Datasheet AS2536T, AS2536P, AS2535T, AS2535P, AS2534ET Datasheet (Austria Mikro Systeme International)

1

Rev. 7

July 1998

Data Sheet AS2533...6

Multi-Standard CMOS Single Chip

Telephone IC with Dual Soft Clipping

®

Austria Mikro Systeme International AG

Package

Available in 28 pin SOIC or DIP.

LINE ADAPTATION

POWER EXTRACTION

DC MASK

DIALLER

SOFT CLIP

AGC

LI STB

RI

LINE

CURRENT

SENSE

V

DD

CS

LS

MUTE

RO

M1

M2

Z

BAL

V

DD

MO

FCI

MELODY

SEQUENCER

RING

FREQUENCY

DISCRIMINATION

CONTROL

LOGIC

HS/DP

C4C3C2C1

R4
R3

R2

R1

3.58

MHz

OSC

Vss

A

GND

La

Lb

LLC

RAM

OSC

LLC Hi
LLC Lo
LLC Off

AS253x

MODE

MFL

TONE

GENERATOR

A

GND

LED

Z2

Z1

CI

KEY

PAD

Key Features

❑ Line/speech circuit, LD/MF repertory dialler and

tone ringer on one 28 pin CMOS chip

❑ Operating range from 13 to 100 mA (down to 5 mA

with reduced performance)

❑ Soft clipping to avoid harsh distortion
❑ Volume control of receive signal
❑ Line loss compensation selectable by pin option
❑ Low noise (max. - 72 dBmp)
❑ Real or complex impedance
❑ NET 4 compatible
❑ LD/MF switchable dialling
❑ Pacifier tone during programming
❑ 31 digit last number redial
❑ Repertory memories (not AS2534), 4 direct/10

indirect (AS2533/6), 12 direct (AS2535)

❑ Repeat dialling by busy or engaged (not AS2535)
❑ Sliding cursor protocol with comparison
❑ Pause key for access pause or wait function
❑ 3 flash keys, 100 ms, 280 ms and 375/600 ms
❑ On chip MF filter (CEPT CS 203 compatible)
❑ Ring frequency discrimination
❑ 3-tone melody generator

Block Diagramme

General Description

The AS253x is a CMOS integrated circuit that contains
all the functions needed to form a high performance
electronic telephone.

The device incorporates LD/MF repertory dialling, melody
generation, ring frequency discrimination and a high
quality line/speech circuit.

A RAM is on chip for a 31 digit last number redial and
memories (not AS2534) each containing up to 21 digits/
data. The sliding cursor procedure makes the LNR
function easy to use under various PABX systems. Also
centrex keys (not AS2535) are provided.

The device incorporate a volume control for the earpiece.
The volume can be controlled by the VOL key (+ 5.4 dB)
or by the –/+ keys (+8.1 dB/-5.4 dB in 5 steps).

The versatility of the circuit is provided by pin options
and a few external components. This allows easy
adaptation to different PTT requirements.

2

Rev. 7

July 1998

Data Sheet AS2533...6

Pin Description

Pin # Symbol Function

23 M1 Microphone Inputs
24 M2 Differential inputs for the microphone (electret).

3ROReceive Output

This is the output for driving a dynamic earpiece with an impedance of 140 to 300 Ω.

5A

GND

Analogue Ground

This is the analogue ground for the amplifiers.

28 RI Receive Input

This is the input for the receive signal.

6 STB Side Tone Balance Input

This is the input for side tone cancellation.

1LSLine Current Sense Input

This is the input for sensing the line current.

27 LI Line Input

This input is used for power extraction and line current sensing.

25 CS Current Shunt Control Output

This N-channel open drain output controls the external high power shunt transistor for the
modulation of the line voltage and for shorting the line during make period of pulse dialling.

4VDDPositive Voltage Supply

This is the supply pin for the circuit.

26 V

SS

Negative Power Supply

8MOMelody Output

PDM output of the melody generator for tone ringing. Hi-Z when not active.

21 FCI Frequency Comparator Input

This is a Schmitt trigger input for ring frequency discrimination. Disabled during off-hook.

10 HS/DP Hook Switch Input and Dial Pulse Output

This is an I/O that is pulled high by the hook switch when off-hook and an open drain pulls
it low during break periods of pulse dialling and flash.

11 OSC Oscillator Input

Pin for ceramic resonator (3.58 MHz). Recommended: Murata CSA 3.58MG312AM.

9 LLC Line Loss Compensation

Select pin for line loss compensation (see also figure 4 to 7).
LLC = A

GND

: 20 - 50 mA LLC = VDD: 45 - 75 mA LLC = VSS: none.

22 LED LED Output Driver

Output for driving an LED that will be flashing when in Programme/Mute state.

Continues…

3

Rev. 7

July 1998

Data Sheet AS2533...6

Pin Description cont´d

Pin # Symbol Function

12 MODE Signalling Mode Select Input

Mode pin Function
Open Dialling inhibited
Row 1 LD mode, 10 pps, 33/66 ms
Row 2 LD mode, 10 pps, 40/60 ms
Row 3 LD mode, 20 pps, 33/66 ms
Row 4 LD mode, 20 pps, 40/60 ms
Row 5 LD mode, 10 pps, 33/66 ms, Temp. MF with tone on first * key entry
Row 6 MF only, 82/82 ms
Row 7 MF only, 82/160 ms

During temporary MF: 82/160 ms

20 R1 Keyboard Rows
19 R2 (see key arrangement in figure 2)
18 R3
17 R4

16 C1 Keyboard Columns
15 C2 (see key arrangement in figure 2)
14 C3
13 C4

7CIComplex Impedance Pin

For complex impedance a capacitor should be connected to this pin.

2 MFL MF Level Setting

A voltage divider connected from this pin to A

GND

and VSS can be used to set the DTMF

level.

Selection Overview

Function AS2533 AS2534B AS2534E AS2535 AS2536

Direct memories (one-key) 4 0 0 12 4
Indirect memories (two-key) 10 0 0 0 10
Repeat dialling yes yes yes no yes
LNR key yes yes yes yes yes
Pause insertion by LNR key yes yes yes yes yes
Pause (PS) key yes yes yes no yes
P/M or MT key P/M P/M MT P/M P/M
Tone/Pulse (T/P) key yes yes yes no yes
Temperary MF by * key yes yes yes yes yes
Centrex (A - D) keys yes yes yes no yes
Volume (VOL, –/+) keys yes yes yes yes yes
Volume reset by off-hook yes no no yes no
Programming of tone ringer yes yes no yes yes
R3 Flash duration 600 ms 600 ms 375 ms 600 ms 600 ms

4

Rev. 7

July 1998

Data Sheet AS2533...6

Keyboard Connections

Key closure, RON max. = 1 kohm
Key open, R

OFF

min. = 1 Mohm

(Either VOL or +/– keys)

PP//M

M

1

1

2

2

3

3

4

4

5

5

6

6

7

7

8

8

9

9

0

0

*

*

#

#

RR1

1

RR2

2

RR3

3

LLNNR

R

VVOOL

L

+

+

–

–

A

A

B

B

C

C

D

D

RRP

P

PPS

S

TT//P

P

C1 C2 C3 C4

R1

R2

R3

R4

Figure 2b (AS2534)

PP//M

M

1

1

2

2

3

3

4

4

5

5

6

6

7

7

8

8

9

9

0

0

*

*

#

#

RR1

1

RR2

2

RR3

3

LLNNR

R

VVOOL

L

+

+

–

–

A

A

B

B

C

C

D

D

RRP

P

PPS

S

TT//P

P

MM1

1

MM2

2

MM3

3

MM4

4

C1 C2 C3 C4

R1

R2

R3

R4

MMR

R

Figure 2a (AS2533/6)

For AS2534E
P/M is MT key.

5

Rev. 7

July 1998

Data Sheet AS2533...6

Power On Reset

The on chip power on reset circuit monitors the supply
voltage (VDD) during off-hook. When VDD rises above
approx. 1.2V, a power on reset occurs which clears the
RAM.

DC Conditions

The normal operating range is from 13 mA to 100 mA.
Operating range with reduced performance is from 5 mA
to 13 mA (parallel operation). In the operating range all
functions are operational.

At line currents below 13 mA the AS253x provides an
additional slope below 4.5V in order to allow parallel
operation (see figure 13).

The dc characteristic (excluding diode bridge) is
determined by the voltage at LI and the resistor R1 at line
currents above 13 mA as follows:

VLS= VLI+ I

LINE

⋅R1

The voltage at LI is 4.5V in the normal operating range.
During pulse dialling the speech circuit and other part of

the device not operating is in a power down mode to
save current. The CS pin is pulled to VSS in order to turn
the external shunt transistor on to keep a low voltage
drop at the LS pin during make periods.

AC Impedance

The ac impedance of the circuit is set by external
components. The impedance can be real or complex.
The ac impedance is determined as follows:

Z

AC

= 33•Z1

The dc value of Z1 should be 30 Ω to maintain correct dc
performance.

Return loss and side tone cancellation can be determined
independant of each other.

Speech Circuit

The speech circuit consists of a transmit and a receive
path with dual soft clipping, mute, line loss compensation
and sidetone cancellation.

Transmit

The gain of the transmit path is 37 dB for 600 Ω line
termination from M1/M2 to LS (see test circuit figure 10).

Keyboard Connections Continued (Either VOL or +/– keys)

Figure 2c (AS2535)

PP//M

M

1

1

2

2

3

3

4

4

5

5

6

6

7

7

8

8

9

9

0

0

*

*

#

#

RR1

1

RR2

2

RR3

3

LLNNR

R

VVOOL

L

+

+

–

–

MM1

1

MM2

2

MM3

3

MM4

4

MM5

5

MM6

6

MM7

7

MM8

8

MM9

9

MM110

0

MM111

1

C1 C2 C3 C4

R1

R2

R3

R4

MM112

2

6

Rev. 7

July 1998

Data Sheet AS2533...6

Line Loss Compensation

The line loss compensation is a pin option. When it is
activated, the transmit and receive gains are decreased
by 6 dB at line currents from 20 to 50 mA when LLC = A

GND

and 45 to 75 mA when LLC = high (@ R1 = 30 Ω). The
line loss compensation is disabled when LLC = low (see
figure 4 and 5).

Dialling Functions

Valid Keys

The key scanning is enabled when HS/DPN is pulled
high and VDD is above V

REF

. A valid key is detected from the
keyboard by connecting the appropriate row to the
column (RON < 1 kΩ). This can be done using an n x m
keyboard matrix with single contacts. Four diodes are
used to extend the number of rows (see keyboard
arrangement fig. 2). It is also possible to connect a
µcontroller to the rows and columns (see application
note AN3010).

P/M and MT Key

The P/M key (not AS2534E) is used to enter the
Programme/Mute state and the MT key for muting
(AS2534E only). Depressing the P/M key mutes the
speech circuit and the device is in programme state.
Repressing the P/M key deactivates the mute and
programme state (toggle function).The MT key works in
a similar way, but has no programme function.

When programme/mute is activated, the LED indication
is turned on (flashing: 80 ms 'on' and 1 sec 'off').

Dial Mode Selection

The default mode (LD or MF) can be selected by the
mode pin. When default LD mode is selected, a temporary
change to MF can be invoked by pressing T/P key (not
AS2535) or the * key (when mode pin = row 5, the MF
tone is generated with the first * key entry). The circuit
will revert to LD by repression the T/P key (not AS2535)
or by pressing the R (R1, R2 or R3) key or by next on­hook.

When MF mode is selected by the mode pin, the circuit
can not be changed temporary to LD but will remain in
MF mode.

Centrex Keys (not AS2535)

The alphameric keys accommodate easy use of centrex
services. The A, B, C and D keys are only valid in MF
mode (including temporary MF) and are not storable.
Pressing one of these keys will invoke the appropriate
MF tones to be transmitted.

The microphone input is differential with an input
impedance of 20 kΩ.

The soft clip circuit limits the output voltage at LI to 2V

PEAK

(see figure 12). The attack time is 30 µs/6 dB and the
decay time is 20 ms/6 dB. When mute is active, during
dialling or after pressing the P/M key, the gain is
reduced by > 60 dB.

Receive

The gain of the receive path is 3 dB for 600 Ω line
termination (test circuit figure 10). The receive input is
the differential signal of RI and STB. When mute is active
during dialling the gain is reduced by > 60 dB. During
DTMF dialling a MF comfort tone is applied to the
receiver. The comfort tone is the DTMF signal with a
level that is -30 dB relative to the line signal.

The receive gain can be changed by pressing the
volume keys. The VOL key gives a +5.4 dB boost and
has a toggle function, i.e. repressing the key resets the
gain to default. As an alternative the +/– keys can be
used. The + key increases the gain by 8.1 dB in 3 steps
and the – key decreases the gain by 5.4 dB in 2 steps
(total range 13.5 dB). On AS2533/5 the volume is reset
to default by next off-hook and on AS2534/6 the volume
setting will remain at last setting. A POR will always reset
the volume to default.

The soft clip circuit limits the voltage at the receive
output (RO) to 1V

PEAK

(see figure 11). It prevents harsh

distortion and acoustic shock.

Sidetone

A good sidetone cancellation is achieved by using the
following equation:

Z

BAL

Z

LINE

=

Z

2

Z

1

The sidetone cancellation signal is applied to the STB
input.

Z

LINE

Z1

Z2

Z

BAL

Figure 3

Side Tone Balance

7

Rev. 7

July 1998

Data Sheet AS2533...6

The centrex keys are not stored in the RAM, and
subsequently entered digits are buffered in FIFO.

Last Number Redial

LNR is a facility that allows resignalling of the last
manually dialled number without keying in all the digits
again. The LNR is repeatable after each off-hook.

The current content of the RAM is overwritten by new
entries.

A manually entered number is automatically stored in
the LNR RAM. The capacity of the RAM is 31 digits. If a
number greater than 31 digits is entered, the LNR facility
will be inhibited (until new entries < 32 digits) and further
entries will be buffered in FIFO.

Pauses can be inserted by pressing the PS key (not
AS2535).

Post dialled digits, i.e. digits manually entered after LNR
has been invoked, are not stored in RAM but buffered in
FIFO.

Repeat Dialling (not AS2535)

The last manually dialled number can be repeated
without going on-hook by pressing the RP key. If a
called number is engaged, pressing the RP key will
break the line for 1.6 second (to get a new dial tone) and
after a pause the number will be repeated.

The repeat function is enabled when prior to pressing
the RP key, a number has been dialled, and it can be
invoked an unlimited number of times until next on-hook.
During the 1.6 second break the device is in power down
mode to save current.

Recall Function

A recall (R1, R2 or R3 key) activation will invoke a flash
(timed loop break), however, the R1 flash is never
executed in LD mode. R2 and R3 will be executed
independent of the mode.

If recall is the first entry in a digit string, it will be stored
in LNR RAM when digit(s) are entered after the recall.

If the recall key is depressed after a digit string has been
entered or dialled out, the recall will not be stored but
buffered in the FIFO together with subsequently entered
digit.

If pressing the recall key is not followed by digit entries,
the LNR RAM remains intact.

After a recall a 270 ms pause will automatically be
executed.

Memory Keys (not AS2534)

The keys M1 to M12 are direct memory access keys and
the MR key (AS2533/6 only) is used for abbreviated
dialling.

Memory arrangement AS2533/6 AS2534 AS2535
Storable numbers 14 0 12
Direct memory keys 4 0 12
Indirect memories 10 0 0

In the on chip RAM, numbers can be stored. Each
number can contain up to 21 digits (including pauses).

During programming multiple pauses can be inserted by
pressing the PS (not AS2535) or the LNR key. Each
pause inserted within the first 5 entries will automatically
be terminated after 2 seconds whereas pauses inserted
after location 5 in a digit string will halt dialling and can
be terminated manually by pressing the PS (not AS2535)
or the LNR key. The halt function allows in-dialling to an
extention on a PABX.

Example (45678–123 is stored in M1, where – is a
pause/wait and 123 the extention number):

off-hook, wait for dial tone
press M1 (45678 is dialled out)
await dial tone from called PABX
press PS or LNR (123 is dialled out).

Memory dialling is cascadable. However, the content of
one memory must be dialled out before a new can be
invoked.

Sliding Cursor Procedure

To accommodate easy and uncomplicated redialling
(LNR) behind a PABX, a sliding cursor protocol is
implemented. If new entries match the previous RAM
contents, pressing the LNR key will dial out the remaining
digits.

If there is an error in matching, the LNR will be inhibited
until next on-hook, and the RAM will contain the new
number.

Example (LNR content 912345, where 9 is access
code):

off-hook, wait for PABX dial tone
press 9 and wait for external dial tone
press LNR (12345 will be dialled out).

Tone Generator

The tone generator incorporates the DTMF tones, 3
basic frequencies for the tone ringer and pacifier tones.

8

Rev. 7

July 1998

Data Sheet AS2533...6

DTMF

The DTMF generator provides 8 frequencies, namely:
Low group

Digit 1-2-3-A 697 Hz
Digit 4-5-6-B 770 Hz
Digit 7-8-9-C 852 Hz
Digit * -0-# -D 941 Hz

High group

Digit 1-4-7- * 1209 Hz
Digit 2-5-8-0 1336 Hz
Digit 3-6-9-# 1477 Hz
Digit A-B-C-D 1633 Hz (not AS2535)

The MF output level can be set with an external voltage
divider on pin MFL.

Voltage at pin MFL (2) DTMF Level (Low Group)

1.50 V (A

GND

) -4.0 dBm

1.27 V -5.2 dBm

1.15 V -6.4 dBm

1.03 V -7.6 dBm

0.90 V -8.8 dBm

0.70 V -10.0 dBm

0.54 V -11.2 dBm

0.42 V -12.4 dBm

0.30 V -13.6 dBm

0.18 V -14.8 dBm

0.00 V (VSS) -16.0 dBm

(Z

LINE

= 600 ohm)

The preemphasis is 2.6 dB.
The MF tones are according to CEPT recommendations.

Tone Ringer (Melody/Volume)

The three basic frequencies of the melodies are:
F1 = 800 Hz, F2 = 1067 Hz, and F3 = 1333 Hz (± 5%).
The repetition rate and the volume of the tone ringer

melodies can be programmed by pressing P/M and #
followed by a digit as follows (not AS2534E):

Digit Repetition Rate Volume

1 1 time (50 ms pause) - 16 dB
2 1 time (50 ms pause) - 7 dB
3 1 time (50 ms pause) 0 dB (max.)
4 4 times - 16 dB
5 4 times - 7 dB
6 4 times (default) 0 dB (max.)
7 10 times - 16 dB
8 10 times - 7 dB
9 10 times 0 dB (max.)
0 None Off

The procedure is ended by repressing the P/M key.
The default setting is digit 6, i.e. after a power on reset

the device will start up with repetition rate 4 and maximum
volume. If digit 0 is programmed, the tone ringer will be
turned off until next off-hook where it will turn back to the
last setting before 0. The programmed settings are
stored in the on chip RAM.

Repetition rate means that a sequence of 6 frequencies
is repeated 1, 4 or 10 times within 1 second.

The sequence of the frequencies is controlled by the
sequence register as follows:

Sequence F1 F2 F3 F1 F2 F3 …

The AS2534E is fixed to default settings and can not be
programmed to other settings.

Pacifier Tone

By MF dialling the DTMF tones are provided to the
earpiece as comfort tone.

During programming a key entry is acknowledged by a
pacifier tone of 1477 Hz. The level of the pacifier tone is
approximately 60 mV at the RO output. The duration is
40 ms after every key entry in programme mode.

When terminating the programme mode with the P/M
key an acknowledge tone of 140 ms is provided. An
invalid key entry, however, will cause a termination of
the programme mode indicated by a rejection tone of 4

times 40 ms with 28 ms pauses between the tone bursts.

Ring Frequency Discrimination

The ring frequency discriminator assures that only signals
with a frequency between 13Hz and 70 Hz are regarded
as valid ring signals. The time for recognising a valid ring
signal is 1/f seconds, where 'f' is the ring frequency.

When a valid ring signal is present for 73 ms continuously,
the melody generator is activated and remains active as
long as the ring signal is present.

Once the melody generator has been started, the ring
signal is continuously monitored and the melody
generator is instantly turned on or off according to the
momentary presence of a valid or unvalid ring signal
respectively (until next POR or off-hook).

9

Rev. 7

July 1998

Data Sheet AS2533...6

Typical Characteristics of Line Loss Compensation

Fig. 4

20 30 40 50 60 70 80

29

30

31

32

33

34

35

(dB)

Tx Gain

(mA)

DC Line
Current

LLC = V

SS

LLC = A

GND

LLC = V

DD

f = 800 Hz
Z

LINE

= 600Ω

V

LS

= -10 dBm

Fig. 5

20 30 40 50 60 70 80

-2

-1

0

+1

+2

+3

+4

(dB)

Rx Gain

(mA)

DC Line
Current

LLC = V

SS

LLC = A

GND

LLC = V

DD

f = 800 Hz
Z

LINE

= 600Ω

V

LS

= -10 dBm

VOL = 0 dB (neutral)

10

Rev. 7

July 1998

Data Sheet AS2533...6

AC Model of Speech Circuit

Figure 8

+

Z

LINE

30Ω

300Ω

Z

BAL

(10 x Z

LINE

)

RI

LI

CS

CI

STB

RO

COMFORT

TONES

DTMF

M1

M2

Z

SYN

(970Ω)

Z

REF

32.3 x Z

REF

–

+

–

+

–

+

–

+

20 k

20 k

8 k

80 k

0 dB

–

+

LLC & SC

LLC &

VOLUME

26dB

10dB

23dB12dB

PRIVACY

MUTE

SC

11

Rev. 7

July 1998

Data Sheet AS2533...6

Typical Application

Complex Impedance
(270 Ω + 750 Ω // 150 nF)

Figure 9

Only the components
necessary for
presenting the
complete functions of
the AS253X are
included.

The external components
might change to comply
with various national PTT
regulations and to interface
to different transducers.

Since the AS253x is a
component and not a complete
system, it can not be approved
as a stand alone part by the
standard bodies. Hence, full
conformance to any standards
is depending on the application
in which the AS253x is being
used, and therefore, approvals
by the standard bodies are the
responsibility of the customer
and Austria Mikro Systeme will
not have tested the product to
meet specific standards.

For further application
information please refer to
application note AN2201.

LINE ADAPTATION

POWER EXTRACTION

DC MASK

DIALLER

SOFT CLIP

AGC

R1

30 Ω

LI

STB

RI

LINE

CURRENT

SENSE

V

DD

CS

LS

MUTE

RO

M1

M2

1k8

V

DD

MO

18V

10 µF

FCI

MELODY

SEQUENCER

RING

FREQUENCY

DISCRIMINATION

470 µF

CONTROL

LOGIC

HS/DP

C4

C3

C2

C1

R4

R3

R2

R1

100 k

3.58

MHz

OSC

Vss

A

GND

2k2

0.68 µF

LLC

5M1

RAM

5V1

220 k

220 k

300Ω

OSC

330 k

LLC Hi

LLC Lo

LLC off

AS253x

100 µF

470 k

220 k

10 n

MODE

100 µ

10 µ

1 µ

2k2

1k8

1k8

10 n

10 n

4148

R5

10 k

10V

1 M

10 µF

MFL

TONE

GENERATOR

A

GND

LED

CI

BC547

47 k

2SA1209

BC327

2N5551

KEY

PAD

(see fig. 2)

7k5

10 n

15 n

100 k

56 k

300Ω

12

Rev. 7

July 1998

Data Sheet AS2533...6

Operating Procedures

Procedure Principles

The procedures for utilizing the features of the AS253x are optimized out of consideration for the human factor in
order to:

- meet the user´s expectations

- be easy to learn and relearn

- not invoke any automatic functions which the user doesn´t expect

- protect the user from committing critial errors, e.g. dialling wrong numbers, deleting stored numbers, etc.

- be consistent, simple and usable.
The following pages describe the operating procedures for the provided features. Pressing an unvalid key or key

combination during programming will cause the device to abort the programme state. Pressing any key
combination or sequence which is not described or defined may cause the device to enter a state or mode that
does not comply with the expectation of the user. In such cases, any undesired state can be terminated at any time
by going on-hook / off-hook which will generate a functional reset.

Idle (on-hook,
no ringing)

Speech mode

Programming

False programme
entry

Invalid entry

TEXT

State according
to text

Privacy mute

X

sec

or

Time out (x sec.)

Dialling
(LD or MF)

Storing (writing
into RAM)

Processing
according to text

TEXT

reading from
memory

KEY

Going off-hook

Going on-hook

Pressing a key

Entering a
number

Entry according
to text

TEXT

Symbols

STATES

ENTRIES PROCESSING

13

Rev. 7

July 1998

Data Sheet AS2533...6

Programming Tone Ringer

(not AS2534E)

P/M

P/M

M1-12

Programme State
Speech circuit muted
LED flashing

#

Storing

Numbers

Any invalid key

entry will abort

programme

state

MR

Storing

Numbers

Digit Repetition Rate Volume
1 1 time (slow) - 16 dB
2 1 time (slow) - 7 dB
3 1 time (slow) 0 dB (max.)
4 4 times - 16 dB
5 4 times - 7 dB
6 4 times (default) 0 dB (max.)
7 10 times (fast) - 16 dB
8 10 times (fast) - 7 dB
9 10 times (fast) 0 dB (max.)
0 None Off *

*) When digit 0 (tone ringer off) has been programmed,
the device will automatically return to the previous
setting (different from 0) by next off-hook.

14

Rev. 7

July 1998

Data Sheet AS2533...6

Temporary MF

RAM

FIFO

FIFO

R

R

D

FIFO

EXIT FIFO

Pressing any other
key does not
change the state.

*

*

T/P

T/P

T/P

MODE pin connected
to row 1, 2, 3, 4 or 5

When MODE pin = row 5, pressing the * key
also transmits the tone by MF select.
The T/P key (not AS2535) can be used
alternatively to
the * key.

15

Rev. 7

July 1998

Data Sheet AS2533...6

Storing Numbers (not AS2534)

P/M

P/M

M1-12

MR

0 - 9

Programme State
Speech circuit muted
LED flashing

#

Programming

Tone Ringer

Melodies

Any invalid key

entry will abort

programme

state

Entries (0-9, *, #, PS or LNR, R1, R2,
R3) will be written directly into the
selected memory location

Key entries different to the procedure will be ignored.
Exit programme mode from each state with on-hook
or with the P/M key.

16

Rev. 7

July 1998

Data Sheet AS2533...6

Automatic Dialling

or

M1-12

0 - 9

Postdialled digits are not stored
but buffered in FIFO

MR

LNR

17

Rev. 7

July 1998

Data Sheet AS2533...6

Timing Diagrammes

LD Dialling

MUTE
MASK

HS/DPN

t

IDP

t

PDP

t

M

t

IDP

t

B

t

B

t

M

t

PDP

t

B

t

M

MUTE
MASK

HS/DPN

t

IDP

t

PDP

t

M

t

IDP

t

B

t

B

t

M

t

PDP

t

B

t

M

t

AP

LD Dialling With Access Pause

MUTE
MASK

HS/DPN

TONE

t

TD

t

TD

t

TD

t

ITP

t

ITP

t

ITP

t

AP

MF Dialling

Continues....

18

Rev. 7

July 1998

Data Sheet AS2533...6

Flash

MUTE
MASK

HS/DPN

t

M

t

FD

t

M

t

PFP

t

M

t

FD

t

M

RP key

MUTE

DIALLING

HS/DPN

Power

Down

Number

engaged

New

connection

t

RP

t

AP

Repeat Dialling (not AS2535)

19

Rev. 7

July 1998

Data Sheet AS2533...6

Electrical Characteristics

Absolute Maximum Ratings

Positive Supply Voltage.................................................................................................................. -0.3V ≤ V

DD

≤ 7V

Input Current ............................................................................................................................................... ± 25 mA

Input Voltage (LS) ......................................................................................................................... -0.3V ≤ VIN ≤ 10V

Input Voltage (LI, CS)...................................................................................................................... -0.3V ≤ VIN ≤ 8V

Input Voltage (STB, RI) ......................................................................................................... -2V ≤ VIN ≤ VDD + 0.3V

Input Voltage (MO) ......................................................................................................................-0.3V ≤ VIN ≤ +35V

Digital Input Voltage ............................................................................................................-0.3V ≤ VIN ≤ VDD + 0.3V

Electrostatic Discharge................................................................................................................................ ± 1000V

Storage Temperature ..................................................................................................................... -65°C to +125°C

Recommended Operating Conditions

Supply Voltage * (Speech Mode) ....................................................................................................... 4V ≤ VDD ≤ 5V

Oscillator Frequency (Resonator: Murata CSA 3.58M G312AM) ..............................................................3.58 MHz

Operating Temperature ...................................................................................................................- 25°C to +70°C

* This voltage is generated internally

DC Characteristics (I

LINE

= 15 mA unless otherwise specified)

Symbol Parameter Conditions Min Typ M ax Units

I

DD

Operating Current Speech mode 3 5 mA

MF dialling 4 mA
LD dialling, VDD = 2.5V 200 µA
Ring mode, VDD = 2.5V 300 µA

I

DD0

Retention Current Idle mode, VDD = 2V 0.05 µA

T

AMB

= 25°C

V

LI

Line Voltage (default) 13 mA ≤ I

LINE

≤100 mA 4.5 V

I

OL

Output Current, Sink VOL = 0.4V 1.5 mA
CS, HS/DP, MO

I

OL

Output Current, Sink; LED VOL = 0.4V 4 mA

V

IL

Input Low Voltage HS/DPN; FCI V

SS

0.3 V

DD

V

T

AMB

= 25°C

V

IH

Input High Voltage HS/DPN; FCI 0.7 V

DD

V

DD

V

T

AMB

= 25°C

20

Rev. 7

July 1998

Data Sheet AS2533...6

AC Characteristics (I

LINE

= 15 mA; f = 800 Hz unless otherwise specified)

Tx Transmit Test Circuit Fig. 10

A

TX

Gain, Transmit M1/M2 to LI 35.1 36.6 38.1 dB

∆A

TX/F

Variation with Frequency f = 500 Hz to 3.4 kHz ±0.8 dB

THD Distortion VLI ≤ 0.25V

RMS

2%

V

AGC

Soft Clip Level VLI =2V

PEAK

A

SCO

Soft Clip Overdrive 20 dB

t

ATTACK

Attack Time 30 µs/6 dB

t

DECAY

Decay Time 20 ms/6dB

Z

IN

Input Impedance (M1/M2) 20 kΩ

A

MUTE

Mute Attenuation Mute activated 60 dB

V

NO

Noise Output Voltage T

AMB

= 25°C -72 dBmp

V

IN Max

Input Voltage Range Differential ±1 V

PEAK

(M1/M2) Single Ended ±0.5 V

PEAK

BJT Output Driver

V

IN MAX

Input Voltage Range (LI) ±2 V

PEAK

V

TX

Dynamic Range ±2 V

PEAK

RL Return Loss ZRL=1000Ω; T

AMB

= 25°C18 dB

∆Z

AC/TEMP

Temperature Variation 0.5 Ω/°C

Rx Receive Test Circuit Fig. 10

A

RX

Receive Gain (Vol. default) LI to RO 1.5 3 4.5 dB

A

VOL

Volume Gain VOL key +5.4 dBr

A

VOL

Volume Gain –/+ keys -5.4/+8.1 dBr

∆A

RX/F

Variation with Frequency f = 500 Hz to 3.4 kHz ±0.8 dB

THD Distortion VRI ≤ 0.25V

RMS

2%

V

AGC

Soft Clip Level VRO =1V

PEAK

A

SCO

Soft Clip Overdrive 10 dB

t

ATTACT

Attact Time VRI > 0.8V

RMS

30 µs/6 dB

t

DECAY

Decay Time 20 ms/6dB

V

NO

Noise Output Voltage T

AMB

= 25°C -72 dBmp

V

UFC

Unwanted F. Components 50 Hz....20 kHz -60 dBm

Z

IN

Input Impedance (RI) 8 kΩ

V

IN RI

Input Voltage Range (RI) ±2 V

PEAK

A

ST

Sidetone Cancellation VRI ≤ 0.25V

RMS

26 dB

V

IN ST

Input Voltage Range (STB) ±2 V

PEAK

Z

IN

Input Impedance (STB) 80 kΩ

Symbol Parameter Conditions Min T y p Max Units

21

Rev. 7

July 1998

Data Sheet AS2533...6

AC Characteristics (cont´d) (I

LINE

= 15 mA; f = 800 Hz unless otherwise specified)

Symbol Parameter Conditions Min T yp M ax Units

Keyboard

t

D

Key Debounce Time 15 ms

HS/DPN Input

t

HS-L

Low to High Debounce Going off-hook 15 ms

t

HS-H

High to Low Debounce Not LD dialling 210 ms

During LD dialling 270 ms

DTMF

F Frequency deviation Note 5 1.2 %

V

MF

MF Tone Level (Low group) MFL = A

GND

- 2.5 - 4 - 5.5 dB

MFL = V

SS

- 14.5 - 16 - 17.5 dB

∆V

L-H

Preemphasis Low to High 1.8 2.4 3.0 dB

V

UFC

Unwanted F. Componets 300 Hz...5 kHz -40 dBm
Note 3; MFL = V

SS

5 kHz...14 kHz -50 dBm

14 kHz...28.5 kHz -70 dBm

28.5 kHz...40 kHz -80 dBm

t

TD

Tone Duration Note 1&6; Mode=row 6 or 7 80 82.3 85 ms

t

ITP

Inter Tone Pause Note1; Mode=row 6 80 82.3 85 ms

t

ITP

Inter Tone Pause Note 1 & 6; Mode=row 7 150 165 170 ms

t

TR

Tone Rise Time Note 2 5 ms

t

TF

Tone Fall Time Note 2 5 ms

LD

t

DR

Dial Rate Mode = row 1, 2 or 5 9.53 10 10.5 pps

Mode = row 3 or 4 19.05 20 21 pps

t

/B

Break Period Mode = row 2 57 61.2 63 ms

t

/B

Break Period Mode = row 4 28.5 30.6 31.5 ms

t

/B

Break Period Mode = row 1 or 5 63 66 69 ms

t

/B

Break Period Mode = row 3 31.5 33 34.5 ms

t

M/

Make Period Mode = row 2 38 40.8 42 ms

t

M/

Make Period Mode = row 4 19 20.4 21 ms

t

M/

Make Period Mode = row 1 or 5 31.5 33 34.5 ms

t

M/

Make Period Mode = row 3 15.7 16.5 17.3 ms

t

PDP

Pre-Digit Pause 35 ms

t

IDP

Inter Digit Pause Mode = row 1, 2, 3, 4 or 5 800 840 880 ms

t

HS-H

High to Low Debounce During LD dialling 270 ms

t

MO

Mute Overhang t

M

22

Rev. 7

July 1998

Data Sheet AS2533...6

Symbol Parameter Conditions Min Typ Max Units

t

FD

Flash Duration 1 R1 key 100 102 ms
Flash Duration 2 R2 key 270 300 ms
Flash Duration 3 R3 key (AS2533/4B/5/6) 600 650 ms

R3 key (AS2534E only) 312 375 450 ms

t

PFP

Post Flash Pause 274 ms

t

AP

Access Pause Note 8 2.0 2.05 2.12 sec

t

RP

Repeat Break Time 1.6 sec

Tone Ringer

V

MO

Melody Output PDM

t

MD

Melody Delay 10 ms
F1 Frequency 1 800 Hz
F2 Frequency 2 1067 Hz
F3 Frequency 3 1333 Hz
t

DT

Detection Time Initial 1/f + 73ms s
t

TO

Detection Time-out note 4 ms
f

MIN

Min. Detection Frequency 13 Hz
f

MAX

Max. Detection Frequency 70 Hz

Pacifier Tone Programme Mode Only
f

PT

Frequency P/M mode, key entry 1477 Hz
V

RT

Level (RO) Key entry 60 mV
t

RTD-E

Duration, Key Entry Valid key entry, prog. 40 ms
t

RTD-A

Duration, Acknowledge Terminate with P/M key 140 ms
t

RTD-R

Duration, Reject Invalid key entry, note 7 4x40 ms

LED Output

t

LED-ON

"on-time" P/M state 80 ms
t

LED-OFF

Interval P/M state 1 sec

Comfort Tone (DTMF)

V

CT

Level (RO) Relative to LS -30 dBr

Note 1: The values are valid during automatic dialling and are minimum values during manual dialling, i.e. the tones will

continue as long as the key is depressed.
Note 2: The rise time is the time from 10% of final value till the tone amplitude has reached 90 % of its final value.
Note 3: Relative to high group.
Note 4: The FCI circuit is reset by POR and HS/DPN pulled high (off-hook). After a reset the FCI circuit is in a standby state. A

positive edge on FCI will start a 73 ms timer and the frequency discrimination is initiated. Whenever a period of the ring

signal is missing, the timer is reset. When a valid ring signal is present for 73 ms, the melody generator is started and is

directly controlled by the ring signal. This condition will remain until a new reset.
Note 5: This does not include the frequency deviation of the ceramic resonator.
Note 6: During temporary MF mode.
Note 7: An invalid key entry in programme mode will invoke a tone sequence with 4 tone bursts of 40 ms and pauses between

bursts of 28 ms and abort the programme mode.
Note 8: Pauses inserted within the first 5 entries of a digit string will be automatically terminated after 2 seconds. Pauses

inserted after location 5 can only be terminated manually by pressing the PS or LNR key.

23

Rev. 7

July 1998

Data Sheet AS2533...6

Test Circuit

Figure 10

5V6

100 µ

LS

1

28

6

RI

STB

LI

CS

27

25

26

2

Vss

MFL

FCI

21

M1

M2

23

24

3

22

RO

LED

10

HS/DP

5

A

GND

MO

V

DD

8

4

C1C2C3C4R1R2R3

R4

16

15

14

13

20

19

18

17

12

MODE

OSC

CI

LLC

11

7

9

MULTI-STANDARD

SINGLE CHIP TELEPHONE

22 µ

30 Ω

300 Ω

6 k

10 µ

1 µ

BC 327

3.58 MHz

10V

150 Ω

I

LINE

B

U

L

600 Ω

A

100 µ

AS253x

100 µ

10 n

24

Rev. 7

July 1998

Data Sheet AS2533...6

Fig. 11 Receive Soft Clipping and Distortion Fig. 12 Transmit Soft Clipping and Distortion

1009080706050403020100

0

1

2

3

4

5

6

7

8(V)

VLS

VLI

(mA)

Line Current

Typically
No ac signals
Tamb: 25°C

Fig. 13 DC Mask

Characteristic Curves (Typical)

2,001,751,501,251,000,750,500,250,00

0,0

0,2

0,4

0,6

0,8

1,0

1,2

0

1

2

3

4

5

6

7

8

9

10

11

12

Line Input Voltage (LS)

Receive Output Voltage (RO)

Distortion

(Vp) (%)

(Vp)

Line Current: 20 mA
Frequency: 800 Hz
Tamb: 25°C
Typically

soft clipping

VRO

THD

1501251007550250

0,0

0,5

1,0

1,5

2,0

2,5

0

1

2

3

4

5

6

7

8

9

10

Microphone Input Voltage (M1/M2)

Line Output Voltage (LS)

Distortion

(Vp)

(mVp)

VLS

THD

Line Current: 20 mA
Frequency
Tamb: 25°C
Typically

soft clipping

(%)

25

Rev. 7

July 1998

Data Sheet AS2533...6

Pin Configuration

28 Pin SOIC (suffix T)

1
2
3
4
5
6
7
8
9
10
11
12
13
14

28
27
26
25
24
23
22
21
20
19
18
17
16
15

LS

MFL

RO

V

DD

A

GND

STB

CI

HS/DP

MO

LLC

MODE

C4

C3

C2

RI
LI
V

SS

CS
M2
M1
LED
FCI
R1

OSC

R2
R3
R4

AS253x

C1

28 Pin DIP (suffix P)

1
2
3
4
5
6
7
8
9
10
11
12
13
14

28
27
26
25
24
23
22
21
20
19
18
17
16
15

AS253x

LS

MFL

RO

V

DD

A

GND

STB

CI

MO

LLC

HS/DP

OSC

MODE

C4
C3

RI
LI
V

SS

CS
M2
M1
LED
FCI
R1
R2
R3
R4
C1
C2

Ordering Information

Device Package Memories Volume Centrex Special keys

AS2533 T 28 pin SOIC 4 direct/10 indirect yes, note 1 A B C D P/M, LNR, R1-3, MR, RP, PS, T/P
AS2533 P 28 pin DIP 4 direct/10 indirect yes, note 1 A B C D P/M, LNR, R1-3, MR, RP, PS, T/P
AS2534B T 28 pin SOIC none yes, note 2 A B C D P/M, LNR, R1-3, RP, PS, T/P
AS2534B P 28 pin DIP none yes, note 2 A B C D P/M, LNR, R1-3, RP, PS, T/P
AS2534E P 28 pin DIP none yes, note 2 A B C D MT, LNR, R1-3, RP, PS, T/P
AS2534E T 28 pin SOIC none yes, note 2 A B C D MT, LNR, R1-3, RP, PS, T/P
AS2535 T 28 pin SOIC 12 direct yes, note 1 no P/M, LNR, R1-3
AS2535 P 28 pin DIP 12 direct yes, note 1 no P/M, LNR, R1-3
AS2536 T 28 pin SOIC 4 direct/10 indirect yes, note 2 A B C D P/M, LNR, R1-3, MR, RP, PS, T/P
AS2536 P 28 pin DIP 4 direct/10 indirect yes, note 2 A B C D P/M, LNR, R1-3, MR, RP, PS, T/P

Conditions for delivery as dice see also data sheet AS2533/4B/5/6-CX.
Note 1: volume is reset to default by on-/off-hook and by POR

Note 2: volume is reset by POR only.

Devices sold by Austria Mikro Systeme/Thesys are covered by the warranty and patent idemnification provisions appearing in its Term of Sale. Austria Mikro Systeme/Thesys makes no warranty,
express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the decribed devices from patent infringement. Austria Mikro Systeme reserves
the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with Austria Mikro Systeme for current
information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability
applications, such as military, medical life-support or life-sustaining equiment are specifically

not

recommended without additional processing by Austria Mikro Systeme/Thesys for each application.

Copyright © 1995-8, Austria Mikro Systeme International AG, Schloss Premstätten, 8141 Unterpremstätten, Austria. Trademarks Registered ®. All rights reserved. The material herein may not be
reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner.

The information furnished here by Austria Mikro Systeme/Thesys is believed to be correct and accurate. However, Austria Mikro Systeme/Thesys shall not be liable to recipient or any third party
for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any
kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of Austria Mikro
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