LMR38020: Which JEDEC environment and JEDEC thermal board are used for each thermal metric?

Kento Adachi

Part Number: LMR38020

Hello experts,

I'd like to confirm which JEDEC environment and JEDEC thermal board are used for each thermal metric in LMR38020. I drew the table below.

Could you check wthether my understanding is correct?

Thermal Metric	Measurement Environment	Board uesd for a measurement
ThetaJA	JESD51-2A	JESD51-7 High-k board with vias defined in JESD51-5
ThetaJA(Effective)	JESD51-2A	LMR38020 EVM board
ThetaJC(top)	JESD51-14	No board. Dierct connection with a heat sink or thermal grease is used between a DUT and a heat sink.
ThetaJB	JESD51-8	JESD51-7 High-k board
PsiJT	JESD51-2A	JESD51-7 High-k board with vias defined in JESD51-5
PsiJB	JESD51-2A	JESD51-7 High-k board with vias defined in JESD51-5
ThetaJC(bot)	JESD51-14	No board. Dierct connection with a heat sink or thermal grease is used between a DUT and a heat sink.

Regards,

Kento

over 1 year ago

+1 Marshall_Beck over 1 year ago

TI__Mastermind 35210 points

Hi Kento,

That seems to be right. I am not sure about JESD51-14 but if that is in the spec' we follow it. Only thing is there wasn't a defined measurement environment for the EVM measurement. The measurement done for that is a rough estimate based on measured case temperature rise for given dissipated power.

We follow JESD51-7 and use the high-k 2s2p board.

"These values were calculated in accordance with JESD 51-7, and simulated on a 4-layer JEDEC board. They do not represent the performance obtained in an actual application."

This is a good appnote on our thermal characterization (if you haven't seen it already)

https://www.ti.com/lit/an/spra953d/spra953d.pdf?ts=1713193179523&ref_url=https%253A%252F%252Fwww.ti.com%252Flit%252Fds%252Fsymlink%252Flmr38020.pdf%253Fts%253D1713193159588%2526ref_url%253Dhttps%25253A%25252F%25252Fwww.ti.com%25252Fproduct%25252FLMR38020

0 Kento Adachi over 1 year ago in reply to Marshall_Beck

TI__Expert 4365 points

Hello Marshall,

Thank you for your reply.

Marshall_Beck said:
Only thing is there wasn't a defined measurement environment for the EVM measurement.

So don't we use the measurement environment as shown in the figure below for the EVM measurement? I know the board is not compliant with JESD51, however I thought measurement environment was compliant with JESD51-2A.

Marshall_Beck said:
I am not sure about JESD51-14 but if that is in the spec' we follow it.

Could you check this point to a team which is in charge of thermal information? I've already read the document you mentioned above, and I found there was no description for JESD51-14. However, JESD51-14 defines how to measure ThetaJC, and I'd like to confirm TI's measurement is done by this measurement method.

Thanks,
Kento

0 Marshall_Beck over 1 year ago in reply to Kento Adachi

TI__Mastermind 35210 points

Hi Kento,

For the EVM measurement, we don't follow a defined spec.

I am going to confirm with our thermal modeling team on that table you provided.

0 Kento Adachi over 1 year ago in reply to Marshall_Beck

TI__Expert 4365 points

Hello Marshall,

Thank you for your confirmation.

Sorry for your inconvenience.

+1 Marshall_Beck over 1 year ago in reply to Kento Adachi

TI__Mastermind 35210 points

Hi Kento, quite alright. You had a real good question.

I confirmed with the modeling team that the table is correct (besides EVM) and we follow the specs mentioned as closely as possible.

0 Kento Adachi over 1 year ago in reply to Marshall_Beck

TI__Expert 4365 points

Hello Marshall,

I understood and clarified all of my questions!! Thank you for your cooperation.

Thanks,

Kento

0 Marshall_Beck over 1 year ago in reply to Kento Adachi

TI__Mastermind 35210 points

You are welcome, Kento.

I hope to talk to you again soon.

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LMR38020: Which JEDEC environment and JEDEC thermal board are used for each thermal metric?