AN3981 datasheet(41/54 Pages) STMICROELECTRONICS

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AN3981

Common application information

Doc ID 022217 Rev 1

41/54

5.2

Daisy chain connection

In real applications, typically, the number of LEDs to drive leads to the use of more drivers.

A common configuration (daisy chain) of the drivers is shown in Figure 50. This way to

connect the drivers implies that all ICs in the chain share some serial interface signals, like

CLK, LE and

Figure 50.

LED drivers connected in daisy chain configuration

All data go through each device of the chain. Every time the information (displayed by LEDs)

must be updated, the data packet to load contains a number of bits equal to the number of

bits necessary for each device (4, 8, 16 or 24) multiplied by the number of devices contained

in the chain, as shown in Figure 51.

Figure 48.

Thermal performance of the

TSSOP- 24

Figure 49.

Thermal performance of the

HTSSOP - 24

AM10648v1

111.3°C

Hottest spot on package surface

TSSOP-24

AM10649v1

Hottest spot on package surface

HTSSOP-24

80.2°C

AM10650v1

SDI

CLK

µC

….

OUT0

OUTn

STPxPyy05

IC#1

VDD

R-EXT

GND

SDI

CLK

….

OUT0

OUTn

STPxPyy05

IC#m

VLED

SDO

VDD

R-EXT

GND

….

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