• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 387 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.

UCD9244-EP: Doubts on few pins functionality

Binayak Shrestha88
Expert 1520 points
Part Number: UCD9244-EP
Other Parts Discussed in Thread: UCD74120,

Hi,

I'm using UCD9244EP and UCD74120 to power the variable CVDD rails of two TMS3206678 DSPs.

I'm using the DCR method to generate the current sense voltage in UCD74120.

[1] Is it necessary to use the TEMP functionality in UCD9244-EP? It basically tells the temperature of the regulator (inductor - in case of DCR method). We have never used the regulator temperature in any of the designs we have done previously.

[2] If we are not planning to use TEMP functionality (or if it corresponds to an unused rail), what should we do to this pin - float/pull down/ pull up? In addition, what parameter do we need to disable in the PMBUS command?


[3] In the datasheets of UCD9244-EP, the typical application shows VIDS being pulled up using 100k resistor for both used and unused rails. However, in the K2H EVM (K2EVM-HK Rev.4, pg.#40), the unused VIDS pin is pulled up using 4.7K. Why is it necessary to pull up the the VIDS pin for the unused rail? In addition, is it necessary to pull it up for the used rail? We are already pulling the VID lines at 1.8V to 3.3V level translators.

[4] What should be done to the PMBUS_CNTRL pin if it will be used to enable the rails? Should it be pulled down to ground (using 1M resistor) or pulled up to 3.3V (using 10K) or both?

 

Thanks,

Binayak

  • 0
    TI__Mastermind 24075 points

    Hi Bianyak, 

    1. It is a system requirement whether or not Temp function is needed. 

    2. If Temp function is not needed, pull the pin down. I don't think you need to disable any PMBus command. 

    3. VID pin is input pin. Pulling up unused pin prevent the pin being damaged by noise. 

    4. If MBus_CNTRL pin is used to turn on/off rail, pull the pin high to turn on the rail and pull the pin low to turn off rail. 

    Thanks

    Qian

  • 0 in reply to Qian Chen
    Expert 1520 points

    Hi Qian,

    Thanks for your help. Just few followup doubts to your advice:

    2. I'm planning to pull down all TEMP pins to ground through one 10K resistor. Is it ok?

    3. Do I need to pull up all the unused VID pins or only VIDS pin as shown in the datasheet?

    4. To use the PMBUS_CNTRL pin as enable/disable pin for the rails, I'm planning to put the resistors as follows in the connector side. 

           

          Are the resistor values fine?

     

    Thanks and Regards,

    Binayak

     

  • 0 in reply to Binayak Shrestha88
    TI__Mastermind 24075 points

    HI Binayak,

    2. It is fine. 

    3. I would suggest to pull up all the unused VID pins via resistor. 

    4. The resistor values looks fine. 

    Thanks

    Qian