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Original question:

ULN2003A: ULN2003ADR Failure issue

ULN2003A: ULN2003ADR

Roberto Calderon1
Prodigy 50 points
Part Number: ULN2003A

Hi I am having a similar problem. When an output fails it is shorted to ground. Is there a way to protect the outputs? Not all output will fail on the IC. I have accidentally at times connected the output to 24vdc and the output will short to ground. some times the out put is just driving a diode on a 5vDC line and the diode will remain on, which means that the output is shorted to ground. 

  • 0
    TI__Genius 13760 points

    Hi Robert,

    Welcome to E2E!

    When an output fails it is usually because the channel is being stressed over the specifications. This is usually caused by thermal events caused by power dissipation which is directly affected by the current going through the channels. I have a few questions about your problem in order to find a solution.

    1. Do you notice the output of the device to fail when turning the channel of the device on or does the channel of the device fail over time?

    2. How much current is being driven through each channel?

    3. Are all the channels being used at the same time?

    4. Would you happen to know the duty cycle of your application?

    5. Would you be able to provide a schematic of your application?

    Best regards,

    Andy Robles

  • 0 in reply to Andy Robles
    Prodigy 50 points

     

    Andy Robles replied to ULN2003A: ULN2003ADR.

    Hi Robert,

    Welcome to E2E!

    When an output fails it is usually because the channel is being stressed over the specifications. This is usually caused by thermal events caused by power dissipation which is directly affected by the current going through the channels. I have a few questions about your problem in order to find a solution.

    1. Do you notice the output of the device to fail when turning the channel of the device on or does the channel of the device fail over time? I have used the IC to drive external LEDs, and Coils. The failures happen very randomly. Unless I accidentally connect the output to a 24VDC line.

    2. How much current is being driven through each channel? Coils, 250mA. I usually have to channels driving the coils. The LEDs are 10mA using one channel.

    3. Are all the channels being used at the same time? NO

    4. Would you happen to know the duty cycle of your application? The LEDs are on for up to 10 minutes, and the coils are energized for 2 minutes.

    5. Would you be able to provide a schematic of your application? Attached 3 uses if the IC.

    The fuses are 200mA resettable.

    Best regards,

    Andy Robles

     

  • 0 in reply to Roberto Calderon1
    TI__Genius 13760 points

    Hi Roberto,

    Given that the device does fail over time means that the channels are being stressed over time and slowly deplete the lifetime of the device.

    Given that the LED's aren't pulling nearly enough current to reach the max threshold of the device do you see the device failing mostly with the coils with the LED's or is it truly random?

    Furthermore, are your coils and LED's exposed to any ESD events caused by the environment?

    Best regards,

    Andy Robles

  • 0 in reply to Andy Robles
    Prodigy 50 points

    Given that the LED's aren't pulling nearly enough current to reach the max threshold of the device do you see the device failing mostly with the coils with the LED's or is it truly random?random

    Furthermore, are your coils and LED's exposed to any ESD events caused by the environment?Only +24v at the output. Its open drain. So it shouldn't damage the output right?

  • 0 in reply to Roberto Calderon1
    TI__Genius 13760 points

    Hi Robert,

    Judging by the schematic configuration of the ULN2003 device the application should be working as expected. As long as none of the absolute maximum specifications are exceeded then the device should maintain normal functionality.

    The only thing that I can think of at this point is that something else on the board might be failing and damaging the ULN2003 over time. Have you tried switching a faulty ULN2003 for a good ULN20003 to ensure that the fail is within the device?

    Best regards,

    Andy Robles

  • 0 in reply to Andy Robles
    Prodigy 50 points

    Hi Andy,

    The only thing that I can think of at this point is that something else on the board might be failing and damaging the ULN2003 over time. Have you tried switching a faulty ULN2003 for a good ULN20003 to ensure that the fail is within the device? Yes. The channels work normal after replacing the damaged ULN2003. 

    I have seen the same problem on both leaded and SMT parts.  

    Thanks, 

    Roberto Calderon

  • 0 in reply to Roberto Calderon1
    TI__Genius 13760 points

    Hi Roberto,

    Judging by the implementation of the device it doesn't seem like they are being stressed beyond the datasheet specifications by the application.

    The only other thing that could be damaging the parts would physical stress or the age of the devices. Are these devices exposed and could come in contact with anything? How long do the devices usually last before you see the failures?

    Best regards,

    Andy Robles