TPS54318 / Thermal Resistance Performance

Ryuji

Guru 20090 points

Other Parts Discussed in Thread: TPS54318, TPS54618

Hello,

TPS54318 θJctop = 1°C/W
TPS54618 θJctop = 46.09°C/W

Both package is QFN 3mm x 3mm.

In my understanding, thermal resistance in similar package has similar thermal resistance performance.

However there is big difference in both thermal resistance.

Are these value correct ?

Best Regards,

Ryuji Asaka

over 11 years ago

0 JohnTucker over 11 years ago

TI__Guru**** 191445 points

That TPS54318 Theta JT number is actually Psi JT not Theta JT. If you compare the Psi JT numbers it is 1 C/W for TPS54318 and 0.9 C/W for TPS54618. TPS54618 has the latest thermal modeling numbers, only Theta JA is based on the same conditions as the TPS54318 thermal data.

0 Ryuji over 11 years ago in reply to JohnTucker

Guru 20090 points

Hello John san,

Thank you for your prompt response.

I found the 0.69 C/W only for TPS54618 Psi JT.

Is this correct ?

Could I have the Theta Jc of the TPS54318 ?

Best Regards,

Ryuji Asaka

0 JohnTucker over 11 years ago in reply to Ryuji

TI__Guru**** 191445 points

I show Psi JT to be 0.9 C/W for TPS54618. I can look tomorrow if there are updated parameters for TPS54318.






yJT Junction-to-top characterization parameter	0.9

0 Ryuji over 11 years ago in reply to JohnTucker

Guru 20090 points

Hello John san,

Thank you. I wait your reply.

I can find the below thermal information from the datasheet.

Best Regards,

Ryuji Asaka

0 JohnTucker over 11 years ago in reply to Ryuji

TI__Guru**** 191445 points

The datasheet I have is different. It looks like the thermal parameters are revised, so 0.69 C/W is correct.

0 Ryuji over 11 years ago in reply to JohnTucker

Guru 20090 points

Hi John san,

OK. I understood.

I wait your reply about the theta Jc of TPS54318.

Best Regards,
Ryuji Asaka

0 JohnTucker over 11 years ago in reply to Ryuji

TI__Guru**** 191445 points

From the thermal modeling site:

description	TPS54318RTE
Result- Theta JA-High K (standard datasheet value)	49.9
Result-Theta JC, top (standard datasheet value)	52.4
Result-Theta JB (standard datasheet value)	22.8
Result- Psi JT (standard datasheet value)	0.8
Result- Psi JB (standard datasheet value)	22.8
Result-Theta JC, bottom (standard datasheet value)	8.1
Modelling Assumptions	C/W

0 Ryuji over 11 years ago in reply to JohnTucker

Guru 20090 points

Thank you very much John san.

Best Regards,

Ryuji Asaka

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TPS54318 / Thermal Resistance Performance