DRV8701: DRV8701

Soumya

Part Number: DRV8701

Hi,

Can you please help with below customer inquiry?

I’m hoping that you might be able to provide us with some insight to some behaviour on the DRV8701 that isn’t documented in the datasheet.

See below for traces of the SO and SNSOUT signals. We’re curious if the intermediate spikes are something we should dive deeper into. We recently dropped our VREF voltage and increased the SP:SN resistance in an effort to reduce peak current draw when running the compressor. These intermediate spikes go away as the tank pressure increases, but are present right after the H-Bridge starts up for a few hundred milliseconds.

Would appreciate any insight you could provide.

See attachment for traces. NOTE: [Attachment removed]

over 6 years ago

0 Hector Hernandez Luque over 6 years ago

TI__Expert 8985 points

Hi Soumya,

Is it possible to get scope captures of the gate high/low and sense high signals?

What is the exact motor/load being run? I am wondering about any case during a drive period where the load requires an inrush of current (current spike).

Thank you.

0 Brad Zarikoff over 6 years ago in reply to Hector Hernandez Luque

Prodigy 185 points

Hi Hector,

The load is a 16 A compressor. Curves are below. The inrush is only at the start-up.

0 Hector Hernandez Luque over 6 years ago in reply to Brad Zarikoff

TI__Expert 8985 points

Hi Brad,

Can we get the gate high/low, and sense high scope captures? Those ones are for SO and SP/SN.

Also, there appears to be a current spike during the drive period. I am wondering if it comes from the load connected requiring a current spike during each drive period (the current spike shown).

0 Hector Hernandez Luque over 6 years ago in reply to Hector Hernandez Luque

TI__Expert 8985 points

Hi Brad,

Any updates here? Thank you.

0 Brad Zarikoff over 6 years ago in reply to Hector Hernandez Luque

Prodigy 185 points

Thanks Hector. Should be soon.

0 Hector Hernandez Luque over 6 years ago in reply to Brad Zarikoff

TI__Expert 8985 points

Hi Brad,

I do not see a reply to this thread. It has been over a week. I will close this thread. If there is an update in the future, feel free to open a new thread.

0 Brad Zarikoff over 6 years ago in reply to Hector Hernandez Luque

Prodigy 185 points

Hi Hector,

Apologies for the delay. Here are the scope captures you requested. Can you ascertain if there is anything odd in the plots?

There appears to be a initial spike on the gate high. The compressor is activated for a period between 1 to 20 seconds.

0 Hector Hernandez Luque over 6 years ago in reply to Brad Zarikoff

TI__Expert 8985 points

Hi Brad,

I will close this thread given the amount of time the e2e has been up.

Please, open a new thread. Below are questions I have that you can answer in the new e2e:

1. Is the IC utilized DRV8701E or DRV8701P?

2. Is the driver configured in half bridge or full bridge mode?

3. What is the IDRIVE setting? What FETs are being utilized?

4. Has the datasheet section 8.2.1.2 Detailed Design Procedure been followed when selecting the IDRIVE setting, FETs, and PWM frequency?

5. Have there been any trials utilizing a different motor/load? Isolating the variables that can cause a current spike and removing them will help to determine where the issue comes from.

6. If there any more scope captures from the bridge stage (e.g. GL1, GH1, etc.) that you can capture before and right when the current spike occurs, it will help get as much information to me as possible.

7. From what you are showing, is it fair to assume that, around 696 and 726 ms, GH2 is not being driven by the driver and there are two spikes, one fast at 696 ms and the other prolonged at 726 ms but GL2 is being drivenat 696 ms, correct?

8. Can you share scope captures of the digital PWM signals IN1 and IN2?

9. Does the application circuit have the required capacitor values and voltage ratings? Are the capacitors X7Rs?

Motor drivers

Motor drivers forum

DRV8701: DRV8701