TFDU7100 Datasheet, PDF (8/14 Pages) Vishay Siliconix – Infrared Transceiver Module (FIR, 4 Mbit/s) for IrDA combined with Remote Control Receiver (36 kHz to 38 kHz Carrier)

TFDU7100
Vishay Semiconductors
I/O and Software
In the description, already different I/Os are men-
tioned. Different combinations are tested and the
function verified with the special drivers available
from the I/O suppliers. In special cases refer to the I/
O manual, the Vishay application notes, or contact
directly Vishay Sales, Marketing or Application.
Mode Switching
The TFDU7100 is in the SIR mode after power on as
a default mode, therefore the FIR data transfer rate
has to be set by a programming sequence using the
TXD and SD inputs as described below. The low fre-
quency mode covers speeds up to 115.2 kbit/s. Sig-
nals with higher data rates should be detected in the
high frequency mode. Lower frequency data can also
be received in the high frequency mode but with
reduced sensitivity.
To switch the transceivers from low frequency mode
to the high frequency mode and vice versa, the pro-
gramming sequences described below are required.
The SD-pulse duration for programming should be
limited to a maximum of 5 µs avoiding that the trans-
ceiver goes into sleep mode.
Setting to the High Bandwidth Mode
(0.576 Mbit/s to 4.0 Mbit/s)
1. Set SD input to logic "HIGH".
2. Set TXD input to logic "HIGH". Wait t_s > 200 ns.
3. Set SD to logic "LOW" (this negative edge latches
state of TXD, which determines speed setting).
4. After waiting t_h > 200 ns TXD can be set to logic
"LOW". The hold time of TXD is limited by the maxi-
mum allowed pulse length.
After that TXD is enabled as normal TXD input and
the transceiver is set for the high bandwidth (576 kbit/
s to 4 Mbit/s) mode.
Setting to the Lower Bandwidth Mode
(2.4 kbit/s to 115.2 kbit/s)
1. Set SD input to logic "HIGH".
2. Set TXD input to logic "LOW". Wait t_s > 200 ns.
3. Set SD to logic "LOW" (this negative edge latches
state of TXD, which determines speed setting).
4. TXD must be held for t_h > 200 ns.
After that TXD is enabled as normal TXD input and
the transceiver is set for the lower bandwidth (9.6 kbit/s
to 115.2 kbit/s) mode.
SD
50 %
TXD
t_s
50 %
t_h
High : FIR
50 %
Low : SIR
14873
Figure 3. Mode Switching Timing Diagram
Table 2.
Truth table
SD
TXD
high
x
Inputs
Optical input Irradiance mW/m²
x
low
high
x
low
high
x
> 100 µs
x
low
> specified RC sensitivity (RC-
protocol)
low
low
<4
low
low
> minimum irradiance in angular
range (IrDA)
< maximum irradiance in angular
range (IrDA)
low
low
> maximum irradiance in angular
range (IrDA)
Outputs
RXD
weakly pulled
(500 kΩ to V_CC1)
active low (echo)
high
Transmitter
0
I_e
0
x
0
high
0
low (active)
0
x
0
Remark
RC-RXD
x
x
x
active low (envelope)
x
x
x
www.vishay.com
8
Document Number 84773
Rev. 1.1, 27-Sep-06