Part Number: DRV8432
Hi,
I intend to use DRV8432 chip to run stepper motor in microstepping mode. I've reviewed DRV8432 data sheet but found no information on how to set up a microstepping mode. It's my understading that in order to do so I have to set up the chip for cycle-by-cycle (CBC) current limiting mode and be able to adjust OC threshold externally by using voltage DAC or otherwise. I looked up through this forum and found reference to DRV8412-C2-KIT that is capable of microstepping mode. I've then checked the schematic diagram of the driver board included with the kit and found that the circuit contains PWM DACs and allows for external OC threshold control. However, it's not clear so far as to how to choose the DAC's output voltage and OC_ADJ pin's resistor value for a given desired OC threshold value. The description of current limiting function in the DRV8432 datasheet is very limited and skimpy and it's insufficient to gain full understanding of circuit's functionality. So my questions are as follows.
1. Would you please provide a more in-depth explanation of current sensing and OC protection functionality, perhaps, with detailed block diagram of the circuitry involved?
2. Would you please provide a formula that accurately describes functional relationship between DAC output voltage, external OC_ADJ resistor's value, and desired OC CBC protection threshold?
3. What is the typical response time of the DRV8412 to the changes on the OC_ADJ pin?
Michael