M5482B7(1993) データシートの表示（PDF） - STMicroelectronics

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M5482B7
(Rev.:1993)

LED DISPLAY DRIVER

STMicroelectronics 

M5482

POWER DISSIPATION OF THE IC

b)

+V C

The power dissipation of the IC can be limited using

different configurations.

a)

+V C

R

ID

VD

VOUT

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 − VO

NMAX ⋅ ID

MIN

The worst case condition for the device is when

roughly half of the maximum number 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 Ptot limited.

In this configuration the drop on the serial con-

nected diodes is quite stable if the diodes are

properly chosen.

The total power dissipation of the IC is, in first

approximation, depending only on the number of

segments activated.

c)

+VC

VOUT +VD

In this configuration VOUT + VD is constant. The total

power dissipation of the IC depends only on the

number of segments activated.

5/6

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