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DRV8844 with sense resistor?

Thorsten Ostermann
Intellectual 310 points
Other Parts Discussed in Thread: DRV8844, DRV8880

I'm looking for a replacement for the good old L298. DRV8844 seems what I'm looking for, but I'm not sure if I can add sense resistors for external current regulation to the device? The functional block diagramm in section 8.2 of the DS implies that there are seperate negative outputs for each half-bridge, but I can not see which VNEG pin belongs to which bridge. So I assume they are connected internaly?

With kind regards,

Thorsten Ostermann

  • 0
    TI__Guru** 114905 points
    Hi Thorsten,

    We will investigate and reply soon.

    Can you provide a brief description of your application (motor, voltage, current, any other details)? Perhaps we have a better fit.
  • 0 in reply to Rick Duncan
    TI__Guru** 114905 points
    Hi Thorsten,

    I realized you are probably looking for stepper control. The DRV8844 can be modified to control steppers using sense resistors.

    Pin 6 is the low side FET source for OUT1 and OUT2. Pin 9 is the low side FET source for OUT3 and OUT4. Pins 14, 28, and PPAD is VNEG, the negative supply (dual supplies) or ground (single supply).

    Sense resistors can be added from pins 6 and 9 to pins 14,28, and PPAD. If doing so, the voltage difference between pins 6 or 9 and pins 14,28,PPAD should be less than +/-0.6V.

    Also, we have recently released several stepper motor drivers that may be of interest.
    The DRV8880 with AutoTune automatically adjusts the current at each step to minimize current ripple. With a STEP/DIR interface control is simple.
    The DRV8881E has a AutoTune plus a PH/EN interface and 2 VREF inputs, allowing high levels of microstepping.
    The DRV8880 has integrated current sensing, eliminating the need for external sense resistors.

    All three have EVMs available for evaluation.
  • 0 in reply to Rick Duncan
    Intellectual 310 points

    Dear Rick,

    thats good news. Thank you for your fast reply. Indeed this is a stepper motor application. In this case we are reworking an old design, switching from THT to SMD technology while keeping most of the design. For new projects I'll keep my eye on the DRV8880.

    With kind regards,

    Thorsten Ostermann