AS2574B Datasheet, PDF (1/24 Pages) ams AG – 20 NUMBER ONE TOUCH DIALLER WITH SERIAL BUS FOR DISPLAY DRIVER

Data Sheet
AS2574B
20 NUMBER ONE TOUCH DIALLER WITH
®
Austria Mikro Systeme International
SERIAL BUS FOR DISPLAY DRIVER
Key Features
u Low operating voltage (2.5V to 5.5V)
u Low current consumption (typ. 200 µA in LD mode)
u Oscillator using ceramic resonator (681 kHz)
u MF level independent of supply voltage
u Direct ´wake-up´ from keyboard
u Automatic Call Progress by direct memory key
u Data protection with 8 digit FIFO
u Sliding cursor protocol with comparison
u Diode options for different PTT requirements
u Automatic pause generation after access code
u Temporary MF select via keyboard
u 36 digit LNR (Last Number Redial)
u 20 memories addressable with direct keys and the
2nd key or indirect with a MEM key
u Notepad
u Serial interface to display driver AS2590
u Consistent, simple and useable procedures
u Input for dial tone recognizer
General Description
The AS2574B is an integrated CMOS device for feature
telephones. It is a very versatile LD/MF dialler with serial
interface to a display driver. The device is designed to be
used in a wide variety of applications together with the
companion display driver, AS2590.
The on chip RAM can contain up to 20 memories (each
with maximum 18 digits), a 36 digit Last Number Redial
(LNR) and an 18 digit notepad. Access to the 20 memo-
ries is either with direct keys, abbreviated dial code or a
combination of both. The AS2574B provides a unique
feature, Automatic Call Progress (ACP), on all memory
keys, i.e. the circuit automatically seizes the line and
waits for the dial tone and dials the number just by
pressing any of the memory keys (including LNR).
The circuit features 2 different access code procedures
to allow easy use under a PABX. A dial tone input
enables the use of a dial tone recognizer.
Application
High feature telephone sets.
Package
Available in 28 pin DIP and PLCC.
Direct wake-up is an AMS patented
solution providing line seizing with
a telephone, that is entirely
powered from the telephone line,
by pressing a key in a key matrix
connected to a dialler/controller
that is constantly connected to the
line by means of a line voltage
limiter and yet maintaining a high
dc isolation resistance in idle state
(on-hook).
The wake-up feature allows the
user to go off-hook by pressing a
direct memory key or a
loudspeaker key, so-called on-
hook dialling or call progress
monitoring, and thereby seize the
line.
La
Lb
E
MODE
ACP
M/B
MS
Flash
Ground
Loop
1
2
3 ENTER M1 M5
4
5
6
R M2 M6
7
8
9 2ND M3 M7
*
0
# MUTE M4 M8
LS LNR M9 MEM M10
ER
DP
R1
VDD
R2
HS
R3
MASK
R4
TONE
R5
C6
OSC1
C5
C4
OSC2
C3
C2
TB
C1
A S 2 5 7 4 B_CD
Vss
MT
SCL
MR
SDA
LS
681kHz
DISPLAY
VDD
SDA
MS
SCL
V23
X1
V13
VLCD
X2
BIAS
Vss
32.768kHz
SPEECH
LOUDHEARING
HANDSFREE
TONE RINGER
Rev. 1
1
Jan. 1995