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UCC27524: UCC27524 Pin2 discussion

TT_Chin
Expert 2025 points
Part Number: UCC27524

Hi

We have a product design UCC27524.

We use electric meter (diode position)to measure the pin2 voltage . See the picture as attached.

We can measure some components exist 0.8V and some components doen't exist any measurement voltage.

Do you have any idea about what the voltage value when I measure pin2(INA) to PIN3(GND) by diode position of electric meter?
Just mentioned, the measurement is static measurement on component itself, we don't apply any voltage to Pin6(VDD)of component.UCC27524_Pin2 measurement.docx

Sincerely,

Chin

  • 0
    TI__Genius 13445 points
    Hi Chin,

    Thanks for your interest in our part, my name is Mamadou Diallo, I will help address your concerns.

    How many devices have you tested? How many are showing the diode voltage? and how many are not showing? Are the devices out of the box or soldered off of a PCB board? In some cases, measurements errors may occur due to various reasons including false current injection, instrument calibration, existing voltage on device, etc...

    Based on 5 samples (very limited sample number), I am showing a diode 0.8V when Fluke +Terminal on pin 3 and Fluke -Terminal on pin 2 with stand alone devices right out of box, no supply on VDD pin.

    Regards,

    -Mamadou
  • 0 in reply to Mamadou Diallo
    Expert 2025 points

    Hi Mamadou,

    Thank you for your great support!

    We test 3474 pcs of device and 157 pcs are not showing the diode voltage. The result is measured the component soldered on PCB board.

    We soldered off the device from PCB board and measured 10 pcs of 157 quantity again and found if the device is hot (we measured the device immediately when soldered off the device from PCB) it is showing the diode voltage (0.8V) but after the deive cool down, it is not showing diode voltage.

    The inner circuit should be has a  ESD diode that we measured 0.8V, is it correct? (see attaced)

    Also if the device are not showing diode voltage, they should be the failure devices and we need return to TI for analysis?

    INA.docx

    Sincerely,

    Chin

  • 0 in reply to TT_Chin
    TI__Genius 13445 points
    Hi Chin,

    Thanks for the additional information.

    I can confirm that yes there are ESD diodes connecting inputs INA(pin 2), INB(pin 4) to GND(pin 3), so there should be a 0.8V from in your measurement.

    Are you observing the same results when measuring between Pin 4 (INB) and Pin 3 (GND) as well or just Pin 2 (INA)? Whether hot or cold?

    Thanks.
  • 0 in reply to Mamadou Diallo
    Expert 2025 points

    Hi Mamadou,

    Yes, some devives obseved the same results in measure Pin4 (INB) and Pin3 (GND) as well. The symptom are also the same as measured Pin2(INA) in hot/cold test.

    Attached is the mark of devices that we bought from TI.

    By the way, if either Pin2(INA) or Pin4 (INB) can be measured the value of 0.8V then we can say the device is okay?

    Or need both Pin2(INA) and Pin4 (INB) have to observe 0.8V?

    Also if it can observe 0.8V in hot condition, we also can say it is good device?

    We are thinkg how to process it, return to TI or ignor the issue? (if the issue just impact ESD function)

    Thanks!

    Sincerely,

    Chin

    UCC27524 mark.docx

  • 0 in reply to TT_Chin
    TI__Genius 13445 points
    Hi Chin,

    The 0.8V simply indicates the limited built-in ESD protection of the device therefore observing the 0.8V at the inputs alone whether at cold or hot temperature may not confirm whether it is good/bad device.

    You may solder a device with the 0.8V reading and a separate device without the ESD diode reading and compare the performance of both in an application. I would suspect similar performance from both devices assuming neither devices were subject to electrostatic discharge as the ESD diode is a protection feature.

    First I would advise to compare a pair of both sets of devices in your application to see if you observe any difference in performance before making a decision.

    Please let us know if you have further applications concerns.

    Regards,

    -Mamadou
  • 0 in reply to Mamadou Diallo
    Expert 2025 points
    Hi Mamadou,
    Okay, I will receive the device from our factory tomorrow and update the compared performance to you.
    Thanks!

    Sincerely,
    Chin
  • 0 in reply to TT_Chin
    TI__Genius 13445 points
    Hi Chin,

    Sounds good.

    In the meantime, I will mark this thread as resolved.

    Please let us know if you further application questions by posting on this thread.

    Regards,

    -Mamadou