ETC AS2522/AS2523/AS2524

austriamicrosystems
Handsfree Line Interface
Demoboard
AN523/24
Key Features
-
Complete handsfree telephone with AS2523/24 Line
Interface
Jumper selectable AC impedance
Easily configurable passive sidetone network on 8-pin
socket
PRELIMINARY APPLICATION NOTE
Applications
-
Feature handsfree telephones
AS2524 for handsfree telephones connected to a
standard dialer
AS2523 for handsfree telephones controlled via serial
interface.
General description
PTT spec conformity
This application note describes operation and features of
the AS2523 and AS2524 Handsfree Line Interface IC
including all external components necessary for the DB523
Demoboard, which is a handsfree telephone with a
standard dialer interface on AS2524 and a serial interface
on AS2523.
The application notes hereafter should be understood as
guidelines for other designs based on the AS252x circuit.
No guarantee can be given for completeness or full
conformity to PTT specification requirements. As
requirements differ from country to country, each required
parameter must be individually tested and adjusted, if
necessary.
Further guidelines for adjustment is given in the
documents, listed in other applicable documents and
papers.
Revision 1.01, Preliminary
Page 1 of 16
Application Note AN523/24
austriamicrosystems
Table of Contents
OTHER APPLICABLE DOCUMENTS AND PAPERS
3
Further Applications
3
REVISION STATUS
3
Revision history
3
Demo kit contents
3
GENERAL DESCRIPTION
3
Getting started
3
CONNECTOR AND JUMPER LOCATIONS
4
APPLICATION SCHEMATIC, ANALOG PART
5
DB523/24 DEMOBOARD: LAYOUT (TOP VIEW)
6
DB523/24 DEMOBOARD: COMPONENT PRINT
6
EXTERNAL COMPONENT SELECTION
7
Passive components
7
Transistors
7
COUNTRY SPECIFIC SETTINGS
7
Hardware and software settings
AC impedance
Sidetone cancellation
Sending and receiving frequency response
7
7
8
8
Adaption to pan-European regulations TBR21,EN301437,TBR38
Current limiter
AC impedance, Echo Return Loss
Sending and receiving Loudness ratings
Sidetone cancellation
8
8
8
8
9
Startup in speech mode
9
CONNECTING A MICROCONTROLLER
9
AS2523/24 BLOCK DIAGRAM
10
Signal truth table AS2523
11
Programming options
11
PROGRAMMING EXAMPLES
14
Going off-hook
14
Generating a flash
14
Generating a dial pulse
14
Muting the transmit and receive path
14
RELATED STANDARDS
15
APPROVALS
15
ORDERING INFORMATION
15
COPYRIGHT
15
CONTACT
16
SALES OFFICES
16
DISTRIBUTORS & REPRESENTATIVES
16
APPLICATION SUPPORT
16
Revision 1.01, Preliminary
Page 2 of 16
austriamicrosystems
Application Note AN523/24
Other applicable documents and
papers
General description
Data Sheet: AS2523/24 Handsfree Line Interface Circuit
Application Notes AN500-x: General analogue telephone IC
descriptions
Remark: all subsequent component numbering refers to
the application schematics, shown in pt. Application
Schematic.
Getting started
Further Applications
Applications based on the AS2523/24 are continuously
updated. Visit our home-page:
http: //www.austriamicrosystems.com
-
Revision status
AS2523/24 Datasheet
AN523/24 Application note (this document):
DB523/24 Demoboard schematic:
DB523/24 Demoboard layout
Rev.:
Rev.:
Rev.:
Rev.:
1.9
1.01
A01
A01
Revision history
Demoboard and Application note are the first Revision
Demo kit contents
The available demo-kit DB523/24 contains the following
parts:
AS2523/24 Single Chip Handsfree Phone Demoboard
DB523/24 “ready-to-go”
handset
handsfree microphone
application note AN523/24
AS2523/24 Datasheet
Revision 1.01, Preliminary
-
connect the handset (included in demo kit) to J2
select AC impedance (J23, J7)
connect the telephone line connector to J1
connect the handsfree microphone (included in demo
kit) to “HF mic”(J4), observe polarity: capsule case is
negative terminal
for realistic performance check, you may connect an
existing handsfree telephone with extended wires from
the internal handsfree microphone and loudspeaker
connect a 25…32Ω loudspeaker (not included in demo
kit) to “Speaker” (J11)
select line connector pins on J2,J5
operation in handset mode: activate hookswitch S1 on
left upper corner of PCB:
depressed position: on-hook, released position: offhook
operation in handsfree mode: toggle “h/free”-switch
SW2
Remark:
The hookswitch and handsfree functionality depends from
the controller on the digital interface (J25)
-
Page 3 of 16
austriamicrosystems
Application Note AN523/24
Connector and Jumper locations
Listed below are the various connectors and jumpers. The default settings are indicated in bold letters:
J1: line connector
J2,J5 [3,4]: line
input pin selector
J11: connect VSS
ringer to VSS
AS2523/24
[open/closed]
J24: VSS test pin
J23 [closed],J7[opend]: AC
impdeance setting:
J3[opend],J13[closed]:
enable/disable on-board
current limiter
C omplex / 600Ω
Ω
see table
LS1: loudspeaker
connector
J22:[open/closed]
enable/disable BNM
MIC1: handsfree
microphone connector
J22: Tone Input
connector
J25: Connector to
controler interface
J2: handset
connector
Figure 1: Connector and Jumper locations
Revision 1.01, Preliminary
Page 4 of 16
5
-
2 J2
D1
DSS301L
RO
3
4 J5
5
-
+
D2
BRIDGE
C 15 replaced
with a wire jumper
C15
n.c.
2
4
S1
3
6
1
5
7
8
HookSwitch1
4
R10
1M
LN_I
D3
4004
HS
R15
470k
D5
4004
HF
1
LS
7
6
8
D4
10V/1W
Q1
J3
MPSA92
LN_O
U2
HFI
HFO
OUT
Q4
2N5551
R9
10k
CTL
Q2
MPSA92
R7
100k
R16
82k
VCC
RSL
LFI
LFO
GND
R41
390k n.c.
J23
n
p
3
R11
300R
R22
18k
Q13
2N5551 n.c.
R21
10k
R17
2k7
J15
LK_10
X1
R48
18k n.c.
15nF
C22
R8
1k8
C12
100uF
C26
220nF
R32
390k
C33
620pF
Piezo
R5
30R
30
9
12
13
15
C5
10uF
C10
1uF
14
22
AS2523/24_sel
AS2523/24_sel
U1
LS
RI
2
LH/HF_Sel
TONE IN
M3
M1
M4
LI
LN_O
LN_O
RECI
LO
RECV
DI / xPD
xCS / xMUTE
CLK / HFI
TXO
TXV
Q9
R39
13R
29
28
M4
M3
7
5
RO
M2
M1
6
8
17
20
21
23
25
26
27
C31
33uF
cw
R1
2k2
R2
0R
J22
R6
2k
R12
8k2
cw
P2
25k
C21
22nF
P3
25k
TONE_IN
R3
1k2
R13
1k2
R20
680R
n.c.
C24
1
5
2
C1
220uF
R4
1k2
R14
1k2
3
C20
100uF 4
xCS/xMUTE
DI/xPD
CLK/HFI
Header26
2
4
6
8
10
12
14
16
18
20
22
24
26
1
Sheet
1
2
M-
LS1
Tele_Hand
M+
J4
HF MIC
J6
+
-
1
LH/HF_SEL
TONE_IN
Rev
A00
VPP
1
D
C
A
AS2523/24_sel B
2
LS2
J8
Speaker
J17
J18
LK_10
TIP
RING
of
DET1
J16
LK_10
1
Figure 2: Application Schematic, analog part
LH/HF_SEL
P1
25k
C7
100nF
C4
100nF
C2 cw
100nF
C6
n.c.
C8
15nF
C9
C11
10nF 15nF
J14
LK_10 100nF
C13
Rx offset
R26
0R
C19
22nF
J25
1
3
5
7
9
11
13
15
17
19
21
23
25
EC1 EC11 EC12
on the demoboard wired
jumpers are used
1nF 1nF 1nF instead
of 10R
resistors
for R29 R46 and R47
Burst protection
R29
10R
R46
10R
R47
10R
C23
100uF
J9
R49
47k
Tuesday, July 15, 2003
Document Number
(BGR) austriamicrosystems
J21
LK_10
VDD_uC
J19
LK_10
HF
HS
CLK/HFI
DI/xPD
DPN
FCI
xCS/xMUTE
VDD
VSS
Size
B
DB523
Date:
Title
Disable BNM
J13
R43
10k
Q12
BC327
C35
10uF/50V
R38
1k2
R40
LS
1k2
current limiter
for TBR21(optional)
C29 C30
22uF 1uF
RO
M2
AS2523/24
STB
CS
CI
SS
VPP
VDD
C28
100uF
BSS92 n.c.
Q6
VSS
VSSA
VPP
11
24
J24
VSS
VDD
C18
10nF
Q10
10
BC327
16
J7
Q11
BC327
C25
470uF
D8
1N4148 n.c.
C38
22uF n.c.
D10
5V1
D12
5V1 n.c.
LN_I
Hook transistor options:
Q7
LN_I2SA1625 n.c. LN_O
D11
12V n.c.
BC557
2
LINE
2
3
510k 4
5
R42
Sidetone Network
J1
Tele_Line
C17
+
C16
1000pF n.c.1000pF n.c.
2
DPN
Rx offset biasing
Rx offset
CBN
1
SW1
R25
1M
C32
100nF
R35
TXV
TXV
4
D
C
1
C36
MOSFET
TXO
3
FT1
2
VDD
18
R24
0R
wired jumper
R23
2k2/0.5W
R27
1.5Meg n.c.
C27
10uF/50V
R36
10k
C37
high gain PNP
transitor
AGND
AGND
19
R19
30k n.c.
R28
2k2
D7
27V
R31
330k
J11
4.7nF
Aktive HP
J12
Tx HP Filter
C36 is replaced
with a wired jumper
on the demoboard
J20
LK_10
VDD_uC
TXO
R44
390k n.c.
3
CTL
R30
330k n.c.
R34
330k n.c.
EC10
390k n.c.
CTL
BA8206
R18
30k n.c.
M3
D6
BRIDGE
EC9
4
AGND
RING
DET1
EC8
n.c.
R45
n.c.
1
2
3
4
CAS detection
(optional)
M2
LA
EC7
LB
TIP
VDD
LB
100nF
TONE
D9
27V n.c.
R33
330k n.c.
M4
FCI
EC6
1nF n.c.
C34
10nF n.c.
EC5
1nF/250V
R37
220k n.c.
EC4
1nF
5
LA
1nF/250V
C14
680nF/250V
1nF n.c.
LINE
uC ring detect circuit
(optional)
EC3
1nF n.c.
B
A
EC2
100nF 1nF
M1
Page 5 of 16
Revision 1.01, Preliminary
austriamicrosystems
Application Note AN523/24
Application Schematic, analog part
austriamicrosystems
Application Note AN523/24
DB523/24 demoboard: Layout (top view)
Figure 3: DB523/24 demoboard: Layout (top view)
DB523/24 Demoboard: Component Print
Figure 4: DB523/24 Demoboard: Component Print
Revision 1.01, Preliminary
Page 6 of 16
austriamicrosystems
Application Note AN523/24
External component selection
Passive components
All resistors can be ¼ Watt or less, except:
R5 (30Ω)
P= I Line ,max ² * 30Ω (e.g. 0.2W @ 80mA)
R38 and R40 (each 1k2 / 0.75W; TBR21 application only):
The maximum voltage rating for all caps is ≥6V DC, except:
C5 (10µ, RI input)
25V
C12 (10µ, AC impedance setting)
25V
C23 (100µ, speaker decoupling)
16V
C6,C7 (0.9µ ringer caps)
160V
C35 (10µ, TBR 21 application only)
50V
Transistors
Most transistors can be general purpose types. Their function and minimum requirements are shown in the table below:
Part Nr.
Q7(optional)
Type on
demoboard
2SA 1625K
function,
minimum requirements
pol.
PNP
hook transistor option: high voltage / high gain
equivalent type(s)
KSA 1625K
V CEO ,V CBO : ≥-200V; hFe ≥100; I C <-100mA
Q1,Q2
MPSA 92
PNP
hook transistor option: high voltage darlington
V CEO ,V CBO : ≥-200V; I C <-100mA
Q6 (optional)
BSS92
P-Ch
hook transistor option: VMOS,
MPSA 93,
KSP 92/93
BSP 92 (SMD)
enhancement V DS ≥-200V , I D <-100mA
Q4
2N5551
NPN
driver transistor for Q1,Q2
MPSA / KSP 42/43
V CEO ,V CBO : ≥200V IC ≈ 1mA
Q10, Q11
BC327-25
PNP
line shunt regulation and Vpp supply generation
various
general purpose.: V CE <-10V , hFe ≥160 I C <-100mA,
PD ≤450mW
Q13(optional)
2N5551
NPN
Q13: ringer startup; generate V DD from ringer signal;
if not limited by ext. zener diode after bridge RB2, maximum
voltage is the peak ringing voltage. High transient voltages may
occur during pulse dialing ( clamped by V1)
Q9, Q12
BC557
PNP
opt. current limiter
general purpose V CE <-10V
various
BC327-25
PNP
opt. current limiter
various
general purpose V CE <-40V , hFe ≥160 I C <-100mA
PD ≤450mW
Country specific Settings
Some analogue parameters however, require modifications
of external passive components. These are:
Hardware and software settings
AC impedance
Most parameters (timings, gains, etc.) can be changed by
software via the serial bus interface on AS2523. On
AS2524 the gains are fix programmed and can be adjusted
over external resistors in an easy way.
The internal AC impedance of the chip is 1000Ω./real.
By adding a capacitor at pin CI (#16), the synthesized
impedance becomes complex (close J7).
Revision 1.01, Preliminary
Page 7 of 16
austriamicrosystems
Application Note AN523/24
A parallel resistor (R8; DC-decoupled by C12) from pin LS
(#15) to V SS (#11,) lowers the total AC impedance in the
form of a parallel connection between
a) the IC’s impedance (1000Ω),
b) R9 (typ. 10kΩ) and
c) R8: R AC = 1k //R9//R8
Sending and receiving frequency response
Although transmit and receive gains can be set by
software, additional frequency shaping may be required
(depending on acoustic handset characteristics). This can
be done by modifying
¯
Example: To set an AC impedance of 600Ω, R8 must be
1,8kΩ (close J23 and open J7):
R AC = 1000Ω // 10kΩ // 1k8 = 600Ω
Remark: When a MOSFET (optional) hook transistor is
used, R9=10kΩ must be excluded from the calculation,
because it is not in parallel to the line: gate-source
resistance is high ohmic!)
On the demoboard, two jumpers, J23 and J7 are provided
to quickly change the AC impedance between 600Ω and
complex AC impedance. The table printed on the PCB
describes the setting:
-
For 600Ω, close J23 and open J7: R8 is connected to
LS and CI is left open
For complex impedance, open J23 and close J7: no
parallel resistor at LS, C12 connected to CI
Sidetone cancellation
For sidetone cancellation, a passive complex network
(R17,R21,C22) must be connected, which should be 10
times the value of the (complex) line termination for
sidetone measurements:
-
Sidetone network resistor values = 10 times of line
termination resistor values
Sidetone network capacitor value = 1/10 of line
termination capacitor value
¯
¯
Adaption to pan-European regulations
TBR21,EN301437,TBR38
The DB523/24 demoboard can be easily adapted to meet
the TBR21/38/EN301437 regulations. The main change is,
that a current limiter is required to meet the DC mask
requirements for this specification.
Current limiter
The current limiter must be connected between hook
transistor and pin LS (see schematic: optional current
limiter). This device is already installed on the demoboard,
but can be bypassed with jumper J3 (J13 = open).
To activate it, open J3 and close J13.
See also for pt. Related Standards links to the European
Telecommunications Standards Institute.
AC impedance, Echo Return Loss
Requirement: The AC impedance must be set to 1000Ω /
complex. Echo Return Loss must be ≥14dB @ Z REF (270Ω
+ 750Ω // 150nF)
⇒
⇒
Example: for a line termination of 270Ω + 750Ω // 150nF,
the equivalent sidetone network would be
(R17 + R21 // C22) = 2k7 + 7k5 // 15nF
If R8 is installed (e.g. for 600Ω impedance setting),
resistor R22 (= 10 times the value of R8) should be
connected in parallel to the sidetone network to
compensate for the additional load of R8
On the demoboard, an 8-pin DIP socket is provided for the
sidetone network to allow easy replacement of the
components.
Revision 1.01, Preliminary
C4, C5, C7, R6 for handsfree sending frequency
shaping
C8, C9, C11, R25 for handset sending frequency
shaping
R28, C26...27 for handset receiving frequency shaping
remove R8 and C12 (or open J23) and remove R22
short J7 (make sure C18 is 10nF)
⇒
Sending and receiving Loudness ratings
Requirement: SLR = +3 ±4dB, RLR = -8 ±4dB
With the included handset, the loudness ratings
requirements can be met by using the resistor and
capacitor values shown in the application schematic.
Remark: if necessary, handset Tx and Rx gains can be
adjusted by programming on AS2523. On AS2524 gains
must be adjusted with resistors. See pt. Signal truth table
AS2523.
Page 8 of 16
austriamicrosystems
Application Note AN523/24
Sidetone cancellation
Requirement: Sidetone cancellation is measured with 3
different terminations:
a) Zref = 82Ω + 600Ω // 68nF
STMR ≥ 5dB
b) Zref = 270Ω + 750Ω // 150nF
STMR ≥ 10dB
c) Zref = 220Ω + 1800Ω // 15nF
STMR ≥ 7dB
⇒
Figure 5 and Table XXXX shows the pin description for the
DB523/24 digital interface.
J25
HF (1)
HS (3)
CLK/HFI (5)
DI/xPD (7)
n.c. (9)
xCS/xMUTE (11)
n.c. (13)
VDD (15)
n.c. (17)
DPN (19)
FCI (21)
n.c. (23)
VSS (25)
Good sidetone cancellation is achieved with the
installed sidetone network: R17 = 2k7, R21 = 10kΩ,
C22 = 15nF, R22=21kΩ
some fine tuning may be necessary. Generally, the
sidetone network should be 10 X the line termination.
R22 is to compensate resistors R9 (10kΩ).
Startup in speech mode
As soon as either the hookswitch is closed or the
handsfree button is pressed, The line transistor is turned
on via R15,R16 and Q4.
LS is clamped to 10V by the external zener diode D2 and
V DD is quickly charged via LI (and an internal path from LI
to V DD ). The rising supply voltage generates an internal
power-on-reset (POR) on AS2523/24.
The POR sets the AS2523/24 into default state (see pt.
Signal truth table AS2523 default settings).
The first job for the controller is to detect the hook event
and hold the hook transistor in off-hook state by turning pin
19 (DPN on controller interface jumper J25) on. This is
necessary because in case the handsfree button was
pressed, it would only turn Q4 ON, while it is closed.
Therefore DPN must go HIGH, before the handsfree button
is released again.
The hookswitch (SW1) on the other hand, would always
keep Q4 ON, as long as it is offhook (=closed).
Next, depending on hook event, the AS2523 must be set to
the corresponding speech mode (handset mode, handsfree
mode) by sending the proper command (“D4“ for handset
mode, “D6” for handsfree mode) to the serial bus.
Remark: Per default the AS2523 is set into handset mode
after a POR.
The AS2523 serial interface will accept commands, as
soon as V DD is powered up.
(2) AS2523/24_sel
(4)
(6) n.c.
(8) n.c.
(10) TONE
(12) n.c.
(14) n.c.
(16)
(18) RING
(20) n.c.
(22) DET1
(24) n.c.
(26)
Figure 5: Controller interface on DB523/24
Pin Nr.
Pin Name
description
1
HF
2
AS2523/24_sel Selector for AS2523/24 (only for COB)
Handsfree hook signal
3
HS
Handset hook signal
4
LH/HF_Sel
Selector for Loudhearing or Handsfree
(only for COB)
5
CLK/HFI
CLK clock signal on AS2523
HFI Handsfree pin on AS2524
6
n.c.
not connected
7
DI/xPD
DI Data input on AS2523
xPD Power down pin on AS2524
8
n.c.
not connected
9
n.c.
not connected
10
TONE IN
Analog tone input forDTMF, FSK ..
Signals
11
xCS/xMUTE
xCS Chip select on AS2523
xMute pin on AS2524
12
n.c.
not connected
13
n.c.
not connected
14
n.c.
not connected
15
VDD
Supply voltage analog
16
TIP
for CID (optional)
17
n.c.
not connected
18
RING
for CID (optional)
19
DPN
Connecting a Microcontroller
20
n.c.
not connected
21
FCI
Ring frequency detetcion (optional)
One of the major benefits, when using AS2523 is, that it
can be interfaced with almost any microcontroller.
For the serial interface only 3 signals are necessary to
control the AS2523: Chip Select, Clock and Data In.
The digital interface on the Demoboard DB523/24 provides
the most common signals, which are required for an analog
telephone design.
22
DET1
for CID (optional)
23
n.c.
not connected
24
n.c.
not connected
25
VSS
Common ground
VPP
Supply voltage
Revision 1.01, Preliminary
26
Table 1: Pin description controller interface
Page 9 of 16
austriamicrosystems
Application Note AN523/24
AS2523/24 Block Diagram
Figure 5: AS2523/24 Block Diagram
Revision 1.01, Preliminary
Page 10 of 16
austriamicrosystems
Application Note AN523/24
Signal truth table AS2523
CS
CLK
↓
A3
DI (from µC)
↓
A2
↓
A1
↓
A0
↓
D3
↓
D2
↓
D1
↓
D0
For programming the AS2523, three signals are required: Chip Select (XCS), Clock (CLK), and Data In (DI).
The falling edge of CS enables the internal shift register. Data at DI is read with every rising edge of CLK, A3 must be clocked
in first, D0 is last. After 8 clock pulses, CS should be pulled high. With the rising edge of CS, the shift register data is sent to
the internal registers.
Programming options
Each command consists of a 4-bit address and 4 bit data. The following commands are possible:
Command
[Hex]
A3
A2
A1
A0
D3
D2
D1
D0
Default settings are shown in D 3 ...D 0 and in bold letters:
0x
0
0
0
0
X
x
X
x
Not used
1x
0
0
0
1
X
X
X
X
Not used
2x
0
0
1
0
X
X
X
X
Not used
3x
0
0
1
1
x
X
x
X
Not used
A0
0
Confidence Tone, DC-mask, Line Loss Compensation
Co = Confidence tone: [0]= off, [1]= on
L = LI-Voltage: [0]= 3,5V, [1]= 4,5V
A 1 ,A 0 : 11= 01 = noLLC,
00= LO (20-50mA),
10= HI (45-75mA)
40...4F
50...5F
0
0
1
1
0
0
0
Co
0
Liv
0
A
BR
A
BS
0
Revision 1.01, Preliminary
1
1
C1
C0
0
T1
1
0
T0
0
0
SR
0
Analog Tone confidence tone level:
AB R : Tone is sent to receiver (RO) : on[1] / off[0]
AB S : Tone is sent to Speaker (LO) : on[1] / off[0]
1
C 1 /C 0 : confidence tone level @RO /LO1,2 rel. to LS:
00 = -36dB -15dB
01 = -30dB -9dB
10 = -24dB -3dB
11 = -18dB +3dB
ST
0
Transmit comperator gain and soft clipping:
T 1 /T 0 : Tx comperator gain settings for Handsfree adjustment
00 = +8dB
01 = +11dB
10 = +14dB
11 = +17dB
S R : Soft clipping at RO: on[1] / off[0]
S T : Soft clipping at LS: on[1] / off[0]
1
0
60...6F
A1
0
Page 11 of 16
austriamicrosystems
Application Note AN523/24
Command
[Hex]
70...7F
80...8F
A3
0
1
A2
1
0
A1
1
0
A0
D3
D2
D1
D0
R1
R0
D
B
0
0
1
1
X
1
X
0
x
1
x
1
1
0
Default settings areshown in D 3 ...D 0 and in bold letters:
Rx- DC offset, Switching delay and Noise monitoring:
R 1 /R 0 : Rx DC offset:
00 = 0mV
01 = 12mV
10 = 40mV
11 = 120mV
D: 10ms switching delay: on[1] / off[0]
B: Handsfree Background noise monitoring: on[1] / off[0]
Handsfree receive end gain; speaker volume [1011]
16 steps, total attenuation range = -20dB:
0000=min Vol; Rx gain = -20dB; Tx gain = -30dB
1111=max Vol; Rx gain = 0dB; Tx gain = -50dB
Handsfree voice switching speed 1/2/4/8x:
S 1 ,S 0 : 00 ≈ 1ms / 6dB (maximum speed )
01 ≈ 2ms / 6dB
10 ≈ 4ms / 6dB
90...93
1
0
0
1
O1
1
O0
0
S1
0
S0
0
11 ≈ 8ms / 6dB (minimum speed)
with BNM on, switching from Tx->idle, Rx->idle is
≈30/60/120/240 ms/6dB respectively
O 0 ,O 1 Background Noise Monitor Offset
O1
0
0
1
1
A0...AF
1
Revision 1.01, Preliminary
0
1
0
O0
0
1
0
1
BGN-offset
120mV
180mV
240mV
300mV
T3
T2
T1
T0
Transmit gain [0111]
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Data[Hex]
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
Handset mode
30dB
31dB
32dB
33dB
34dB
35dB
36dB
37dB
38dB
39dB
40dB
41dB
42dB
43dB
44dB
45dB
Handsfree mode
39dB
40dB
41dB
42dB
43dB
44dB
45dB
46dB
47dB
48dB
49dB
50dB
51dB
52dB
53dB
54dB
Page 12 of 16
austriamicrosystems
Application Note AN523/24
Command
[Hex]
A3
A2
A1
A0
D3
D2
D1
D0
Default settings areshown in D 3 ...D 0 and in bold letters:
R3
R2
R1
R0
Receive gain [0111]
Data[Hex]
B0...BF
C0...C7
D0...DF
1
1
1
0
1
1
1
0
0
1
0
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
H
0
M
0
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
R
1
S2
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
M
0
S1
0
handset mode:
LS->RO
-6dB
-5dB
-4dB
-3dB
-2dB
-1dB
0dB
1dB
2dB
3dB
4dB
5dB
6dB
7dB
8dB
9dB
handsfree mode:
LS->[email protected] vol.
22dB
23dB
24dB
25dB
26dB
27dB
28dB
29dB
30dB
31dB
32dB
33dB
34dB
35dB
36dB
37dB
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
T
0
High pass for loudhearing , Receive comperator, Mute,
Tone:
H: High pass cut off frequency: 200Hz [1] / 2000Hz[0]
R: Signal to Rx comperator : on[1] / off[0]
M: Mute: on[1] / off[0]
T: Tx signal path: Tone in signal path[1] / Tx signal path on[0]
S0
0
Mask Bit, Speech modes: S 2 ,S 1 ,S 0 :
M: Maske:[0]: normal
[1]: power save; LI Forced to 0.7V(for LD dialing)
S 2 ,S 1 ,S 0 , Speech modes:
0xx = power down, no line regulation
100 = Handset mode
101 = not allowed
110 = Handsfree mode
111 = Loudhearing mode
E0...EF
1
1
1
0
K5
K3
K2
S
S Only for the loudhearing mode!
S: [0]:Normal voice switching speed
[1]:fast change to TX, slow change to Rx, no IDLE
S 2 ,S 1 ,S 0 for factory testing only [0000]
Fx
1
1
1
1
X
x
x
x
Reset to default settings
Revision 1.01, Preliminary
Page 13 of 16
Application Note AN523/24
austriamicrosystems
Programming examples
Generating a dial pulse
The following examples give some guidelines on how to
perform specific functions when using the AS2523 in a
system design. All commands, addresses and data are in
Hex-numbers, component numbers refer to the DB523/24
schematic in pt.Application Schematic, analog part:
The break-period of a dial pulse is generated in the same
way as a flash (see pt. Generating a flash), the makeperiod is generated by turning the hook transistor on while
leaving the AS2523 in the power-save mode (MASK-bit =
1). In power-save, LI is pulled down to 1.2V, resulting in a
low DC-resistance at the tip/ring terminals during the
make-period.
Going off-hook
After power up (close hookswitch & apply line current), the
AS2523 line regulation is active (see defaults Addr. D).
The first command must therefore set the AS2523 in the
detected speech mode:
command = D4 for handset mode,
D6 for handsfree mode
D7 for loudhearing mode
Afterwards, if necessary, the other parameters, like DCmask, Line loss compensation, Tx-Rx gains and soft
clipping can be sent.
For handsfree operation, voice switching speed, speaker
volume and background noise monitoring can be selected.
Muting the transmit and receive path
The receive path can be muted by setting bit M of
addr. C.:
There is no dedicated mute-bit for the transmit path, but
you may mute the transmit path by switching to Tone In
mode while there is no tone applied at the tone pin:
command = C1 (Tone path = on).
Generating a flash
A flash is a timed interruption of the line, consequently it
must be performed by turning off the hook transistor during
the flash (Q1, via Q4). However, as soon ad the hook
transistor is turned off, there is no more line current
available to support the ICs. Therefore, V DD must be
supplied from the buffer capacitor (C10). To avoid fast
discharge of the V DD buffer cap by high supply current
during the flash, the AS2523 shall be switched to a powersave mode:
command = DC (MASK-bit = 1).
Revision No.1.01, Date November 2003
Page 14 of 16
austriamicrosystems
Application Note AN523/24
Related Standards
The product, AS25xx, is designed to be in compliance with
ETSI standards for connection to the analogue PSTN of
terminal equipment including voice telephony services or
other voice band communication when installed into a
properly designed system. The specification of the product
is based on following standards and requirements:
NET 4
ETS 300 001, PSTN basic
access; analogue terminal equipment
general requirements, March 1996.
EN55022
EMC ( Electro Magnetic
Compatibility)
IEC 1000-4-3 Electromagnetic Irradiation
(CE approval)
TBR 21
pan-European approval for connection to
the analogue Public Switched Telephone
Network (line interface part)
TBR 38
pan-European approval for connection to
the analogue Public Switched Telephone
Network (acoustics). See
http://www.etsi.org for further information
Note: Some national PTT authorities may have additional
requirements exceeding the above standards and
requirements. Such additional requirements have only
been respected to the extent that they were known to
austriamicrosystems prior to designing the product.
However, austriamicrosystems shall not be liable to
recipient or any third party in connection with the approval
procedures of applications in which the AS25xx is used.
specifications and prices at any time and without notice.
Therefore, prior to designing this product into a system, it
is necessary to check with austriamicrosystems AG 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 equipment
are specifically not recommended without additional
processing by austriamicrosystems AG for each
application.
Copyright
Copyright © 1999, austriamicrosystems AG, Schloss
Premstaetten, A-8141 Unterpremstaetten, Austria-Europe.
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 austriamicrosystems AG
is believed to be correct and accurate. However,
austriamicrosystems AG 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
austriamicrosystems AG rendering of technical or other
services.
Approvals
Since the AS25xx is a component and not a complete
system, it can not be approved as a stand alone part by the
standards bodies. Hence, full conformance to above
standards is depending on the application in which the
AS25xx is being used, and therefore, approvals by the
standards bodies are the responsibility of the customer and
austriamicrosystems will not have tested the product to
meet the above standards.
Ordering information
Devices sold by austriamicrosystems AG are covered by
the warranty and patent identification provisions appearing
in its Term of Sale. austriamicrosystems AG makes no
warranty, express, statutory, implied, or by description
regarding the information set forth herein or regarding the
freedom of the described devices from patent infringement.
austriamicrosystems AG reserves the right to change
Revision No.1.01, Date November 2003
Page 15 of 16
austriamicrosystems
Application Note AN523/24
Contact
Headquarters
austriamicrosystems AG
accento! Business Unit Communications
A 8141 Schloss Premstätten, Austria
T. +43 (0) 3136 500 0
F. +43 (0) 3136 525 01
[email protected]
www.austriamicrosystems.com
USA (west)
austriamicrosystems USA, Inc.
Suite 116, 4030 Moorpark Ave,
San Jose, CA 95117, USA
Phone: +1/408/345 1790
Fax: +1/408/345 1795
USA (east)
Sales Offices
austriamicrosystems USA, Inc.
Suite 300, 4030 Wake Forest Road
Raleigh, NC 27609, USA
Phone: +1/919/719 7214
Fax: +1/919/719 2799
Germany
United Kingdom
austriamicrosystems Germany GmbH
Tegernseer Landstrasse 85
D-81539 München, Germany
Phone: +49/89/693643-0
Fax: +49/89/693643-66
austriamicrosystems UK, Ltd.
Coliseum Business Centre, Watchmoor Park
Camberley, Surrey, GU15 3YL, UK
Phone: +44/1276/23 3 99
Fax: +44/1276/29 3 53
France
austriamicrosystems France S.a.r.l.
124, Avenue de Paris
F-94300 Vincennes, France
Phone: +33/1/43 74 00 90
Fax: +33/1/43 74 20 98
Italy
austriamicrosystems Italy S.r.l.
Via Leone Tolstoi, 64
I-20146 Milano, Italy
Phone: +39/0242/36713
Fax: +39/0242/290889
Switzerland
austriamicrosystems Switzerland AG
Rietstrasse 4
CH-8640 Rapperswil, Switzerland
Phone: +41/55/220 9000
Fax: +41/55/220 9001
Revision No.1.01, Date November 2003
Japan
austriamicrosystems AG
Shin Yokohama Daini, Center Bldg. 10F
3-19-5, Shin Yokohama
Kohoku-ku, Yokohama 222-0033, Japan
Phone: +81/45/474 0962
Fax: +81/45/472 9845
Distributors & Representatives
austriamicrosystems AG is represented by distributors in
the following countries. Please contact your nearest
regional sales office for the distributor address:
Spain, Israel, Korea, Hong-Kong, Taiwan, Malaysia,
Singapur, India, Brazil
Application Support
Please contact your local sales office or your distributor.
Page 16 of 16