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MCF8316A: Schematic Question Asking

Part Number: MCF8316A

Hi team,

My customer has some issue about MCF8316A,

Could you please give me some advice on these questions.
and I give some comments on my customer questions, but I am not sure if I am right or wrong, please help me check.
Below figure is the schematic of MCF8316A

1.) How to connect the pin EXT_WD/EXT_CLK/ ALARM
[Me]: for EXT_WD/EXT_CLK => connect to the control interface. (I2C)
         for ALARM => Open-drain output requires an external pull-up resistor to 1.8V to 5.0V. Or leave this pin floating.

2.) Should I connect Pin  BRAKE/DIR/DRVOFF  via I2C Register 
[Me]: If you need to control this pin, you should connect it via I2C register.

3.) Could you help me to check if SPEED( to DDP442X CW_PWM) / nFlAULT (to DDP442X  PMD_INTZ) connect correct?
[Me]: Both SPEED and nFlAULT are controlled by control interface, I do not understand why my customer need to put the resistor in there. is this correct or my customer should remove it.

4.) My customer replace PMD1000 to MCF8316A, but MCF8316A do not have CWCTR signal ,does my customer need to remove it?

  • Hi Jason,

    Here's my response.

    1.) How to connect the pin EXT_WD/EXT_CLK/ ALARM

    These pins can be left floating.

    2.) Should I connect Pin  BRAKE/DIR/DRVOFF  via I2C Register 

    No, all three pins are hardware pins. 

    Brake pin High → Brake the motor when High
    Brake pin Low → normal operation

    DIR pin when low phase driving sequence is OUT A → OUT B → OUT C
    DIR pin when high→ phase driving sequence is OUT A → OUT C → OUT B

    DRVOFF pin when high→ device stops driving the motor by turning OFF all MOSFETs

    DRVOFF pin when low→ device returns to normal state of operation.

    We recommend 5V pull up voltage on all three pins via 4.7k pull up resistor. 

    3.) Could you help me to check if SPEED( to DDP442X CW_PWM) / nFlAULT (to DDP442X  PMD_INTZ) connect correct?

    Motor speed can be controlled via PWM, Analog or I2C mode. Looks like the customer has a 10k resistor connected to SPEED pin. If they wish to control the motor speed via analog mode, a 25kΩ 0.5W potentiometer pulled to 5V can be connected to speed pin to vary the motor speed. 

    Check section 7.3.8 (SPEED Control) in the datasheet for more details. 

    nFAULT is a fault indicator. Pulled logic-low with fault condition; It is an open-drain output which requires an external pull-up resistor to 1.8V to 5.0V.

    4.) My customer replace PMD1000 to MCF8316A, but MCF8316A do not have CWCTR signal ,does my customer need to remove it?

    I'm not sure what CWCTR means. Can you provide more details? 

    Regards,

    Vishnu.

  • Hi Vishnu,

    Thanks for your comments,

    please see my update.

    1.) How to connect the pin EXT_WD/EXT_CLK/ ALARM

    These pins can be left floating.

    If my customer want to control theses pin, how should connect? I2C/ hardware?

    2.) Should I connect Pin  BRAKE/DIR/DRVOFF  via I2C Register 

    No, all three pins are hardware pins. 

    We recommend 5V pull up voltage on all three pins via 4.7k pull up resistor. 

    But the TI's reference design control these pin via I2C register, do you know why?

    3.) Could you help me to check if SPEED( to DDP442X CW_PWM) / nFlAULT (to DDP442X  PMD_INTZ) connect correct?

    Motor speed can be controlled via PWM, Analog or I2C mode. Looks like the customer has a 10k resistor connected to SPEED pin. If they wish to control the motor speed via analog mode, a 25kΩ 0.5W potentiometer pulled to 5V can be connected to speed pin to vary the motor speed. 

    Check section 7.3.8 (SPEED Control) in the datasheet for more details. 

    I do not see how to connect the speed pin in the datasheet, could you tell me how to know customer need to add a 25kΩ 0.5W potentiometer pulled to 5V 


    4.) My customer replace PMD1000 to MCF8316A, but MCF8316A do not have CWCTR signal ,does my customer need to remove it?
  • If my customer want to control theses pin, how should connect? I2C/ hardware?

    Please check section 4.1.4 (Improving Speed Accuracy with External Clock Source) in the tuning guide for the details. 

    But the TI's reference design control these pin via I2C register, do you know why?

    Yes, the Brake and DIR pins can also be controlled via I2C by overriding these pins, however we recommend these pins to be put in a known state by either pulling to GND or pulling up to AVDD via pull up resistor. 

    I do not see how to connect the speed pin in the datasheet, could you tell me how to know customer need to add a 25kΩ 0.5W potentiometer pulled to 5V 

    Please refer to the attached MCF8316AEVM schematic (page-2).

    MD038A1(001)_Sch.PDF

    Regards,

    Vishnu

  • Hi Vishnu

    Thanks for your comments,

    Please refer to the attached MCF8316AEVM schematic (page-2). 
    I still not see the 25k in the circuit.
    I only see this figure on the page 2 



    Jason

  • Jason,

    R4 is the potentiometer. Part number is 3352T-1-253LF.

    Regards,

    Vishnu

  • Hi Vishnu,

    I got it, thanks.

    Jason

  • Jason,

    Do you need any additional help?

    If your issue has been resolved, please help us out by clicking the green “This Resolved My Issue” button.

    Regards,

    Vishnu

  • Hi Vishnu,

    OK!