS (GHx, GLx), for the actual voltage level. You will find they are both very similar.

Regards,

-Adam

0 Eggsy Pang over 4 years ago in reply to Adam Sidelsky

TI__Expert 4985 points

Hi Adam,

As for " "MOSFET drain sense pin voltage slew rate", I didn't see this spec in DRV8323 datasheet.

1. May I know what value of DRV8323 "MOSFET drain sense pin voltage slew rate" is?

2/ And MOSFET drain sense pin voltage slew rate is meaning MOSFET VDS dv/dt, right?

3. MOSFET VDS dv/dt is related with IDRIVE. So 2V/us of voltage slew rate will limit gate driver current?

Thanks!

0 Adam Sidelsky over 4 years ago in reply to Eggsy Pang

TI__Guru 61380 points

Eggsy,

This does not pertain to the DRV832x.
Yes this is right.
Yes this is right.

Regards,

-Adam

0 Eggsy Pang over 4 years ago in reply to Adam Sidelsky

TI__Expert 4985 points

Hi Adam,

I think 2V/us is too small to dv/dt.

Customer use 50V for MOSFET drain. And if swicth frequecy is 100Khz, it mean, dv/dt=50V/10us=5V/us and is bigger than 2V/us. What will it happen? Chip broken?

Thanks!

0 Adam Sidelsky over 4 years ago in reply to Eggsy Pang

TI__Guru 61380 points

Eggsy,

The frequency of the switching does not decide the slew rate of the Vds. Please check for the output slew rate to decide if this is being violated.

Regards,

-Adam

0 Eggsy Pang over 4 years ago in reply to Adam Sidelsky

TI__Expert 4985 points

Hi Adam,

But in my mind, The frequency of the switching = The frequency of Vgs =The frequency of Vds.

0 Adam Sidelsky over 4 years ago in reply to Eggsy Pang

TI__Guru 61380 points

Eggsy,

This is not directly correlated.

Regards,

-Adam

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DRV8353: What is "MOSFET drain sense pin voltage slew rate"?