M5480B7 STMicroelectronics, M5480B7 Datasheet - Page 4

• Manufacturer Part Number: M5480B7
• Description: IC LED DISPLAY DRIVER 28-PDIP
• Manufacturer: STMicroelectronics

Specifications of M5480B7

• Display Type: LED
• Configuration: 7 Segment
• Interface: Serial
• Digits Or Characters: 3.5 Digits
• Current - Supply: 7mA
• Voltage - Supply: 4.75 V ~ 13.2 V
• Operating Temperature: -25°C ~ 85°C
• Mounting Type: Through Hole
• Package / Case: 28-DIP (0.600", 15.24mm)
• Number Of Digits: 3.5
• Number Of Segments: 23
• Operating Supply Voltage: 13.2 V
• Maximum Supply Current: 7 mA
• Maximum Power Dissipation: 940 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• Minimum Operating Temperature: - 25 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

M5480
FUNCTIONAL DESCRIPTION
The M5480 is specifically designed to operate 31/
2 digit alphanumeric displays with minimal inter-
face with the display and the data source. Serial
data transfer from the data source to the display
driver is accomplished with 2 signals, serial data
and clock. Using a format of a leading "1" followed
by the 35 data bits allows data transfer without an
additional load signal. The 35 data bits are latched
after the 36th bit is complete, thus providing non-
multiplexed, direct drive to the display.
Outputs change only if the serial data bits differ
from the previous time.
Display brightness is determined by control of the
output current for LED displays. A 1nF capacitor
should be connected to brightness control, pin 13,
to prevent possible oscillations.
Figure 4. Input Data Format
There must be a complete set of 36 clocks or the
shift registers will not clear.
When power is first applied to the chip an internal
power ON reset signal is generated which resets
all registers and all latches. The START bit and the
first clock return the chip to its normal operation.
Figure 5 shows the timing relationships between
Data, and Clock. A maximum clock frequency of
0.5MHz is assumed.
Table 3 shows the Output Data Format for the
M5480. Because it uses only 23 of the possible 35
outputs, 12 of the bits are "Don’t Care".
For applications where a lesser number of outputs
are used, it is possible to either increase the cur-
4/10
CLOCK
DATA
LOAD
(INTERNAL)
RESET
(INTERNAL)
START
1
BIT 1
A block diagram is shown in Figure 3. The output
current is typically 20 times greater than the cur-
rent into pin 13, which is set by an external vari-
able resistor.
There is an internal limiting resistor of 400 Ω nom-
inal value.
Figure 4 shows the input data format. A start bit of
logical "1" precedes the 35 bits of data. At the 36th
clock a LOAD signal is generated synchronously
with the high state of the clock, which loads the 35
bits of the shift registers into the latches.
At the low state of the clock a RESET signal is
generated which clears all the shift registers for
the next set of data. The shift registers are static
master-slave configurations. There is no clear for
the master portion of the first register, thus allow-
ing continuous operation.
rent per output, or operate the part at higher than
1V V
The following equation can be used for calcula-
tions.
T
(132 °C/W) + T
where:
T
V
I
132 °C/W = thermal coefficient of the package
T
LED
j
j
amb
OUT
= [ (V
= junction temperature (150 °C max)
= the LED current
OUT
= ambient temperature
= the voltage at the LED driver outputs
OUT
.
) (I
LED
amb
BIT 34 BIT 35
) (No.of segments) + V
36
DD
. 7 mA]