SN74AHCT1G125: ψjt mesurement condition

Kuramochi Tadahiko

Guru 28715 points

Part Number: SN74AHCT1G125

Hi,

I think that ψjt of DCK package is so low compared to other devices.

How condition was this measured?

Best Regards,

Kuramochi

over 3 years ago

0 Chad Crosby over 3 years ago

TI__Expert 6680 points

Hi Kuramochi,

I'll have to check on this - on first glance I think you're right, this looks like a typo.

In the mean time, I'll see if the thermal modelling team can redo this sim.

Thanks!

Chad Crosby

0 Kuramochi Tadahiko over 3 years ago in reply to Chad Crosby

Guru 28715 points

Hi Chad-san,

How is this situation?

If you have checked that this is the typo, please let me know.

Best Regards,

Kuramochi

0 Rami Mooti1 over 3 years ago in reply to Kuramochi Tadahiko

TI__Mastermind 23793 points

Hello Kuramochi,
Typically we'll need to allow 1-2 weeks for the thermal modeling team to complete one of these requests. We'll keep you posted on the results as soon as we know.

In the meantime, to give more insight on how these values are measured, here's an app report that provides more information:

https://www.ti.com/lit/slua844b

Section 4 talks about the setup and table 2 expands more on the calculation of the thermal resistance.

Thanks,
Rami Mooti

0 Kuramochi Tadahiko over 3 years ago in reply to Rami Mooti1

Guru 28715 points

Hi Rami-san,

How is this situation?

Best Regards,

Kuramochi

0 Rami Mooti1 over 3 years ago in reply to Kuramochi Tadahiko

TI__Mastermind 23793 points

Hello Kuramochi,

The modeling team hasn't completed the request yet. Sorry for the delay. Typically I would have expected the results to already be completed by now, but it seems they're a little backed up with request. I'm hopeful this week we will have the results, though. I will keep you updated as I learn more information.

Thanks,
Rami

0 Kuramochi Tadahiko over 2 years ago in reply to Rami Mooti1

Guru 28715 points

Hi,

How is this situation?

Best Regards,

Kuramochi

+1 Rami Mooti1 over 2 years ago in reply to Kuramochi Tadahiko

TI__Mastermind 23793 points

Kuramochi,

So sorry for the delay. This took a bit longer than usual but the results came in this morning as follows :

Theta JA-High K:	233.2
Theta JC, top:	150.0
Theta JB:	122.4
Psi JT:	43.5
Psi JB:	121.9
Theta JC, bottom:	n/a

Psi JT seems to be significantly higher so good find on that. These values vary quite a bit from the datasheet probably due to a routine datasheet update. TI now uses an improved thermal model to calculate thermal impedance values, and these new thermal values may differ slightly from the existing values in the datasheet. The materials used, manufacturing process, and device core have not changed, so electrical performance will remain the same. Only the thermal characteristics of the datasheet will see changes. I'll log this in to be change.

Thanks,
Rami

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SN74AHCT1G125: ψjt mesurement condition