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SN74AHC1G09: junction-to-case thermal resistance value, and the max junction temperature of the component

Shuqin Yuen
Prodigy 30 points
Part Number: SN74AHC1G09

What is the junction-to-case thermal resistance value, and the max junction temperature of the component?

  • 0
    TI__Guru* 96782 points
    Hi Shuqin,
    The max junction temperature of all standard logic devices is 150C -- there's an FAQ on this topic here: e2e.ti.com/.../716186

    For the junction-to-case thermal resistance, I will have to submit a request to our internal thermal modelling team. It will take up to two weeks to get the results.

    Out of curiosity, why do you need this value? The AHC1G09 isn't going to be able to sink enough power to have any sizable temperature increase (at least not before you damage it)... is there some special use case that I don't know about?
  • 0 in reply to Emrys Maier
    TI__Guru* 96782 points

    Hey Shuqin,

    I didn't notice when I posted last, but you didn't provide a package.  

    I found 2 packages in our thermal database already:

    Package 

    Package Rθjc(top)
    DCK 92.7 °C/W
    DBV 160.3 °C/W

    Just FYI, if this device is being operated at 10 MHz, 5.5V, driving a heavy load (70pF), the power consumption would be:

    P_static(max) = V_CC * I_CC(max) = 5.5 * 20uA = 110uW

    P_dynamic = (1/2) * (C_L + C_PD) * F * V_CC^2 = 0.5 * (70+5pF) * 10MHz * 5.5^2 = 11.34 mW

    The 1/2 comes from the device being open-drain. There is no positive side driver, so the power is half that a normal CMOS driver would have.

    So, the expected temperature increase in open air (using  RθJA = 252 C/W) would be 0.01134 * 252 = 2.86 C .... which really isn't much. Like I said - this isn't a power delivery device.