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ULN2803A: ULN2803AWD

JITENDER KUMAR
Prodigy 40 points

Part Number: ULN2803A

Hello

I have query regarding source & sink current of ULN2803 IC at input pin side. I am interfacing this IC with LPC2138 Micro controller  having 4 mA souce & sink current( operating gat 3.3 V) . Please suggest input current requirement of this ICs.

SO that this IC can be interface with LPC2138 safely.

  • 0
    Prodigy 40 points

    As i Am interacting ULN2803 IC with LPC2138 MCU. Pins of Microcontroller goes into permanently  low level stage. Please suggest .

    LPC2138  ------------> ULN2802 IC

  • 0 in reply to JITENDER KUMAR
    TI__Genius 15750 points

    Hi Jitender,

    The current specification for the inputs of the ULN2803A is 0.93mA typical and 1.35mA max. My understanding is that the input current is preventing you from pulling up the voltage at the input terminals of the device. In general, is this amount of current capable of preventing you from pulling up these inputs?

    Thanks,

    Alek Kaknevicius

  • 0 in reply to Aleksandras_Kaknevicius
    Prodigy 40 points

    Hello

    LPC2138 Microcontroller has 4 mA source & sink current. As per your reply. ULN2803 has 0.93 mA requirement. SO lpc2138 can easily provide desired current as per requirement of iC without overloading.

    But I am not understanding why LPC2138 MCU pin goes to permanently low stage (i.e. fails) after using circuit in 1-2 months.

    I have upload circuit.

    Please suggest.

  • 0 in reply to JITENDER KUMAR
    TI__Genius 15750 points

    Hi Jitender,

    Apologies for the delay here. So just to be sure, the device works normally (switches on/off) for the first 1-2 months, but then after this time the IN1 pin can no longer be pulled high. Is this correct?

    If so, I have a few questions to help come up with a conclusion here: 

    1. Do you know how much current the ULN2003A is pulling when IN1 is brought high after it fails?
    2. Does swapping the ULN2003A unit with a replacement solve the issue?
    3. How high are the current loads on the outputs of the ULN2003A?

    Thanks,

    Alek Kaknevicius

  • 0 in reply to Aleksandras_Kaknevicius
    TI__Mastermind 32650 points

    Hi Jitender,

    Have you resolved your issue?

    I am going to close this thread for now but feel free to respond and we will resume support.