FAULT

CC

SET

GND

DAP

(GND)

1

2

3

4

8

7

6

5

SHDN

IN

OUT

OUT

CIN

VIA connect to ground layer

VIA connect to VOUT

COUT

CCC

R1

R2

RPULLUP

17

LP3982

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SNVS185F – FEBRUARY 2002 – REVISED APRIL 2017

Product Folder Links: LP3982

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10 Layout

10.1 Layout Guidelines

Best performance is achieved by placing CIN, COUT, and CCC on the same side of the PCB as the LP3982 device,

and as close as is practical to the package. The ground connections for CIN and COUT must be back to the

LP3982 device GND pin using as wide and as short of a copper trace as is practical.

Avoid connections using long trace lengths and narrow trace widths. These add parasitic inductances and

resistance that results in inferior performance especially during transient conditions.

10.2 Layout Example

Figure 21. WSON Package Adjustable Version (Not to Scale)

10.3 WSON Mounting

The WSON package requires specific mounting techniques which are detailed in TI Application Report Leadless

Leadframe Package (LLP) (SNOA401). Referring to the section PCB Design Recommendations, the pad style

which must be used with the WSON package is the NSMD (non-solder mask defined) type. Additionally, it is

recommended the PCB terminal pads 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. 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 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 pin 3 (GND). Alternately, but not recommended, the DAP may be left floating (no

electrical connection). The DAP must not be connected to any potential other than ground.