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AS1108

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

Shutdown Mode

The AS1108 features a shutdown mode, consuming only 10µA (max) current. Shutdown mode is entered via a write to

the Shutdown Register (see Table 8). At that point, all segment current sources are pulled to ground and all digit driv-

ers are connected to VDD, so that all segments are blanked.

Note: During shutdown mode the Digit-Registers maintain their data.

Shutdown mode can either be used as a means to reduce power consumption or for generating a flashing display

(repeatedly entering and leaving shutdown mode). For minimum supply current in shutdown mode, logic input should

be at GND or VDD (CMOS logic level).

The device needs typically 250µs to exit shutdown mode, and during shutdown mode the AS1108 is fully programma-

ble. Only the display test mode (see page 11) overrides shutdown mode.

When entering or leaving shutdown mode, the Feature Register is reset to its default values (all 0s) when Shutdown

Register bit D7 (page 10) = 0. When bit D7 = 1, the Feature Register is left unchanged when entering or leaving shut-

down mode.

Note: If the AS1108 is used with an external clock, Shutdown Register bit D7 should be set to 1 when writing to the

Shutdown Register.

Digit- and Control-Registers

The AS1108 contains four Digit-Registers and six control-registers, which are listed in Table 7. All registers are

selected using a 4-bit address word, and communication is done via the serial interface.

Digit Registers – These registers are realized with an on-chip 32-bit memory. Each digit can be controlled directly

without rewriting the whole register contents.

Control Registers – These registers consist of decode mode, display intensity, number of scanned digits, shut-

down, display test and features selection registers.

Table 7. Register Address Map

Register

HEX Code

Address

Page

D15:D12

D11

D10

D9

D8

No-Op

0xX0

X

0

0

0

0

13

Digit 0

0xX1

X

0

0

0

1

N/A

Digit 1

0xX2

X

0

0

1

0

N/A

Digit 2

0xX3

X

0

0

1

1

N/A

Digit 3

0xX4

X

0

1

0

0

N/A

Decode-Mode

0xX9

X

1

0

0

1

10

Intensity Control

0xXA

X

1

0

1

0

12

Scan Limit

0xXB

X

1

0

1

1

12

Shutdown

0xXC

X

1

1

0

0

10

N/A

0xXD

X

1

1

0

1

N/A

Feature

0xXE

X

1

1

1

0

13

Display Test

0xXF

X

1

1

1

1

11