DRV8704: DRV8704-FAULT

Pandiyan,

Do you have any scope captures of the inputs and outputs of the IC?  Is nFAULT low?  Can you post a schematic?

Regards,

Ryan

drv8704.pdfHere i have attached the schematic, kindly check that.
Can we use 32V actuators in this driver??

Hello,

We are investigating and will reply within a few days

Regards,

Shinya

Pandiyan,

Schematic looks good, but I am a little confused when you see that you do NOT use SPI.  You must in order to enable the motor.  It is the first bit in the very first register.  

Regards,

Ryan

we just follow the below table only, SPI options only ,we are not use the spi communication 

Pandiyan,

The driver will not be enabled with a SPI write to the first bit in the first register.  Please check the datasheet.

Regards,

Ryan

Ryan,

As you mentioned about the First bit of the first register,which is CTRL register,is SET already in default as shown in the attachment,what else can be an issue of continuous fault detection of the driver,Thanks in advance.

Regards,

Pandiyan

Pandiyan,

That is my mistake!  I was looking at some old documentation.  

This is going to be impossible to debug without some scope captures or ability to read back status with the SPI bus.  Since it looks like nFAULT is going low, a fault of some sort is happening.  And there are many reasons why that could occur.

Would it be possible to order and EVM?  You can wire over the SPI signals from the EVM to your board and use our GUI to read status registers when faulting.

Regards,

Ryan

Thanks for your concern and guide Ryan,yet still can anyone please provide some sample code for DRV8704 driver's SPI communication using CCS compiler,as i'm new to TI controller it will be of great help to me.Thanks in advance.

Pandiyan,

Please see example code here:

https://www.ti.com/tool/BOOST-DRV8711

It will be under the "support software" section.  The SPI section can be reused.

Regards,

Ryan

Thanks for the needfull help Ryan.

Ryan,

I've attached the scope captured images of GATE and SOURCE pulses of FET(SQJB00EP-T1_GE3),can you have a look over and suggest us something

Pandiyan,

It would be helpful if you can point to your schematic and label the plots showing where on the schematic you are capturing these scope captures.  Also, you said earlier that you are NOT using PWM.  So, what are the inputs fixed to?  Telling me input condition would be helpful.  As much information as you can provide would be helpful.  Is there a load?  

Regards,

Ryan.

we are measuring as per the below attachment, check that, we are not using the pwm ,enable the sleep pin and toggle the AIN1 and AIN2motor specification-30V BDC motor, No load condition 1A,with load maximum 4A,

If i connect the LEDs 30V ,300mA, there is no glitches in the gate and AOUT, but if i connect the Actuator(30V BDC motor) we are facing this issues, how to solve this problem??  

waiting for your quick response.

Thank you.

Pandiyan,

We may be getting somewhere.  The device might be going into current regulation.  See section 8.2.2.3 and figure 19 & 20.  

If you calculate the current regulation using the formula given and defaults for the TORQUE register and ISGAIN register, I get 2.75A.  

To disable current regulation, try shorting out the sense resistors completely.  Just directly connect low-side source to GND.  

Regards,

Ryan

Ryan,

We tried configuring TORQUE and ISGAIN registers through SPI but observed same results,so we added bulk capacitor (100uf, 63V) in the MOSFET so the initial peak current is arrested and the issue got solved.Thanks for the required help Ryan.

Regards,

Pandiyan

Ryan,

   Yes we are adding another one 100uf electrolytic capacitor.