DRV8323R: DVDD got failed while fast rise time of blower

dinesh kumar

Part Number: DRV8323R
Other Parts Discussed in Thread: CSD88537ND,

Im using DRV8323RH, i need fastest rise time within 0.4 secs from min to max RPM, so i tried to do that, but all the times Driver IC got failed and in hardware DVDD pin of IC is short circuit with GND.

I fixed 0.01uF from VM to SPA,SPB,SPC pins to avoid fault condition in rise time.

Im using CSD88537ND MOSFET, should i change this?

over 2 years ago

0 dinesh kumar over 2 years ago

Prodigy 150 points

0 dinesh kumar over 2 years ago in reply to dinesh kumar

Prodigy 150 points

0 Michael Arrant over 2 years ago in reply to dinesh kumar

TI__Expert 3535 points

Hi Dinesh,

This MOSFET is probably okay as it has a very low Qgd of 2.3nC. What IDRIVE setting are you using? You can also reduce the IDRIVE setting by putting a series gate resistor (couple ohms).

Rise time can by calculated with Qgd = (IDRIVE Current) * RiseTime

So two of these variables are known, and you can set the IDRIVE setting to give you the desired rise time.

Thanks,

Michael

0 Grzegorz Pelikan over 2 years ago in reply to Michael Arrant

Genius 3580 points

Hi Michael,

Dinesh probably meant acceleration time of 0.4s from min to max rpm.

Regards,

Grzegorz

+1 Michael Arrant over 2 years ago in reply to Michael Arrant

TI__Expert 3535 points

Hi Dinesh,

I see now that you were referring to spinning the motor from 0 to max RMP in 0.4 seconds.

What is your VM voltage?

Whenever you spin a motor from 0 RPM to max RPM there is a large rush of current that passes through the FETS, through the coil windings, and finally to ground. This large current surge can cause ground bouncing. Since DVDD is referenced to ground through the 1uF cap, this could cause a higher than abs max voltage to be forced on DVDD, which would fry DVDD.

I'm recommending you add more bulk capacitance from VM to SPx. Typically we recommend 2 uF per motor power watt. So for a 50W motor, we would recommend a 100uF cap.

If possible, please provide the PCB layout so I can review it.

Below is a FAQ for Best Practices for Board Layout of Motor Drivers:

https://e2e.ti.com/support/motor-drivers/f/motor-drivers-forum/746299/faq-best-practices-for-pcb-layout-of-motor-drives

Thanks,

Michael

0 dinesh kumar over 2 years ago in reply to Michael Arrant

Prodigy 150 points

Now we added 0.01uF capacitor between VM & SPx.

0 dinesh kumar over 2 years ago in reply to Michael Arrant

Prodigy 150 points

I attached the gerber file & BOM for your reference

0 Michael Arrant over 2 years ago in reply to dinesh kumar

TI__Expert 3535 points

Hi Dinesh,

What power is your motor rated to, and what is your voltage on VM?

I will review the layout over the weekend and get back to you Monday morning.

Thanks,

Michael

0 dinesh kumar over 2 years ago in reply to Michael Arrant

Prodigy 150 points

Our blower is BA6560 from TKFAN, As you said, i reduced the I drive current to 20mA & i fixed 47uF/50V tantalum capacitors across VM to SPX, now its 100 % perfectly running without any issues, we are validating it with maximum duty with 0.4 secs rise time.

0 dinesh kumar over 2 years ago in reply to Michael Arrant

Prodigy 150 points

My Vm=24VDC and i added a backemf suppressor PCB between supply and BLDC driver, to avoid tripping of SMPS due to BEMF while fastest fall time of motor.

0 dinesh kumar over 2 years ago in reply to Michael Arrant

Prodigy 150 points

Kindly add this Vm to SPx capacitor details with DRV8323R datasheet, this is not mentioned anywhere in datasheet, it would be use full for all.

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DRV8323R: DVDD got failed while fast rise time of blower