Part Number: DRV8320
I really like most of the features on the DRV8320 part #'s but there are a few missing features that make this part less than ideal for personal electric vehicles (specifically electric skateboards).
For simplicity I would like to run a sensored brushless motor in the "1X PWM Mode" which takes the Hall Signals and automatically commutates. This is great, but I see a few problems.
1) on the non-SPI models there is no ability to disable Synchronous Rectification. I really wish this part had an input pin to enable/disable SR. In our product we need the ability to coast the motor, but with synchronous rectification always on, if the rider tries to drive the motor at a speed that is slower than the motor is moving, it will have an undesired braking effect, instead of freewheeling which is what the customer would expect (That is the ability to coast). Please consider adding this enable/disable SR pin on future non-SPI products as it is a critical features for most Personal EVs that want the ability to coast/freewheel. Yes I realize you can disable/enable SR in the SPI version of the part, but the requirement to use SPI adds additional complexity to our motor controller firmware that we rather avoid
2) your logic table for HALL INPUTs (Table 5 and 6) in "1X PWM Mode" shows in the second row that if all Hall Inputs are Logic High (which is a hall error that can happen for a variety of reasons including the hall connector becoming disconnected from the motor controller), the the 3 lower mosfets will be turned on, resulting in full braking which will result in the customer getting knocked off the personal EV. Meaning if the hall connector comes loose in the middle of the ride, full brakes will suddenly be applied, which is really dangerous. It would be desirable to be able to choose that in the event of a hall error (all inputs high or low) that either the motor applies brakes or coasts, but right now there is no ability to specify this, making an inherent safety issue. Again it would be nice to have an I/O pin on the non-SPI version that determines what happens when a hall error occurs. I believe even in the SPI version there is no ability to specify this. Is that correct?
Also, I wanted to ask:
On the SPI version, are the register settings volatile or non-volatile? in other words, at every power up, do all registers need to be programmed? or do they remember their settings after powercycling?
Thanks for your attention and let me know if you have any suggestions to address the above shortcomings for personal EV applications. I really hope you can add these features on new revisions of this IC.