Data Sheet

Rev. 3

3

AS2578 /B

March 1997

PinDescriptioncont´d

Pin #

Symbol

Function

18

DPN

Dial Pulse Output

This is the push-pull output for controlling the hook-switch transistor. It is low during on-

hook and break periods and high during off-hook (see timing diagrammes).

19

GL

GroundLoopOutput

This push-pull output is high during ground loop

20

PositivePowerSupply

21

R4

KeyboardRows

22

R3

23

R2

24

R1

25

C5

Keyboard Column (AS2578)

This column is for the memory keys

C6

Keyboard Column (AS2578B)

This column is for centrex keys (A - D keys). Automatic pause insertion and Temporary

MF select 1 are fixed enabled (AP open)

26

AP

Access Pause Select Input (AS2578)

This input is used to select the automatic access pause insertion or sliding cursor (no

centrex keys):

AP pin

Function

High

Sliding cursor enabled

Temporary MF select 2

Open

Automatic pause insertion enabled

Temporary MF select 1

Low

Sliding cursor and pause disabled

Temporary MF select 1

C5

Keyboard Column (AS2578B)

This column is for the memory keys

27

MV

Melody Volume Select Input

This input is used to select the volume of the melodies in 4 steps by connecting the MV

pin to row 1, 2, or 3. Leaving the pin open is the default setting (max. volume).

28

RR

Repetition Rate Select Input

This input is used to select the repetition rate of the melodies. 4 different rates can be

selected by either leaving the pin open (default) or connecting it to column 1, 2, or 3.

Power On Reset

The on chip power on reset circuit monitors the supply

voltage (V

reference voltage, Vref (typically 1.1V), the oscillator is

inhibited. When V

ms/V), a reset signal is generated to assure correct start-

up.

Initial Setup

A low to high transition on the CE input will initiate an

automatic setup, i.e. the pin options are scanned and

(when an EEPROM is connected) the stored LM codes

and melody settings are read from the EEPROM. This is

done independently of the hook state (see timing

diagrammes).

Note: "Open" means

≥ 100 kΩ.