DRV8847: DRV8860 with I2C

Hi Marco,

We have two new BDC motor H-bridge driver devices that have I2C. These devices also have advanced features for BDC application that may not be interesting to drive solenoids. These are DRV8214, https://www.ti.com/lit/ds/symlink/drv8214.pdf and DRV8234, https://www.ti.com/lit/ds/symlink/drv8234.pdf. We have new upcoming SPI options for 8-ch solenoid drive. There are quite a few hardware IO based driver options but no other I2C based like you mentioned. Thanks.  

Regards, Murugavel

Hi Murugavel,

The customer came back with some more project details, hopefully this will help hone in on a suggestion. Thanks for your reply and looking forward to your n next response. Thanks!

"This is for a board that drives multiple solenoids. That is why I need > 6 outputs. My idea to use I2C is to transmit over long ribbon cable (~12”max). I am concerned about using SPI with the fast edges that may create EMI problem. I am thinking that I2C is open drain and therefore can slow down the edges somewhat."

Marco

Hi Marco,

Thank you for providing more information about the project requirements.

In addition to EMI concerns reliable communication should also be a concern for transmission outside of the system PCB. Both I2C and SPI are designed for inter IC communication purpose.

I2C has open drain which means the falling edge will still be a fast edge. With SPI both rising and falling edges could be fast edges. SPI clock can be slowed down to the same level as the I2C clock, for example 100 kHz and the edges can be smoothed out by transmission line capacitance itself or small capacitors such as 10 to 20 pF can be added on to all the SPI lines without affecting the data integrity. 12" max. is not super long. All four signals for the SPI or the 2-lines for I2C should be kept identical to ensure the delays in them are similar, although it may not be a major challenge at 100 kHz. Alternative option would be to add a small MCU to the solenoid driver board and use UART / RS232 communication for control from the main processor. 

The DRV8860 would be a better fit from a multi-channel solenoid driver standpoint.  

Regards, Murugavel

Hi Murugavel,

The customer said he will stick with the DRV8860 now. He was also thinking about adding ferrite beads to slow down the edges, just as an additional bit of feedback. Thanks for your help!

Marco