Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 1 of 18
austriamicrosystems
General Des cription
The AS254 0 is a CMOS int egrated ci rcuit that
incorpo rates a speec h circui t (line-a daptation, 2/4-wire
convers ion, separ ate Rx- a nd Tx-ampl ifiers f or handset
and modem ), MF dial ler, ri ng frequenc y detecto r, ring
melody ge nerator an d a two wi re serial i nterface . It
shall act as an a/b-line-powered device in order to
interface a main-p owered CP U to the anal ogue
telephon e line.
AS2540 ca n operate in a so-cal led mainpow er mode
and in a backup mod e. During mainpowe r mode, a
watchdo g timer is r unning on AS25 40, which h as to be
reset vi a the seri al interface, which is c onnected to the
CPU thro ugh opto -couplers. During back up mode ( =
The main-power failure or SW engine problem),
AS2540 ca n operate as an indepe ndent basic MF
dialler (digits 0-9*#)
Applications
- Web Tel ephones
- Answering Machines
- Fax Machines
- Base Stati on of Co rdless Tel ephones
- Hospital Communica tion Units
Key Feature s
- Line Int erface, Sp eech Circ uit, MF Di aller and To ne Ringer
on a 28 pi n CMOS chip
- Programm able via 2 -wire s erial int erface
(UART 9 600 baud, 8 N1)
- Watch do g timer for B ackup Mode
- Additional input fo r modem trans mit path
- Additional output fo r modem recei ve path
- CMOS for hi gh EMC i mmunity
- Low Noi se (max. –72 dBm)
- Operating range from 15mA to 100mA (down to 5mA with
reduced performa nce)
- Soft clip ping for h andset oper ation to avoid harsh dis tortion
- Line loss compensati on selectabl e by pin option
- Real an d complex i mpedance sel ectable by external
components
- Side tone adaption s electable by external c omponents
- Ring frequency discrimination
- 3-tone ring melo dy generat or
Package
- 28 pin SOI C
- Dice-on-Foil
Block Diag ram
LS
ROH
ROT
M1
M2
TIT
AGND
Line LI
RI
STB
CS
CI
DPn
C1
C2
C3
R1
R2
MODE
RFD
-2d B
+6dB
+2dB
Mask
DTMF-
generator
DIALLER UART
STIT
SROH
SROT
SMUTE
Dial
Digit
SMASK
SDPn
MO
RxD
TxD
VDD
EHS
MHS
VSS
OSC
Main Power Mode
LS
ROH
ROT
M1
M2
TIT
A
GND
Line LI
RI
STB
CS
CI
DPn
C1
C2
C3
R1
R2
MODE
RFD
-2dB
+6dB
+2dB
Mask
DTMF-
generator
DIALLER UART
STIT
SROH
SROT
SMUTE
Dial
Digit
SMASK
SDPn
MO
RxD
TxD
VDD
EHS
MHS
VSS
OSC
Backup Mode
Remote Controlled Single-Chip-Telephone
AS2540 DATA SH EET (PRELIMI NARY)
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 2 of 18
Pin Descripti on
Pin # Symbol Function
15 RFD Ring Fre quency Discrimination
Schmitt trigger i nput for ri ng freque ncy discri mination. Di sabled du ring off-ho ok.
7LS
Line Current Sense In put
Input f or sensing t he line cu rrent
5LI
Line Input
Input us ed for powe r extractio n and lin e current se nsing
6RI
Receive Input
Input f or ac-sepa rated recei ve signal
2STB
Side Tone Balance Input
Input for s ide ton e cancellatio n network
3CS
Current Shunt Control Output
N-chan nel open d rain output t o control t he extern al high pow er shunt t ransistor f or synthesi sing ac- and
dc- impedanc e, modulation of line voltage and shorti ng the line du ring make periods of p ulse dialling
8CI
Complex Impedance In put
Input pi n for the c apacitor t o program a c omplex i mpedance
16 DPn Dial Pulse Outp ut
Open drain output pulls low during break periods of pulse dialling and flash
17 EHS Electronic Hook Switch
Schmitt T rigger Input to detect an electroni c off-hook .
18 MHS Manual Hook Switch
Schmitt T rigger Input to detect a manual off -hook.
19 MODE DTMF Level Selection
-4/-6dBm —> DLS open
-6/-8dBm —> DLS-r1
-8/-10dBm —> DLS-r2
Line Loss Compensa tion Select Pin
45mA-75mA —> LLC op en
20mA-50mA —> LLC-r3
None —> LLC-r4
28 MO Ring Mel ody Output
PDM output of the ring melody generator.
11 VDD Voltage Drai n Drain
Positive Power Supply
4 VSS Voltage Sou rce Source
Negative Power Supply
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 3 of 18
Pin # Symbol Function
25 OSC Oscillator Input
Input f or ceramic resonato r 3.58MHz.
Recomme nded type: Mu rata CSA 3.58MG312AM or compati ble
12 AGND Analogue Ground
Special ground for the inter nal amplifie rs
26 RXD Receive Data Input
Schmitt trigger i nput to seri al interface
27 TXD Tra nsmit Dat a Output
Open drai n output f rom serial i nterface
20
21 R1
R2 Keyboard Rows
22
23
24
C1
C2
C3
Keyboard Columns
10 ROT Receive Output to Transformer
Output f or driving a transforme r with an ac i mpedance l arger than 10kΩ
1TIT
Transfo rmer Input f rom Transformer
Single end ed input f or transf ormer
9ROH
Receive Output to Handset
Output f or driving a dynamic ea rpiece wit h an impedanc e from 1 50Ω to 300Ω
13
14 M2
M1 Micropho ne Inputs
Differe ntial inputs for the microphon e (electre t)
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 4 of 18
Functional Description
Modes of operation
There a re 4 possibl e modes:
Idle Mode
Manual hook -switch and elect ronic hook-switch (e.g. rel ay)
is open ( MHS ∩ EHS = l ogical 0) , no ring sig nal is appli ed,
the oscillator is st opped, signalling via the serial interface
is not pos sible.
Ringing Mode
AS2540 is s upplied vi a the rin g capacitor and exter nal
path, m anual hook -switch and electroni c hook-swi tch is
open (MH S ∩ EHS = logical 0), the oscillator is running, a
valid i ncoming rin ging is si gnalled via the serial interface to
the CP U. If the CP U does not reply the AS 2540 switc hes
into back up mode an d sends a rin g melody t o the MO
output.
Backup Mode
Manual h ook-switc h and/or el ectronic ho ok-switch is closed
(MHS ∪ EHS = logi cal 1), AS 2540 is suppl ied with li ne
current, the oscillator is running, the keyscan is enabled
and the ha ndset path is switched on, signalling via th e
serial in terface is possible. After AS2540 has starte d
dialling i n backup mode, he must not be int errupted any
more in order to e nsure consis tent diall ing. A mode
transiti on BM -> MPM is only poss ible befo re AS2540 has
started dialling digits i ndependently.
Main Power Mode
Manual h ook-switc h and/or el ectronic ho ok-switch is
closed, AS2540 is sup plied with line curre nt (MHS ∪ EHS
= logical 1), th e oscillator is running, the keyscan is
disabled , AS2540 is c ontrolle d via the s erial int erface,
handset path or moni tor path or modem path is on,
signall ing via the s erial inte rface is p ossible.
Select Operation Mode
Command Message Switches O N Switches OFF
<SetHandsetP ath> SROH SROT & STIT
<SetModemPa th> SROT & STIT
<SetMonit orPath> SROH & SROT STIT
Example Main Power Mode
LS
ROH
ROT
M1
M2
TIT
A
GND
Line LI
RI
STB
CS
CI
DPn
C1
C2
C3
R1
R2
MODE
RFD
-2dB
+6dB
+2dB
Mask
DTMF-
generator
DIALLER UART
STIT
SROH
SROT
SMUTE
Dia l
Digit
SM A SK
SDPn
MO
RxD
TxD
VDD
EHS
MHS
VSS
OSC
Start-up in backup mode
As soon as AS2540 is s upplied with l ine cur rent, the
external Vdd capacitor will be cha rged up via t he LI and
VDD pin and after t he Vdd voltage has reached the
operati ng level, t he handset p ath of the s peech circ uit is
switched o n. This off -hook status is also si gnalled to t he
internal l ogic via the MHS or EHS pin in ord er to start t he
pinscan and subseq uently set the country sp ecific modes .
Additional ly a <LineEv ent> message i s sent to t he CPU.
Start-up in ring mode
When a ri nging sig nal is applie d to the li ne, Vdd of AS254 0
is char ged up via an external path. After Vdd has reache d
the operating voltage the oscillator starts and AS2540
discrimi nates the ri ng frequ ency. Afte r a valid ri ng
frequenc y is appli ed on the RFD pin, the logic sends a
<LineEvent> message i s sent to th e CPU and a w atchdog
timer is started. Wh en the <Lin eEvent> messag e is not quit
by the C PU before t he watchdog timer has finished th e
countdo wn, AS2540 cha nges into b ackup mode and sends
out a mel ody via the MO pin.
DC conditions
The nor mal operating mode is fro m 15mA to 10 0mA. An
operating mode with re duced performance is from 5mA to
15mA. I n the line h old range fr om 0mA to 5mA the devic e
is in a power down mode and t he voltage a t LI is red uced
to a maximum of 3.5V
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 5 of 18
The DC ch aracteristi c is det ermined by the voltage at LI
pin and a 30Ω resistor b etween LI a nd LS pin. I t can be
calculate d by the foll owing equati on: VLS = VLI + ILine *
30Ω. The t.m. v oltage at t he LI pin is 4.5V. The c alculation
leads t o the follo wing DC res istances: 330Ω to 75Ω at line
currents f rom 15mA to 100mA.
2/4 wire conversion
AS2540 has a built-i n dual Wheats tone brid ge with on e
common ground. This provides a maximum of
independ ence of AC i mpedance and side tone f rom each
other. One can adapt side tone wi thout chan ging the A C
impedance.
A1=3.4/3.5 A2=-0.4
AC impedance
The ac i mpedance of AS 2540 is se t to t.m. 100 0Ω. With
the exte rnal capac itor at CI pi n it can be program med
complex. With a paral lel impedanc e at the L S pin it ca n be
program med to 600Ω.
Side Tone
A good sid etone cancel lation can be achiev ed by using t he
following equation:
ZBAL/ZLINE = 10
Transmit path
The gain o f the M1/ M2 —> LS trans mit path is s et to 38dB
for ac-i mpedance 1000Ω. The inp ut is differe ntial with an
impedance of 25kΩ. The s oft clip ci rcuit limits the output
voltage at LS to 2Vp. Th e attack time is 30µs/6dB and th e
decay time is 20ms/6dB.
The gain o f the TIT —> LS transmit path is se t to 8dB for
ac-imped ance 1000Ω. T he input is single ende d with an
impedance of 25kΩ. The s oft clip circuit i s not active f or
this inp ut. The dyna mic range of t his path is 2.5Vp at LS.
Receive path
The gain o f the LS —> ROH recei ve path is s et to 2dB fo r
ac-imped ance 1000Ω. T he receive i nput is the differenti al
signal of RI and STB. During DTMF dialling a MF comfort
tone is ap plied to ROH which is -30dB rel ative to t he line
level. The soft clip circuit limits the output voltage at ROH
to 1Vp. It p revents hars h distortion and acousti c shock.
The gain o f the LS —> ROT receive path is set t o 0dB for
ac-imped ance 1000Ω. T he receive i nput is the differenti al
signal o f RI and STB. T he soft cli p circuit is not active for
this outpu t.
Modescan
The DTMF -level on the line an d the functi on of the li ne loss
compensati on can be s elected wi th the con nection of t he
MODE-pin to the keyboa rd matrix. T he MODE-pi n is
scanned o nce after eac h OFF-Hook transitio n.
R1 1
PIN
C1
2 3
R2 4 5 6
7 8 9
* 0 #
PI
N
C2 PIN
C3
PIN
R1
PIN
R2
PIN
MODE
c1 C2 C3
C3 C2 C1 R2 R1 LLC Dtmf L evel
45mA-75mA -6dBm
XX45mA-75mA -8dBm
X45mA-75mA -10dBm
X20mA-50mA -6dBm
X20mA-50mA -8dBm
XX 20mA-50mA -10dBm
XX No LLC -6dBm
XX No LLC -8dBm
XXX No LLC -10dBm
X indicates connection to pin mode
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 6 of 18
Serial interface
The com munication p rinciple is derive d from a s tandard UA RT:
- Baud Rate 9600
- Start Bit 1
- Data Bits 8
- Parity None
- Stop Bit 1
- LSB is transferred prior to MSB
Rx - messages
Message F ormat
X
MSB Xd5d4d3d2d11
LSB
d7 d6 d5 d4 d3 d2 d1 d0 DTMF-dia l message Notes
xx010101 Digit 0 Starts DTMF dialling of digit
xx000011 Digit 1 Starts DTMF dialling of digit
xx000101 Digit 2 Starts DTMF dialling of digit
xx000111 Digit 3 Starts DTMF dialling of digit
xx001001 Digit 4 Starts DTMF dialling of digit
xx001011 Digit 5 Starts DTMF dialling of digit
xx001101 Digit 6 Starts DTMF dialling of digit
xx001111 Digit 7 Starts DTMF dialling of digit
xx010001 Digit 8 Starts DTMF dialling of digit
xx010011 Digit 9 Starts DTMF dialling of digit
xx010111 Digit * Starts DTMF dialling of digit
xx000001 Digit # Starts DTMF dialling of digit
xx011001 Digit A Starts DTMF dialling of digit
xx011011 Digit B Starts DTMF dialling of digit
xx011101 Digit C Starts DTMF dialling of digit
xx011111 Digit D Starts DTMF dialling of digit
xx100001 KeyReleased Stops Dialling
d7 d6 d5 d4 d3 d2 d1 d0 Pin-Con trol message Notes
xx101101 SetDPn_ HIGH Release pi n Dpn ( open drain)
xx100011 SetDPn_LOW Force pin DPn = VSS
xx100101 SetMas k Force LI -Voltage to 1.2 V
xx100111ResetMask
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 7 of 18
d7 d6 d5 d4 d3 d2 d1 d0 Pin-Con trol message Notes
xx101111 SetTestmode FOR FACTORY TEST ONLY
xx101001 MuteON Mute Tra nsmit path
xx101011 MuteOFF
d7 d6 d5 d4 d3 d2 d1 d0 Path -Control message Notes
xx110011 SetHandsetPath
xx111011 SetMonitorPath
xx110101 SetModemPath
xx110001 RequestS tatus AS2540 se nds Status in formation
xx110111reserved <LineEvent>
xx111001reserved <LineEvent>
xx111101reserved <LineEvent>
xx111111reserved <LineEvent>
Tx messages
<Ack> message
<Ack> message format for <RequestS tatus>
b7
MSB b6b5b4b3b201
LSB
b7b6b5 b4b3b2 b1 b0 Status Remark
10 1 valid ring signal detected
00 1 no ring signal
10 1 manual hook switch - off-hook (pin MHS)
00 1 manual hook switch - on-h ook (pin MHS)
10 1 el ectronic hook switch - of f-hook (pi n EHS)
00 1 el ectronic hook switch - on -hook (pi n EHS)
Status of AS2540
0000 1 no L LC comparator .............. .......
0010 1 LLC comparator 20mA (45mA ) ...
0100 1 LLC comparator 26mA (51mA ) ...
0110 1 LLC comparator 32mA (57mA ) ...
1000 1 LLC comparator 38mA (63mA ) ...
1010 1 LLC comparator 44mA (69mA ) ...
1100 1 LLC comparator 50mA (75mA ) ...
coded sta tus of
LLC com parator
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 8 of 18
<Line Event> Message
<LineEven t> message fo rmat
b7
MSB b6b511111
LSB
b7b6b5 b4b3b2 b1 b0 Status Remark
11 1 1 10 1 valid ri ng signal d etected
01 1 1 10 1 no ring signal
11 1 1 10 1 manual hook switch - off-hook (pin MHS)
01 1 1 10 1 manual hook switch - on-hook (pin MHS)
11 1 1 10 1 electroni c hook switc h - off-hook (pin E HS)
01 1 1 10 1 electroni c hook swi tch - on-h ook (pin E HS)
Status of AS2540
Protocol
Line Events
AS2540 has 3 inputs, namely MHS (Manual Hook Switch),
EHS (Electronic Hook Switch) and RFD (Ring Frequency
Detecto r), which s ense the sta te of the two hook-s witches
and disc riminate a n applied ri ng signal . The MHS is
connected to the manu al hook swi tch which i s operated by
the hands et and the E HS is conn ected to an el ectronic
hook swi tch which i s operated by the CPU. W henever t he
state of these inputs c hanges, AS2 540 immedia tely sends
<LineEvent> to the CP U after a d ebounce tim e. MHS and
EHS up-de bouncing lasts 15ms , down-deb ouncing las ts
85ms. RF D start to discriminat e the ring frequency
immediately but will send a <LineEvent> message with a
delay of 1 02ms. A stat us change o f MHS and EHS pi ns
must not change the m omentary s elected path of the
speech ne twork.
The <Lin eEvent>-mess age is sent without cons ideration of
the moment ary activiti es of AS2540 in order to meet PTT
requirements (e.g. line break signalling). The code for the
<LineEvent> -message i s chosen wi th regar d to the
minimum c urrent cons umption i n order to op erate the
optocoupl ers. Pending <Ack>-mess ages will be queued
after the <LineEvent>- message. An already runni ng
transmissions of <Ack> will not be interrupted and
<LineEvent> will be sent afterwards in this case.
- Mode transitions Idle →
→→
→ BM →
→→
→ MPM →
→→
→ Idle
AS2540 al ways starts u p in backu p mode and is prepared
to act li ke an indep endent dialle r. <LineEven t> is sent to
the CP U and AS2540 remains in back-up mode until any
valid message is sent from the CPU. This makes sure that
a non-operable CPU does not disable basic dialling
functions.
- Mode transition MPM →
→→
→ BM
A watchd og timer is s tarted af ter <LineEve nt> and is res et
wheneve r AS2540 rec eives a mess age from the CPU vi a
the serial interf ace. If the CPU does no t send any f urther
valid mess age withi n 2400ms, AS2 540 goes b ack into
back-up mode, immediately locks the UART and remains in
backup mode till next on-hook.
Dialling Functions
DTMF
The DTMF generat or provides 8 frequenc ies (in Hz):
1
1
1
697+1209 2
2
2
697+1336 3
3
3
697+1477
4
4
4
770+1209 5
5
5
770+1336 6
6
6
770+1477
7
7
7
852+1209 8
8
8
852+1336 9
9
9
852+1477
*
*
*
941+1209 0
0
0
941+1336 #
#
#
941+1477
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 9 of 18
The MF output level s are set to -4/-6dB which shoul d allow
efficien t backup dial ling unde r all line c onditions. T he
TONE/PA USE ratio is 90ms/90ms. Th e preemphas is
betwee n low group and high grou p frequenci es is t. m.
2.6dB.
FLASH timing
CPU can control th e DPn pin and the MASK-m ode of
AS2540 via serial i nterface.
Tone Ringer
Ring frequency discrimination
The ri ng frequency discrimin ation assures that only signals
with a f requency b etween 13Hz a nd 70Hz are regar ded as
valid ring signals.
When a v alid ring si gnal is pr esent for 10 2ms contin uously,
the ring melody generato r is activated and remains active
as long as a valid ri ng signal is present .
Once the ring melody generator h as starte d, the rin g signal
is contin uously moni tored an d the ring mel ody gener ator is
instantly turned off accordin g to the mom entary pres ence
of a vali d or inval id ring si gnal until next off-ho ok.
Toner ringer melody
The 3 basi c melody frequencies are:
- F1=880Hz
- F2=1067Hz
- F3=1333Hz
The rep etition rate i s set to 4 whi ch means that the
sequence of F1, F2, F3, F1, F2, F 3 is repeat ed 4 times
within a second.
Keyboard connections
R1 1
PIN
C1
2 3
R2 456
789
*0#
PI
N
C2 PI
N
C3
PI
N
R1
PI
N
R2
PIN
MODE
c1 C2 C3
Double co ntacts unde r keys 0 -9*#: One contac t is
connected to AS2540, t he other on e to CPU.
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 10 of 18
Timing diagrams (unscaled)
Dialling - MF mode
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 11 of 18
Electrical ch aracteristi cs
Electrical characteristics are measured with the Test Circuit application. Typical mean values will not be tested.
Absolute maximum ratings
Positive S upply Volta ge -0.3V <= VDD <= 7V
Input Cu rrent +/- 25mA
Input Vol tage (LS) -0.3V <= Vin <= 10V
Input Vol tage (LI, C S) -0.3V <= Vin <= 8V
Input Voltage (STB, RI) -2V <= Vin <= VDD+0.3V
Digital Input Voltage -0.3V <= Vin <= VDD+0.3V
Electrostatic Discharge (HBM 1.5kΩ-100pF) +/- 800V
Storage T emperature -65°C to +125°C
Recommended operating conditions
Supply Voltage (generated internally) 3.6V <= VDD <= 5V
Oscillator Frequency
Resonator Murata CSA 3.5 8MG312AM 3.58MHz
Operatin g Temperatur e -15°C to +60° C
DC characteristics
ILine=15mA w/o operation of SI through optocouplers, unless other specified
Symbol Parameter Conditions Min Typ Max Units Test
IDD Operatin g Current Speech M ode
Speech M ode with SI
MF Dialling
LD Dialling, VDD=2.5V
Ring Mode, VDD=2.5V
3
5
4
200
300
5mA
mA
mA
µA
µA
Y
N
N
N
N
VLI Line Volta ge 15mA<=ILINE<=100mA 4.2 4.5 4.8 V Y
IOL Output Current, Sink CS,
DPn, MO
TXD VOL=0.4V
VOL=10mA 1
10 mA
mA N
N
IOH Output Current, Sourc e MO VOH=VDD-0.4V -1 mA N
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 12 of 18
Transmit characteristics
Symbol Parameter Conditions Min Typ Max Units Test
AMTX Transmi t Gain
M1/M2 —> LS ZAC(syn)=1000Ω+36.5 +38 +39.5 dB Y
ATTX Transmi t Gain
TIT —> LS ZAC(syn)=1000Ω+6.5 +8 +9.5 dB Y
THD Distortion VLS=0.25VRMS 2%Y
VAGC Soft Clip Level
M1/M2 —> L S at LS 2.0 VPN
ASCO Soft Clip Overdrive
M1/M2 20 dB N
ZIN Input Impe dance
M1/M2 - TIT 20 kΩN
VNO Noise O utput Voltage
LS TAMP=25°C -72 dBmp Y
RL Retur n Loss ZAC(syn)=1000Ω18 dB Y
Receive characteristics
Symbol Parameter Conditions Min Typ Max Units Test
AHRX Receive Gain
LS —> RO H ZAC(syn)=1000Ω+0.5 +2 +3.5 dB Y
ATRX Receive Gain
LS —> ROT ZAC(syn)=1000Ω-3.5 -2 -0.5 dB Y
Y
THD Distortion VLS=0.25VRMS 2%Y
VAGC Soft Clip Level
ROH 1VPN
ASCO Soft Clip Overdrive
ROH 10 dB N
VNO Noise O utput Voltage
ROH - ROT TAMP=25°C -72 dBmp Y
ZIN Input I mp. RI 8 kΩN
ST Sidetone VRI<=0.25VRMS 24 dB Y
RL Retur n Loss ZAC(syn)=1000Ω18 dB Y
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 13 of 18
LD characteristics
Symbol Parameter Conditions Min Typ Max Units Test
t(td) Fl ash Duration DPN pin s tatus ca n be directl y
control led via se rial inte rface
DTMF characteristics
Symbol Parameter Conditions Min Typ Max Units Test
VMFlow Tone Level Low Group
LS -6 dBm Y
∆VL-H Preemphasi s L-H 2.0 2.6 3.2 dB Y
UFC Unw anted Freque ncy
Components 300 Hz - 4.3kHz
4.3kHz - 7kHz
7kHz - 10kHz
10kHz - 14kHz
14kHz - 28.5kHz
28.5kHz – 40kHz
-40
-46
-52
-58
-70
-80
dBm
dBm
dBm
dBm
dBm
dBm
Y
Y
Y
Y
Y
Y
∆fFrequency Deviation 1.2 % Y
t(td) Tone Duration 80 82.3 85 ms Y
t(itp) Inte r Tone Paus e 80 82.3 85 ms Y
t(mo) Mute Ove rhang 6 ms Y
VCT-H Comfort To ne (DTMF ) ROH rel . to LS -30 dB N
Ringer characteristics
Symbol Parameter Conditions Min Typ Max Units Test
f1 Frequency 1 770 800 830 Hz Y
f2 Frequency 2 1025 1067 1110 Hz Y
f3 Frequency 3 1280 1333 1385 Hz Y
fMIN Min. Det. Frequency 12 13 14 Hz Y
fMAX Max. Det. Frequency 68 70 75 Hz Y
tDT Detection Time Initially 102 ms N
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 14 of 18
Serial Interface
Symbol Parameter Conditions Min Typ Max Units Test
tRXD-r RXD signal rise time Vdd=4V,RPull-up=1.2kΩ30 µsN
tRXD-f RXD signal fall time 30 µsN
Vcomp Input comparator level at
RXD Vdd/2 V N
BRRXD RXD baud rate +/-2% 9600 bps N
BRTXD TXD baud rate +/-2 % 9600 bps Y
Miscellaneous
Symbol Parameter Conditions Min Typ Max Units Test
tDKey Debo uce Time 15 ms N
ttime-out Watch-dog Tim er 2400 ms N
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 15 of 18
Typical Appl icati on
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 16 of 18
Test Circuit
R7
9k
C3
10u
AC
R5
100
R6
300
C9
100u
R11
330k
C4
100u
Y1
3.58MHz
C1 100n
R4
30
R10
330k
D1
10V
AC
D2
5V6
C11
10n
C7
1u
ILine
U1
AS2540
15
7
5
6
2
3
8
16
17
18
28
11
4
25
12
26
27
19
20
21
22
23
24
10
1
9
13
14
RFD
LS
LI
RI
STB
CS
CI
DPn
EHS
MHS
MO
VDD
VSS
OSC
AGND
RxD
TxD
MODE
R1
R2
C1
C2
C3
ROT
TIT
ROH
M1
M2
C5 100n
C8
10uR8
600
R1
330k
R9
6k
Q1
BC327
C6
100u
AC
R2
1k
C2 100n
R3
140
AS2540
C10
22u
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 17 of 18
Packaging
The devi ce is avail able in the packages o utlined belo w (not
to scale ). For exact mechani cal package di mensions
please s ee austria microsystems AG packaging informatio n.
28-pin plastic SOIC (suffix T)
Max. Body Length 18.1mm / 713mil
Max. Body Width 7.6mm / 30 0mil
Pitch 1.27mm / 50mil
Pin-out
1– TIT MO– 28
2– STB TxD– 27
3 – CS RxD – 26
4 – VSS OSC – 25
5– LI C3– 24
6 – RI C2 – 23
7– LS C1– 22
8 – CI R2 – 21
9– ROH R1– 20
10 – ROT MODE – 19
11 – VDD MHS – 18
12 – AGD EHS – 17
13 – M1 DPn – 16
14 – M2 RFD – 15
Marking
YYWWAAA
AS2540
Austria
YY year of production
WW calendar week of p roduction
AAA amsAG assembl y ID
Ordering Information
Number Package Description
AS2540T SOIC28 plastic sm all outline package -
28 leads (suffix T )
AS2540Q Dice-on-Foil dice
Devices sold by austriamicrosystems AG are covered by
the warr anty and p atent identi fication provi sions appe aring
in its Term of Sale. austriamicrosystems AG makes no
warranty , express , statutory, implied, or by descri ption
regardi ng the inf ormation set f orth he rein or reg arding the
freedom o f the desc ribed devic es from paten t infrin gement.
austriamicrosystems AG reserves the right to change
specific ations and prices at any time an d without noti ce.
Therefore, prior to designin g this product in to a system, it
is necessary to check with austriamicrosystems AG fo r
current i nformation. This prod uct is inte nded for use i n
normal c ommercial applicatio ns. Applicati ons requi ring
extended temperatu re range, unus ual environmental
requirements, or high reliability applications, such as
military, medical life-support or life-sustaining equipment
are speci fically not recomme nded witho ut additional
processing by austriamicrosystems AG for each
application.
Copyright
Copyright © 1997-2002, austriamicrosystems AG, Schloss
Premstaetten, 8141 Unterpremstaet ten, Austria-Europe.
Trademarks Registered ®. All rights res erved. The material
herein may not be r eproduced, ad apted, mer ged,
translate d, stored , or used wi thout the p rior writ ten consent
of the c opyright ow ner.
The information furnished here by austriamicrosystems AG
is believed to be correct a nd accurate. However,
austriamicrosystems AG shall not be liable to recipient or
any third party fo r any damages , includi ng but not li mited
to pers onal injury , property damage, loss of profits , loss of
use, inte rruption of business or indirect , special, i ncidental
or conse quential dam ages, of a ny kind, in c onnection wi th
or arisi ng out of t he furnishi ng, perform ance or us e of the
technical data herein. No obligation or liability to recipient
or any third party shall aris e or flow out of
austriamicrosystems AG rendering of technical or other
services.
Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 18 of 18
Contact
Headquarters
austriamicrosystems AG
Communic ations Busin ess Unit
A 8141 Sc hloss Premst ätten, Austri a
T. +43 (0) 3136 500 0
F. +43 (0) 3136 525 01
www.austriamicrosystems.com
Sales Offices
Germany
austriamicrosystems Germany GmbH
Tegernseer Landstrasse 85
D-81539 Münc hen, Germany
Phone: + 49/89/69364 3-0
Fax: +49/89/693643-66
France
austriamicrosystems France S.a.r.l.
124, Ave nue de Paris
F-94300 Vincennes, F rance
Phone: + 33/1/43 74 00 9 0
Fax: +33/1/43 74 20 98
Italy
austriamicrosystems Italy S.r.l.
Via Leon e Tolstoi, 64
I-20146 Mi lano, It aly
Phone: + 39/0242/367 13
Fax: +39/ 0242/29088 9
Switzerland
austriamicrosystems Switzerland AG
Rietstrasse 4
CH-864 0 Rappers wil, Swi tzerland
Phone: + 41/55/220 90 00
Fax: +41/55/220 9001
USA (we st)
austriamicrosystems USA, Inc.
Suite 116 , 4030 Moo rpark Ave,
San Jose, CA 95117, USA
Phone: + 1/408/345 17 90
Fax: +1/408/345 1795
USA (east)
austriamicrosystems USA, Inc.
Suite 400 , 8601 Six Fo rks Road
Raleigh, NC 27615, USA
Phone: + 1/919/676 52 92
Fax: +1/919/676 5305
United Kingdom
austriamicrosystems UK, Ltd.
Coliseum Business Centre, Watchmoor Park
Camberl ey, Surrey, G U15 3YL, U K
Phone: + 44/1276/23 3 99
Fax: +44/1276/29 3 53
Japan
austriamicrosystems AG
Shin Yokohama Daini, Center Bldg. 10F
3-19-5, Shin Yokohama
Kohoku-k u, Yokohama 222-0033, Japan
Phone: + 81/45/474 09 62
Fax: +81/45/472 9845
Distribu tors & Representative s
austriamicrosystems AG is represented by distributors in
the follo wing coun tries. Pleas e contact yo ur nearest
regional sales office for the distribut or address:
Spain, Is rael, Kore a, Hong-Kon g, Taiwan, M alaysia,
Singapore, India, Brazil
Application Support
Please c ontact your local sales office or y our distrib utor.
