todx295 TOSHIBA Semiconductor CORPORATION, todx295 Datasheet - Page 7

• Manufacturer Part Number: todx295
• Description: Fiber Optic Transceiving Module
• Manufacturer: TOSHIBA Semiconductor CORPORATION

7. Precautions during use
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Soldering
Noise resistance
Fixing fiber optical transceiving module
Shielding and wiring pattern of fiber optic transceiving modules
Maximum rating
The maximum ratings are the limit values which must not be exceeded during operation of device.
None of these rating value must not be exceeded. If the maximum rating value is exceeded, the
characteristics of devices may never be restored properly. In extreme cases, the device may be
permanently damages.
Lifetime of light emitters
If an optical module is used for a long period of time, degeneration in the characteristics will mostly
be due to a lowering of the fiber output power (Pf). This is caused by the degradation of the optical
output of the LEDs used as the light source. The cause of degradation of the optical output of the
LEDs may be defects in wafer crystallization or mold resin stress. The detailed causes are, however,
not clear.
The lifetime of light emitters is greatly influenced by the operating conditions and the environment in
which it is used as well as by the lifetime characteristics unique to the device type. Thus, when a light
emitting device and its operating conditions determined, Toshiba recommend that lifetime
characteristics be checked.
Depending on the environment conditions, Toshiba recommend that maintenance such as regular
checks of the amount of optical output in accordance with the condition of operating environment.
Optical modules are comprised of internal semiconductor devices. However, in principle, optical
modules are optical components. During soldering, ensure that flux does not contact with the emitting
surface or the detecting surface. Also ensure that proper flux removal is conducted after soldering.
Some optical modules come with a protective cap. The protective cap is used to avoid malfunction
when the optical module is not in use. Note that it is not dust or waterproof.
As mentioned before, optical modules are optical components. Thus, in principle, soldering where
there may be flux residue and flux removal after soldering is not recommended. Toshiba recommend
that soldering be performed without the optical module mounted on the board. Then, after the board
has been cleaned, the optical module should be soldered on to the board manually.
If the optical module cannot be soldered manually, use non−halogen (chlorine−free) flux and make
sure, without cleaning, there is no residue such as chlorine. This is one of the ways to eliminate the
effects of flux. In such a cases, be sure to check the devices
It is believed that the use of optical transfer devices improve noise resistance. In theory, optical fiber
is not affected by noise at all. However, receiving modules which handle signals whose level is
extremely small, are susceptible to noise.
TOSLINK improve noise resistance to use a conductive case. However, the current signal output by
the optical receiving modules
the case may not achieve sufficient noise resistance.
First systems which incorporate TOSLINK, Toshiba recommend testing using the actual device to
check its noise resistance.
Use a simple noise filter on TOSLINK fiber optic transceiving module
power supply used is significant, reinforce the filter.
The optical module is to be used in an area which is susceptible to radiated noise, increase the
shielding by covering the optical module and the power line filter with a metallic cover.
Vibration and shock
This module is plastic sealed and has its wire fixed by resin. This structure is relatively resistant to
vibration and shock. In actual equipment, there are sometime cases in which vibration, shock, or
stress is applied to soldered parts or connected parts, resulting in lines cut. A care must be taken in
the design of equipment which will be subject to high levels of vibration.
Solder the fixed pin (pins 9 and 10) of fiber optic transceiving module TODX295 to the printed circuit
board to fix the module to the board.
To shield, connect the fixed pins (pins 9 and 10) of fiber optic transceiving module TODX295 to the
GND.
Where the fiber optic transceiving module uses conductive resin, be careful that the case does not
touch wiring (including land).
To improve noise resistance, shield the optical module and the power line filter using a metallic cover.
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photodiode is extremely small. Thus, in some environments, shielding
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reliability.
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s power line. If the ripple in the
TODX295
2001-07-26