M5480 データシートの表示（PDF） - STMicroelectronics

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コンポーネント説明

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M5480

LED DISPLAY DRIVER

STMicroelectronics 

M5480

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 3 shows the timing relationships between

Data, and Clock. A maximum clock frequency of

0.5MHz is assumed.

Figure 4 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 current

per output, or operate the part at higher than 1V

VOUT.

The following equation can be used for calcula-

tions.

Tj = [ (VOUT) (ILED) (No.of segments) + VDD . 7 mA

] (132 °C/W) + Tamb

where:

Tj = junction temperature (150 °C max)

VOUT = the voltage at the LED driver outputs

ILED = the LED current

132 °C/W = thermal coefficient of the package

Tamb = ambient temperature

Figure 3

CLOCK

DATA

300ns (min.)

Figure 4 : Serial Data Bus / Outputs Correspondance

5451

5480

35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19

X 23 22 21 20 19 X X 18 X 17 16 15 14 13 12 X

START

START

5451 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 START

5480 X X X 11 10 9 8 X X X 7 6 5 4 3 2 1 X START

TYPICAL APPLICATION

BASIC 3 1/2 Digit Interface.

23 SEGMENTS

M5480

DISPLAY DRIVER

a)

+V C

R

ID

VD

VOUT

CLOCK

DATA

POWER DISSIPATION OF THE IC

The power dissipation of the IC can be limited using

different configurations.

In this application R must be chosen taking into

account the worst operating conditions.

R is determined by the maximum number of seg-

ments activated.

R

=

VC

−

VD MAX − VOUT

NMAX ⋅ ID

MIN

4/6

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