• State TI Thinks Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 248 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.

LMZ14203H: LMZ14203HTZX/NOPB

Asif Khan1
Prodigy 70 points
Part Number: LMZ14203H

I am using LMZ14203H as a 24V regulator in my application. The part blows and shorts input to output. Once I replace the part it works OK. This has happened 5 times, in the past week. 

Asif Khan

310-984-3613

  • 0
    TI__Guru 50120 points

    Hi Asif,

    Please provide full schematic and PCB layout for review. 

    Also is the failure observed at time zero or some time after stable powerup?'

    How stable is your input voltage; as in, will the input voltage ever surge pass the recommended input maximum rating?

    Regards,

    Jimmy

  • 0 in reply to Jimmy Hua
    Prodigy 70 points

    Hi,

    The failure is observed after power up.pwr_pcb_rev19.pdfGerber_PWR_BRD_16out.zip

  • 0 in reply to Asif Khan1
    TI__Guru 50120 points

    I believe i had provided my initial schematic review to a mmFAE that covers Sakura. If this was not circulated to you yet, I have also attached the review below. 

    Please see attached ppt for my comments and inquiries from just the schematic .

    Sakura Preliminary Schematic Review.pptx

    In addition to this, can you comment on the following below:

    1. Do they have any waveforms of on the input voltage rail starting up? Any chance there is overshoot, when looking across the VIN and GND pins at the device?
    2. Is there any additional bulk cap on the 36V or is it just the 10uF ceramic on the input of the device?

    I will be reviewing the PCB layout which will take some time. I hope to provide further feedback by the end of this week.

  • 0 in reply to Jimmy Hua
    Prodigy 70 points

    Yes, I’ve checked for the shorts that you mentioned below. The point is that the board works OK most of the time and then I had the failures of the 24V Reg. On the failed boards, after I replace LMZ14203H, they work OK. 

    I have one of the failed module. If you can send me the address, RMA#, etc., I can send it to you.

    Thanks,

    Asif Khan

  • 0 in reply to Asif Khan1
    TI__Guru 50120 points

    On the failed boards that have been replaced with the LMZ14203H and are now OK, have they ever failed again after multiple power up/ standard operation?

    Looking at the schematic again, the 24V output rail from the LMZ14203H is powering multiple A4950 motor drivers with no bulk capacitor. However, the datasheet for the A4950 motor driver recommend typical 100uF electrolytic capacitor placed close to the load supply pin VBB. This will help reduce transient voltage spikes.

    Again what I want to confirm is if the input or the output voltages can spike above the typical operational conditions. 

    Can you add the 100uF electrolytic bulk caps to the VBB of each A4950 motor driver as recommended in that datasheet? 

    Also is it possible that either the 36V input from the AC/DC adapter can surge above the input voltage. If that is the case then add an electrolytic bulk cap on the input of the LMZ14203H input pin. 

    Regards,

    Jimmy 

  • 0 in reply to Jimmy Hua
    Prodigy 70 points

    Hi,

        Thanks for the support. I've added a 100uF, 50V cap to each of  A4950 and also to the input of LMZ14203H as shown in the attached schematic. I'll run some tests under load & if everything is OK, I'll close the case.

    Again, thanks for your support.

    Asif Khan

  • 0 in reply to Asif Khan1
    TI__Guru 50120 points

    Please keep me updated on this and let me know if you have any further questions.