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DRV8884: Looking for a 6phase half step driver; not this 8 phase half step driver.

Part Number: DRV8884
Other Parts Discussed in Thread: DRV8834, DRV8848

Small steppers used for mechanical gauges use a 6 phase half step similar in pattern to the 3 phase brushless run motors. We need a stepper motor driver similar to 8844 but with the 6 phase half step these small gauge motors require. I have a discrete logic circuit that provides the proper signaling for a 6 phase half step, but we would like to use microstepping in these 6 phase half step devices. We would also like to end with a smaller footprint circuit...

  • Small steppers used for mechanical gauges use a 6 phase half step similar in pattern to the 3 phase brushless run motors.

    We need a stepper motor driver similar to DRV8884 but with the 6 phase half step these small gauge motors require.

    I have a discrete logic circuit that provides the proper signaling for a 6 phase half step, but we would like to use microstepping in these 6 phase half step devices. We would also like to end with a smaller footprint circuit...

  • Hi Ken,

    Can you provide the datasheet or a part number of the motor? What are the voltage and current requirements?

    We do not have anything that will do this directly, but perhaps we could find something that may work.
  • Here you go Rick. it is a 5 to 8v 20ma coil motor with 6 phases of half steps to a full cycle unlike conventional steppers that have 8.

    These are seen in mechanical gauges and are usually driven by a uProcessor. I am tasked to do this without that help.

    an up/down counter parallels a three bit ring counter driving the three motor inputs in my design. Would like to microstep, limit current, and make a smaller footprint.

    All the stepper motor drivers seen are 8phase, at 1/2 step, and the 3phase BLDC drivers are for run motors.

    X25_xxx_03_SP_E.pdf

  • Hi Ken,

    There are some devices that could be used to create the sequence. The DRV8834 ( 16 mm sq in QFN package) and DRV8848 (32 mm sq) can be controlled by 4 inputs to create any sequence desired.

    Please look at these devices. If either of these would work, we can provide more details regarding the sequence to drive the motor.
  • Thanks for getting back with this Rick. The 8834 just like the 8884 only does an 8ph, 45° per half step, indexing with step and direction as inputs. We need something like that but with the 6ph per half step that gives 60° each for the motor specified above. We would like to use it at 1/4 or 1/8 stepping. The motor hardly needs a driver, just something that can do 50mA. But without a similar indexer, a lookup table in a uProcessor, or FPGA, may be required to get the control needed. We have this working with a 8884, but the motor does not move smoothly without its intended waveform pattern. The 8848 driver is two half bridges, we need three, and the PWM would still need external timings created.
  • Hi Ken,

    We do not have a device with the sequence you desire. The two devices mentioned (DRV8834 and DRV8848) require a lookup table for control.

    The DRV8834 should be operated with CONFIG set low (phase/enable mode). As mentioned the DRV8834 was suggested because of the size and voltage.

    Would you mind if the thread e2e.ti.com/.../2516236 is merged with this one? Brian and I are in contact so we can discuss options.
  • I think what we need is a BLDC three phase controller that works down to zero Hz

  • Hi Ken,

    It does not appear our BLDC controllers are set up for the sequence of the motor. Even it it was, external circuitry to control the 3 phase inputs would be required.

    The DRV8834 using CONFIG set low is the closest match. The two windings can be controlled separately using the xPHASE/xENBL inputs.
    The components shown around the DRV8834 in the block diagram can be minimized for this application.