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SN65LVDT41: Need Recommended Operating Junction Temperature Limit and Package Thermal Resistances: Theta JC and Theta JB

Part Number: SN65LVDT41
  1. SN65LVDT41PW

    • ThetaJC and ThetaJB are not provided in the datasheet, can you provide those package thermal resistances for this component?

    • What is the recommended operating Tj (Junction Temperature)?

      1. Part is rated for -40 °C to +85 °C ambient operation

      2. Using rated power dissipation of 774 mW (for Ta < 25 °C) and ThetaJA of 161.29 °C/W at Ta = 25 °C, one could infer an operating Tj limit of 150 °C

      3. Our usage condition results in an estimated Tj = 120 °C

      4. Can I run this part at Tj = 120 °C and be assured of full functionality?

        • If not, do you offer a part that will provide this functionality with a higher Recommended Operating Junction Temperature?

  • Hello,

    The Thermal parameters for this device are not readily available. I have submitted a request to generate them and will get back to you when it is ready (in a few days).

  • Hello,

    Here are the thermal parameters for this device:
    Result- Theta JA-High K: 86.9 ᵒC/W
    Result-Theta JC, top: 28.4 ᵒC/W
    Result-Theta JB : 38.2 ᵒC/W
    Result- Psi JT : 1.4 ᵒC/W
    Result- Psi JB : 37.8 ᵒC/W

  • Thank you.

    I also need the Recommended Operating Junction Temperature upper limit.

    A Recommended Operating Temperature range is only provided for Free-Air Temperature, not for Junction Temperature.

    From the rated powers and operating factor  in the Package Dissipation Ratings table under Absolute Maximum Ratings, I could infer a Junction temperature limit of 150 ᵒC, but that is under "Absolute Maximum Ratings" section... per note (1) Absolute Maximum Ratings are damage limits, not limits up to which functionality is assured (see attached excerpt from datasheet).

    I need to know up to what junction temperature is functionality is assured.

    The Theta JA you provided of 86.9 ᵒC/W is not consistent with the Theta JA provided in the datasheet of 161.3 ᵒC/W.

    Which Theta JA should be I be using?

    (The Theta JA is not provided directly in the datasheet, rather it is provided as the "Operating Factor above Ta = 25 ᵒC" of 6.2mW/ᵒC ... the inverse of which is Theta JA (ᵒC/W) see attached excerpt from datasheet).

  • Hi Dave,

    Sorry for the late reply. Regarding the calculations, the numbers in datasheet are for the package and cannot be used to calculate junction temperature. Please use the numbers I have posted. Using device RθJA = 86.9 ᵒC/W, and device max ICC of 35mA, PD max = 35mA x 3.6V = 126mW. For ambient temp of 85 ᵒC, a rough (not accurate) estimate of the expected junction temp would be: 85 ᵒC + 86.9 * .126 = 96 ᵒC .
    For the max operating junction temperature that the device can tolerate, I don't have a definitive answer. I believe it is 125C or more, but I am still trying to confirm.

  • Hi Dave,

    The abs max junction temp is 150 C. The part should function properly at operating junction temp of 125C or lower.