Data Sheet

LC840PA
Datasheet
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6.2 PCB Layout on Host PCB - General
Checklist (for PCB):
▪ MUST locate LC840PA module close to the edge of PCB (mandatory for the 453-00087 for on-board PCB trace antenna to
radiate properly).
▪ Use solid GND plane on inner layer (for best EMC and RF performance).
▪ All module GND pins MUST be connected to host PCB GND.
▪ Place GND vias close to module GND pads as possible.
▪ Unused PCB area on surface layer can flooded with copper but place GND vias regularly to connect the copper flood to
the inner GND plane. If GND flood copper is on the bottom of the module, then connect it with GND vias to the inner GND
plane.
▪ Route traces to avoid noise being picked up on VDD, VDDH, VBUS supply and AIN (analogue) and SIO (digital) traces.
LC840PA pin 2 and 4 (SIO_34 and SIO_36) which are Do No Connect pins are especially important.
▪ Ensure no exposed copper is on the underside of the module (refer to land pattern of LC840PA development board).
6.3 PCB Layout on Host PCB for the 453-00087 w/integrated PCB trace antenna
6.3.1 Antenna Keep-out on Host PCB
The 453-00087 has an integrated PCB trace antenna and its performance is sensitive to host PCB. It is critical to locate the 453-
00087 on the edge of the host PCB (or corner) to allow the antenna to radiate properly. Refer to guidelines in section PCB land
pattern and antenna keep-out area for the 453-00087. Some of those guidelines repeated below.
▪ Ensure there is no copper in the antenna keep-out area on any layers of the host PCB. Keep all mounting hardware and
metal clear of the area to allow proper antenna radiation.
▪ For best antenna performance, place the 453-00087 module on the edge of the host PCB, preferably in the edge center.
▪ The LC840PA development board has the 453-00087 module on the edge of the board (not in the corner). The antenna
keep-out area is defined by the LC840PA development board which was used for module development and antenna
performance evaluation is shown in Figure 9, where the antenna keep-out area is ~5 mm wide, ~39.95 mm long; with PCB
dielectric (no copper) height ~1 mm sitting under the 453-00087 PCB trace antenna.
▪ The 453-00087 PCB trace antenna is tuned when the 453-00087 is sitting on development board (host PCB) with size of
132 mm x 85 mm x 1mm.
▪ A different host PCB thickness dielectric will have small effect on antenna.
▪ The antenna-keep-out defined in the Host PCB Land Pattern and Antenna Keep-out for the 453-00087 section.
▪ Host PCB land pattern and antenna keep-out for the LC840PA applies when the 453-00087 is placed in the edge of the
host PCB preferably in the edge center. Figure 9 shows an example.