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Revision 1.34

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AS1105

Data Sheet - A p p l i c a t i o n I n f o r m a t i o n

9 Application Information

Supply Bypassing and Wiring

In order to achieve optimal performance the AS1105 shall be placed very close to the LED display to minimize effects

of electromagnetic interference and wiring inductance. Furthermore, it is recommended to connect a 10µF electrolytic

connected to ground.

higher currents are needed, external drivers must be used. In that case it is no longer necessary that the AS1105

Ω. In cases that the AS1105 only drives few digits Table 10

acceptable limits for ambient temperature, segment current, and the LED forward-voltage drop.

4x8 LED Dot Matrix Driver

The example in Figure 7 uses the AS1105 to drive an 4x8 LED dot matrix. The LED columns have common cathode

and are connected to the DIG0-3 outputs. The rows are connected to the segment drivers. Each of the 32 LEDs can be

addressed separately. The columns are selected via the digits as shown in Table 5. The decode mode register (0xX9)

has to be programmed to ‘00000000’ as stated in Table 7. The single LEDs in a column can be addressed as stated in

Table 10, where D0 corresponds to segment G and D7 to segment DP. For a multiple digit dot matrix several AS1105

have to be cascaded.

Figure 7. Application example as LED dot matrix driver

SEG F

SEG G

SEG E

SEG D

SEG C

SEG B

SEG A

SEG DP

DIG 0

DIG 3

4x8 LED Dot

SEG A-G DIG 0-3

18

19

VBAT

9.53k

DIN

LOA

CLK

GND

GND

ISET

VDD

DOUT

1

12

9

1

SEG F

SEG G

SEG E

SEG D

SEG C

SEG B

SEG A

SEG DP

DIG 0

DIG 3

4x8 LED Dot

SEG A-G DIG 0-3

18

19

VBAT

9.53k

DIN

LOA

CLK

GND

GND

ISET

VDD

DOUT

1

12

9

1

µP

Diode Arrangement