AS1107 datasheet(13/22 Pages) TAOS

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AS1106, AS1107

Datasheet - Detailed Descr i pti on

8.5.4 Intensity Control Register (0xXA)

The brightness of the display can be controlled by digital means using the Intensity Control Register and by analog means using RSET (see

Selecting RSET Resistor Value and Using External Drivers on page 14).

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 31/32 down to 1/32 (15/16 to 1/16 for the AS1107) of the

peak current set by RSET.

8.5.5 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

800Hz. 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 influences the brightness, RSET should be adjusted accordingly. Table 16 lists the

maximum allowed current when fewer than 4 digits are used.

Note:

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

Table 14. Intensity Register Format (Address (HEX) = 0xXA))

Duty Cycle

HEX Code

AS1106

AS1107

1/32 (min on)

1/16 (min on)

0xX0

XXXX

0000

3/32

2/16

0xX1

XXXX

0001

5/32

3/16

0xX2

XXXX

0010

7/32

4/16

0xX3

XXXX

0011

9/32

5/16

0xX4

XXXX

0100

11/32

6/16

0xX5

XXXX

0101

13/32

7/16

0xX6

XXXX

0110

15/32

8/16

0xX7

XXXX

0111

17/32

9/16

0xX8

XXXX

1000

19/32

10/16

0xX9

XXXX

1001

21/32

11/16

0xXA

XXXX

1010

23/32

12/16

0xXB

XXXX

1011

25/32

13/16

0xXC

XXXX

1100

27/32

14/16

0xXD

XXXX

1101

29/32

15/16

0xXE

XXXX

1110

31/32 (max on)

15/16 (max on)

0xXF

XXXX

1111

Table 15. Scan-Limit Register Format (Address (HEX) = 0xXB))

Scan Limit

HEX Code

Display digit 0 only (see Table 16)

0xX0

XXXX

Display digits 0:1 (see Table 16)

0xX1

XXXX

Display digits 0:2 (see Table 16)

0xX2

XXXX

Display digits 0:3

0xX3

XXXX

Display digits 0:4

0xX4

XXXX

Display digits 0:5

0xX5

XXXX

Display digits 0:6

0xX6

XXXX

Display digits 0:7

0xX7

XXXX

Table 16. Maximum Segment Current for 1-, 2-, or 3-Digit Displays

Number of Digits Displayed

Maximum Segment Current (mA)

110

220

330

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