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Reliability data of ULN2803A

Mohd Zulhadi Zainal Abidin
Prodigy 80 points
Other Parts Discussed in Thread: TPL9202, TPL9201

Hallo,

Could TI provide me a realibility data for the ULN2803A (MTTF,FIT,usage temp,switchcycling, ect ).I would like to use the darlington array for sinking 250mA each channel for an extended period of time. The system need to be realiable enough for >5 years.

Thank you for your help

  • 0
    TI__Guru**** 152046 points

     Mohd,

    That data is available on the product page in the Quality & Environmental Data section.
    http://www.ti.com/product/ULN2803A

    The worst case VCE(SAT) is 1.4V (per data sheet). With 250mA, that is 350mW per channel.
    With a package TJA of 73C/W, the temperature rise per output is 0.35W*73C/W = 26C.
    At TA=25C 4 channels would have a TJ around 130C (based on MAX Vsat).

    Connecting two channels together would give 4 channels per IC and should be good for 5 years if the ambient temperature is not too high. Now the math is 125mA for a worst VSAT of 1.15V. A total current of 250mA * 4 gives 1.15 watt total per IC. That is a 84C junction temperature rise. Actual results will be better because VSAT with 125mA output will drop with temperature.

    If ambient temperature is too high then two TPL9201 or TPL9202 will be better because they have a lower saturation voltage (less power dispassion) and they have a heat sink tab on the bottom of the IC (PWP package).

  • 0 in reply to Ron Michallick
    Prodigy 80 points

    Hallo Ron,

    Thank you for the link for the FIT value.

    You are right,  temperature is a issue. I will redesign the system so that the chips does't need to dissipate so much current.

    Anyway thanks again