www.austriamicrosystems.com/LED-Driver-ICs/AS1118

Revision 1.01

13 - 20

AS1118

Datasheet - D e t a i l e d D e s c r i p t i o n

Display brightness is controlled by an integrated pulse-width modulator which is controlled by the lower-nibble of the

Intensity Control Register. The modulator scales the average segment-current in 16 steps from a maximum of 15/16

Scan-Limit Register (0x0B)

The Scan-Limit Register controls which of the digits are to be displayed. When all 8 digits are to be displayed, the

update frequency is typically 0.8kHz. If the number of digits displayed is reduced, the update frequency is increased.

The frequency can be calculated using 8fOSC/N, where N is the number of digits. Since the number of displayed digits

Note: To avoid differences in brightness this register should not be used to blank parts of the display (leading zeros).

Table 17. Intensity Register Format

Duty Cycle

HEX Code

Register Data

Duty Cycle

HEX Code

Register Data

MSB

D2

D1

LSB

MSB

D2

D1

LSB

1/16 (min on)

0xX0

0

0

0

0

9/16

0xX8

1

0

0

0

2/16

0xX1

0

0

0

1

10/16

0xX9

1

0

0

1

3/16

0xX2

0

0

1

0

11/16

0xXA

1

0

1

0

4/16

0xX3

0

0

1

1

12/16

0xXB

1

0

1

1

5/16

0xX4

0

1

0

0

13/16

0xXC

1

1

0

0

6/16

0xX5

0

1

0

1

14/16

0xXD

1

1

0

1

7/16

0xX6

0

1

1

0

15/16

0xXE

1

1

1

0

8/16

0xX7

0

1

1

1

15/16 (max on)

0xXF

1

1

1

1

Table 18. Intensity Register Address

Register HEX Address

Register Data

Type

D7:D4

D3:D0

0x0A

Global

X

Global Intensity

0x10

Digit

Digit 1 Intensity

Digit 0 Intensity

0x11

Digit

Digit 3 Intensity

Digit 2 Intensity

0x12

Digit

Digit 5 Intensity

Digit 4 Intensity

0x13

Digit

Digit 7 Intensity

Digit 6 Intensity

Table 19. Scan-Limit Register Format (Address (HEX) = 0x0B))

Scan Limit

HEX

Code

Register Data

Scan Limit

HEX

Code

Register Data

D7:D3 D2

D1

D0

D7:D3 D2

D1

D0

Display digit 0 only

0xX0

X

0

0

0

Display digits 0:4

0xX4

X

1

0

0

Display digits 0:1

0xX1

X

0

0

1

Display digits 0:5

0xX5

X

1

0

1

Display digits 0:2

0xX2

X

0

1

0

Display digits 0:6

0xX6

X

1

1

0

Display digits 0:3

0xX3

X

0

1

1

Display digits 0:7

0xX7

X

1

1

1