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DRV8886AT: Inquiries about Microstepping Setting of DRV8886

Part Number: DRV8886AT
Other Parts Discussed in Thread: DRV8886

Hi, TI expert

A customer is using TI's DRV8886, and I have a question about it.

Q1) When using 1/8 Step among the microstepping settings below, when R453(10K) and R454(10K) are connected to 3.3V instead of in Z state to the Tri-Level input M0 pin, what mode does it operate in internally?

The output port of the MCU that controls M0 is open, and a 3.3V voltage divided in half is put in the M0 pin. However, during actual measurement, about 1V is measured as the DRV8886 internal resistance value, and the operation is operated in 1/8 Step, which was intended to be controlled.

Q2) At the time of this design, it is estimated that there was a design mistake while changing from 1/16 to 1/8. Before opening the most obvious resistors R453 and R454, I would like to inquire about what will happen.

Please check. Thank you.

  • Hello,

    There is a figure in the datasheet with the internal resistor divider on the M0 pin.  This divider will hold the voltage to ~1.14V.  

    There is also a specification in the datasheet that gives the range that can be expected.

    I am not sure I understand your second question.  If you need 1/16 ustep, you would just force 3.3V on the MO pin.  If you MCU has the capability to HIZ the port, the resistors in question are not needed at all.