# Thermal resistance psi jt ΨJT of ADP5062

There is the theta JA and JC on your datasheet table-5.

Do you have the way for calculation of ΨJT?

Technical note or application note?

I could not find it in your web pages well.

Thanks Kaos

When I get the update, then I will put it here again, thanks again, Kaos.

• Hi Allustrisimo,

After know psi-JT, customer would calculate his TJ.

Customer's purpose:
After bring the TJ(die junction temp)=die temp by calculation,
customer would like to confirm that his aplication have been driven by more than 125C(max Operating Junction Temperature Range).

From your info, customer cannot know the TJ(die temperature).
(cannot take the temperature at internal of die )

Customer can bring the PD and TD.
PD = the add-voltage X comsumption current
TD = can measure the package surface temp
but cannot measure the die temperatute.

So after get your psi-JT, custoer will calculate die temperature(JT).

How should we fix this?

Thanks Kaos

• Thank you Alex

Thank you for your kindly support !!! Kaos

• Hi Alex,

I just got the reply from our customer.

Simply he say,
Do you have the value of psi JT of ADP5062 or not?

Your answer TA and theta-JA come from air, so there is much error.
And TC and theta-JC are difficult to measure due to there is thr under of package as for TC.

Thanks Kaos

• Hi Kaos,

The ADP5062 data sheet does not provide value for psi-JT, but only theta-JA and theta-JC. If the customer wants to calculate the junction temperature (JT), he may use the formula stated in the equation 5 on page 39/44 of the data sheet which uses the given value for theta-JA or equation 6 if he wants to use theta-JC.

Since theta-JA and theta-JC are given, you can use these formula below to calculate the junction temperature.

TJ = TA + (PD × θJA) or  TJ = TC + (PD × θJC)

If you have any concerns, please let me know.

Thanks,

Alex