[IBIS] Determining correct Junction temperature for IBIS models

IBIS experts,

I am in the midst of creating numerous IBIS models for a wide variety of products. The issue that has come up is the selection of the proper junction temperature values for my 3 corners.

Given that the specified temperature for a device is -40 C to 85C.

Corner supplies are 4.5V, 5V, and 5.5V.

The package theta-ja 100 C/W.

The nominal room temperature quiescent power dissipation at 5V power supply voltage is 50 mW. theta-ja * 50mW = 5C

The nominal room temperature operating power dissipation at 5V power supply voltage is 100 mW. theta-ja * 100mW = 10C

The nominal cold power quiescent dissipation (@ -40C, 5V supply) is 40mW. theta-ja * 40mW = 4C

The nominal cold power operating dissipation (@ -40C, 5V supply) is 80mW. theta-ja * 80mW = 8C

The nominal hot power quiescent dissipation (@ 85C, 5V supply) is 60mW. theta-ja * 60mW = 6C

The nominal hot power operating dissipation (@ 85C, 5V supply) is 120mW. theta-ja * 120mW = 12C

Which option is correct?

Option 1: Create IBIS model with

-40C, 25C, and 85C temperatures

Option 2: Calculate nominal quiescent room temperature power dissipation and multiply that times the package theta-ja. Add this delta temperature to all three temperatures. In this case the IBIS temperatures are

-35C, 30C, and 90C.

Option 3: Calculate nominal quiescent room temperature power dissipation and multiply that times the package theta-ja. Add this delta temperature to the two higher temperatures. In this case the IBIS temperatures are

-40C, 30C, and 90C.

Option 4: Calculate the quiescent power dissipation at all temperatures and multiply that times theta-ja. The IBIS temperatures in this case would be

-36C, 30C, and 91C.

Option 5: Apply the mathematics of quiescent power and theta-ja to the two higher temperatures. In this case the IBIS temperatures are

-40C, 30C, and 91C.

Option 7: Apply Option 2 to operating power dissipation conditions. In this case the IBIS temperatures are

-30C, 35C, and 95C.

Option 8: Apply Option 3 to operating power dissipation conditions. In this case the IBIS temperatures are

-40C, 35C, and 95C.

Option 9: Apply Option 4 to operating power dissipation conditions. In this case the IBIS temperatures are

-32C, 35C, and 97C.

Option 10: Apply Option 5 to operating power dissipation conditions. In this case the IBIS temperatures are

-40C, 35C, and 97C.

Option 11: Add 15 deg C to -40C, 25C, and 85C or create IBIS model with

-25C, 40C, and 100C.

Option 12: Add 15 deg C to 25C and 85C or create IBIS model with

-40C, 40C, and 100C.

Bonnie

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