• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 33 subscribers
  • Views 1087 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.

ULN2004A: Semiconductor failure in automotive application

Sebastian Alves
Prodigy 30 points
Part Number: ULN2004A

We use the ULN2004AN (DIP) as a relay driver, in automotive application, so that the working voltages never exceed 14V / 15V, we attach the electrical circuit of the application, which we have been manufacturing for years. You may notice that the incoming signals are from the vehicle's lights.


The problem we have for some time, is that some ULN2004AN burn for no apparent cause, since they work well, and then "stick" some outputs and the tablet has burn, left unused outputs and other times are activated more than one output both. The consumption per output is approximately 30mA per relay.

You would need to know clearly if it is possible to have voltage with a input voltage of 14V on the ULN2004AN, since the input resistance uses the integrated itself.

We used more than 1500 ones. annually of the ULN2004AN, and those that failed are about 30/40 units but ALWAYS after having worked well previously. Will it be within the estimated volume margin of failure?


I appreciate your help with this problem.

Greetings from Argentina.

  • 0
    TI__Genius 10855 points
    Hi Sebastian,

    I'm glad to help. We need some more information about the devices that fail. How long before the ULN2004A starts failing? Do they always fail after a specific test, or just during normal operation?

    I'm not sure I understand "stick some outputs and the tablet has burn, left unused outputs and other times are activated more than one output both"
    Are you saying that some output channels are activated even when they aren't being used? You can tie the channels that are not being used to GND.

    If the input voltage is kept around 14/15V and each output is pulling only 30mA, the device should be working fine. Can we have a copy of the design schematic?

    Thank you,
    Arthur Huang
  • 0 in reply to Alpha H
    Prodigy 30 points

    Hello Arthur, I appreciate your quick response on the problem we are having, as soon as possible we help you to bring information about the application, and also the electrical diagram that we are using several years ago.

    With regard to the failure, when we manufacture the equipment, all are tested, and never failed in the factory.

    The failure occurs in the client as follows:

    They install the equipment, they test it, and in a random way, it can fail to the second test or later. We do not know what is due, and the failure occurs in a similar way every time when we send the equipment to repair.

    But to advance a little, I commented that if the inputs in principle, do not exceed 14 / 15V, since they are signals of the vehicle's lights (nominal voltage 13.8V, with the alternator charging), and the outputs of the ULN2004AN activate some relays of general use, whose coil is 12V 30mA of average consumption.

    I consult you, how do I attach the electrical diagram? 

    (I apologize for the translation, I try to be as clear as possible, the ideal is to attach an image or pdf to indicate the faults)

    From already thank you very much,

    Regards, Sebastian Gamba Alves

  • 0 in reply to Sebastian Alves
    TI__Genius 10855 points
    Hi Sebastian,

    You can send the electrical diagram to me at a-huang@ti.com. I can take a look at it and check what's wrong. 14/15V and 30mA looks fine, there shouldn't be an issue from that.

    Can you describe how the failure occurs? You mention that it occurs in a similar way every time, I would like to learn more on the failure.

    Don't worry about translation, I can understand you! Feel free to send me an email and I can look at the schematic.

    Thanks,
    Arthur Huang