• Locked Locked
  • Replies 6 replies
  • Subscribers 30 subscribers
  • Views 579 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

DRV8718-Q1: 8718 PGND connection issue & brake issue

sheldon zhu
Prodigy 20 points
Part Number: DRV8718-Q1

hello  team

I use the 8718 to control four BDC,but different current on each H-bridge,such as 10A,2A,etc

the sample resistors are all connected in low side sense configuration ,how should i connect the PGND1 & PGND from the mosfet to the IC to get a more accuray diagnosis or protection funciton

BTW,what should I take care while driving different load power motors with 8718

The 2rd issue

about the BRAKE function issue,if use with the internal overvoltage monitor

the threshold is around 30V,but the announced OP voltage is close to 37V,how should i understand the acutual operation voltage with normal load driver function

  • TI__Mastermind 37683 points

    Hi Sheldon,

    Thank you for posting to the forum. Let me research your question and I will get back to you with an answer by 24 hours.

  • in reply to Pablo Armet
    TI__Mastermind 37683 points

    Hi Sheldon,

    I'm still researching. Please give another 24 hours. Thank you in advance for your patience.

  • in reply to Pablo Armet
    TI__Mastermind 37683 points

    Hi Sheldon,

    Apologies for the delays.

    sheldon zhu said:
    how should i connect the PGND1 & PGND from the mosfet to the IC to get a more accuray diagnosis or protection funciton

    Please connect the source of the LOW side MOSFET of half-bridge 1-2 to PGND1. PGND1 needs to be as close to the value of the source of the MOSFET since there is a VGS monitoring circuit that measure the voltage across the gate and source of the FET.

    However, the difference between PGNDx and GND should not exceed 0.3V. This means that the resistor value should be such that the voltage drop across it never greator than 0.3V.

    sheldon zhu said:
    the threshold is around 30V,but the announced OP voltage is close to 37V,how should i understand the acutual operation voltage with normal load driver function

    Let me discuss this with the team internally and I will get back to you within two business days.

  • in reply to Pablo Armet
    Prodigy 20 points

    hi pablo

    thanks for your explanation

    why the voltage drop between PGND and GND not exceed 0.3V. in fact,most of the time, it won't . if there is a common mode input voltage of Vgs comparator limited input voltage,but 0.3V is too low.

  • in reply to sheldon zhu
    TI__Mastermind 37683 points

    Hi Sheldon,

    Power of braking is ONLY active in the device SLEEP mode. So doesn’t interfere with operation during normal mode.

    POB must activate before the power supply reaches 37/40-V to protect the system and device which is why the threshold is lower. The threshold is selected to be just above automotive double battery condition.

    The 0.3V maximum difference between PGND and GND is specified in the datasheet. The IC GND and PGND should be close in value to prevent offsets in the ground reference. 0.3V is the value that we have tested and analyze to be the maximum different between the grounds to make sure the device operates normally.

  • in reply to Pablo Armet
    TI__Mastermind 37683 points

    Hi Sheldon,

    I want to make a correction on my previous reply. The maximum difference between PGND and GND should be -2V not -0.3V.