LM2676: Power dissipation equation

Vincent Chen64988

Part Number: LM2676
Other Parts Discussed in Thread: LM2576,

Hi Arief,

In the LM2576 and LM2676 datasheet, customer found a lot of difference on the parameter of RθJC(top). Since both parts have similar function and I don't see any heat sink applied on LM2676 datasheet. Customer just wondering is it a typo?

LM2576

LM2676

Customer will do thermal calculation before evaluation, he don't want to calculate out wrong data. (there is a typo on this chart, LM2678)

Best Regard,

Vincent

over 6 years ago

0 Timothy Hegarty over 6 years ago

TI__Guru 73522 points

Hi Vincent,

I forwarded this to the product expert.

Regards,
Tim

0 Frank De Stasi over 6 years ago in reply to Timothy Hegarty

TI__Guru 72545 points

The two devices are quite different, with different process and different die sizes, etc.
I would expect them to have different thermal performance.

0 Vincent Chen64988 over 6 years ago in reply to Frank De Stasi

TI__Expert 4480 points

Hi Frank,

There is another question from customer.

RθJA=RθJC+RθCA, right? Why RθJC is larger than RθJA?

Thanks very much.

Vincent Chen

0 Frank De Stasi over 6 years ago in reply to Vincent Chen64988

TI__Guru 72545 points

The value of thetaJA is measured under specific JDEC conditions and will usually be smaller than the thetaJC from

the top of the package, which is plastic. The attachement may make this a little more clear.

0333.spra953c.pdf

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LM2676: Power dissipation equation