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M5482

Table 2. Static Electrical Characteristics

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 40mA.

FUNCTIONAL DESCRIPTION

The M5482 uses the M5451 die which is packaged

to operate 2-digit alphanumeric displays with min-

imal interface with the display and the data source.

Serial data transfer from the data source to the dis-

play driver is accomplished with 2 signals, serial

data and clock. Using a format of a leading "1" fol-

lowed by the 35 data bits allows data transfer with-

out 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 se-

rial 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 pre-

vent possible oscillations.

A block diagram is shown in Figure 3. The output

current is typically 20 times greater than the cur-

rent into Pin 9, which is set by an external variable

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.

Symbol

Parameter

Test Conditions

Min.

Typ.

Max.

Unit

Supply Voltage

4.75

13.2

V

Supply Current

7mA

Input Voltage Logical "0" Level

± 10µA Input Bias

- 0.3

0.8

V

Logical "1" Level

4.75

2.2

V

V

Brightness Input Current (note 2)

0

0.75

mA

Brightness Input Voltage (pin 9)

Input Current = 750

34.3

V

Off State Out. Voltage

13.2

V

Out. Sink Current (note 3)

Segment OFF

10

µA

Segment ON

Brightness In. = 0

µA0

10

µA

Brightness In. = 100

µA2

2,7

4

mA

Brightness In. = 750

µA12

15

25

mA

Input Clock Frequency

0

0.5

MHz

Output Matching (note 1)

± 20

%