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Please provide thermal data for

EP53F8QI and EN6347QA as I need to verify that my design is below a max junction for 85C in vacuum.

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Hello Tim,

You can calculate the junction temp based on the Theta_JA parameter and the expected PLoss.

As an example For EN6347QA: Theta_JA=30C/W (Please check the datasheet page 5)

- Assuming your Vin=5, Vout=3.3 and Iload=4A
- Eff with that input output setting will be 92% (Please check the datasheet)
- Pout= Vout*Iload= 13.2W
- Pin=Pout/eff=14.35W
- So PLoss= Pin-Pout=1.148W
- Delta_T= Theta_JA* PLoss = 35C
- So if we assume the ambient temp (TA)= 25
- Then the T_Junction = TA+ Delta_T = 60C

I hope that example is clear on how to calculate the expected junction temp.

Thanks,

Mostafa

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Hi Mostafa,

Yes I know how to calculate the junction from Theta_JA. However, this is not very helpful as I need to measurethe junction when the chip is in vacuum and here the Theta_JA is not any good. I need to know the junction to top case so I can measure the top case temperature and the calculate the junction

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Hello Tim,

Ok, got your point.

Here is Theta_J-TC( junction to top case):

- For Ep53F8QI =47°C/W
- For EN6347QA = 25°C/W

Thanks,

Mostafa

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