tfds4400 Vishay, tfds4400 Datasheet - Page 6

• Manufacturer Part Number: tfds4400
• Description: Sir Transceiver Module 115.2 Kbit/s 2.7 V To 5.5 V
• Manufacturer: Vishay

Recommended Circuit Diagram
The only required components for designing an
IrDA 1.2 compatible design using Vishay SIR
transceivers are a current limiting resistor to the IRED.
However, depending on the entire system design and
board layout, additional components may be required
(see figure KEIN MERKER). It is recommended that
the capacitors C1 and C2 are positioned as near as
possible to the transceiver power supply pins. A tanta-
lum capacitor should be used for C1, while a ceramic
capacitor should be used for C2 to suppress RF noise.
Also, when connecting the described circuit to the
power supply, low impedance wiring should be used.
R1 is used for controlling the current through the IR
emitter. For increasing the output power of the IRED,
the value of the resistor should be reduced. Similarly,
to reduce the output power of the IRED, the value of
the resistor should be increased. For typical values of
R1 (see figures 4 and 5), e.g. for IrDA compliant
operation (V
of 14
limitation is dependent on the duty cycle and is given
by the absolute maximum ratings on the data sheet
and the eye safety limitations given by IEC825–1.
R2, C1 and C2 are optional and dependent on the
quality of the supply voltage V
An unstable power supply with dropping voltage during
transmission may reduce sensitivity (and transmission
range) of the transceiver.
Table 1. Recommended Application Circuit Components
TFDS4400
Vishay Semiconductors
6 (14)
www.vishay.com
Component
V
V
GND
Rxd
Txd
CC2
CC1
SC
C1
C2
R1
R2
Figure 3. Recommended Application Circuit
is recommended. The upper drive current
Note: outlined components are optional depending
CC2
C1
4.7 mF, Tantalum
0.1 F, Ceramic
14 , 0.25 W (recommended using
two 7 , 0.125 W resistors in series)
47
R2
= 5 V 5%), a current control resistor
on the quality of the power supply
R1
C2
, 0.125 W
IRED
Cathode
Rxd
V
GND
Recommended Value
CC1
CC1
/SD
TFDx4x00
and injected noise.
Anode
IRED
Txd
SC
NC
14377
14378
293D 475X9 016B 2T
VJ 1206 Y 104 J XXMT
CRCW–1206–6R98–F–RT1
CRCW–1206–47R0–F–RT1
480
440
400
360
320
280
240
200
160
120
760
720
680
640
600
560
520
480
440
400
360
320
280
240
200
160
120
80
40
80
40
0
0
6
0
"15 off axis, max. V
1
15 off axis, max. V
8
V
Current Control Resistor ( W )
V
Figure 4. Ie vs. R1
Figure 5. Ie vs. R1
cc
2
cc
Vishay Part Number
= 4.75 V, min. efficiency,
=2.7V, min. intensity
V
Serial Resistor ( W )
axis, min. V
cc
max. efficiency, center,
3
min. V
10
=3.3V, max. intensity on
V
cc
4
F
= 5.25 V,
, min. V
F
12
F
F
, max. V
, max. V
, min. V
5
Document Number 82524
CEsat
6
Rev. A1.5, 31-May-00
14
CEsat
CEsat
CEsat
7
16
8