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SN74LV07A: Max junction Temperature

owen lin
Prodigy 10 points
Part Number: SN74LV07A

Dear Team,

 

When the measured case temperature of SN74LV07A becomes 85-degree Celsius, will the IC gets damaged?

 

Thank you.

 

  • 0
    TI__Guru* 96977 points

    Hello Owen,

    No, 85C case temperature will not damage the device, however if you are seeing a large temperature increase in the device in normal operation, I would recommend reviewing your design to see if it is violating any of the maximum ratings of the device.  This device does not typically heat up that much (assuming a 25C ambient temp with 85C case temp).

    This device is rated to operate up to 125C ambient temperature.  That would imply that the case and junction can exceed 125C.

    The maximum junction temperature for the device is 150C.

  • 0 in reply to Emrys Maier
    TI__Genius 11800 points
    Hello Emrys,

    Sorry we have follow up questions for this case.

    1. May I know if SN74LV07A total output current (sum of the 8-port) is 50mA? In the ds page 8, the Recommended Output Conditions says that 50mA total for the part?

    Recommended Output Conditions:
    – Load currents should not exceed 35 mA per output and 50 mA total for the part.

    2. To calculate the power consumed of this part, should I multiply Isink current and VOL and use the number to calculate with thermal resistance and ambient temperature? Could you show me an accurate way to calculate its power dissipation?

    Thank you.
    Regards,
    Ting
  • 0 in reply to Ting Ye
    TI__Guru* 96977 points

    Hi Ting,

    The maximum output current is clearly stated in the Absolute Maximum Ratings table.

    That's 50mA total for the device (since it only has 1 ground pin) and 35mA max per pin.

    Your power consumption calculation is correct for DC, however if you are using the datasheet's VOL values, you are calculating the absolute worst case rather than the typical power consumption.

    For this device, assuming an even split of current (35/8 = 4.375mA) and 5V operation, we can expect to see power consumption of 8*( 0.004375 * (0.55V*4mA/16mA) ) = 4.8125 mW.  This gives an expected temperature increase of 0.0041825 *  0.484 C (in the D package).  In other words - if operated within datasheet specs, the device shouldn't heat up.

    ***** Correction *****

    I accidentally used the 35 mA instead of 50 mA in my calculation. 50mA / 8 = 6.25mA, new Vol(max) = 0.55V * 6.25mA/16mA = 0.21484V.

    This gives an updated power consumption of 10.742 mW and a temp increase of 1.08 C.  Sorry about that.

    Note that this is only for DC operation.  If the device is switching, there will be added power consumption from switching as described in this document: CMOS Power Consumption and CPD Calculation