+

-

LM3243

VBATT_PA

VIN DC-DC

VBATT

+

*

*Proper decoupling on VBATT_PA

is strongly recommended.

*

Star connection at VBATT

VIN

+

-

VBATT_PA

LM3243

www.ti.com

SNVS782C – OCTOBER 2010 – REVISED AUGUST 2015

Layout Guidelines (continued)

fewer bypass capacitors.

VBATT Star Connection: It is critically important to use a ‘Star’ connection from VBATT supply to LM3243 PVIN

and from VBATT to PA modules as implementing a ‘daisy chain’ supply connection may add noise to the PA

output.

Figure 26. VBATT Star Connection on VIN And VBATT_PA

10.1.2 Manufacturing Considerations

The LM3243 package employs a 16-pin (4 × 4) array of 0.24-mm solder balls, with a 0.4-mm pad pitch. A few

simple design rules will go a long way to ensuring a good layout.

•

Pad size should be 0.225 ± 0.02 mm. Solder mask opening should be 0.325 ± 0.02 mm.

•

As a thermal relief, connect to each pad with 9 mil wide, 6 mil long traces and incrementally increase each

trace to its optimal width. Symmetry is important to ensure the solder bumps re-flow evenly. Refer to TI

Application Note AN-1112 DSBGA Wafer Level Chip Scale Package (SNVA009).

10.2 Layout Example

Figure 27. Simplified LM3243 RF Evaluation Board Schematic

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