hsdl-3208 LiteOn Technology Corp., hsdl-3208 Datasheet - Page 17

• Manufacturer Part Number: hsdl-3208
• Description: Ultra Small Profile Package Irda Data Compliant Low Power 115.2 Kbit/s Infrared Transceiver
• Manufacturer: LiteOn Technology Corp.

17
Appendix B: PCB Layout
Suggestion
The HSDL-3208 is a shieldless part
and hence does not contain a shield
trace, unlike the other transceivers.
The following PCB layout guide-
lines should be followed to obtain a
good PSRR and EM immunity,
resulting in good electrical
performance. Things to note:
1. The AGND pin should be
2. C1 and C2 are optional supply
3. VLED can be connected to either
4. Preferably a multi-layered board
connected to the ground plane.
filter capacitors; they may be left
out if a clean power supply is
used.
unfiltered or unregulated power
supply. If VLED and V
the same power supply and C1 is
used, the connection should be
before the current limiting
resistor R2. In a noisy environ-
ment, including capacitor C2 can
enhance supply rejection. C1 is
generally a ceramic capacitor of
low inductance providing a wide
frequency response while C2 is a
tantalum capacitor of big volume
and fast frequency response. The
use of a tantalum capacitor is
more critical on the V
which carries a high current.
should be used to provide
sufficient ground plane. Use the
layer underneath and near the
transceiver module as V
sandwich that layer between
LED
CC
CC
share
line,
, and
The area underneath the module at
the second layer, and 3 cm in all
directions around the module, is
defined as the critical ground plane
zone. The ground plane should be
maximized in this zone. Refer to
application note AN1114 or the
Lite-On IrDA Data Link Design
Guide for details. The layout below
is based on a 2-layer PCB.
Figure 26. PCB layout suggestion.
ground connected board layers.
Refer to the diagram below for
an example of a 4-layer board.
Top View
Bottom View
TOP LAYER
CONNECT THE METAL SHIELD AND MODULE
GROUND PIN TO BOTTOM GROUND LAYER.
LAYER 2
CRITICAL GROUND PLANE ZONE. DO NOT
CONNECT DIRECTLY TO THE MODULE
GROUND PIN.
LAYER 3
KEEP DATA BUS AWAY FROM CRITICAL
GROUND PLANE ZONE.
BOTTOM LAYER (GND)