HCMS-2919 Avago Technologies US Inc., HCMS-2919 Datasheet - Page 13

• Manufacturer Part Number: HCMS-2919
• Description: LED DISPLAY 5X7 8CHAR 3.8MM BLUE
• Manufacturer: Avago Technologies US Inc.
• Series: HCMS-29xxr

Specifications of HCMS-2919

• Display Type: Alphanumeric
• Millicandela Rating: *
• Size / Dimension: 1.40" L x 0.40" W x 0.20" H (35.6mm x 10.2mm x 5.1mm)
• Color: Blue
• Configuration: 5 x 7
• Voltage - Forward (vf) Typ: *
• Package / Case: 26-DIP
• Number Of Digits/alpha: 8
• Digit/alpha Size: 0.15" (3.8mm)
• Number Of Digits: 8
• Illumination Color: Blue
• Wavelength: 428 nm
• Operating Voltage: 5.5 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Luminous Intensity: 170 ucd
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Common Pin: -
• Lead Free Status / Rohs Status: Details

V
The display uses two independent electrical systems.
One system is used to power the display’s logic and
the other to power the display’s LEDs. These two
systems keep the logic supply clean.
Separate electrical systems allow the voltage applied
to V
V
the Dot or the Control Registers. V
between 4.0 to 5.5 V without any noticeable variation
in light output. However, operating V
may cause objectionable mismatch between the pixels
and is not recommended. Dimming the display by
pulse width modulating V
V
either the displayed message or the display intensity.
However, operation below 4.5 V will change the timing
and logic levels and operation below 3 V may cause
the Dot and Control Registers to be altered
The logic ground is internally connected to the LED
ground by a substrate diode. This diode becomes
forward biased and conducts when the logic ground is
0.4 V greater than the LED ground. The LED ground
and the logic ground should be connected to a
common ground, which can withstand the current
introduced by the switching LED drivers. When
separate ground connections are used, the LED ground
can vary from -0.3 V to +0.3 V with respect to the logic
ground. Voltages below -0.3 V can cause all the dots
to be ON. Voltage above +0.3 V can cause dimming
and dot mismatch.
Using a decoupling capacitor between the power
supply and ground will help prevent any supply noise
in the frequency range greater than that of the
functioning display from interfering with the display’s
internal circuitry. The value of the capacitor depends
on the series resistance from the ground back to the
power supply and the range of frequencies that need
to be suppressed. It is also advantageous to use the
largest ground plane possible.
Electrostatic Discharge
The inputs to the ICs are protected against static
discharge and input current latchup. However, for best
results, standard CMOS handling precautions should
be used. Before use, the HCMS-29XX should be stored
13
LOGIC
LED
LOGIC
LED
can vary from 0 to 5.5V without affecting either
and V
can vary from 3.0 to 5.5 V without affecting
and V
LED
LOGIC
Considerations
to be varied independently. Thus,
LED
is also not recommended.
LED
LED
can be varied
below 4.5 V
in antistatic tubes or in conductive material. During
assembly, a grounded conductive work area should
be used and assembly personnel should wear
conductive wrist straps. Lab coats made of synthetic
material should be avoided since they are prone to
static buildup. Input current latchup is caused when
the CMOS inputs are subjected to either a voltage
below ground (V
than V
forced into the input. To prevent input current latchup
and ESD damage, unused inputs should be connected
to either ground or V
applied to the inputs until V
the display.
Appendix C. Oscillator
The oscillator provides the internal refresh circuitry with
a signal that is used to synchronize the columns and
rows. This ensures that the right data is in the dot
drivers for that row. This signal can be supplied from
either an external source or the internal source. A
display refresh rate of 100 Hz or faster ensures flicker-
free operation. Thus for an external oscillator the
frequency should be greater than or equal to 512 x
100 Hz = 51.2 kHz. Operation above 1 MHz without
the prescaler or 8 MHz with the prescaler may cause
noticeable pixel to pixel mismatch.
Appendix D. Refresh Circuitry
This display driver consists of 20 one-of-eight column
decoders and 20 constant current sources, 1 one-of-
eight row decoder and eight row sinks, a pulse width
modulation control block, a peak current control block,
and the circuit to refresh the LEDs. The refresh counters
and oscillator are used to synchronize the columns and
rows. The 160 bits are organized as 20 columns by 8
rows. The IC illuminates the display by sequentially
turning ON each of the 8 row-drivers. To refresh the
display once takes 512 oscillator cycles. Because there
are eight row drivers, each row driver is selected for
64 (512/8) oscillator cycles. Four cycles are used to
briefly blank the display before the following row is
switched on. Thus, each row is ON for 60 oscillator
cycles out of a possible 64. This corresponds to the
maximum LED on time.
LOGIC
(V
IN
> V
IN
< ground) or to a voltage higher
LOGIC
LOGIC
) and when a high current is
. Voltages should not be
LOGIC
has been applied to