• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 29 subscribers
  • Views 382 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DRV8703-Q1EVM: DRV8703-Q1EVM about MODE

Dexter Choi
Expert 2795 points
Part Number: DRV8703-Q1EVM

Dear Sir,

My customer tested DRV8703-Q1EVM with Brushed motor as attached report.

3 mode tested but different operation.

When PH/EN Control Interface and Independent PWM Control. Motor spin at 2% of duty cycle.

but When Standard PWM Control. Motor spin at 31% duty cycle. the motor doesn't spin below 30% duty cycle.

Could you explain this situation to me?

and When Standard PWM Control, Mode voltage is 1V. could you give me information for Mode pin.

TI_DRV8703Q1EVM.pptx

  • 0
    TI__Guru** 114905 points

    Hi Dexter,

    To match the motor behavior in all three modes, the inputs in Standard PWM should be changed to create the same sequence.

    In PH/EN mode, the outputs are changing from Reverse to Brake Low side Slow decay.

    In Independent half bridge mode, the outputs are changing from Forward to Brake Low side Slow decay. So the motor should be operating in the opposite direction.

    In both modes above the current can recirculate to provide torque to move the motor.

    In Standard PWM mode, the outputs are changing from Forward to Coast - Bridge Disabled.

    In this mode, the current is removed through the body diodes.

    To match the behavior of PH/EN and Independent half bridge, set both IN1 and IN2 at 100%. Then lower IN2 to 98%. Doing this will change the outputs from Forward to Brake High side Slow decay.

    About the mode pin:

    From the Pin Functions Description of the datasheet:

    Mode control pin. Pull this pin to logic low to use H-bridge operation. Pull this in to logic high for independent half-bridge operation. This pin is connected to an internal resistor divider. Operation of this pin is latched on power up or when exiting sleep mode. This pin is connected to an internal pullup and pulldown resistors.

    Also refer to Figure 32 of the datasheet.

  • 0 in reply to Rick Duncan
    Expert 2795 points

    Dear Rick,

    Thank you for your reply.

    I have a question for VIO in datasheet.

    I know VIO spec is 5mV.

    but I see 50mV for example in datasheet.

    I am confusing... please let me know VIO spec 5mV or 50mV?

  • 0 in reply to Dexter Choi
    TI__Guru** 114905 points

    Hi Dexter,

    The VIO spec is 5mv typical. The 50mV below Equation 1 is incorrect. 

    The statement: For example, if a 50-mΩ sense resistor and a VREF value of 3.3 V are selected, the full-scale chopping current is 3.28 A. The AV is 19.8 V/V and VIO is assumed to be 50 mV in this example.


    should be:

    For example, if a 50-mΩ sense resistor and a VREF value of 3.3 V are selected, the full-scale chopping current is 3.28 A. The AV is 19.8 V/V and VIO is assumed to be 5 mV in this example.