TOTX197 TORX196
VCC GND
4.3 kΩ
Input
4
56
321
Soldered to
PC board
Fiber-optic connector
insertion side
Optical
Transmitting Module
Optical
Receiving Module
Soldered to
PC board
(Bottom view) VCC
GND
GND GND
47 µH
0.1 µF
Output
4
56
321
(Bottom view)
Fiber-optic connector
insertion side
–30 –28 –26 –24 –22 –20
Received optical power (dBm)
Analog output voltage (V)
–18 –16 –14 –12 –10 –8
5
4
3
2
1
0
Ta = 25˚C, V
CC
= 5 V
With APF
VCC
Analog output
Digital output
GND
GND
GND
GND
4
3
2
1
Amplifier
ATC circut
PIN-PD
Comparator
Reference
voltage
Generator
500 k 1 M 2 M 3 M4 M6 M 10 M 20 M 30 M 50 M 100 M
—
2
—
4
—
6
—
8
—
10
—
12
—
14
—
16
—
18
—
20
—
22
—
24
—
26
—
28
—
30
—
32
—
34
Ta = 25°C, VCC = 5 V
: 190 series
: 170 series
Received optical power (dBm)
Data transmission rate (Mb/s)
TODX270A TODX297
TODX297
TODX270A
NRZ random patterns
APF
P
MIN
P
MIN
P
MAX
P
MAX
P
MAX: Maximum receivable power
P
MIN: Minimum receivable power
Receivings modules with an analog output for optical flux monitor—TORX198
Application circuits
Receivings modules with an analog output for optical flux monitor—TORX198
General-Purpose Optical Modules
Toshiba defines general-purpose optical modules as those having a
data rate of up to 6 Mb/s (NRZ) over distances up to 40 m (APF).
General-purpose optical modules come in two versions: simplex
types compatible with F05 connectors and duplex types compatible
with F07 connectors. All general-purpose optical modules are
housed in molded resin packages.
Whereas the 170 Series requires the external resistor value to be
adjusted according to the transmission distance, the 190 Series
needs no such adjustment.
The figure at right illustrates the dynamic ranges of the 170 and 190
Series. The 190 Series offers a dynamic range more than 6 dB wider
than the 170 Series.
Application circuits for the TOTX197 and TORX196, a pair of transmitting
and receiving modules, are shown in the figure on the right.
The TOTX197 transmission module requires an external resistor to supply
current to the LED.
The TORX196 receiving module requires an inductory capacitor noise filter
on the Vcc line. The module case is made of conductive resin to provide a
shielding effect against external noise. Pins #5 and #6 must be connected
to the system ground.
There are also duplex modules in the general-purpose TOSLINK series;
their application circuits are generally the same as for simplex modules.
All the general-purpose modules have a TTL interface for easy connection
with peripheral digital ICs.
Toshiba also offers a general-purpose receiving module with not only a
digital output but also an analog output. This receiving module, designated
the TORX198, provides an analog voltage from the internal amplifier,
which changes with the optical power input into the receiving module.
Hence, by monitoring the analog output it is possible to measure optical
power without dedicated optical power meter.
Incorporating such a feature in your system helps to simplify optical power
measurements for regular system maintenance.
When optical flux monitoring is not required, the TORX198 handles digital
data transmission like the other TOSLINK receiving modules. In this case,
the analog output pin may be left open.
Toshiba's TOSLINK offerings also include a duplex module with an analog
output, called the TODX298, which is targeted for a PCF cable.
Application circuits
Application circuits for the TOTX197 and TORX196
Receiving module with an analog output
for optical flux monitoring
Dynamic ranges of general-purpose TOSLINK modules