TFDU8108 Datasheet, PDF (8/27 Pages) Vishay Siliconix – Very Fast Infrared Transceiver Module (VFIR, 16 Mbit/s), Serial Interface Compatible, 2.7 V to 5.5 V Supply Voltage Range

TFDU8108
Vishay Semiconductors
Recommended Circuit Diagram
Operated with a low impedance power supply the
TFDU8108 needs no external components. However,
depending on the entire system design and board lay-
out, additional components may be required (see fig-
ure 1).
V_CC2
V_CC1
Rxd
R1
R2
IRED
Cathode
Rxd
IRED
Anode
Txd
Recommended Application Circuit Com-
ponents
Component
C1
C2
R1
R2
Recommended Value
4.7 µF, 16 V
0.1 µF, Ceramic, 16 V
Recommended for V_CC1 ≥ 4 V
Depending on current limit
4.7 Ω, 0.125 W
I/O and Software
For operating the device from a Controller I/O a driver
software must be implemented.
GND
V_logic
SCLK
Txd
C1 C2
Vcc
GND
SCLK
V_logic
17089
Mode Switching
The generic IrDA "Serial Interface programming"
needs no special settings for the device. Only the cur-
rent control table must be taken into account. For the
description see the Appendix and the IrDA "Serial
Interface specification for transceivers"
Figure 1. Recommended Application Circuit
All external components (R, C) are optional
Vishay Semiconductors transceivers integrate a sen-
sitive receiver and a built-in power driver. The combi-
nation of both needs a careful circuit board layout.
The use of thin, long, resistive and inductive wiring
should be avoided. The inputs (Txd, SCLK) and the
output Rxd should be directly (DC) coupled to the I/O
circuit.
R1 is used for controlling the maximum current
through the IR emitter. This one is necessary when
operating over the full range of operating temperature
and V_CC1 - voltages above 4 V. For increasing the
max. output power of the IRED, the value of the resis-
tor should be reduced. It should be dimensioned to
keep the IRED anode voltage below 4 V for using the
full temperature range. For device and eye protection
the pulse duration and current are internally limited.
R2, C1 and C2 are optional and dependent on the
quality of the supply voltage V_CC1 and injected noise.
An unstable power supply with dropping voltage dur-
ing transmission may reduce sensitivity (and trans-
mission range) of the transceiver.
The placement of these parts is critical. It is strongly
recommended to position C2 close to the transceiver
power supply pins. An electrolytic capacitor should be
used for C1 while a ceramic capacitor is used for C2.
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Document Number 82558
Rev. 1.6, 12-Aug-04