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DRV8847: How to replace KA3100D with DRV8847 ? i tried with 2 pin interface .but when i sent Inp1 & Inp2 both o or 1 , the respective outputs are improper.

Kalpana Nachnekar
Prodigy 10 points
Part Number: DRV8847

Tool/software:

 i tried with 2 pin interface .but when i sent Inp1 & Inp2 both o or 1 , the respective outputs are improper.

  • 0
    TI__Genius 12051 points

    Hi Kalpana,

    My team mate will be looking at this and responding, Please give him another couple of days to respond.

    Thanks,

    Ibinu

  • 0
    TI__Mastermind 19860 points

    Hi Kalpana,

    The DRV8847 has two different configurations for forward and reverse operation while using the 2-pin setup. If possible, could you elaborate on how the output signals are "improper" by taking scope captures of input and output signals?

    The control table above shows that IN3 should always be grounded, and the MODE pin supplied with external voltage supply while using the 2-pin interface. 

    Best,

    David

  • 0 in reply to David Medis
    Prodigy 10 points
    Dear David sir,
     
    Thank you for your reply.
    I am using this motor driver DRV8847  for moving thermal printer motor.
     
    I have used the 2 pin interface . According to 2 pin interface table,
     
    NSLEEP    IN1    IN2    IN3   IN4   OUT1   OUT2  OUT3  OUT4  FUNCTION (DC MOTOR)
    0         X      X     X        X       Z            Z            Z          Z              Sleep mode
    1           0                   0         X        L           H                                      Reverse direction
    1               1                   0         X        H          L                                      Forward direction
    1                  0          0          X                                    L           H        Reverse direction
    1                        1          0         X                            H           L        Forward direction
     
    1. I kept IN1 as logic 1 and IN2 also logic 1 for forward motion of DC motor. But motor becomes on and stuck on same place while printing on.
    2. I kept IN1 as logic 0 and IN2 also logic 0 for Reverse motion of DC motor. But motor becomes on and stuck on same place while printing on.
    3. I kept IN1 as logic 1 and IN2 logic 0. motor moves forward or backward .
    4. I kept IN1 as logic 0 and IN2 logic 1. motor moves forward or backward .
    If we are sending data on IN1 pin , what would be the status of the IN2 pin at the same time? As in the interface table ,IN2 pin does not show any input while IN1 pin is 1 or 0.
     
    Please reply back.
     
    Thank you . 
    Regards,
    Kalpana
  • 0 in reply to Kalpana Nachnekar
    TI__Mastermind 19860 points

    Hi Kalpana,

    Only 2 inputs should be given to the inputs when using the 2-pin interface and IN3 is one of the inputs and should always be 0. For example, during forward operation, IN2=1 and IN3=0, no input should be given to IN1 at this time. In the logic table, if no value is specified then it means no input should be given to the pin. 

    Numbers 3 and 4 sound like the device is functioning as intended. 

    Best,

    David

  • 0 in reply to David Medis
    Prodigy 10 points

    Dear David,

    Thank you for reply.

    The present motor driver KA3100D gives  output on the output pins for driving  thermal printer motor are as follows,

    IN1     IN2        Out1         Out2        Out3       Out4        

      L          L          H                 L              H            L         forward direction

      H         H          L                 H              L             H        Reverse direction

    So now to replace KA3100D, we need to get same output on the output lines.

    Can you please suggest which  mode we should use in DRV8847? also please suggest the sense resistor values to be used .

    Thank you,

    Regards,

    Kalpana

  • 0 in reply to David Medis
    Prodigy 10 points

    Dear David,

    In our hardware we are sending IN1,IN2,nSLEEP signals  to DRV8847 serially using IC 74HC595 . Hence these signal bits either can be 0 or 1 . For moving thermal printer motor in forward direction , we  are setting IN1 bit as 1, nSLEEP bit as 1 and IN3 pin is grounded. Please let us know how to make IN2 pin float as it's connected to DRV8847 serially.

    Or whether we need to connect IN2 direct from Microcontroller to DRV8847?

    Thank you.

    Regards,

    Kalpana

  • 0 in reply to Kalpana Nachnekar
    TI__Mastermind 19860 points

    Hi Kalpana,

    Is you load a stepper motor or brushed-DC motor?

    If the load is a stepper motor, using the 2-pin interface, IN1 and IN2 will need to be set 90 degrees out of phase with each other to achieve a full-step sequence. 

    Best,

    David