2000 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA SCE5740/1/2/3/4/5
www.infineon.com/opto • 1-888-Infineon (1-888-463-4636)
OSRAM Opto Semiconductors GmbH & Co. OHG • Regensburg, Germany
www.osram-os.com • +49-941-202-7178 11 March 28, 2000-10
Electrical and Mechanical Considerations
Thermal Considerations
Optimum product performance can be had when the following
electrical and mechanical recommendations are adopted. The
IC is constructed in a high speed CMOS process, consequently
noise on the SERIAL DATA, SERIAL DATA CLOCK, LOAD and
RESET lines may cause incorrect data to be written into the
serial shift register. Adhere to transmission line termination
procedures when using fast line drivers and long cables
(>10 cm).
Good ground and power supply decoupling will insure that ICC
(<400 mA peak) switching currents do not generate localized
ground bounce. Therefore it is recommended that each display
package use a 0.1 µF and 0 µF capacitor between VCC and
ground.
When the internal MUX Clock is being used connect the
CLKSEL pin to VCC. In those applications where RESET will not
be connected to the system’s reset control, it is recommended
that this pin be connected to the center node of a series 0.1, µF
and 100 kΩ RC network. Thus upon initial power up the RESET
will be held low for 10 ms allowing adequate time for the sys-
tem power supply to stabilize.
ESD Protection
The input protection structure of the SCE574x provides signifi-
cant protection against ESD damage. It is capable of withstand-
ing discharges greater than 2.0 kV. Take all the standard
precautions, normal for CMOS components. These include
properly grounding personnel, tools, tables, and transport carri-
ers that come in contact with unshielded parts. If these condi-
tions are not, or cannot be met, keep the leads of the device
shorted together or the parts in anti-static packaging.
Soldering Considerations
The SCE574x can be hand soldered with SN63 solder using a
grounded iron set to 260°C.
Wave soldering is also possible following these conditions: Pre-
heat that does not exceed 93°C on the solder side of the PC
board or a package surface temperature of 85°C. Water soluble
organic acid flux (except carboxylic acid) or rosin-based RMA
flux without alcohol can be used.
Wave temperature of 245°C ±5°C with a dwell between 1.5 sec.
to 3.0 sec. Exposure to the wave should not exceed tempera-
tures above 260°C for five seconds at 0.063" below the seating
plane. The packages should not be immersed in the wave.
Post Solder Cleaning Procedures
The least offensive cleaning solution is hot D.I. water (60°C) for
less than 15 minutes. Addition of mild saponifiers is accept-
able. Do not use commercial dishwasher detergents.
For faster cleaning, solvents may be used. Exercise care in
choosing solvents as some may chemically attack the nylon
package. For further information refer to Appnotes 18 and 19.
An alternative to soldering and cleaning the display modules is
to use sockets. Naturally, 14 pin DIP sockets .300” wide with
.100" centers work well for single displays. Multiple display
assemblies are best handled by longer SIP sockets or DIP sock-
ets when available for uniform package alignment.
Optical Considerations
The 0.180" high character of the SCE574x gives readability up
to five feet. Proper filter selection enhances readability over
this distance.
Using filters emphasizes the contrast ratio between a lit LED
and the character background. This will increase the discrimina-
tion of different characters. The only limitation is cost. Take into
consideration the ambient lighting environment for the best
cost/benefit ratio for filters.
Incandescent (with almost no green) or fluorescent (with
almost no red) lights do not have the flat spectral response of
sunlight. Plastic band-pass filters are an inexpensive and effec-
tive way to strengthen contrast ratios. The SCE5740 is a red
display and should be used with long wavelength pass filter
having a sharp cut-off in the 600 nm to 620 nm range. The
SCE5742 is a high efficiency red display and should be used
with long wavelength pass filter having a sharp cut-off in the
570 nm to 600 nm range. The SCE5744 is a high efficiency
green display and should be used with long wavelength pass
filter that peaks at 565 nm.
Additional contrast enhancement is gained by shading the
displays. Plastic band-pass filters with built-in louvers offer the
next step up in contrast improvement. Plastic filters can be
improved further with anti-reflective coatings to reduce glare.
Optimal filter enhancements are gained by using circular polar-
ized, anti-reflective, band-pass filters. The circular polarizing fur-
ther enhances contrast by reducing the light that travels
through the filter and reflects back off the display to less
than 1%.
Several filter manufacturers supply quality filter materials.
Some of them are: Panelgraphic Corporation, W. Caldwell, NJ;
SGL Homalite, Wilmington, DE; 3M Company, Visual Products
Division, St. Paul, MN; Polaroid Corporation, Polarizer Division,
Cambridge, MA; Marks Polarized Corporation, Deer Park, NY,
Hoya Optics, Inc., Fremont, CA.One last note on mounting fil-
ters: recessing displays and bezel assemblies is an inexpensive
way to provide a shading effect in overhead lighting situations.
Several Bezel manufacturers are: R.M.F. Products, Batavia, IL;
Nobex Components, Griffith Plastic Corp., Burlingame, CA;
Photo Chemical Products of California, Santa Monica, CA;
I.E.E.-Atlas, Van Nuys, CA. The trade-off is fuzzy characters.
Mounting the filters close to the display reduces this effect.
Take care not to overheat the plastic filter by allowing for
proper air flow.
Microprocessor Interface
The microprocessor interface is through the serial port, SPI
port or one out of eight data bits on the eight bit parallel port
and also control lines SDCLK and LOAD.
Power Up Sequence
Upon power up display will come on at random. Thus the dis-
play should be reset at power-up. The reset will set the
Address Register to Digit 0, User RAM is set to 0 (display
blank) the Control Word is set to 0 (100% brightness) and the
internal counters are reset.