Datasheet M5481 Datasheet (SGS Thomson Microelectronics)

FEATURES

■ 2 DIGIT LED DRIVER (14 segments)

■ CURRENT GENERATOR OUTPUTS (no

registor required)

■ CONTINUOU BRIGHTNESS CONTROL

■ SERIAL DATA INPUT

■ DATA ENABLE

■ WIDE SUPPLY VOLTAGE OPERATION

■ TLL COMPATIBILITY

■ APPLICATION EXAMPLES

■ MICROPROCESSOR DISPLAYS

■ INDUSTRIAL CONTROL INDICATOR

■ RELAY DRIVER

■ INSTRUMENTATI ON READ O U TS

DESCRIPTION

The M5481 is a monolithic MOS integrated circuit
produced with a N-channel silicon gate techn olo­gy. It uses the M54 50 die packaged in a 20-pin
plastic package copper frame, making it ideal for a
1-digit display. A single pin controls the LE D dis­play brightness by setting a reference current
through a variable resistor connected either to

V

DD

or to a separate supply of 13.2V maximum.
The M5481 is a pin-to-pin replacement of the NS

MM 5481.

PIN CONNECTIONS

M5481

LED DISPLAY DRIVER

DIP20

(Plastic package)

ORDER CODE: M54 81 B7

Output Bit 8
Output Bit 7
Output Bit 6
Output Bit 5
Output Bit 4
Output Bit 3
Output Bit 2
Output Bit 1

Brightness Control

V

DD

1
2
3
4

5
6
7
8
9

10

20
19
18
17

16

15

14
13
12

11

Output Bit 9
Output Bit 9
Output Bit 9
Output Bit 9
Output Bit 9
V

SS

Output Bit 9
Data Enable

Data In
Clock

Version 4.1

April 2000 1/8

1

M5481

1 - BLOC DIAGRAM

Figure 1.

Brightness

Control

100kΩ

V

10

DD

Output

Bit 14

14

Output

Bit 1

8

9

35 Output Buffers

1nF

Load

Data Enable

Serial Data

Clock

13

12

11

35 Latches

35-Bit Shift Register

Reset

15

2 - ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

DD

Vi Input Voltage -0.3 to 15 V

Vo(off) Off-state Output Voltage 15 V

Io Output Sink Current 40 mA

Supply Voltage -0.3 to 15 V

Total package power Dissipation

P

tot

T

j

T

oper

T

stg

Stresses exceed ing those list ed under “Ab solute Max imum Rating s” may caus e permanen t damage to the device a nd
affect its reliability.

2/8

Junction Temperatu re 150 °C
Operating Temperature Range -25, +85 °C
Staorage Temperature Range -65, +150 °C

at 25°C
t 85°C

1.5

800

W

mW

2

3 - STATIC ELECTRICAL CHARACTERISTICS

(T

within operational range, VDD=4.75V to 13.2V, VSS=0V, unless otherwise specified)

amb

Symbol Parameter Test Conditions Min Typ Max Unit

V

DD

Idd Supply Current V

Supply Voltage 4.5 13.2 V

=13.2V 7 mA

DD

M5481

Input Voltages

Vi

IB Brightness Input Current (Note 2) 0 0.75 mA

VB Brightness Input Voltage (pin9)

Vo(off) Off-state Output Voltage 13.2 V

Io

fclock

Io Output Matching (Note 1)

Note 1 Output matching is calculated as the percent variation from Imax+Imin/2
Note 2 With a fixed resistor on the brightness input some variation in brightness will occur from one device to another.
Note 3 Absolute maximum for each output should be limited to 40mA.
Note 4 the Vo voltage should be regulated by the user.

Logical “0” Level
Logical “1” Level

Output Sink Current (Note 3)
Segment OFF
Segment ON

Input Clock Frequency 0 0.5 MHz

+10µA Input Bias

4.75≤V
V

DD

Input Curren=750µA
T

amb

Vo=3V
Vo=1V (Note 4)
Brightness In.=0µA
Brightness In.=100µA
Brightness In.=750µA

DD

>5.25

=25°C

≤5.25

-0.3

2.2

V

-

DD

2

3 4.3 V

0
2

12

2.7
15

0.8

V

DD

V

DD

10
10

4

25

±20 %

V
V
V

µA
µA

mA
mA

4 - FUNCTIONAL DESCRIPTION

The M5481 uses the M5450 die which is packaged
to operate 2-digit alphanumeric displays with mini­mal interface with the display and the data source.

Serial data transfer from the data source to the dis­play driver is accom plished with 2 signals, serial

data and clock. using a format of a leadi ng “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 c ontrol (pin 9) to pre­vent possible oscillations.

A bloc diagram is shown on F igure 1. The output
current is typically 20 times g reater than the cur­rent into pin 9, which is set by an external variable
resistor.

The latter is an internal limiting resistor of 400Ω
nominal 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 is generated synchronously with the
high state of the clock, which l oads the 35 bits of
the shift registers into the latches.

3/8

M5481

Figure 2. Input Data Format

1

CLOCK

DATA

LOAD
(INTERNAL)

RESET
(INTERNAL)

START

BIT 1

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 shift register, thus al­lowing continuous operation.

There must be a complete set of 36 clocks or the
shift registers will not clear.

When power is first a pplied t o the chip an internal
power ON reset signal is generated which resets
all registers and all latches. The START bit and the
first clock reset the chip to its normal operation.

Figure 3 shows the timing relationships between

Data, Clock and DATA ENABLE

.

A maximum clock frequency of 0.5MHz is as­sumed.

Figure 4 shows the Output Data Format for the

M5481. Because it uses only 14 of the possible 35

outputs, 21 of the bits are “Don’t Cares”.
For applications where a lesser number of outputs

are used it is possible to either increase the cur­rent per output or operate the part at higher than
1V Vout.

Figure 4. Seri al Bus/ Outputs Co rrespondan ce

36

BIT 34 BIT 35

The following equation can be used for calcula­tions.

Tj=[(Vout)(I

)(No. of segments)+VDDx7mA]

LED

x(80°C/W)+Tamb
where:
Tj=junction temperature (150°Cmax)
Vout= voltage at the LED driver outputs
ILED= LED current
80°C/W=thermal coefficient of the package
Tamb=ambiant temperature

Figure 3.

CLOCK

DATA

300ns (min.)

DATA ENABLE

100ns (min.)

5450 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 START

5481 XXXX13XXXXX1211109XXXSTART

5450 1716151413121110987654321START
5481 X8765XXXX4321XXXXSTART

4/8

5 - TYPICAL APPLIC ATION

14 SEGMENTS

M5481

DISPLA Y DRIVER

PROCESSO RKEYBOARD

PLL

SYNTHESIZER

LED DISPLAY

BASIC electronically tuned TV system.

6 - POWER DISSIPATION OF THE IC

M5481

The power dissipation of the IC can be limited us­ing different configurations.

+V

C

R

I

D

V

D

V

OU T

In this application R must be chosen by taking into
account the worst operating conditions.

R is determined by the maximum nu mber of seg­ments activated.

VCV

– V

----------------------------------------------------------------=

R

The worst case condition for the device i s when
roughly half of the max imum num ber of segments
are activated.

It must be checked that the total power dissipation
does not exceed the absolute maximum ratings of
the device.

In critical cases more resistors can be used in con­junction with groups of segments. In this case the
current variation in the single resistor is reduced
and P

limited.

tot

DMAX

N

–

MAXxID

OMIN

5/8

M5481

+V

C

+V

C

V

OUT+VD

In this configuration the drop on the serial connect­ed diodes is quite stable if the diodes are properly
chosen.

The total power dissipation of the IC depends only,
in first approximation, on the num ber of segm ent s
activated.

In this configuration V

OUT+VD

is constant. the total
power dissipation of the IC depends only on the
number of segments activated.

6/8

7 - PACKAGE MECHANICAL DATA

20 Pins — Plastic Dip

N

e

K1

K2 R1

Z

N

b

B

e3

D

R1

a1

M5481

N

I

A

L

Tie Bar Center

K

C F

Ee4

b1

R2

Dimensions

20

1

Millimeters Inches

Min. Typ. Max. Min. Typ. Max.

11

10

A 3.25 3.30 3.35 0.128 0.130 0.132

a1 0.508 0.020

B 1.39 1.65 0.055 0.065
b 0.381 0.457 0.533 0.015 0.018 0.021

b1 0.20 0.254 0.30 0.008 0.010 0.012

C 5.20 5.33 5.46 0.205 0.210 0.215
D 24.9 25.15 25.4 0.980 0.990 1.000
E 7.8 8.5 9.1 0.307 0.335 0.358

e 2.29 2.54 2.79 0.090 0.100 0.110
e3 22.60 22.86 23.11 0.890 0.900 0.910
e4 7.36 7.62 7.87 0.290 0.300 0.310

F 6.22 6.35 6.50 0.245 0.250 0.255

I 3.42 3.68 3.93 0.135 0.145 0.155
L 3.17 3.30 3.42 0.125 0.130 0.135
N7d 7d

R1 0.152 0.006
R2 0.762 0.030

K 1.524 0.060

K1 0.762 0.030
K2 0.762 0.030

Z 1.27 1.34 0.050 0.053

7/8

M5481

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