JAJSBA0Q January 2000 – December 2017 LP2950-N , LP2951-N
PRODUCTION DATA.
The NGT (no pullback) 8-lead WSON package requires specific mounting techniques which are detailed in AN-1187 Leadless Leadframe Package (LLP). Referring to the PCB Design Recommendations section, note that the pad style which should be used with the WSON package is the NSMD (non-solder mask defined) type. Additionally, TI recommends that the PCB terminal pads to be 0.2 mm longer than the package pads to create a solder fillet to improve reliability and inspection.
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.
For the LP2951-N in the NGT 8-lead WSON package, the junction-to-case thermal rating, RθJC, is 35°C/W, where the case is the bottom of the package at the center of 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 4 (that is, GND). Alternately, but not recommended, the DAP may be left floating (that is, no electrical connection). The DAP must not be connected to any potential other than ground.