0

20

40

60

80

100

0

1

2

3

4

5

6

AMBIENT TEMPERATURE (°C)

LM2941S (TO-263)

JA= 35°C/W

JA= 30°C/W

JA= 26°C/W

JA= 24°C/W

LM2941, LM2941C

SNVS770G – JUNE 1999 – REVISED APRIL 2013

www.ti.com

For the LM2941S in the KTT TO-263 package, the junction-to-case thermal rating,

CASE is defined as the bottom of the package at the center of the TAB area. The junction-to-ambient thermal

performance for the LM2941S in the TO-263 package, using the JEDEC JESD51 standards is summarized in the

following table:

Board

Thermal

Type

Vias

JEDEC

2-Layer

None

1°C/W

73°C/W

JESD 51-3

1

1°C/W

35°C/W

JEDEC

2

1°C/W

30°C/W

4-Layer

4

1°C/W

26°C/W

JESD 51-7

8

1°C/W

24°C/W

WSON Mounting

The NGN (Pullback) 8-Lead WSON package requires specific mounting techniques which are detailed in

Application Note 1187 (literature number SNOA401). Referring to the section PCB Design Recommendations

in AN-1187 (Page 5), it should be noted that the pad style which should be used with the WSON package is the

NSMD (non-solder mask defined) type.

The thermal dissipation of the WSON package is directly related to the printed circuit board construction and the

amount of additional copper area connected to the DAP.

The DAP (exposed pad) on the bottom of the WSON package is connected to the die substrate via a conductive

die attach adhesive, and to device pin 2 and pin 7. As such, it is strongly recommend that the DAP area be

connected copper area directly under the DAP that is extended into the ground plane via multiple thermal vias.

Alternately, but not recommended, the DAP area may be left floating (i.e. no direct electrical connection). The

DAP area must not be connected to any potential other than ground.

10

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