STATIC ELECTRICAL CHARACTERISTICS

Symbol

Parameter

Test Conditions

Min.

Typ.

Max.

Unit

Supply Voltage

4.75

13.2

V

Supply Current

7

mA

Input Voltages

Logical "0" Level

Logical "1" Level

± 10 µA Input Bias

4.75

– 0.3

2.2

0.8

V

V

V

Brightness Input Current (note 2)

0

0.75

mA

Brightness Input Voltage (pin 9)

Input Current = 750

µA

3

4.3

V

Off State Output Voltage

13.2

V

Output Sink Current (note 3)

Segment OFF

Segment ON

Brightness In. = 0

µA

Brightness In. = 100

µA

Brightness In. = 750

µA

0

2

12

2.7

15

10

10

4

25

µA

µA

mA

mA

Input Clock Frequency

0

0.5

MHz

Output Matching (note 1)

± 20

%

2. With a fixed resistor on the brightness input some variation in brightness will occur from one device to another.

3. Absolute maximum for each output should be limited to 40 mA.

FUNCTIONAL DESCRIPTION

The M5482 uses the M5451 die which is packaged

to operate 2-digit alphanumeric displays with mini-

mal interface 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 9, to prevent

possible oscillations.

A block diagram is shown in Figure 1. The output

current is typically 20 times greater than the current

into Pin 9, which is set by an external variable

resistor.

There is an internal limiting resistor of 400

Ω nomi-

nal value.

Figure 2 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.

36

BIT 34

BIT 35

CLOCK

DATA

LOAD

(INTERNAL)

RESET

(INTERNAL)

START

BIT 1

1

Figure 2 : Input Data Format

M5482

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