uA78L05CPK Power Tab Is It Isolated or attached circuitry inside the regulator and What is JESD-51-7

W HS

1) I am designing in a UA78L05CPK. This linear regulator has a bit of extra metal on it to reduce Theta-ja. I need to know if this metal is attached to any circuitry inside of the regulator. We plan to put some copper under this metal tab and drop vias from this copper to an internal power or ground plane.

2) JESD-51-7 is a test board used to establish the Theta-JA rating of this regulator. Does anyone know what land pattern was used on the JESD-51-7 Low K board in conjunction with this regulator. Unfortunately, the application information on the TI data sheet is very sparse regarding copper area and Theta-JA.

over 11 years ago

0 W HS over 11 years ago

Prodigy 170 points

I have found that the metal tab is connected to common by looking at the physical print for the packaging. With regard to Theta-JA, JESD-51-7 may help TI quote a theta j-a that removes the embellishments that competing marketing departments make, but it is of little use to circuit designer. A competitors data sheet gives a theta j-a with a 6sq cm thermal land.

0 Ron Michallick over 11 years ago

TI__Guru**** 164976 points

W HS,

I asked the thermal modeling team and I am expecting an answer soon.

0 Ron Michallick over 11 years ago in reply to Ron Michallick

TI__Guru**** 164976 points

WHS,

I have the answer from thermal modeling team.

The PK is modeled with just a lead-width copper trace coming off of the fat lead. No other special thermal plane or enhancements were used.

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uA78L05CPK Power Tab Is It Isolated or attached circuitry inside the regulator and What is JESD-51-7