DRV8711: External source on V5?

Thorsten Ostermann

Other Parts Discussed in Thread: DRV8711

We plan to use the DRV8711 together with an AVR µC. To programm the controller in production, we want to use a single connector suppying the necessary SPI signals and 5V voltage supply, but not VM. During normal operation the controller is supplied by V5 from the DRV8711. What will happen if we supply 5V from external while VM is zero (or left unconnected). Is this possible, or will this damage the driver?

Regards

Thorsten Ostermann

over 11 years ago

0 Wilson Zuo over 11 years ago

TI__Mastermind 26065 points

Thorsten

I don't think this will damage the device. But we need to further check about the risk in doing so. Will back to you later.

Best regards,

0 Thorsten Ostermann over 11 years ago in reply to Wilson Zuo

Intellectual 310 points

OK, thanks so far.

Regards,

Thorsten

0 Thorsten Ostermann over 11 years ago in reply to Thorsten Ostermann

Intellectual 310 points

HI Wilson,

any new on this topic?

Regards,

Thorsten

0 Wilson Zuo over 11 years ago in reply to Thorsten Ostermann

TI__Mastermind 26065 points

Hi Thorsten

Sorry this for keep you waiting. I will try to get this in next Monday. We need some verification on this. Can I say the MAX duration of the V5 being charged by external power is within 30s when we do the programming? Also this is a one time thing for each device?

Best regards,

0 Thorsten Ostermann over 11 years ago in reply to Wilson Zuo

Intellectual 310 points

Hi,

it will be once or twice for series production and more often for development samples. 30-60s is reasonable. But if there is a risk of damaging the driver, I would go that way. I don't want to take risks here. It would be really good to have statements about the maximum allowed voltage in the datasheet.

Regards,

Thorsten

0 Wilson Zuo over 11 years ago in reply to Thorsten Ostermann

TI__Mastermind 26065 points

Hi Thorsten

Checked with design side that there is an internal diode from V5 to VM. So if V5 is powered by external source, the VM will get like 4.3V, and the internal logic of the DRV8711 could be actived at this case. Most likely it can be considered as a UVLO condition. So there will be no risk in doing so.

Thanks,

Best regards,

0 Thorsten Ostermann over 11 years ago in reply to Wilson Zuo

Intellectual 310 points

OK, thats great. Thank you very much

Regards,

Thorsten

0 mohammadmehdi golmeshki over 10 years ago in reply to Thorsten Ostermann

Intellectual 320 points

Hello Thorsten Ostermann ,
Can you share your C code programm that you use for Runnig DRV8711 With Avr ?
I work with atmega , I can't run DRV8711 !!
Help me please
my emai : mettiblack72@yahoo.com

0 Wilson Zuo over 10 years ago in reply to mohammadmehdi golmeshki

TI__Mastermind 26065 points

Hi Mohammadnehdi

When you saycan't run DRV8711 with AVR MCU, have you checked all the inputs/SPI signals from MCU to DRV8711? If there is issue on the inputs or SPI, we need to solve the MCU code issue. If the inputs are all correct but DRV8711 is not working, please check nFAULT signal first, then, the analog voltages on the pins such as V5, VCP, net connections, and the layout of DRV8711.

Best regards,

0 mohammadmehdi golmeshki over 10 years ago in reply to Wilson Zuo

Intellectual 320 points

Thanks For Your Reply Wilson Zuo
I Checked the pins of DRV8711 , like nFAULT,V5,VCP . these pins are OK , I think I have problem with my code , I work with codevision compiler
Do you have any C code for codevision compiler ?
Or Can I find C code anywhere ?
Help Please !

0 Thorsten Ostermann over 10 years ago in reply to mohammadmehdi golmeshki

Intellectual 310 points

The I/O interface of the DRV8711 is a bit weird. Please note that the Pins SCS, SDATI and SCKL have internal pulldowns while SDATO has a open drain output. I don't understand who decided to have this strange implementation. Cost me a lot of nerves...

Regards,
Thorsten

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DRV8711: External source on V5?