• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 29 subscribers
  • Views 91 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.

MCT8316Z-Q1: Unable to get internal voltage to turn on

Adam Ambriz
Prodigy 20 points
Part Number: MCT8316Z-Q1
Other Parts Discussed in Thread: MCT8316Z, MCT8316ZTEVM

Hello.

I am trying to troubleshoot a custom PCB that utilizes the MCT8316Z ic for driving a 3-phase DC motor. I have attached a schematic image below for reference (there have been some modifications which are highlighted). The issue I am seeing is the AVDD pin (internal voltage regulator) never reaches 3.3V. The original design had the nFault pin (number 22) pulled up by an external regulator (VCC in the schematic) but after further reading of the datasheet, specifically the section regarding the IC entering test mode, we modified the PCB to have the nFault pin pulled up to AVDD (pin 25), however we still see no voltage on AVDD.

  • 0
    TI__Expert 5502 points

    Hi Adam,

    Thanks for your question on the motor drives E2E forum. Just looking at your schematic there are a couple points I want to highlight. 

    1. Looks like you already caught the nFAULT pullup resistor issue!

    2. FGOUT will also require an external pull up to 1.8V to 5.0V

    3. For nSLEEP, when the pin is logic low, the device goes into a low-power sleep mode. It needs an external pull up to 1.8V to 5.0V. I am not positive of the cause, but this is likely what is causing the issue on AVDD as the device is stuck in sleep mode. Depends on where that DY node goes.

    4. CBK - TI official datasheet recommendation is voltage rating is 2x VM (48V in this case vs 35V you currently have on schematic).

    Try and implement these changes and see if this resolves the issue. Also, please reference our MCT8316ZTEVM schematic and layout which is located on the tool folder here: https://www.ti.com/tool/MCT8316ZTEVM

    See this screenshot for page location:

    Best,

    Robert

  • 0
    TI__Mastermind 18916 points

    Hi Adam, 

    Closing this thread as it looks like the latest response has resolved your problem.

    Please help mark the thread as resolved if that's the case - and if further debug support is needed, you can click "Ask a related question" to re-open the topic.

    Thanks and Best Regards,
    Andrew