DRV8323R: Must DRV8323R use 47nf cap between CPH and CPL pin?

Eggsy Pang

Expert 4985 points

Part Number: DRV8323R

Hi team,

I would like to know DRV8323R must use 47nf cap between CPH and CPL pin. What about 50nf?

Thanks!

over 4 years ago

0 Adam Sidelsky over 4 years ago

TI__Guru 61380 points

Eggsy,

50nF is marginally different and should work. Please make sure that the voltage rating is sufficient per the datasheet.

Regards,

-Adam

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

TI__Expert 4985 points

Hi Adam,

Could you help my customer review the below SCH?

Thanks!

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

TI__Guru 61380 points

Eggsy,

The customer has the device configured in the independent mode, is this intentional? Are they only using the HS of each phase? What is the application?
The customer has MAX IDRIVE programmed. They have the option to lower the IDRIVE and remove the gate resistor, this could reduce their BOM.
Using two series capacitors for the CPH/CPL node is not recommended as the center node between the two caps is unmanaged. If there are differences in capacitors/assembly/soldering then the two caps may not be balanced.

Regards,

-Adam

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

TI__Expert 4985 points

Hi Adam,

Thanks for your help!

Yes, they use independent mode and they just need AB two phase. They use the HS and LS of each phase. Just show the LS part in SCH.

The application is UPS from 48V DC to 220 AC.

Thanks!

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

TI__Expert 4985 points

Hi Adam,

My customer have test their board based on DRV8323H. In the SCH, We know it is Full bridge Circuit.

VM=50V, If D=50%, RSM of output voltage is 25V between SHA and SHB. The load is "transformer"

But they met some problems which DRV8323H is broken when transformer's output voltage is up to 25V.

If transformer's output voltage is smaller than 25V, DRV8323H work find.

And if the load is changed from transformer to resistance, it work find even though output voltage is up to 25V.

May I know why?

We also do the another test. If gate resistance R30 value is changed from 10Ω to 60Ω, DRV8323H work find even though output voltage is up to 25V with transformer.

May I know why ?

Thanks!

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

TI__Guru 61380 points

Eggsy,

The issue here is that if the IDRIVE is too high or the gate resistance is too low, the Gate and Source nodes will have excess ringing with overshoot and undershoot. This will cause excessive chip heating and potentially damage the IC. The damage is not due to the heat but actually due to the overshoot and undershoot exceeding the ABS MAX of the device pins.

Does the customer require gate resistors? If not, they can remove these gate resistors and we can calculate the needed IDRIVE strength for them. This will save them board space and components.

Regards,

Adam Sidelsky