Datasheet

LP2986
SNVS137H –MARCH 1999–REVISED APRIL 2013 www.ti.com
WSON MOUNTING
The LDC08A (Pullback) 8-Lead WSON package requires specific mounting techniques which are detailed in
Application Note AN-1187. 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 this WSON package is the NSMD (non-solder
mask defined) type. Additionally, for optimal reliability, there is a recommended 1:1 ratio between the package
pad and the PCB pad for the Pullback WSON.
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 with a conductive
die attach adhesive. The DAP has no direct electrical (wire) connection to any of the eight pins. There is a
parasitic PN junction between the die substrate and the device ground. As such, it is strongly recommend that
the DAP be connected directly to the ground at device lead 1 (i.e. GROUND). Alternately, but not recommended,
the DAP may be left floating (i.e. no electrical connection). The DAP must not be connected to any potential
other than ground.
For the LP2986 in the NGN0008A 8-Lead WSON package, the junction-to-case thermal rating (θ
JC
) is 7.2°C/W,
where the 'case' is on the bottom of the package at the center of the DAP.
The junction-to-ambient thermal performance for the LP2986 in the NGN0008A 8-Lead WSON package, using
the JEDEC JESD51 standards is summarized in the following table:
Board Type Thermal Vias θ
JC
θ
JA
JEDEC 2-Layer
None 7.2°C/W 184°C/W
JESD 51-3
1 7.2°C/W 64°C/W
2 7.2°C/W 55°C/W
JEDEC 4-Layer
JESD 51-7
4 7.2°C/W 46°C/W
6 7.2°C/W 43°C/W
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