STMICROELECTRONICS TEA7092TQ

APPLICATION NOTE
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
CONTENTS
Pages
I.
TEA7092 GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
I.1.
I.2.
I.3.
I.4.
SETTING THE TEA7092 APPLICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PINOUT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
INPUT/OUPUT CONFIGURATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
4
5
6
II.
II.1.
II.1.1.
II.1.2.
II.1.3.
II.1.4.
II.2.
II.3.
II.3.1.
II.3.2.
II.3.3.
II.3.4.
II.3.5.
II.4.
II.4.1.
II.4.2.
II.4.3.
II.4.4.
II.5.
II.5.1.
II.5.2.
II.5.3.
II.5.4.
II.5.5.
II.6.
SPEECH FEATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DC CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TEA7092 DC Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Telephone Set DC Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Start Up Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Further Information (VCC/VREF/IREF/VMC/VRMC/VLS/VREFL) . . . . . . . . . . . . . . . . . . . . . . .
IMPEDANCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TRANSMIT CHANNEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Information - Maximum Gain Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Softclipping Threshold (Maximum Line Level). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Line Loss Compensation A.G.C. Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A.G.C. Inhibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmit Squelch / Antiacoustic Feedback Stage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SIDETONE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
One Sidetone Network Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Line Tracking Sidetone Network Principle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sidetone Programming for PABX Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RECEIVE CHANNEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Information - Maximum Gain Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum Output Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Line Loss Compensation / A.G.C. Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A.G.C. Inhibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
+6dB Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
HANDSFREE INTERFACE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
14
14
14
15
17
18
19
19
20
21
21
22
23
23
24
24
25
26
26
27
30
30
30
30
III.
CALL PROGRESS MONITOR AND GROUP LISTENING MODES . . . . . . . . . . . . . . .
31
III.1.
III.2.
III.3.
III.4.
III.5.
III.6.
III.7.
III.8.
GENERAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LOUDSPEAKING PART SUPPLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SOFTCLIPPING STAGE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ANTIACOUSTIC FEEDBACK FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAXIMUM OUTPUT POWER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EXTERNAL POWER SUPPLY FACILITY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RING MELODY CONTROL MODE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BEEP ERROR GENERATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31
32
33
33
35
36
37
38
AN848/1096
1/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
CONTENTS (continued)
Pages
IV.
IV.1.
IV.2.
IV.3.
IV.3.1.
IV.3.2.
IV.3.3.
IV.4.
IV.5.
IV.6.
MICROCONTROLLER INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MICROCONTROLLER POWER SUPPLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RESET AND PON SIGNALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SERIAL BUS INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Different Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Software Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Serial Bus Codes Actions on Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RING INDICATOR / LINE CURRENT VARIATION INDICATOR . . . . . . . . . . . . . . . . . .
OSCILLATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MICROCONTROLLER SIGNAL CONTROL IN THE DIFFERENT MODES. . . . . . . . . .
39
39
39
41
41
45
46
47
47
47
V.
DIALER FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
48
V.1.
V.2.
V.3.
DTMF DIALER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SINE WAVE GENERATOR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PULSE DIALER INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
48
49
49
VI.
RINGER FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
50
VI.1.
VI.2.
VI.3.
VI.4.
VI.4.1.
VI.4.2.
VI.4.3.
VI.5.
VI.6.
RINGER POWER SUPPLY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
START UP THRESHOLD LEVEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RING FREQUENCY GENERATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OUTPUT POWER OPTIMIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switch Mode Power Supply Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switch Mode Power Supply Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Power Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MICROCONTROLLER MANAGEMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RING SOFTWARE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
50
50
51
51
51
52
53
54
55
VII.
APPLICATION DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
56
2/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
I - TEA7092 GENERAL INFORMATION
I.1 - Setting the TEA7092 Application
TEA7092 is a telephone set integrated circuit designed to meet various country’s requirements.
TEA7092 is adapted to each country through external component value modifications.
TEA7092 performs the following features :
- Speech (Line interface & 2 wires / 4 wires)
- Call progress monitor (Exchange tone heard in
the loudpeaker & On-Hook dialing)
- Group listening (Handset & loudspeaker used
simultaneously)
- Handfree interface
- Ring on Loudspeaker
- DTMF dialing
- DC mask in Pulse dialing mode (Tip & Ring
voltage reduced during make period)
- Microcontroller interface
- Line current variation detector for transfer
- Waiting melody generator
- Beep error generator
All these features can be programmed by the associated microcontroller through the serial bus interface.
Make a copy of the last page of this document
and keep it as a reference, when you read this
application note, if you want to refer to the
external component names.
When setting the application, it is preferable to
respect the following flow chart :
Speech Part and DTMF Dialing
- Start your application with the default component
values given at the last page of this document
(typical application).
- Adjust the DC and START-UP characteristics.
- Adjust the Impedance (return loss).
- Adjust the Transmit parameters (softclipping
level, gain, frequency response curve).
- Adjust the Sidetone network(s)*.
- Adjust the Receive parameters (gain, frequency
response curve)*.
- Adjust the DTMF output level.
* Each of these two adjustments is influenced by the other one, for
more information, see Sections II.4 & II.5.
Call Progress Monitor and Group Listening
- Adjust the Loudspeaking amplifier (gain, frequency response curve) without handsetconnection in order to avoid influence of the handset
microphone.
- Adjust the Antiacoustic feedback efficiency.
Ringer Part
- Choose the Ring frequency melody.
- Adjust the Ring start up level.
- Optimize the loudspeaker output power.
Further Features
- Tip & Ring DC value in the make period in pulse
dialing mode,
- Line current variation detector for transfer,
- Waiting melody generator,
- Beep error generator,
- Microcontroller interface,
are essentialy software programming.
Note : Throughout the application note, IL is the
current which power supplies the complete application (current is equivalent to the one delivered by
an exchange to power a telephone set). For the
entire application note, unless otherwise specified,
the component values are those given at the last
page of this document (typical application).
3/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
I - TEA7092 GENERAL INFORMATION (continued)
I.2 - Pinout
Pin N°
Name
1
VLS
Loudspeaker Power Supply
2
VMC
Unregulated Microcontroller Power Supply
3
VL
4
VREFL
Loudspeaker Reference Voltage (VLS/2)
5
6
LSIN
LSSOF
Loudspeaker Amplifier Input
Loudspeaker Softclipping Time Constant
7
DTMF1
8
VRMC
Stabilized Microcontroller Power Supply
9
10
OSC
RI/VI
Oscillator Input
Ring Indicator/Line Current Variation Indicator Output (*)
11
RESET
Microcontroller Reset Output (*)
12
PON
Line Current Indicator Output (*)
13
CLK
Serial Bus Clock Input (*)
14
DATA
Serial Bus Data Input (*)
15
SNSL
Short Line Sidetone Network
16
SNLL
Long Line Sidetone Network
17
18
ASQ
ASC
Anti-Acoustic Feedback and Squelch Time Constant
DC Offset Anti-Acoustic Feedback and Squelch Amplifier Suppression
Transmit Output Stage
DTMF Filter 1
19
RECIN
20
REOUT
21
22
GTR
HFIN
Transmit Gain Adjustment
Handfree Microphone Input Referenced to VREF
23
MIC1
Microphone Input 1 Referenced to VREF
24
MIC2
Microphone Input 2 Referenced to VREF
25
VREF
Speech Reference Voltage (VCC/2)
26
VCC
Speech Power Supply
27
TSOFT
28
SOFTL
29
30
IREF
VS
Receive Input and Positive Line Voltage
Receive Output for Handfree Interface and Loudspeaker Input
Transmit Softclipping Time Constant
Transmit Softclipping Level Adjustment
Resistor to Set Reference Current
Active Inductor and DC Characteristic Adjustment
31
SLPE
32
AGND
33
34
ILL
ISL
35
EAR+
Positive Earphone Output
36
EAR-
Negative Earphone Output
37
GREC
38
VZP
39
SWP
Switch Mode Power Supply Output
40
RSU
Ring Start Up Level
41
42
RCO
DTMF2
43
GND
44
LSOUT
* Logic Interface.
4/57
Function
DC Mask Slope Adjustment
Analog Ground and Negative Line Voltage
Long Line Speech Control Gain Adjustment (GMAX)
Short Line Speech Control Gain Adjustment (GMAX - 6dB)
Receive Gain Adjustment
Switch Mode Power Supply Internal Zener
Ring Power Output Control
DTMF Filter 2
Power Ground and Negative Line Voltage
Loudspeaker Output
AN848-01.EPS
GND 0V
RGT
C21
MICRO
EARPHONE
29
25
5
35
24
21
32
GND 43
AGND
ISL 34
ILL 33
GTR
HFIN 22
MIC1 23
MIC2
TSOFT 27
SOFTL 28
ASQ 17
ASC 18
EAR+
EAR- 36
GREC 37
REOUT 20
LSIN
SLPE 31
IREF
VREF
VCC
VL
A=10
VS
VL
3
dc cut
RX & TX
DTMF1
SIDE CODE
I-DAC HF
HAND-FREE
SQUELCH
ANTI-HOWLING
G=200
VREF
AGC
DC
CARACTERISTIC
30
I-DAC LF
SOFTCLIPPING
-1
AMPLIFIER
EARPHONE
MUTE
I&V
REFERENCES
VCC/2
26
7
15
16
DTMF
AGC
42
DTMF2
VREF
BEEF
Tx
AMP
1/RGT
MUTE & DTMF
AGC CONTROL
VERSUS
LINE CURRENT
SIDETONE
MIXER
ILdc
ILdc
19
RECIN SNSL SNLL
Zall
Zasl
1
2
VMC
MUTE
VRMC
8
ILdc
VLS
14
CLK
13
4
SAT
DETECT
200µA
GND 0V
RI/VI
10
OSC
9
3.58MHz
OSCILLATOR
LOGIC CONTROL
VZP
LSOUT
39
40
SWP
RSU
RCO
41
38
44
TEA7092
SWITCH MODE
POWER
SUPPLY
RING
MELODY
GENERATOR
RING
INDICATOR
CONTROL
RING
OUTPUT POWER
RING SIGNAL
OPTIMISATION
VLS
LOUDHEARING
POWER
VLS/2
VREFL
DC BIAS
LOGIC
CTRL
LOGIC
MICROCONTROLLER
SERIAL INTERFACE
ILdc
PON
RESETN DATA
VRMC
11
PON &
RESET
CONTROL
6
DIGITAL
VOLUME
CONTROL
7 steps 4dB
Gtl -10 -15 -20 -25dB
AGC
AGC
INPUTS
I LINE SENSING
STATUS
MUX
SERIAL
DC
REGULATOR
12
LSSOF
HOLD
Gmax-Gtl
POWER
CURRENT
EXTRACTOR
(3mA)
VLS
ILdc 82.ILac I(vls)
LOUDSPEAKER
CURRENT SUPPLY
& OUT TX
ILac+dc
VCC
ILac+dc
ILdc
LINE
VLS
GND 0V
GND 0V
GND 0V
+RING
LOUDSPEAKER
GND 0V
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
I - TEA7092 GENERAL INFORMATION (continued)
I.3 - Block Diagram
5/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
I - TEA7092 GENERAL INFORMATION (continued)
I.4 - Input / Output Configurations
Figure 1 :
VREF (Pin 25) : Transmit and Receive Reference Voltage (VCC/2)
VCC (Pin 26) : Transmit and Receive Power Supply
IREF (Pin 29) : Internal Reference Current
R11a + R11b
From Line
3 VL
The sum of all the currents on Pin 26 (VCC) is equal to 1.3mA
(without ac receive signal)
R10
VCC
26
Internal
IREF
100kΩ
Ip
Internal Amp-op
Current Supply
V REF
IREF
25
29
±1mA
Figure 2 :
300mV
+
100kΩ
C14
R2
30kΩ
AN848-02.EPS
+
C8
SLPE (Pin 31) : DC Mask Slope
VS (Pin 30) : Shunt Regulator
kIL =
VL
IL - 5.6mA
1016
3
VCC
VCC
MIRROR
1
1.5
VCC
IL/85
(to transmit
channel)
IL - 5.6mA
30
50µA
11µA
VS
SLPE 31
1016
R3
225kΩ
C11
Rslope = R3/55
VL = R12 x (40 + 0.5 x IL) E-6 + Rslope (IL - 5.6) E-3 ; IL in mA (for IL < 20mA)
VL = VL (at 20mA) + Rslope x (IL -20) E-3 ; IL in mA (for IL > 20mA)
6/57
AN848-03.EPS
kIL =
R12
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
I - TEA7092 GENERAL INFORMATION (continued)
I.4 - Input / Output Configurations (continued)
Figure 3 :
VLS (Pin 1) : Loudspeaker Part Power Supply
VMC (Pin 2) : Unregulated Microcontroller Power Supply
VRMC (Pin 8) : Stabilized Microcontroller Supply
3 VL
400Ω
ITX/41
(see transmit
channel)
10Ω
VLS
1
+
C1
3
2kΩ
50Ω
VL
ISTART
6V
Switch ON if :
Reset low
& KIL
0.8mA (IL = 4mA)
to 3mA (IL > 20mA)
VRMC
8
+
C15
Info for
PON & RESET
470kΩ
VMC 2
+
C10
6V
AN848-04.EPS
30 to 75µA
VBANDGAP
ILL (Pin 33) : Line Current Regulation Start-up Value
ISL (Pin 34) : Line Current Regulation Stop Value
VCC
300mV
For AGC Control
ILL (Pin 33) or
ISL (Pin 34)
R19 =
300
ISL - 5.6
R18 =
300
ILL - 5.6
R18 and R19 in kΩ ; ILL and ISL in mA
R18 and R19 should be connected
as close to the ground Pin (AGND)
as possible.
AN848-05.EPS
Figure 4 :
R18 or R19
7/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
I - TEA7092 GENERAL INFORMATION (continued)
I.4 - Input / Output Configurations (continued)
Figure 5 :
TSOFT (Pin 27) : Transmit Softclipping Time Constant
SOFTL (Pin 28) : Maximum AC Signal (Softclipping Threshold)
MIC1/MIC2 (Pin 23/24) : Microphone Inputs
HFIN (Pin 22) : Handsfree Microphone Input
DTMF1 (Pin 7) : DTMF Input and Filter
DTMF2 (Pin 42) : DTMF Filter
GTR (Pin 21) : Transmit Gain Adjustment
VCC 26
10µA
20µA
SOFTL 28
20µA
kVLdc
TSOFT 27
R1
2.5V
kVLacpeak
C3
R1 =
8kΩ
R4
5
(Vacpeak + 0.6)
x R12 4
40E-6
VREF 25
ITX
VREF
To Anti-acoustic
Feedback
MIC1 23
MIC2 24
0dB
20kΩ
20kΩ
Microphone
Choice
From Anti-acoustic
Feedback (-9dB)
5kΩ
IL/85
From
DC Path
45kΩ
LOUDSPEAKER
POWER SUPPLY
Mirror 1/40
3 VL
ZB =
ZT//CR1//ZL
ITX/41
Mute
VLS 1
VREF 25
+
2kΩ
18kΩ
AGC
0 to -6dB
1
C1
2
HFIN 22
VREF 25
0dB
1kΩ
21 GTR
R8
0dB
9kΩ
EARCMF
10kΩ
IDTMF
DTMF1 7
8/57
Gtl =
VL (Pin 3)
VMIC1 (Pin 23) - VMIC2 (Pin 24)
= 20 log (820 x
ZB
)
R8//50kΩ
AN848-06.EPS
DTMF2 42
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
I - TEA7092 GENERAL INFORMATION (continued)
I.4 - Input / Output Configurations (continued)
Figure 6 :
SNSL (Pin 15) : Short Line Length Sidetone Network Input
SNLL (Pin 16) : Long Line Length Sidetone Network Input
RECIN (Pin 19) : Receive Input
REOUT (Pin 20) : Receive Output for Handsfree Device
GREC (Pin 37) : Receive Gain Adjustment
EAR+ (Pin 35) : Positive Earphone Output
EAR- (Pin 36) : Negative Earphone Output
ZB
RECIN
19
0.6V
R11a
R11b
VL
60kΩ
3
kIL = 0 for IL = ISL
kIL = 1 for IL = ILL
kIL
+6dB Code
ITX
R13
C12
15
ZASL
R5+R6//C5
C27
20
1 - kIL
16
ZALL
R29+R28//C28
REOUT
0dB
SNLL
SNSL
ZAL = K x ZALL + (1 - K) x ZASL
AGC
21 to 15dB
(Code +6dB not
activated)
26
R14
VCC
GREC
32
VCC
40kΩ
R17
35 EAR+
EARCMF
Mute
10kΩ
Mute
20kΩ
20kΩ
VCC
36 EAR-
VREF 25
AN848-07.EPS
R27
60kΩ
Mute
9/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
I - TEA7092 GENERAL INFORMATION (continued)
I.4 - Input / Output Configurations (continued)
Figure 7 :
LSIN (Pin 5) : Loudspeaker Signal Input
LSOUT (Pin 44) : Loudspeaker Output
VREFL (Pin 4) : LoudspeakerPart Reference Voltage
Ring In
RI
10kΩ
20kΩ
LSIN
Volume
Control
10kΩ
5
50kΩ
DC
Translator
40kΩ
LSOUT
LS AGC
10kΩ
44
+
C2
VLS
Vp(LSOUT)
1
LS
22kΩ
VREFL
+
VLS/2
4
C20
22kΩ
10/57
AN848-08.EPS
C1
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
I - TEA7092 GENERAL INFORMATION (continued)
I.4 - Input / Output Configurations (continued)
Figure 8 :
ASQ (Pin 17) : Anti-Acoustic Feedback and Squelch Peak Voltage
ASC (Pin 18) : Anti-Acoustic Feedback and Squelch Filter
LSSOF (Pin 6) : Loudspeaker Softclipping Time Constant
VCC
To Transmit AGC
10µA
From Microphone
Preamplifier
60mV
VREF
100kΩ
0.5kΩ
0.8kΩ
Attenuation Programmable
from 10 to 25dB
ASQ 17
R16
C25
C16
VREF
ASC 18
60mV
25
VLS
LS AGC
LSSOF 6
Vp(LSOUT)
GND + 0.2
R31
C19
4µA
AN848-09.EPS
VLS - 0.2
Vp(LSOUT)
11/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
I - TEA7092 GENERAL INFORMATION (continued)
I.4 - Input / Output Configurations (continued)
Figure 9 :
VZP (Pin 38) : Switch Mode Power Supply Internal Zener
SWP (Pin 39) : Switch Mode Power Supply Output
RSU (Pin 40) : Ring Start-up Level
RCO (Pin 41) : Ring Power Output Control
L1
VRING
T1
+
I(VZP)
R37
R35
+
C6
D2
D7
C1
R36
R32
C30
R38
T2
D3
VZP 38
40 RSU
R33
SWP 39
24V
VLS 1
VRMC 8
+
C15
IVZP Info
11.2V
SERIAL
REGULATOR
LOGIC
CONTROL
6
RI
VLS > 2.6V
150kΩ
LSSOF
I/17.5kΩ
LOGIC
CONTROL
VRMC > 2.6V
R31
1.2V
C19
150kΩ
100µA
90kΩ
5.6V
40kΩ
26kHz
135kΩ
2.6V
RI
Fi Ring
IA = f{(IVZP)}
LS AMP
VIN
LSOUT
44
(VLS - VLSOUT) < 0.2V
C4
12/57
R40
Gain = 16
+
C2
AN848-10.EPS
RCO 41
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
I - TEA7092 GENERAL INFORMATION (continued)
I.4 - Input / Output Configurations (continued)
Figure 10 : RI/VI (Pin 10) : Ring Indicator/Line
Current Variation
Figure 11 : CLK (Pin 13) : Clock Data Input
DATA (Pin 14) : Data Input
VRMC
VRMC
CLK (Pin 13)
or
DATA (Pin 14)
fMax. = 1MHz
tMin. between
2 bytes : 2µs
AN848-12.EPS
10 RI/VI
IOUT = ±1mA max
AN848-11.EPS
HOLD
120kΩ
INTERNAL
LOGIC
Figure 13 : RESET (Pin 11) : µcontroller Reset
PON (Pin 12) : Power On Output
Figure 12 : OSC (Pin 9) : Oscillator Input
VRMC
VRMC
12 PON
300kΩ
OSC 9
Information for
PON/RESET
30pF
VRMC
IOUT =
±1mA max
30pF
11 RESET
AN848-13.EPS
30µA
INTERNAL
LOGIC
AN848-14.EPS
RI
VRMC
13/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES
II.1 - DC Characteristics
II.1.1 - TEA7092 DC Voltage
The voltage at Pin VL (Pin 3) of the TEA7092 is fixed
by 2 external components :
- R3 connectedbetween Pin SLPE (Pin 31) and the
ground which fixes the DC slope.
- R12 connected betweenPin VL (Pin 3) and Pin VS
(Pin 30) which fixes the DC voltage at IL = 20mA
and a part of the DC slope for IL < 20mA.
The voltage at Pin VL (Pin 3) is equal to :
For IL < 20mA :
−6
VL = R12 ⋅ (40 + 0.5 ⋅ IL) ⋅ 10 +
R3 ⋅ (IL − 5.6)
55
Note : At the maximum line current use, the voltage
at Pin RECIN (Pin 19) should be less than 11VDC,
the following curves stop at the line current where
they reach 11VDC at Pin RECIN (Pin 19), depending of the country’s application, use this information
to optimize the values of R3 and R12.
Figure 14
LA
VBRI
−3
⋅ 10
with IL in mA.
For IL > 20mA :
R3 ⋅ (IL − 20)
55
⋅ 10−3
with IL in mA, VL (20mA) is the Pin VL (Pin 3)
DC value for IL = 20mA.
II.1.2 - Telephone Set DC Voltage
The telephone set DC voltage at line terminal is
equal to (see Figure 14) :
V(LA/LB) = VL + (R11a + R11b) x IL + VSWI + VBRI
with :
- VL : DC voltage on Pin VL (Pin 3) of the TEA7092.
- VSWI : voltage across the pulse dialing switch and
its protection.
- VBRI : voltage across the input rectifier bridge.
The Figures 15 to 18 give DC typical value at
Pin VL (Pin 3) and at line terminal (LA/LB) for different value of R3 and R12.
14/57
VSWI
R11a
R11b
3
VL
R12
VS
RECIN
30
19
TEA7092
AGND
32
43
31
SLPE
R3
GND
C11
AN848-15.EPS
VL = VL (20mA) +
LB
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.1.2 - Telephone Set DC Voltage (continued)
Figure 15 : Telephone Set (DC MASK)
Figure 16 : VRECIN (Pin 19)
12
14
10
6
2
4
R12 = 68kΩ
R12 = 82kΩ
R12 = 110kΩ
4
0
20
40
60
80
IL (mA) R3 = 2.7kΩ
100
120
0
0
20
40
60
80
IL (mA) R3 = 2.7kΩ
100
120
120
Figure 18 : VRECIN (Pin 19)
12
14
10
12
VRECIN (V)
10
8
6
4
0
20
40
60
80
IL (mA) R3 = 1.5kΩ
100
8
6
4
R12 = 68kΩ
R12 = 82kΩ
R12 = 110kΩ
R12 = 68kΩ
R12 = 82kΩ
R12 = 110kΩ
2
120
AN848-18.EPS
VLA/LB (V)
R12 = 68kΩ
R12 = 82kΩ
R12 = 110kΩ
2
Figure 17 : Telephone Set (DC MASK)
2
6
AN848-17.EPS
8
8
AN848-19.EPS
VRECIN (V)
10
AN848-16.EPS
VLA/LB (V)
12
0
0
20
40
60
80
IL (mA) R3 = 1.5kΩ
100
II.1.3 - Start-up Characteristics
When TEA7092 goes from iddle state (ON-HOOK)
to speech mode (OFF-HOOK) the capacitor C10
connected on Pin VMC (Pin 2) and the capacitor
C15 connected on Pin VRMC (Pin 8) are charged in
priority, with the main part of the line current.
The capacitorC10 is used to supply, through a serial
regulator, the microcontroller connected on the
regulated 3.5V supply, Pin VRMC (Pin 8).
In pulse dialing, flash or earth button mode the
capacitor C10 is used to supply the microcontroller,
dependingon the power consumption of the microcontroller and on the country’s requirements for
these different signal durations, it is necessary to
adapt the value of C10.
Typical capacitor values, with a current consumption of 500µA for the microcontroller :
C10 = 470µF , C15 = 4.7µF.
15/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.1.3 - Start-up Characteristics (continued)
Figure 19 describes the start-up principle.
Figure 19
VL
R11a
+ R11b
IL
TEA7092
3
400Ω
RECIN
10Ω
19
MIC
Transmit
Amplifier
Loudspeaker
Current Supply
1
ITX/41
ON if RESET = 0
& IL Present
Pins 23 & 24
50Ω
3mA
+
C1
6V
Istart-up = IVLS
2Ω
VLS
2
VMC
+
C10
6V
Serial
Regulator
3.5V
8
VRMC
+
C15
75µA
Vbandgap
470kΩ
RI 21
LOGIC
BLOCK
When VRMC reaches 2.6V, the Reset goes to high
level, the start-up current source is inhibited and
only connected to Pin VLS (Pin 1), to power supply
the loudspeaker amplifier. The Pin VRMC (Pin 8)
reaches its final value, 3.5V by charging the C10
on Pin VMC (Pin 2) and C15 on Pin VRMC (Pin 8)
with 3mA current source and finally the voltage on
Pin VMC (Pin 2) increases until its final value which
is equal to Pin VL (Pin 3) minus 0.4V.
Figure 20 gives the start up characteristic timing.
When TEA7092 goes from iddle state (ON-HOOK)
to ring mode, only the 4.7µF capacitor C15 on
Pin VRMC (Pin 8) is charged, with Iring current
source, and a fast start up delay could be achieved
in ring mode.
16/57
AN848-20.EPS
RESET 19
Figure 20
START-UP
SPEECH
VL
t
VMC
t
RESET
t
VRMC
t
AN848-21.EPS
PON 20
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.1.4 - Further Information (VCC / VREF / IREF / VMC / VRMC / VLS / VREFL)
For more information on these pins see Section I.4 - Input/output Configurations.
VCC (Pin 26) , VREF (Pin 25) , IREF (Pin 29)
The VCC supplies the transmit path, handset and
handfree microphone amplifiers, the receive path,
earphone amplifier and the transmit squelch/antiacoustic feedback stage.
The current consumption on this pin, I P, is 1.3mA
at a 20mA line current (see Figure 21).
From the VCC supply, the VREF stage is built. VREF
is used as an AC ground for all the stages powered
from VCC.
The output current compliance of VREF is : ±1mA.
The reference voltage at VREF is : VCC/2.
IREF Pin is used as an internal current reference.
The R2 value is fixed and should not be modified.
It is recommended to connect a ±1% resistor value
on this pin.
The voltage at IREF pin has a 300mV constant
value.
The DC value at VMC is :
VMC = VL - 0.4V
and is internally limited at 6V max.
VRMC is powered from the highest DC value between Pin VLS (Pin 1) and Pin VMC (Pin 2) in
OFF-HOOK state or from Pin VLS (Pin 1) in ring
mode.
VRMC is a 3.5V stabilized power supply.
VRMC supplies the oscillator, the logic part (Microcontroller interface, error beep, and ring frequency
generators) and the logic part of the D.A.C. used
for the waiting melody and the DTMF generators.
The current consumption on this pin is 250µA when
the oscillator is ON and 50µA when the oscillator is
OFF code (0111010) is sent.
Note : To reduce the C10 value connected at
Pin VMC (Pin 2), it is recommended to inhibit the
oscillator during the pulse dialing and flash signalizations.
In ring mode only the 4.7µF capacitor connected
on Pin VRMC (Pin 8) is charged to achieve a short
delay to generate the ring signal on the loudspeaker.
10
100
90
80
70
60
50
40
30
20
10
0
ILS
Ip
IVMC
8
6
4
2
0
20
40
60
IL (mA)
80
100
0
120
VMC (Pin 2) , VRMC (Pin 8)
These 2 pins supply the microcontroller. These
2 pins are connected through a serial regulator.
On VMC a 470µF capacitor is connected, this capacitor is charged only when TEA7092 is powered
from Pin VL (Pin 3) (OFF-HOOK state) and is used
to power supply the microcontroller during pulse
dialing, flash and earth button, when the line loop
is open.
As described in Section II.1.3, this capacitor is
quickly charged during the ”Start up” condition.
AN848-22.EPS
ILS (mA)
Figure 21
VLS (Pin 1) , VREFL (Pin 4)
The VLS supplies the loudspeaker amplifier part.
The current source, ILS, between the Pin VL (Pin 3)
and the Pin VLS (Pin 1) gives the main part of the
line current to supply the loudspeaker amplifier
(see Figure 21) :
ILS = 0.74 x IL - 1.8mA ; for IL < 15mA
ILS = 0.92 x IL - 4.5mA ; for IL > 15mA
The internal current consumption on VLS is 1mA,
so the current ILS1 available for the loudspeaker
and other peripherals is :
ILS1 = ILS - 1mA
The DC value at VLS depends of the DC value at
Pin VL (Pin 3) and is equal to :
VLS (Pin 1) = VL(Pin 3) - (0.95 + 10 x ILS) Volts
From the VLS supply, the VREFL stage is built. The
VREFL is buffered in order to be used as an AC
ground for all the stages powered from VLS.
The reference voltage at VREFL is : VLS/2.
17/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.2 - Impedance
Figure 22 : TEA7092 Application Impedance
ILDC + ILAC
CR1
R11a
RECIN
SNLL
R13
R27
ZASL
ZALL
R5
R29
C27
15
Cpc
Rpc
Zsh
VS
C11
SNSL
C12
TEA7092
26
VCC
C5
C8
ILAC
ZT
Allows the user to adjust the set impedance
by changing the value of R10, R9 and C9 ;
In this way the impedance can be adjusted
as a real one (only R10) or as a complex one
(R10, R9, C9).
ZALL Sidetone networks which are in parallel with
ZALS ZT, if the ratio : R13/R11a>>1 and
R27/(R11a+R11b)>>1, ZALL and ZASL are
negligible for the impedance calculation.
ZIC Is the internal impedance of TEA7092.
It includes the impedance of the transmit
path which is equivalent to a current source
in parallel with Cpc (3nF), the impedance of
all the other stages which are equivalent to
Rpc (15kΩ) and the impedance of the shunt
regulator stage (AC/DC decoupling stage)
made on Pin 30 (VS).
TEA7092 application impedance is :
Zimp = ZT//ZIC//(ZALL + R11a + R11b)
//(ZASL + R11a)//CR1
As it will be describe in Section II.4, the sidetone
networks are equal to :
R27
⋅ (ZT//CR1//ZLL)
R11a + R11b
R13
ZASL =
⋅ (ZT//CR1//ZSL)
R11a
Figure 23 : Zsh Impedance
Regulator Shunt
Impedance
Zsh =
ZALL and ZASL >> ZT and : Zimp = ZT//ZIC//CR1
Figure 24 and the Table 1 give the TEA7092 application characteristics at IL = 40mA.
Lsh
R3 + (j x 2 x π x f x R3 x R12 x C11)
55
[Zimp − 600]
200
300
800
550
573
604
80
67
22
556
577
605
8
7
2
Return
Loss
[Rl] (dB)
21.7
24.2
34.6
1 000
1 500
606
608
12
-5
607
608
1
0
38.8
42.1
2 500
3 500
5 000
7 000
9 000
606
603
597
589
579
-28
-43
-67
-94
-119
607
605
601
596
591
-3
-4
-6
-9
-12
32.6
28.8
25
22
19.8
12 000
560
-154
581
-15
17.3
Frequency Real Imaginary Module () Phase
(Hz)
Part ()
Part ()
(deg)
Figure 24 : Return Loss
40
36
32
RI (dB)
Where ZLL is the long line impedance, and ZSL is
the short line impedance.
If R27/(R11a+R11b) and R13/R11aare higher than
100 (R27 and R13 = 3.3kΩ) :
Rslp
Table 1 (RI = 20 ⋅ log [Zimp + 600] )
ZALL =
18/57
R6
R3
AN848-24.EPS
Zimp =
VLAC
AN848-23.EPS
32
28
IL = 20mA
IL = 100mA
Country Limit
Request
24
20
16
12
8
0.1
0.2 0.3
0.5
1
f (kHz)
2
3
5
10
AN848-25.EPS
SLPE AGND
R28
31
C28
R9
3
16
30
C9
VL
19
R12
ZT
R10
VLDC
+ VLAC
R11b
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.3 - Transmit Channel
II.3.1 - General Information
(Maximum Gain Adjustment)
The transmit path amplifies several signals :
- The handset microphone.
- The handfree microphone.
- The DTMF sinewave.
- The waiting melody sinewave.
At one time, only one of these signals is amplified,
the choice is made through the serial bus interconnected with the microcontroller.
Figure 25 gives the transmit channel block diagram.
The first switch selects the microphone used.
The signal coming from the handset microphone,
Pins MIC1 & MIC2 (Pins 23 & 24) is limited by the
softclipping stage, more details are given in Section II.3.2 ”Softclipping threshold” on this stage. Its
gain depends on the gain control stage programming, more details are given in Section II.3.3 ”Line
loss compensation A.G.C. adjustment”. Its absolute value is adjusted on the final stage with
Pin GTR (Pin 21).
The output signal of the handset microphone preamplifier is used for the squelch feature.
Figure 25 : Transmit Channel Block Diagram
IL
ZB = ZT//CR1//ZL R11a + R11b
C3
RECIN
VL
19
R4
27
TSOFT
R1
28
3
SOFTCLIPPING
STAGE
SOFTL
To Loudspeaker
Amplifier
R16
ITX
C16
17
18
ASQ
ASC
ANTI-ACOUSTIC
FEEDBACK
STAGE
C25
MIC1 23
MIC2 24
0dB
20kΩ
VREF
IL/85
from DC Path
VREF
LOUDSPEAKER
CURRENT SOURCE
Mirror 1/40
5kΩ
Microphone
Choice
45kΩ
20kΩ
VLS
1
+
C1
ITX/41
Mute
25
+
C14
AGC
0 to -6dB
2kΩ
1
2
18kΩ
HFIN 22
0dB
1kΩ
0dB
9kΩ
DTMF2
42
C32
10kΩ
IDTMF or ISINWAVE
7
AN848-26.EPS
DTMF1
TEA7092
C13
Gtl = 20 log (820 x
ZB
)
R8//50kΩ
VREF
25
21
R8
GTR
19/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.3 - Transmit Channel (continued)
Figure 26 : Softclipping Stage
MIC1
MIC2
TEA7092
Microphone
Preamplifier
23
REST OF
THE TRANSMIT CHANNEL
24
3 VL
20µA
20kΩ
20kΩ
VCC
VL(DC) - VL(ACp)
VL(DC) - 2.5V
20µA
VCC
VCC
U/I Converter
25
10µA
kVL(ACp)
27
VREF
28
TSOFT
SOFTL
The second switch selects the microphone signal,
the mute mode, the DTMF mode or the sinewave
mode (waiting frequency).
The maximum transmit gain, Gtl is fixed by R8
connected on Pin GTR (Pin 21) and is equal, on
Pin VL (Pin 3) to :
ZT//CR1//ZL + (R11a + R11b) 

Gtl = 20 ⋅ log 820 ⋅

R8//50kΩ


Zimp is the complete telephone set application and
ZL is the line impedance. 50kΩ is the value of the
integrated resistor connected between the
Pin GTR (Pin 21) and the Pin VREF (Pin 25).
If it is necessary, to have a steady gain over the
frequency range 300Hz to 3.4kHz, R8 can be replaced by a complex network : R8 + R7//C7.
The final amplifier stage is the louspeaker current
source supply, which is modulated by the transmit
signal, therefore no significatif line current is used
for the transmit path, and the current source supply
for the loudspeaker part versus the line current is
always optimized.
II.3.2- Softclipping Threshold (Maximum Line Level)
The softclipping stage limits the transmit level on
line.
This level is limited in two ways :
The transmit negative part of the sinewave is com-
20/57
R4
R1
pared to 2.5VDC. This limitation is useful for low line
current when the DC level at Pin VL (Pin 3) is low.
This limitation is useful when two telephone sets
are off-hook in parallel on the same line.
On an absolute line level, this level is fixed by R1
connected on Pin SOFTL (Pin 28) and depends on
R12 value :
Vacpeak = (5 x R12 - 4 x R1) x 10-5 - 0.6
Figure 26 describes the sofclipping stage.
Figure 27 gives an example of the VACPEAK transmit
level versus line current for R12 = 82kΩ and
R1 = 47kΩ.
Figure 27
10
8
1.6VP
6
4
0.9VP
.5
0
20
40
60
IL (mA)
80
100
AN848-28.EPS
C3
VL (V) (Pin 3)
C14
AN848-27.EPS
+
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.3 - Transmit Channel (continued)
Figure 28 g ives the t ransmit line level at
Pin VL (Pin 3) and the transmit distortion versus the
input microphone level (Pin MIC1 (Pin 23) &
Pin MIC2 (Pin 24)) for R12 = 82kΩ, R1 = 47kΩ &
R8 = 1.62kΩ.
Figure 28 : Tx Output Level & Distortion (IL=20mA)
2
12
VLINE
Distortion
10
8
0.5
6
0.2
4
0.1
D[VLA/LB] (%)
1
Figure 30 : dGtx = f(IL)
R19 = 8.2kΩ
R19 = 6.8kΩ
R19 = 4.7kΩ
R19 = 3.9kΩ
R19 = 3.3kΩ
2
0.5
1
2
VMIC
5
10
(mVRMS)
20
0
50 100
Figure 29 gives the maximum transmit level at
Pin VL (Pin 3) versus R1, for R3 = 2.7kΩ & for
different values of R12, at IL = 40mA.
0
dGtx (dB)
0.05
0.2
AN848-29.EPS
VLA/LB (Vrms)
transmit and receive gains are equal to the maximum gain value minus 6dB.
300
in kΩ ; ISL in mA
R19 =
ISL − 5.6
For line current values lower than ILL, the transmit
and receive gains stay at their maximum values.
For line current values upper than ISL, the transmit
and receive gains stay at their minimum values.
Figure 30 gives A.G.C. with a constant start value
(IL = 20mA) and different values of R19.
Figure 31 gives A.G.C. with a constant stop value
(IL = 100mA) and different values of R18.
-2
-4
R12 = 68kΩ
R12 = 82kΩ
R12 = 110kΩ
0
20
40
60
IL (mA)
80
100
80
100
AN848-31.EPS
-6
Figure 31 : dGtx = f(IL)
0
20
40
60
R1 (kΩ)
80
100
120
II.3.3 - Line Loss Compensation/
A.G.C. Adjustment
The TEA7092 uses a line current information to
control the transmit and receive gains variation
versus the line current.
TheAutomaticGainControl(A.G.C.)versus linelength
works in the same way for transmit and receive paths.
Through two external resistors the line current variation, where the A.G.C. occurs, is programmable :
- R18 connected on Pin ILL (Pin 33) sets up the
start up line current value, ILL, for the A.G.C.
300
R18 =
in kΩ ; ILL in mA
ILL − 5.6
- R19 connected on Pin ISL (Pin 34) sets up the
slope and the line current value, I SL, where the
-2
R18 = 18kΩ
R18 = 10kΩ
R18 = 8.2kΩ
R18 = 6.8kΩ
R18 = 5.6kΩ
-4
-6
0
20
40
60
IL (mA)
II.3.4 - A.G.C. Inhibition
The A.G.C. feature can be inhibited through the
serial bus interface by sending the code 0010100.
This code is a toggle one.
When the no A.G.C. mode is selected the transmit
and receive gains stay at their maximum values
-2dB over the line current range variation.
This feature is used for a telephone set connected
behind a PABX or in a country where the A.G.C.
feature is not requested.
21/57
AN848-32.EPS
0
dGtx (dB)
3.25
3
2.75
2.5
2.25
2
1.75
1.5
1.25
1
0.75
0.5
0.25
0
AN848-30.EPS
VLA/LB (V)
Figure 29 : Vac Max On Line
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.3.5 - Transmit Squelch / Antiacoustic Feedback Stage
Figure 32 : Block Diagram
TEA7092
10µA
To Transmit
AGC
V CC
From
Microphone
Preamplifier
0.8kΩ
60mV
VREF
100kΩ
LS AGC
0.5kΩ
60mV
18
ASC
V REF
25
17
ASQ
C25
AN848-33.EPS
R16
C16
Figure 33
Gtx (dB)
Gmax
Low
Microphone
Level
High Microphone Signal
Softclipping Mode
Normal Speech
*
9dB
Gmax - 9.5dB
3dB
Vst
VMIC
Vsoft
GLS is Programmable through
the Volume Control Stage
AN848-34.EPS
GLS
Vsl
x is Programmable through the Serial Bus
(10, 15, 20, 25dB) (default value is 15dB)
GLS - xdB
VMIC
22/57
is adjustable through the C25 capacitor value connected at Pin ASQ (Pin 18). Be aware that when
the threshold level is modified, the cut-off frequency
of the filter is also modified. The squelch threshold
level is determined by the microphone level injected at
Pins MIC1 & MIC2 (Pins 23 & 24). Figure 34 gives
the threshold level with a maximum transmit gain
of 44dB.
Figure 34 : SquelchThreshold (IL = 20mA/fMIC = 1kHz)
44
42
Gtl (dB)
The same stage is used for the transmit squelch
and the antiacoustic feedback feature which is
used in loudspeaking mode. Figure 32 shows the
block diagram of this stage.
When there is no signal on the handset microphone
inputs, the transmit gain is reduced by 9dB, refer
to the maximum gain, and the loudspeaker amplifier is at the gain value set by the volume control
stage, (see Section III - CALL PROGRESS MONITOR AND GROUP LISTENING MODES). When
the handset microphone signal is present and increases progressively, it describes the first curve in
Figure 33 and the loudspeaker amplifier describes
the second curve in Figure 33. The attenuationof the
loudspeaker amplifier for the antiacoustic feature is
programmable from 10dB to 25dB through the serial
bus interface, the default value is 15dB. The squelch
thresholdfeature can be inhibited through the serial
bus interface by sending the code (0011001) without affectingthe antiacousticfeedback control. This
code is a toggle one. The squelch threshold level
C25 = 100nF
C25 = 470nF
C25 = 1µF
40
38
36
-80
-76
-72
-68
-64
VMIC (dBV) (Pins 23 & 24)
-60
-56
AN848-35.EPS
* 60mV at Pin 17
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.4 - Sidetone
II.4.1 - General Information
The sidetone uses the wheatstone bridge principle
(see Figure 35). Figure 36 shows the block diagram
of the sidetone stage.
TEA7092 integrates a line tracking sidetone network which uses two sidetone networks.
One sidetone network, ZALL, is optimized for a
long line length connection and the other one,
ZASL, is optimized for a short line length connection. An internal mixer stage uses a line current
information, kIL, to smooth linearely from ZALL to
ZASL with the following equation :
ZAL = k x ZALL + (1 - k) x ZASL
k = 1 for IL = ILL, k = 0 for IL = ISL and k varied linearly
between 1 and 0 when the line current varied from
ILL to ISL.
Like this, the sidetone is optimized for every line
length.
This concept can be suppressed by shortcircuiting
the two sidetone inputs, Pin SNLL (Pin 16) and
Pin SNSL (Pin 15) and to connect only one sidetone network, in this case the sidetone is only
optimized for one line length, as a standard one,
and the efficiency of the sidetone is lower on all the
other line length connections.
Figure 35
RECIN
V1
V1 - V2
Ry
VL
Rx
TEA7092
IL
To Earphone
SN
ITX
ZAL
TEA7092A
V1 = V2 if ZAL =
V2
Ry
x ZB
Rx
AN848-36.EPS
ZB = ZT//CR1//ZL
Figure 36
RECIN
0.6V
R11a
VL
3
ITX
R13
C27
kIL = 0 for IL = ISL
kIL = 1 for IL = ILL
kIL
+6dB Code
0dB
SNLL
16
15
ZALL
R29+R28//C28
C12 SNSL
ZASL
R5+R6//C5
ZAL = K x ZALL + (1 - K) x ZASL
VCC
20 REOUT
1 - kIL
AGC
21 to 15dB
(Code +6dB
not activated)
26
AN848-37.EPS
R27
60kΩ
R11b
60kΩ
ZBL
or
ZBS
TEA7092
19
+
C8
23/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.4.2 - One Sidetone Network Principle
Figure 37 gives the sidetone connection.
Figure 37
RECIN
TEA7092
19
0.6V
3
60kΩ
VL
60kΩ
R11
ZB
kIL = 0 for IL = ISL
kIL = 1 for IL = ILL
kIL
+6dB Code
ITX
R13
0dB
SNLL
15
C12 SNSL
ZASL
R5+R6//C5
ZAL = K x ZALL + (1 - K) x ZASL
AGC
21 to 15dB
(Code +6dB
not activated)
26
AN848-38.EPS
VCC
20 REOUT
1 - kIL
16
+
C8
The sidetone is optimized if :
V1 - V2 = VRECIN(19) - VSNSL/SNLL (15/16) = 0
R27
⋅ ZB
ZAL =
If, R27 = K1 x R11 and K1 >> 1 :
V1 − V2
R11
Gsid =
=
v1
R11 + ZB
Thesidetoneattenuationis proportionalto R11andZB.
R11
With ZB = ZT//CR1//ZL.
Figure 38 gives the sidetone efficiency versus the
line length.
Figure 38
Low
0
1
2
3
4
Line (Km)
In receive mode the signal V1-V2 is amplified
through the receive path.
The attenuationdue to the external components of
the sidetone stage is :
V1 − V2
R11 + R27
Gsid =
=
R11 + R27 + ZAL
v1
24/57
AN848-39.EPS
Vear
High
II.4.3 - Line Tracking Sidetone Principle
Figure 39 gives the sidetone connection.
The sidetone are optimized if : V1 - V2 = 0
- On long line connection :
V1 - V2 = VRECIN (19) - VSNLL (16) = 0
R27
⋅ ZBL
⇒ ZALL =
R11a + R11b
with ZBL = ZT//CR1//ZLL.
- On short line connection :
V1 - V2 = VRECIN (19) - VSNSL (15) = 0
R13
⋅ ZBS
⇒ ZASL =
R11a
with ZBS = ZT//CR1//ZSL.
ZLL is the long line length impedance and ZSL is
the short line length impedance.
Figure 40 gives the sidetone efficiency versus the
line length for a one sidetone network principle and
a tracking sidetone network principle.
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.4 - Sidetone (continued)
Figure 39
TEA7092
19
R11a
ZBL
or
ZBS
0.6V
RECIN
3
60kΩ
VL
60kΩ
R11b
kIL = 0 for I L = ISL
kIL = 1 for I L = ILL
kIL
+6dB Code
ITX
R27
R13
0dB
C27 SNLL
15
ZALL
R29+R28//C28
C12 SNSL
ZASL
R5+R6//C5
ZAL = K x ZALL + (1 - K) x ZASL
REOUT
AGC
21 to 15dB
(Code +6dB
not activated)
26
AN848-40.EPS
VCC
20
1 - kIL
16
+
C8
Figure 40
Vear
High
Low
0
1
2
3
4
Line (Km)
In receive mode the signal V1-V2 is amplified
through the receive path.
The attenuationdue to the external components of
the sidetone stages are :
- For a line current equivalent to a long line connection :
R11a + R11b + R27
V1 − V2
=
Gsid(l) =
V1
R11a + R11b + R27 + ZALL
If, R27 = K1 x (R11a + R11b) and K1 >> 1 :
R11a + R11b
V1 − V2
=
Gsid(l) =
V1
R11a + R11b + ZBL
The sidetone attenuation is proportional to
(R11a + R11b) and ZBL.
- For a line current equivalent to a short line connection :
R11a + R13
V1 − V2
=
Gsid(s) =
V1
R11a + R13 + ZASL
If, R13 = K1 x R11a and K1 >> 1 :
R11a
V1 − V2
=
Gsid(s) =
V1
R11a + ZBS
The sidetone attenuation is proportionnal to R11a
and ZBS.
AN848-41.EPS
One Sidetone Network
Tracking Sidetone
R11a and R11b should be calculated to have the
same attenuation due to the two sidetone networks. In this way the complete receive channel
gain is fixed on Pin GREC (Pin 43) and in A.G.C.
mode the receive gain is reduced by 6dB between
ILL, line current for a long line connection, and ISL ,
line current for a short line connection.
If an application requests less or more than 6dB on
the complete receive channel,the values of R11a
and R11b will be adapted to it.
II.4.4 - Sidetone Programmating for PABX
Application
When the tracking sidetone network is used, it is
possible to inhibit it through the serial bus interface.
This principle suppresses the switches existing in
a telephone set, when this one can be indifferently
connected to a public exchange or a private exchange. When it is connected on a publicexchange
the tracking sidetone network is used. When it is
connected on a private exchange the tracking sidetone network is inhibited, internally the kIL information which controls the sidetone mixer stage is fixed
independently of the line current value, and can
take two values :
- By sending the code 0011000, the sidetone network is equivalent to :
ZAL =
3
1
⋅ ZALL + ⋅ ZASL
4
4
- By sending the code 0011011, the sidetone network is equivalent to : ZAL = ZASL
25/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.5 - Receive Channel
II.5.1 - General Information (Maximum Gain Adjustment)
The receive path amplifies several signals :
The signal VRECIN - VSNLL or VRECIN - VSNSL
or a combination of both is amplified to the ear- The line signal to the earphone with an intermephone outputs.
diate output, Pin REOUT (Pin 20) so as to use
this signal as an input for the loudspeaker ampliAs described in Section II.4.2 and Section II.4.3 the
fier or for a handfree circuit such as TEA7540.
signal V1 is attenuated through the sidetone net- The DTMF sinewave as a confidence tone level.
work. After this attenuation, the received signal is
- The waiting melody sinewave as an earphone
amplified by the Sidetone mixer and A.G.C. stages
level control.
with an amplification, of 21dB on a long line length,
At one time, only one of these signals is amplified,
ILL, which is the maximum receive gain, and of
the choice is made through the serial bus interface
15dB on a short line length, ISL , when the A.G.C.
with the microcontroller.
feature is used. The final gain adjustment is done
Figure 41 shows the receive channel block diagram.
on Pin GREC (Pin 20) by adjusting R14 and R17
values.
Figure 41
REOUT
IL
RECIN
20
TEA7092
19
R14
0.6V
R11a
Sidetone
Mixer
& AGC
Stages
R11b
60kΩ
60kΩ
VL
VCC
35
EAR+
21 to 15dB
R13
ZASL
R5+R6//C5
C12
ZALL
R29+R28//C28
GREC
R17
A2
R27
32
C27
SNLL
SNSL
16
Mute
40kΩ
15
25
VREF
A1
VCC
C14
20kΩ
26
20kΩ
VCC
10kΩ
+
Vear
C8
DTMF
37
Mute
C13
Mute
26/57
A3
36
EAR-
AN848-42.EPS
Idtmf
or Isinwave
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.5 - Receive Channel (continued)
The gain between Pin RECIN (Pin 19) and the
earphone outputs, Pin EAR+ (Pin 35) and
Pin EAR- (Pin 36) is :
- With tracking sidetone and A.G.C. features, earphone connected in symmetric mode :
• On long line, I L = ILL, maximum gain
Vear
Grl(dB) = 20 ⋅ log
VL
 R17
= 20 ⋅ log(Gsid(l)) + 21dB + 20 ⋅ log2 ⋅

 R14
• On short line, IL = ISL, minimum gain
Vear
Grs(dB) = 20 ⋅ log
VL
 R17 
= 20 ⋅ log(Gsid(s)) + 15dB + 20 ⋅ log2 ⋅

 R14 
- With One sidetone network and A.G.C. features,
earphone connected in symmetric mode :
• On long line, I L = ILL, maximum gain
Vear
Grl1(dB) = 20 ⋅ log
VL
 R17
= 20 ⋅ log(Gsid) + 21dB + 20 ⋅ log2 ⋅

 R14
• On short line, IL = ISL, minimum gain
Grsl(dB) = Grl1 − 6dB
Figure 42 shows the asymmetric connection.
Note : Due to the concept used to power supply
the earphone through the impedance network
(R10) and with the VCC supply, it is preferable to
connect the earphone in asymmetric mode if the
earphone impedance is less than 300Ω, and in
symmetric mode if the earphone impedance is
more than 300Ω. More details are given in the
following paragraph.
II.5.2 - Maximum Output Level
The maximum output level depends on several
parameters :
- The DC level on Pin VL (Pin 3).
- The impedance network value connected between Pin RECIN (Pin 19) and Pin VCC (Pin 26).
- The earphone impedance value.
Figure 43 shows the earphone amplifier supply
principle.
Without AC signal the voltage at Pin VCC (Pin 26) is :
VCC = VL + R11a/b x IL - (R10 + R11a/b) x IP
The value at Pin VL (Pin 3) depends on R12
(see Section II.1.1).
It is possible to use only one output, asymmetric
mode, in this case all the receive gain are reduced
by 6dB.
When an ac signal is amplified, the current driving
the earphone, Iear, flows through R10 and the DC
voltage at Pin VCC (Pin 26) is reduced.
Figure 42
TEA7092
26
VCC
+
C8
RECEIVE AMPLIFIER
A3
-1
A2
From
Sidetone
Mixer
36 EAR-
VREF
20
37
R14
35
GREC
R17
EAR+
+
C24
AN848-43.EPS
REOUT
Earphone
27/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.5 - Receive Channel (continued)
Figure 43
IL - (Ip + Iear)
R11a/b
IL
VL (3)
R12
C11
VS
VL
3
30
Iear
RECIN
19
EAR+ C24
35
R10
Iear
26
+
VCC
Ip
-1
C8
36
EAR-
TEA7092
Rear Symmetric or
Asymmetric Use
With this principle the maximum output voltage at Pin EAR+ (Pin 35) and Pin EAR- (Pin 36), dependingon
the application, is limited in current and in voltage in the following way : R11 = R11a + R11b
IP = 1.3mA at IL = 20mA
IP = 1.7mA at IL = 60mA (see Figure 21).
VRECIN = VL(3) + R11 x (IL - IP - IEAR) and VCC = VRECIN - R10 x (IP + IEAR)
- In asymmetric use; Earphone (REAR) connected on Pin EAR+ (Pin 35).
VCC = 2 x VEAR(peak)(Max.) + 0.4
VEAR(RMS) =
π ⋅ REAR ⋅ IEAR
2
√
VEAR(RMS) (Max.) in VRMS :
π ⋅ REAR
⋅ [VL + R11 ⋅ IL − (R10 + R11) ⋅ IP − 0.4]
2 ⋅ (2π ⋅ REAR + R10 + R11)
√
- In symmetric use; Earphone (REAR) connected between Pin EAR+ (Pin 35) & Pin EAR- (Pin 36).
VCC = VEAR (peak)(Max.) + 0.2
VEAR(RMS) (Max.) =
VEAR(RMS) =
π ⋅ REAR ⋅ IEAR
2⋅√
2
VEAR(RMS) (Max.) in VRMS :
VEAR(RMS) (Max.) =
π ⋅ REAR
⋅ [VL + R11 ⋅ IL − (R10 + R11) ⋅ IP − 0.2]
√2 ⋅ (π ⋅ REAR + 2 ⋅ (R10 + R11))

Notes : 1. In few applications, at low line current (IL < 20mA) and depending on the DC voltage at
Pin VL (Pin 3), the absolute minimum value of VCC, 2V, should be taken into account in the
calculation of VEAR(RMS)(Max.). This limitation happens if : IL = 20mA, R12 = 68kΩ and R10 =
1200Ω (complex impedance DC value).
2. Usually, when the impedance of a transducer, Rear, increases, the efficiency of the transducer
in dBSPL/V decreases. The receive gain is adapted to the earphone impedance to offset this
transducer’sefficiency change, so that the complete acoustical gain of the receive path remains
constant.
28/57
AN848-44.EPS
Ip + Iear
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.5 - Receive Channel (continued)
Table 2
Asymmetric
REAR = 150Ω
33kΩ
680pF
R17
C17
Symmetric
REAR = 300Ω
68kW
330pF
REAR = 600Ω
68kΩ
330pF
REAR = 1kΩ
120kΩ
220pF
The Table 3 gives the value of VEAR(RMS)(Max.), at IL = 20mA & IL = 60mA, for different values of,
R12 (68kΩ, 82kΩ, 110kΩ), R10 (680Ω, 1200Ω to simulate a complex impedance), REAR (150Ω, 300Ω in
asymmetric mode ; 600Ω, 1kΩ in symmetric mode) and a distortion level at 2% and 10%.
Table 3
IL
R10
R12
68kΩ
680Ω
82kΩ
110kΩ
20mA
68kΩ
1200Ω
82kΩ
110kΩ
68kΩ
680Ω
82kΩ
110kΩ
60mA
68kΩ
1200Ω
82kΩ
110kΩ
D (%)
2
10
2
10
2
10
2
10
2
10
2
10
2
10
2
10
2
10
2
10
2
10
2
10
150Ω (A)
0.45
0.51
0.45
0.51
0.46
0.51
0.26
0.29
0.39
0.42
0.46
0.5
0.28
0.32
0.28
0.32
0.29
0.32
0.28
0.32
0.28
0.32
0.29
0.33
Earphone Output Level (VRMS)
300Ω (A)
600Ω (S)
1kΩ
0.77
1.2
0.85
1.3
1.6
0.9
1.4
0.96
1.52
1.92
0.98
1.91
1.1
2
2.56
0.52
0.59
0.57
0.61
0.97
0.64
0.87
0.69
0.89
1.33
0.89
1.32
0.95
1.37
1.8
0.6
1.2
0.69
1.4
2.5
0.6
1.25
0.69
1.42
2.5
0.62
1.27
0.7
1.44
2.6
0.6
1.23
0.69
1.4
1.98
0.6
1.25
0.69
1.33
2.3
0.62
1.28
0.7
1.45
2.6
(S)
1.5
1.8
2.4
0.95
1.25
1.65
2.3
2.3
2.3
1.9
2.15
2.3
The sidetone mixer stage has a limiter to avoid acoustic signal higher than 120 dBSPL on the earphone.
Example : Electrodynamic transducer : 150Ω / 122 dBSPL/V
- R10 = 680Ω ;
• At IL = 20mA : VEAR(Max.) = 0.51VRMS ⇒ 116.2 dBSPL
• At IL = 60mA : VEAR(Max.) = 0.33VRMS ⇒ 112.4 dBSPL
If this acoustic limitation is too low, it is possible to modify it by :
- Decreasing the gain of the sidetone attenuation = Decrease R11a & R11b.
(R13 & R27 should also be modified).
- Increasing the gain on Pin GREC (Pin 37), to maintain the same total receiving gain
⇒ Increase R17.
29/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
II - SPEECH FEATURES (continued)
II.5.3 - Line Loss Compensation /
A.G.C. Adjustment
The characteristics of the A.G.C. stage in the receive path are the same as those in the transmit
path.
For more information see Section II.3.3.
II.5.4 - A.G.C. Inhibition
The characteristics of the A.G.C. inhibition stage in
the receive path are the same as those in the
transmit path.
For more information see Section II.3.4.
II.5.5 - +6dB Mode
Through the serial bus interface, it is possible to
increase the receive gain amplifier by 6dB.
This code (0010110) is a toggle code.
II.6 - Handsfree Interface
Figure 44 shows the interconnection between
TEA7092 and Handsfree circuit such as TEA7540.
TEA7092 should be in Handsfree mode (0110010).
The Handsfree circuit is supplied through the
Pin VLS (Pin 1)
I n t h is mod e t he sig n a l inje c t e d on
Pin HFIN (Pin 22) is amplified, the antiacoustic
feedback stage is inhibited and the loudspeaker
amplifier is activated.
The receive path of the Handsfreecircuit is inserted
between Pin REOUT (Pin 20) and Pin LSIN (Pin 5).
Figure 44
TEA7092
LSOUT 6
43 GND
VLS 1
L
HFIN REOUT LSIN
22
20
5
3
15
26
INR
OUTR
13 INE
Handfree
Microphone
30/57
V+ 28
TEA7540
AN848-45.EPS
OUTE
GND
1
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
III - CALL PROGRESS MONITOR AND GROUP LISTENING MODES
III.1 - General Information
The Call Progress Monitor and Group Listening
modes are OFF-HOOK modes with the loudspeaker being used.
The Call Progress Monitor, or ”ON-HOOK dialing”
is an OFF-HOOK mode where the line is taken
through a dedicated key which closes the line
without using the handset. In this mode only the
loudspeaker is enabled, to hear the different tones
coming from the exchange. As soon as the handset
is off-hook the loudspeaker is disabled and no
longer used. In Call Progress Monitor, the handset
microphone is muted and the anti-acoustic feature
is disabled.
The group listening mode is an OFF-HOOK mode
where the handset and the loudspeaker are simultaneously used. The receive signal can be heard in
the earphone and in the loudspeaker. In Group
listening mode, the anti-acoustic or anti-howling
feature is enabledto prevent any feedbackfrom the
handset microphone to the loudspeaker which can
cause howling effect.
Figure 45 shows the loudspeaker amplifier path.
The signal coming from Pin REOUT (Pin 20), intermediate receive output, is injected into the loudspeaker amplifier on Pin LSIN (Pin 5). Between pin
REOUT (Pin 20) and Pin LSIN (Pin 5) a filter can
be added to offset the loudspeaker frequency response curve. The loudpeaker is connected on Pin
LSOUT (Pin 44). The maximum gain between Pin
LSIN (Pin 5) and Pin LSOUT (Pin 44) is 34dB.
When a handsfree circuit is used, its receive path
is connected between Pin REOUT (Pin 20) and
Pin LSIN (Pin 5).
The loudspeaker amplifier, as described in Figure 45, is controlled by the following signals :
- LS AGC from the anti-acoustic feedback stage
which attenuates the loudspeaker amplifier gain
when the handset microphone level goes upper
the threshold to avoid howling effect.
- Pin LSSOFT (Pin 6) which attenuates the loudspeaker amplifier gain, to drive properly the loudspeaker when the LSOUT output reaches the
saturation of the output stage compared to VLS or
the ground, through VPP(LSOUT) information.
This information acts as a softclipping stage, so
the gain is reduced without any distortion.
- The volume control stage adjusts, by 4dB step,
the loudspeaker amplifier gain, with a maximum
depth of 28dB.
Note : In default mode, the gain of the volume
control stage is egal to Gmax -28dB.
Figure 45
Ring in
RI
10kΩ
20kΩ
Volume
Control
10kΩ
SIN 5
40kΩ
50kΩ
DC
Translator
LS AGC
LSOUT
10kΩ
44
+
C2
Vp(LSOUT)
AN848-46.EPS
TEA7092
L
31/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
III - CALL PROGRESS MONITOR AND GROUP LISTENING MODES (continued)
Figure 46
IL
VL
TEA7092
3
400Ω
10Ω
Switch Close,
if RESET Low
and IL Present
ITX/41
(See Transmit
Channel)
Istart-up
+
C1
The final stage of the transmit path is simultaneously used to amplify the transmit signal and to
power supply the loudspeaking part.
- IVMC : Current for the microcontroller power supply.
- IVCC : Speech part current consumption.
Other peripherals like a handsfree circuit or discret
CMOS logic can be powered on Pin VLS (Pin 1).
Figure 47
After an OFF-HOOK action, during the start-up
period and still the microcontroller reset is low, the
current power supply of the loudspeaking part is
used to charge quickly the capacitor C10 on pin
VMC (Pin 2), capacitor which is used to power
supply the microcontroller.
Figure 47 shows the line current, IL, partition in the
different paths of the TEA7092.
- ILS : Current available for the loudspeaker part
and other peripherals.
32/57
ILS (mA)
Figure 46 shows the loudspeaking part supply.
10
100
90
80
70
60
50
40
30
20
10
0
ILS
IP
IVMC
8
6
4
2
0
20
40
60
IL (mA)
80
100
0
120
AN848-48.EPS
T h e lo u d s pe a kin g pa rt is p o we red on
Pin VLS (Pin 1).
VMC
+
C10
IP /VMC (mA
III.2 - Loudspeaking Part Supply
2
AN848-47.EPS
1
VLS
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
III - CALL PROGRESS MONITOR AND GROUP LISTENING MODES (continued)
III.3 - Softclipping Stage
The softclippingstage avoids distortion on the loudspeaker output LSOUT (Pin 44) over a range of
input signals on Pin LSIN (Pin 5).
Figure 48 shows the loudspeaker softclipping
stage.
The softclipping stage avoids distortion when there
is n o t e n ou g h DC s u p ply vo lt a g e on
Pin VLS (Pin 1). This is done by detecting the saturation on the Pin LSOUT (Pin 44) compared to
Pin VLS (Pin 1) - 0.2V and GND + 0.2V. When one
of these two voltages is reached, the DC voltage
on Pin LSSOF (Pin 6) increases and the loudspeaker amplifier gain is reduced through the
VPP(LSOUT) signal control.
III.4 - Antiacoustic Feedback Features
The same stage is used to control the antiacoustic
feedback stage, to avoid howling effect, than to
control the squelch stage.
Figure 49 shows the antiacoustic feedback and
squelch stage.
In group listening mode, when the handset and the
loudspeaker are simultaneously used, it is neccessary to avoid howling effect between the handset
microphone and the loudspeaker.
The antiacousticfeedback stage detects the microphone signal and, if this one is higher than the fixed
threshold (60mV), the gain of the loudspeaker is
reduced through LS AGC information.
By default the loudspeaker amplifier gain reduction
is fixed at 15dB, this one can be modified through
the serial bus interface with the following values :
- 10dB : code (0111100).
- 15dB : code (0111101),
equivalent to default mode.
- 20dB : code (0111110).
- 25dB : code (0111111).
These different values allow the adaption of the
antiacoustic feedback stage to different telephone
sets.
Figure 50 shows the behaviour of the antiacoustic
feedback stage (coupled with the squelch feature,
if this one is enabled).
The signal microphone is amplified by the first
stage with a gain close to 200, and filtering on
Pin ASC (Pin 18), the cut off frequency is fixed by
C25 and the internal 0.5kΩ.
Recommended values :
C25 = 470nF or 1µF⇒ fC = 677Hz or 318Hz
On Pin ASQ (Pin 17), the rise and decay times are
fixed by R16, C16 and the 10µA internal current
source.
C16 x 60 x 10−3
- Rise time : tR =
,
10 x 10−6
with C16 = 1µF ⇒ tR = 6ms.
- Decay time : tD = R16 x C16,
with R16 = 330kΩ andC16 = 1.5µF ⇒ tD =330ms.
Figure 48
VLS
TEA7092
LS AGC
Vp(LSOUT)
GND + 0.2
4µA
6
R31
LSSOF
C19
AN848-49.EPS
VLS - 0.2
Vp(LSOUT)
33/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
III - CALL PROGRESS MONITOR AND GROUP LISTENING MODES (continued)
III.4 - Antiacoustic Feedback Feature (continued)
Figure 49
TEA7092
To Transmit
AGC
VCC
10µA
From
Microphone
Preamplifier
60mV
0.8kΩ
100kΩ
0.5kΩ
Attenuation
Programmable
from 10 to 25dB
VREF
LS AGC
60mV
VREF
18
25
VREF
ASQ
C25
R16
AN848-50.EPS
ASC
17
C16
Figure 50
Gtx (dB)
Gmax
Low
Microphone
Level
High Microphone Signal
Softclipping Mode
Normal Speech
*
9dB
Gmax - 9.5dB
3dB
Vsl
Vst
Vsoft
VMIC
* 60mV at Pin 17
GLS - xdB
GLS is Programmable through
the Volume Control Stage
x is Programmable through the Serial Bus
(10, 15, 20, 25dB) (default value is 15dB)
VMIC
34/57
AN848-51.EPS
GLS
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
III - CALL PROGRESS MONITOR AND GROUP LISTENING MODES (continued)
When there is enough line current to drive properly
the charge on the loudspeaker output, the maximum peak to peak dynamic is :
- On Rloudspeaker = 25Ω : VPP = VLS - 1.1V
- On Rloudspeaker = 32Ω : VPP = VLS - 1V
- On Rloudspeaker = 50Ω : VPP = VLS - 0.9V
Figure 51 : Output Power On LSOUT
Figure 53 : Output Power On LSOUT
40 50 60 70 80 90 100 110
IL (mA) (R12 = 68kΩ)
10 20 30
40 50 60 70 80 90 100 110
130
120
110
100
90
80
70
60
50
40
30
20
10
0
0
AN848-53.EPS
LS = 25Ω
LS = 32Ω
LS = 50Ω
LS = 25Ω
LS = 32Ω
LS = 50Ω
10 20 30
40 50 60 70 80 90 100 110
IL (mA) (R12 = 110kΩ)
35/57
AN848-54.EPS
P (mW)
LS = 25Ω
LS = 32Ω
LS = 50Ω
10 20 30
100
90
80
70
60
50
40
30
20
10
0
0
IL (mA) (R12 = 82kΩ)
P (mW)
100
90
80
70
60
50
40
30
20
10
0
0
Figure 52 : Output Power On LSOUT
AN848-52.EPS
P (mW)
III.5 - Maximum Output Power
The loudspeaker part is powered through the
Pin VLS (Pin 1). The VLS power could come from
the line, Pin VL (Pin 3) or an external power supply,
+5V for example.
When it is powered from the line, Pin VL (Pin 3), the
available current, ILS an d t h e v olt a ge at
Pin VLS (Pin 1) depend on the line current IL.
- VLS (Pin 1) = VL (Pin 3) - (0.95 + 10 x ILS)
- ILS = 0.74 x IL - 1.8mA ; if IL < 15mA
- ILS = 0.92 x IL - 4.5mA ; if IL > 15mA
The current consumption of the loudspeaker amplifier is 1mA, so the current available for the loudspeaker is : ILS1 = ILS - 1mA
Figures 51, 52 and 53 give the maximum power
available on the loudspeaker for different loudspeaker impedances (25, 32, 50Ω) and different
values of R12 (R12 sets up the DC voltage at
Pin VL (P in 3) an d t h e DC v o lt ag e a t
Pin VLS (Pin 1), thus it has an influence on the
maximum power available on the loudspeaker).
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
III - CALL PROGRESS MONITOR AND GROUP LISTENING MODES (continued)
III.6 - External Power Supply Facility
Figure 54
TELEPHONE SET
LA
LINE
LB
LINE INTERFACE
- EHKS Interface
- Pulse Dialing Interface
- RC Ring Interface
DP HKS
VRING
LS
TEA7092
Application
MIC
HFIN REOUT LSIN VLS
1
2
3
VRMC
TKL EHKS
MICROCONTROLLER 1
Application
4
SW1
ANSWERING
MACHINE
SW2
RECORDER
+5V
MICROCONTROLLER 2
MAIN
MAIN POWER ISOLATION AND SUPPLIES
The loudspeaker amplifier can be powered
through an external power supply, such as a
+5V one.
This external power supply facility allows the use
of TEA7092 in a terminal such as an answering
machine, a cordless or others, with a direct interface with the +5V external power supply.
Figure 54 shows how to connect the TEA7092 in
an answering machine.
The different inputs/outputs are :
- Line Interface :
• LA/LB : line wire terminal
- Line Interface / TEA7092 :
• VRING : TEA7092 supply in ring mode
• VSPEECH : TEA7092 supply in OFF-HOOK mode
- Line Interface / Microcontoller 1 :
• DP : Pulse interface control
• HKS : Hook switch information
• EHKS : On-hookdialing or handsfreeinformation
• TKL : µP line seizure feedback in EHKS mode
- TEA7092 / Microcontroller 1 / 2 :
• RESET
• PON : Line current presence
• RI : Ring information
• DATA / CLK : Serial bus interface
36/57
- TEA7092 / Answering Machine :
• 1) Outgoing message registration ; The line is
open, TEA7092 is powered from the +5V and
the switch SW1 is closed.
• 2) Outgoing message is sent to the line ;
TEA7092 is powered from the line and the
o u t g o in g m es sa g e is s e nt o n
Pin HFIN (Pin 22), amplified through
TEA7092 and sent to the line.
• 3) Incoming message registration ; TEA7092 is
powered from the line and the incoming
message is sent to the answering machine
through the intermediate receive output, Pin
REOUT (Pin 20).
• 4) Incoming message playback ; The line is
open, TEA7092 is powered from the +5V and
the incoming message is sent from the
answering machine to TEA7092 through the
Pin LSIN (Pin 5) and amplified in TEA7092
loudspeaker amplifier to be heard in the
loudspeaker.
Wh en T EA7 092 is powered wit h +5V on
Pin VLS (Pin 1), the maximum power on the loudspeaker is :
- On RLS = 25Ω : 100mW
- On RLS = 32Ω : 80mW
- On RLS = 50Ω : 50mW
AN848-55.EPS
EAR
VSPEECH
RESET
DATA
CLK
PON
RI
KEYBOARD
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
III - CALL PROGRESS MONITOR AND GROUP LISTENING MODES (continued)
III.7 - Ring Melody Control Mode
Note : For complementary information, see Section
IV.3 - Serial bus interface.
In OFF-HOOK mode it is possible to control the ring
melody using the loudspeaker.
The ring melody is audible only in the loudspeaker.
This feature is enabled by the serial code :
0 1 1 0 0 1 1.
Figure 55 : Flow Chart
ON-HOOK
OFF-HOOK
HANDSFREE MODE
0110010
or
OFF-HOOK
HANDSET MODE
HANDSFREE MODE
CONFIGURATION CODES
SETTING
OPERATING CODES
- AGC ON or OFF
- Sidetone configuration
- Squelch ON or OFF
- Decay PON current value
- Antiacoustic feed back value
- Speech
- Dialing sequence
- Mutes
- Error beep
- Sine wave sequence
RING MELODY CONTROL
0 11 0 01 1
Fi1 Code
+ Divider 1 Code
0 00 XX X X + 1 XX X X X X
The Ring melody is made
of N frequencies, the duration
of each frequency is determined
by the microcontroller
Fi2 Code
+ Divider 2 Code
0 00 XX X X + 1 XX X X X X
FiN Code + Divider N Code
0 00 XX X X + 1 XX X X X X
HANDSFREE MODE
with
the last OPERATING code used
before Ring melody control
and
Configuration codes still stored
or
HANDSET MODE
0 11 0 00 0
HANDSET MODE
with
the last OPERATING code used
before Ring melody control
and
Configuration codes still stored
AN848-56.EPS
HANDSFREE MODE
0110010
37/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
III - CALL PROGRESS MONITOR AND GROUP LISTENING MODES (continued)
III.8 - Beep Error Generator
Note : For complementary information, see Section IV.3 - Serial bus interface.
In OFF-HOOK mode it is possible to send a square
wave signal in the earphone and in the loudspeaker
by using the ring frequency generator, all frequencies available in ring mode are available in Beep
error mode.
This feature is enabled by the serial code :
0 0 1 1 1 0 0 , which sent the square wave in the
earphone.
To send the beep error on the loudspeaker it is
necessary to complete the previous sequence with
the Group listening code : 0 1 1 0 0 0 1.
Figure 56 : Flow Chart
ON-HOOK
ON-HOOK
OFF-HOOK
HANDSET MODE
OFF-HOOK
HANDSET MODE
Fi Code
+ Divider Code
0 00 X XXX + 1 XX X XX X
VOLUME CONTROL
010 0XXX
ERROR BEEP
00 11 100
GROUP LISTENING CODE
0 11 0001
BEEP SENT IN THE EARPHONE
GROUP LISTENING MODE
SPEECH CODE
00 10 000
Fi Code
+ Divider Code
0 00XXXX + 1XXXXXX
NEW BEEP
Yes
ERROR BEEP
0 01 1100
No
HANDSET MODE
BEEP SENT IN THE EARPHONE
AND IN THE LOUDSPEAKER
SPEECH CODE
0 01 0000
Yes
No
GROUP LISTENING MODE
38/57
AN848-57.EPS
NEW BEEP
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
IV - MICROCONTROLLER INTERFACE
IV.1 - Microcontroller Power Supply
The microcontroller is used in every modes,
speech, dialing and ring.
It is requested to start quickly in ring mode, less
than 200ms and to maintain the supply on the
microcontroller in pulse dialing mode, with a low
voltage across the telephoneset, or during an earth
loop connection, in these two modes the microcontroller is supplied through the energy previously
stocked in a capacitor and this capacitor should be
able to maintain the power on the microcontroller
during one second.
This compromise between the different modes is
carried out through the microcontroller power management which is connectedon Pin VMC (Pin 2) and
on Pin VRMC (Pin 8).
Figure 57 shows the microcontroller power supply
management.
In OFF-HOOK mode :
- C10 on Pin VMC (Pin 2) is charged in priority with
the Istartup (ILS) currentsource and is, after Reset
high, powered with IVMC (see Section II.1.3 START UP CHARACTERISTICS).
- The voltage on Pin VMC (Pin 2) is equal to :
VL (Pin 3) - 0.4V
- In Pulse dialing mode the microcontroller connected
on the 3.5V regulated voltage, Pin VRMC (Pin 8), is
powered through the serial regulator.
In Ring mode :
- For the microcontroller power supply only the
c a p ac it or C1 5 of 4 . 7µF co n n e c te d o n
Pin VRMC (Pin 8) has to be charged, so the startup time in ring mode can be less than 200ms.
IV.2 - Reset and Pon Signals
These two pieces of information give the status of
the Pin VRMC (Pin 8) and of the line current, IL.
In OFF-HOOK mode :
- Pin RESET (Pin 11) goes at high level when VRMC
reaches 2.6V and then remains at high level until
VRMC reaches the decay threshold fixed at 2.5V,
or the Reset code (0 0 1 0 1 1 1) is received
through the serial bus interface when PON is at
low level. If the Reset code has been previously
sent Pin RESET (Pin 11) goes back to an high
level, if VRMC is higher than the rise threshold, on
a rise edge of PON signal.
Note : when PON is at high level, the Reset code
is inhibited.
- Pin PON (Pin 12) goes at high level when the
voltage at Pin VRMC (Pin 8) reaches 2.6V and the
line current (IL) reaches the value of 12mA, and
then remains at high level until the line current (IL)
goes below the threshold level fixed through the
configuration code sent on the serial bus interface.
• Decay threshold level : IL = 12mA by default
configuration.
• Decay threshold level : IL = 4mA if the code
(0 1 1 1 0 0 1) is sent.
Figure 57
VL
3
TEA7092
IVMC
Battery
1 VLS
Close if
RESET Low and
IL Present
VRMC
2
8
+ C10
470µF
Info for
PON & RESET
3.5V
+
C15
4.7µF
µF
+
LCD
470kΩ
AN848-58.EPS
VMC
ISTART = ILS
VBANDGAP
39/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
IV - MICROCONTROLLER INTERFACE (continued)
IV.2 - Reset And Pon Signals (continued)
Figure 58 shows the RESET and PON signals in
different modes.
Different modes :
- A: ON-HOOK mode RESETand PONstayat lowlevel
- B : START UP, as soon as the voltage on VRMC
reaches the rising threshold and the line current,
IL is higher than 12mA, RESET and PON go at
high level.
- C : PULSE DIALING, PON follows the line current, IL and RESET stays at high level.
- D : SPEECH or DTMF, RESET and PON stay at
high level
- E : LINE BREAK EXCHANGE duration less than
td, as soon as the line current, IL, goes lower than
the programmed threshold level (12 or 4mA), the
PON signal goes to low level, the microcontroller
detects it and starts an internal counter, if the
feeding break is less than a prefixed td value
(200ms for example), PON goes back to high
level with the line current, IL and the feedingbreak
is ignored by the kit TEA7092and microcontroller.
- F : LINE BREAK EXCHANGE duration more than
td, as soon as the line current, IL, goes lower than
the programmed threshold level (12 or 4mA), the
PON signal goes to low level, the microcontroller
detects it and starts an internal counter, if the
feeding break is more than a prefixed td value
(200ms for example), when the counter reaches
200ms is sent the Reset code (0 0 1 0 1 1 1) to
the TEA7092 and the pin RESET (Pin 11) goes
to low level, on this signal the microcontroller
goes in reset condition.
In RING mode :
- Pin RESET (Pin 11) goes at high level when the
voltage at Pin VRMC (Pin 8) reaches the rise
threshold and then remains at high level until
Pin VRMC (Pin 8) reaches, when the ring input
voltage disappears, the decay threshold.
- Pin PON (Pin 12) stays at low level.
Figure 58
IL
A
B
C
D
E
D
F
D
A
t
VMC
5.6V
2.7V
2.6V
t
VRMC
3.5V
2.6V
2.5V
t
PON
tD
tD
t
RESET
t
Td : Delay Fixed by the Microcontroller
40/57
Reset code (0010111)
sent by the microcontroller
AN848-59.EPS
A : ON-HOOK
B : START-UP + SPEECH
C : PULSE DIALING
D : SPEECH or DTMF
E : LINE BREAK EXCHANGE DURATION
F : LINE BREAK EXCHANG DURATION > td
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
IV - MICROCONTROLLER INTERFACE (continued)
IV.3 - Serial Bus Interface
Figure 59
t1
t2
t1
t1
t1
t1 > 1µs ; t2 > 2µs
CLK
Pin 13
DATA
Pin 14
a0
a1
a2
a3
a4
a5
a6
AN848-60.EPS
Synchro
Datas should Change During Clk = 1
A Standard 8-bit Code can be Sent, the Last One is Ignored
IV.3.1 - Different Codes
The serial bus interface works with 7 significant
bits, a standard 8 bit code can be used, TEA7092
only takes care of the seven first bits.
Figure 59 shows the timing of the Pin CLK (Pin 19)
and of the Pin DATA (Pin 20).
TEA7092 Initialization
After Pin RESET (Pin 11) goes high, TEA7092 is
initialized, the internal default programmed codes
are given in Bold in the following code tables.
Codes programming TEA7092 are :
- The MODE codes :
The mode codes are the upper level of codes.
Codes
a6 a5 a4 a3 a2
0 1 1 0 0
0 1 1 0 0
0 1 1 0 0
a1
0
0
1
Remarks
a0
0 Handset Mode
1 Group Listening Mode
0 Handsfree Mode
- The OPERATING codes which are related to the
MODE codes :
Each operating code can be used under each
mode code. When an operating code is sent, the
previous one is cancelled.
Codes
Remarks
a6 a5 a4 a3 a2 a1 a0
0
0
1
0
0
0
0
Speech
0
0
1
0
0
0
1
Dialing
0
0
1
0
0
1
0
Mute in Transmit and
Receive Paths
0
0
1
0
0
1
1
Mute in Transmit Path
0
0
1
1
1
0
0
Error Beep
0
0
1
1
1
0
1
Sine wave
High Frequency Group
0
0
1
1
1
1
0
Sine wave
Low Frequency Group
41/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
IV - MICROCONTROLLER INTERFACE (continued)
IV.3.1 - Different Codes (continued)
- The FLIP-FLOP codes, each time they are sent,
TEA7092 returns to the previous configuration.
Each Flip-Flop code is an independent one, its
configuration is not modified by any other code,
excepted the ”Initialization” code and the ”Reset”
code.
These codes are accessible through the telephone set user, for example : The +6dB mode on
the earphone which increases the earphone level
is accessible through a dedicated key of the
telephone set keyboard.
Codes
Remarks
a6 a5 a4 a3 a2 a1 a0
0
0
1
0
1
0
1
VL(3) DC Speech /
VL(3) DC Pulse Dialing
0
0
1
0
1
1
0
Normal Receive Gain /
+6dB Receive Gain
0
0
1
1
0
1
0
No Transfer /
Transfer Request
0
1
1
0
1
1
0
Normal Transmit Gain /
-6dB Transmit Gain
0
1
1
1
0
1
0
Oscillator ON /
Oscillator in Stand by
Mode
- The CONFIGURATION codes, which are generally sent once to program a telephone set at each
OFF-HOOK action, such as PABX connection or
PON threshold level for example. are not accessible through the telephone set user. Excepted
the Antiacoustic feedback stage attenuator value
and the Decay PON current threshold, each code
is an independant one, its configuration is not
modified by any other code, except for the ”Initialization” code and the ”Reset” code.
Except for the Antiacoustic feedback stage attenuator programmation codes and the Decay
PON current threshold,all the other Configuration
codes are Flip-Flop codes.
42/57
Codes
Remarks
a6 a5 a4 a3 a2 a1 a0
0 0 1 0 1 0 0 AGC on Tx & Rx Paths /
No AGC on Tx & Rx Paths
0 0 1 1 0 0 0 Line Tracking Sidetone
Network /
Single Sidetone Network
= 3/4 x ZALL + 1/4 x ZASL
0 0 1 1 0 1 1 Line Tracking Sidetone
Network /Single Sidetone
Network = ZASL
0 0 1 1 0 0 1 Squelch Feature ON /
Squelch Feature Inhibited
0 1 1 1 0 0 0 Dec ay P O N C u r ren t
Threshold = 12mA
0 1 1 1 0 0 1 Dec a y PO N C urr en t
Threshold = 4mA
0 1 1 1 1 0 0 Antiacoustic F eedback
Stage Attenuator = 10dB
0 1 1 1 1 0 1 Antiacoustic Feedback
Stage Attenuator = 15dB
0 1 1 1 1 1 0 Antiacoustic F eedback
Stage Attenuator = 20dB
0 1 1 1 1 1 1 Antiacoustic F eedback
Stage Attenuator = 25dB
- The LOUDSPEAKER VOLUME CONTROL codes.
These codes are memorized, independtly from
the mode or operating code. For example one of
these codes can be sent in Handset mode and
when the Group listening mode code is sent, the
loudspeaker output volume will be the one programmed in the Handset mode.
Codes
Remarks
a6 a5 a4 a3 a2 a1 a0
0 1 0 0 1 1 1 Gmax
0 1 0 0 1 1 0 Gmax - 4dB
0 1 0 0 1 0 1 Gmax - 8dB
0 1 0 0 1 0 0 Gmax - 12dB
0 1 0 0 0 1 1 Gmax - 16dB
0 1 0 0 0 1 0 Gmax - 20dB
0 1 0 0 0 0 1 Gmax - 24dB
0 1 0 0 0 0 0 Gmax - 28dB
0 1 1 1 0 1 1 -21dB Attenuation
Adder In Ring Mode*
* Flip-Flop code.
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
IV - MICROCONTROLLER INTERFACE (continued)
IV.3.1 - Different Codes (continued)
- HFIN input selection
For answering machine or cordless connection, it can be requested to select HFIN (Pin 22) input, without
enabling the loudspeaker, for this the following procedure should be sent :
• Handsfree code : 0 1 1 0 0 1 0
• Tx & Rx mutes : 0 0 1 0 0 1 0
• HFIN input select : 0 1 1 0 1 1 1
To go back to handsfree mode, send :
• Speech mode : 0 0 1 0 0 0 0
Or to go back to handset mode, send :
• Speech mode : 0 0 1 0 0 0 0
• Handset code : 0 1 1 0 0 0 0
- The DTMF and SINE WAVE codes.
These codes are memorized, independtly from the mode or operating code. For example one of these
code can be sent in Handset mode and when the Dialing mode code is sent, the DTMF frequencies sent
on the line are those previously programmed in the Handset mode.
Codes
a6 a5 a4 a3 a2 a1 a0
0 0 0 0 0 0 0
0 0 0 0 0 0 1
0 0 0 0 0 1 0
0 0 0 0 0 1 1
0 0 0 0 1 0 0
0 0 0 0 1 0 1
0 0 0 0 1 1 0
0 0 0 0 1 1 1
0 0 0 1 0 0 0
0 0 0 1 0 0 1
0 0 0 1 0 1 0
0 0 0 1 0 1 1
0 0 0 1 1 0 0
0 0 0 1 1 0 1
0 0 0 1 1 1 0
0 0 0 1 1 1 1
Key in DTMF
Dialing
”2”
”1”
”A”
”3”
”8”
”7”
”C”
”9”
”5”
”4”
”B”
”6”
”0”
”*”
”D”
”#”
DTMF Dialing
(Code 0010001 sent before)
697Hz
697Hz
697Hz
697Hz
852Hz
852Hz
852Hz
852Hz
770Hz
770Hz
770Hz
770Hz
941Hz
941Hz
941Hz
941Hz
+ 1336Hz
+ 1209Hz
+ 1633Hz
+ 1477Hz
+ 1336Hz
+ 1209Hz
+ 1633Hz
+ 1477Hz
+ 1336Hz
+ 1209Hz
+ 1633Hz
+ 1477Hz
+ 1336Hz
+ 1209Hz
+ 1633Hz
+ 1477Hz
SINE WAVE (Code 0011101
or 0011110 sent before)
348Hz or 604Hz
426Hz or 738Hz
385Hz or 668Hz
470Hz or 816Hz
- The Other Codes
Codes
Remarks
a6 a5 a4 a3 a2 a1 a0
0 0 1 0 0 0 1 Ring Start
0 0 1 0 1 1 1 Reset Control (High to Low level on Pin 11 (RESET)), Internal TEA7092 Initialization
and Microprocessor Serial Bus Connection Inhibited
0 1 1 0 0 1 1 Ring Melody Control, to listen the Ring Melody in the Loudspeaker During OFF-HOOK
Mode.
0 1 0 1 0 0 0 TEA7092 Initialization (to go back to internal default programmation)
43/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
IV - MICROCONTROLLER INTERFACE (continued)
IV.3.1 - Different Codes (continued)
- The RING and ERROR BEEP FREQUENCY codes
Ring Frequencies (Hz) (see Note)
Divider Codes
n
1010000
1010001
1010010
1010011
1010100
1010101
1010110
1010111
1011000
1011001
1011010
1011011
1011100
1011101
1011110
1011111
1100000
1100001
1100010
1100011
1100100
1100101
1100110
1100111
1101000
1101001
1101010
1101011
1101100
1101101
1101110
1101111
1110000
1110001
1110010
1110011
1110100
1110101
1110110
1110111
1111000
1111001
1111010
1111011
1111100
1111101
1111110
1111111
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
Fi Codes (Hz)
26321 (000XX10) 23551 (000XX11) 21308 (000XX00) 19455 (000XX01)
1645.0
1548.3
1462.3
1385.3
1316.0
1253.4
1196.4
1144.4
1096.7
1052.8
1012.3
974.8
940.0
907.6
877.4
849.1
822.5
797.6
774.1
752.0
731.1
711.4
692.7
674.9
658.0
642.0
626.7
612.1
598.2
584.9
572.2
560.0
548.3
537.2
526.4
516.1
506.2
496.6
487.4
478.6
470.0
461.8
453.8
446.1
438.7
431.5
424.5
417.8
1471.9
1385.3
1308.4
1239.5
1177.5
1121.5
1070.5
1024.0
981.3
942.0
905.8
872.3
841.1
812.1
785.0
759.7
736.0
713.7
692.7
672.9
654.2
636.5
619.8
603.9
588.8
574.4
560.7
547.7
535.2
523.4
512.0
501.1
490.6
480.6
471.0
461.8
452.9
444.4
436.1
428.2
420.5
413.2
406.0
399.2
392.5
386.1
379.8
373.8
1331.7
1253.4
1183.8
1121.5
1065.4
1014.7
968.5
926.4
887.8
852.3
819.5
789.2
761.0
734.8
710.3
687.3
665.9
645.7
626.7
608.8
591.9
575.9
560.7
546.4
532.7
519.7
507.3
495.5
484.3
473.5
463.2
453.4
443.9
434.9
426.2
417.8
409.8
402.0
394.6
387.4
380.5
373.8
367.4
361.1
355.1
349.3
343.7
338.2
1215.9
1144.4
1080.8
1023.9
972.7
926.4
884.3
845.9
810.6
778.2
748.3
720.6
694.8
670.9
648.5
627.6
608.0
589.5
572.2
555.9
540.4
525.8
512.0
498.8
486.4
474.5
463.2
452.4
442.2
432.3
422.9
413.9
405.3
397.0
389.1
381.5
374.1
367.1
360.3
353.7
347.4
341.3
335.4
329.7
324.2
318.9
313.8
308.8
These codes are memorized, independtly from the mode or operating code. For example one of these
code can be sent in Handset mode and when the Error Beep code is sent, the square wave frequency
sent on the earphone is the one previously programmed in the Handset mode.
Note : It is possible to program n from 1 to 15, 1.0.0.0.0.0.0 to 1.0.0.1.1.1.1, the frequency values are not given in the previous table, but
can be calculated in the same way.
44/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
IV - MICROCONTROLLER INTERFACE (continued)
IV.3.2 - Software Example
Sequence : ON-HOOK ; OFF-HOOK ; AGC OFF ; HANDSET ; DTMF dialing ; GROUP LISTENING ;
ERROR BEEP ; +6dB on earphone ; Normal gain on earphone; ON-HOOK.
Figure 60 : Flow Chart
ON-HOOK
TEA7092 Initializated
in Default Mode
PON = 1 & RESET = 1
OFF-HOOK
HANDSET MODE
VOLUME CONTROL
0 1 00 XX X
UP/DOWN
Loudspeaker Output
Level Adjustment
Yes
No
Configuration Code
AGC Inhibited in Tx
& Rx Paths
AGC OFF
00 101 00
No
NUMERIC
KEY PRESSED
Yes
KEY CODE
0 00 XX XX
DTMF Dialing
DIALING CODE
00 100 01
Fi Code
+ Divider Code
000XXXX + 1XXXXXX
ERROR BEEP
0 0111 00
BEEP SENT IN THE EARPHONE
AND IN THE LOUDSPEAKER
OPERATING CODE
Error Beep Mode
SPEECH CODE
0 0100 00
DTMF SENT
NEW BEEP
MUTE MIC & EAR
00 100 10
Yes
No
GROUP LISTENING MODE
INTER DIGIT PAUSE
HANDSET CODE
0 1100 00
Handset Mode Requested
SPEECH CODE
00 100 00
HANDSET MODE
GROUP LISTENING CODE
01 100 01
+6dB ON EARPHONE
0 0101 10
FILP-FLOP CODE
Earphone Level Change
GROUP LISTENING MODE
NORMAL GAIN ON EARPHONE
0 0101 10
AN848-61.EPS
Group Listening
Requested
ON-HOOK
45/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
IV - MICROCONTROLLER INTERFACE (continued)
IV.3.3 - Serial Bus Code Actions on Switches
Figure 61, Tables below give the switch positions and the generator status for the different serial codes
sent on the serial bus interface.
Figure 61
HANDSET
Microphone
SW1
2
HANDSFREE
Microphone
SW2
0dB
or
-6dB
1
Output Amp
1
To Line
2
DTMF
GENERATOR
SINEWAVE
GENERATOR
From Line
TRANSMIT CHANNEL
SW3
0dB
or
-6dB
1
Earphone
2
SW4
1
SW5
1
RING
GENERATOR
2
2
Loudspeaker
SINEWAVE
GENERATOR
RING MELODY
CONTROL
GENERATOR
ERROR BEEP
GENERATOR
RECEIVE CHANNEL
The mode codes, Handset, Group listening act only on switches SW1 and SW5.
Switches
Codes
Default
Handset Mode
Group Listening Mode
Handsfree Mode
Ring melody control
SW1 SW2 SW3 SW4 SW5
0110000
0110001
0110010
0110011
1
1
1
2
1
1
1
2
2
2
1
1
DTMF
2
2
1
1
2
Generators
Error
Sinewave
beep
Disabled
Ring Melody
Control
Disabled
Disabled
Disabled
Disabled
Enabled
The Operating codes act only on switches SW2, SW3 and SW4, the positions on the switches SW1 and
SW5 are the ones previously determined by the Mode codes.
Note : In Ring Melody Control, the operating codes are not accessible.
Operating Codes
Speech
Dialing
Mute in Tx & Rx
Mute in Tx
Error Beep
Sinewave HF Group
Sinewave LF Group
0010000
0010001
0010010
0010011
0011100
0011101
0011110
SW2
1
2
2
2
1
2
2
Switches
SW3 SW4
1/2*
1
2
2
2
2
1/2*
1
2
2
2
2
2
2
* 1 for Handset and Group listening modes, 2 for Handsfree mode.
46/57
DTMF
Disabled
Enabled
Disabled
Disabled
Disabled
Disabled
Disabled
Generators
Sinewave
Disabled
Disabled
Disabled
Disabled
Disabled
Enabled
Enabled
Error Beep
Disabled
Disabled
Disabled
Disabled
Enabled
Disabled
Disabled
AN848-62.EPS
DTMF
GENERATOR
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
IV - MICROCONTROLLER INTERFACE (continued)
IV.6 - Microcontroller Signal Control
in the Different Modes
The following table lists the configuration of the
signals given by TEA7092 in the different modes :
Signals/Modes
ON-HOOK
OFF-HOO K
RING
Line Current Variation
Detected in Transfer Mode
External Supply Only
Reset
0
1
1
1
PON
0
1
0
1
RI/IVI
0
0
1
1
1
0
0
Figure 62 : Current Line Variation to Detect
Transfer
16
14
12
10
8
6
4
2
0
10 20 30 40 50 60 70 80 90 100 110 120
IL (mA)
47/57
AN848-63.EPS
IV.5 - Oscillator
The Oscillator is powered on Pin VRMC (Pin 8).
The oscillator is only used for DTMF, sine wave,
beep error, ring frequency generator and transfer
feature.
In Pulse dialing flash or earth button, it is preferable
t o r ed u c e , t h e cu rren t co n su mp tion o n
Pin VRMC (Pin 8) as low as possible, in order to
have the lowest possible value of capacitor on Pin
VMC (Pin 2).
The toggle code (0 1 1 1 0 1 0) puts the Oscillator
in stand by mode or not.
The current consumption on Pin VRMC (Pin 8) is :
- Oscillator ON : 250µA
- Oscillator OFF : 50µA
The default condition is Oscillator ON.
If the microcontroller has a 3.58MHz resonator, the
oscillator output of the microcontroller can be connected, through a capacitor, to the Pin OSC (Pin 9)
so as to provide TEA7092 with the 3.58MHz signal.
∆IL (mA)
IV.4 - Ring Indicator - Line Current Variation
Indicator
The Pin RI/VI (Pin 10) is used for different modes :
- In Ring mode, when the threshold level, programmed on Pin RSU (Pin 40), is reached and
t h e Pin RE SE T (P in 11 ) is h igh , t h e
Pin RI/VI (Pin 10) goes to high logic level.
- In OFF-HOOK mode the pin RI/VI (Pin 10) gives
an indication of the line current variation when the
transfer feature is requested.
The transfer feature happens when there are two
telephone sets connected in parallel on the same
line and the user wants to transfer the communication from telephone ”1” to telephone ”2” and ONHOOK telephone ”1”.
With TEA7092 in telephone ”1”.
Telephone ”1” is in speech mode, the user presses
the ”Transfer” key on telephone ”1”. When the
”Transfer” key is pressed, the microcontroller
sends the Transfert code (0 0 1 1 0 1 0) and
TEA7092 memorizes the line current value. The
user ON-HOOK telephone ”1”, the line is maintained closed by the microcontroller, through the
pulse dialing high voltage stage.
When the user OFF-HOOK telephone ”2”, the line
current value in telephone”1” decreases, TEA7092
detects this line current variation and the Pin RI/VI
goes to high logic level. When the microcontroller
receives this signal it puts off the high voltage stage
of telephone ”1”.
Telephone ”1” goes in OFF-HOOK mode.
Figure 62 gives the value of the line current variation (∆IL) which generates a high logic level on
Pin RI/VI (Pin 10).
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
V - DIALER FEATURES
V.1 - DTMF Dialer
Figure 63
EAR-
35
36
10kΩ
DTMF2
C32
3
ZB
-1
7
C13
VL
40kΩ
DTMF/SINEWAVE
DTMF1
EAR+
I L/85
from
DC path
10kΩ
42
9kΩ
45kΩ
LOUDSPEAKER
CURRENT SOURCE
Mirror 1/40
Mute
1
V LS
+
C1
0dB
1kΩ
5kΩ
From
Microphone
TEA7092
25
21
AN848-64.EPS
GTR
R8
C14
The DTMF dialer generates the frequencies in order
to drive a telephone set keyboard and complies with
the recommandation Q.23 of the CCITT-T/CS 46-02.
Figure 64
SPEECH MODE
It generates :
- The low frequency group (697, 770, 852, 941Hz)
- The high frequency group (1209, 1336, 1477,
1633Hz)
No
NUMERIC
KEY PRESSED
Yes
Figure 63 shows the DTMF amplifier path.
KEY CODE
000XXXX
The MUTE signal driven through the serial bus,
selects the microphone signal or the DTMF signal
and the confidence tone level for the earphone and
the loudspeaker.
DIALING CODE
0010001
T h e DT MF lev e l is f ix ed by C13 on
Pin DTMF1 (Pin 7) and by R8 on Pin GTR (Pin 21),
C32 on Pin DTMF2 (Pin 42) fixes the cut off frequency of the second filter.
- Cut-off frequency on DTMF1 :
f1 =
1
2 ⋅ π ⋅ 20 ⋅ 103 ⋅ C13
with C13 = 47nF, f1 = 170Hz.
An internal twist between each DTMF frequency
is programmed so as to take care to follow the
T/CS46-02 recommended levels.
- Cut-off frequency on DTMF2 :
f2 =
1
2 ⋅ π ⋅ 10 ⋅ 103 ⋅ C32
with C32 = 2.7nF, f2 = 5.9kHz.
Figure 64 shows the DTMF signaling.
48/57
DTMF MODE
MUTE
0010010
INTERDIGIT PAUSE
Yes
NUMERIC
KEY PRESSED
No
SPEECH CODE
0010000
AN848-65.EPS
VREF
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
V - DIALER FEATURES (continued)
V.2 - Sinewave Generator
The Sinewave generator is programmable like the
DTMF generator. This one generates the DTMF
frequencies divided by 2, in single tone mode in two
groups :
- CodeDTMF + code 0011101: 348,385,426, 470Hz
- CodeDTMF + code 0011110: 604,668, 738, 816Hz
The sinewave level on line is 8dB lower than the
DTMF dialing level.
This sinewave generator can be used in mute
mode to send on line a signal to advise the other
party than you are in Secret mode.
V.3 - Pulse Dialer Interface
In pulse dialing mode, if the code (0 0 1 0 1 0 1) is
used, the voltage across TEA7092 is reduced to 2V
on Pin VL (Pin 3), this way it is possible to achieve
a low voltage across the telephone set during the
make period of the pulse dialing sequence.
Figure 65 shows the DC voltage across TEA7092
and across the telephone set in pulse dialing mode.
Note : It is possible to generatean acoustic control
in the earphone in pulse dialing mode with the
code (0010101). This code should be sent twice
within the break period of the pulse dialing. For example, if the break period is 60ms, send the code
(0010101) 10ms after the start of the break period
and send it again 10ms before the end of the break
period. This will generate a DC level change in the
earphone which will be audible.
Figure 65 : Mask / No Mask Mode
Pulse DialingMode
Other Modes
Flash Other Modes
DP (µP Output)
Code (0 0 1 0 1 0 1) Sent
2
0
VSET (V)
t
5V max.
0
t
AN848-66.EPS
VL (V)
49/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
VI - RINGER FEATURES
VI.1 - Ringer Power Supply
In ring mode only the ring part, the loudspeaker
amplifier, the logic part and the microcontroller
supply are powered.
The supply is provided by a switch mode power
supply.
Figure 66 shows the ring part.
The switch mode power supply converts the high
ac ring line voltage, 30 to 90VRMS at 25 or 50Hz,
into a low DC voltage, 3 to 5.6V, which is used to
supply the loudspeaker amplifier and the microcontroller. The switch mode power supply made by T1,
T2, L1, D7 and the resistors associated, is driven
through the Pin SWP (Pin 39).
The control on SWP is done by a 26kHz oscillator.
The coil L1 is 1mH, the diode D7 is a 1N4148.
VI.2 - Start-Up Threshold Level
By default, the ring threshold level is internally set
up at 18.8VDC on Pin RSU (Pin 40) :
(3 x 5.6V + VBE (0.6V) + 2 x VTHN (2 x 0.7V)),
equivalent to an AC ring level of 13.3VRMS.
As soon as this threshold level is reached, is a 11.2V
hysteresis is introduced to assurethe system’s stability
T h e VRING1 s t art u p le v el is s e t u p o n
Pin RSU (Pin 40) with R35 and if neccessary a
zener diode D5 added in serial with R35, most of
the countries don’t request D5.
VRING1 : Start up level.
 R35

⋅ 0.7 + VZ(D5) in V
VRING1 = 18.8 + 
 300kΩ

Note : Recommended value for R35 is 56kΩ.
Figure 66
L1
VRING
T1
+
+
I(VZP)
R37
R35
C6
D7
D2
C1
R36
R32
C30
T2
R38
D3
VZP
R33
RSU
38
40
SWP
39
24V
VLS
1
8
IVZP Info
+
11.2V
2.6V
5.6V
135kΩ
1.2V
150kΩ
VRMC
100µA
LSSOF
90kΩ
RI
VLS > 2.6V
150kΩ
C15
SERIAL
REGULATOR
LOGIC
CONTROL
26kHz
VRMC
6
I/17.5kΩ
LOGIC
CONTROL
> 2.6V
40kΩ
C19
R31
RI
Fi Ring
IA = f{(IVZP)}
VIN
44
LS AMP
(VLS - VLSOUT) < 0.2V
TEA7092
LSOUT
+
C2
Gain = 16
41
C4
50/57
R40
AN848-67.EPS
RCO
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
VI - RINGER FEATURES (continued)
VI.3 - Ring Frequency Generator
The ring frequency values which can be generated
are those given Page 45 of this application note.
On the Table given at Page 45, only the frequency
values for n > 15 are given, the frequency values
from n = 1 (1000000)to n = 15 (1001111) are also
accessible, if it is neccessary to generate a frequency higher than 1645Hz.
VI.4 - Output Power Optimization
The power available on Pin LSOUT (Pin 44) depends on :
- The country requires :
• Minimum input ac level in test conditions.
• Ring impedance.
Taking in account these main requests the power
on Pin LSOUT (Pin 44) is optimized through the
resistor R40 connected on Pin RCO (Pin 41).
- The yield of the switch mode power supply.
The principal parameters which influence the
yield are :
• D7 VBE value.
• T1 VCEsat and base current values (the maximum IC PEAK value is 100mA).
• L1 serial resistor value.
• Current consumption on Pin VZP (Pin 38) and
on Pin RSU (Pin 40).
• Bias current consumption on Pin VLS
This paragraph gives information on :
- The switch mode power supply concept.
- The switch mode power supply yield.
- The ring output power optimization on Pin LSOUT
(Pin 44).
VI.4.1 - Switch Mode Power Supply Concept
After the ring bridge, the switch mode power supply
concept is represented in Figure 67.
Input voltage equivalent to VRING1
VE
VE1
Input voltage after the switch SW1
IE
Mean input current
VS
Output voltage at Pin VLS (Pin 1)
Mean output current
IS
Voltage across D7 when it is in
VD
forward mode
IE0
Primary bias current
IS0
Secondarybias current
RL1
Resistive part of the coil L1
Switch SW1 - VCEsat of T1 PNP
- IB1, T1 base current
- tD, T1 desaturation time
- VE1 = VE - VCEsat(T1)
Figure 68 gives the voltage,VE1, the current in the
coil, ISELF, the current in D7, IDIODE and the current
in the switch SW1 given by C6, ICAPA.
The value of the maximum current in the coil is fixed
by tON and tOFF depends on RL. When RL decreases, t ON increases. The coil value should be
calculated so that the current in the coil reaches the
zero value with the minimum charge.
VE1 − VLS
(1)
IMax. = tON ⋅
L
L is the value of the coil L1.
The ratio between tON and tOFF is :
tON
VD + VLS
=
(2)
tOFF VE1 − VLS
The output current IS is :
IMax. tON + tOFF
⋅
(3)
IS =
2
t
Figure 67
L1
SW1
VE
C5
IE
IS
RL1
IE0
D7
C1
ISRL
IS0
VLS
RL
VE1
AN848-68.EPS
IEt
51/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
VI - RINGER FEATURES (continued)
VI.4 - Output Power Optimization (continued)
Figure 68
VE1
tON
tOFF
VS
t
-VD
ICOIL
t = 38.46µs
t is internally fixed by the 26kHz Oscillator
t
ICAPA
t
AN848-69EPS
IDIODE
t
VI.4.2 - Switch Mode Power Supply Losses
The sum of all the different losses gives the yield
of the switch mode power supply.
The final yield is :
POUT
ηfinal =
POUT + ΣPi
where : Pi are the different losses, POUT is the
power in the load RL : POUT = 4 x RL x (ISRL)2.
The output current IS is : IS = ISRL + IS0.
Using the equations (1), (2) and (3), the values of
tON and tOFF can be found :
tON
=
t
2⋅L⋅f⋅I ⋅
(V − V ) ⋅ (V +
V )
√
VLS + VD
S
E1
tOFF
=
t
LS
E1
2⋅L⋅f⋅I ⋅
(V + V ) ⋅ (V + V )
√
IMax. =
VE1 − VLS
S
LS
D
E1
2
S
D
(VE1 − VLS) ⋅ (VLS + VD)
⋅I ⋅
V +V 
L⋅f

√
E1
52/57
f = 26kHz
D
D
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
VI - RINGER FEATURES (continued)
VI.4 - Output Power Optimization (continued)
The different losses are :
- In the switch SW1 :
IMax. ⋅ tON
⋅ VCEsat
• VCEsat : PVCEsat =
2⋅t
VLS + VD
= IS ⋅ VCEsat ⋅
VE1 + VD
• T1 base current (IBT1) :
tON
PIBT1 = VE ⋅ IBT1 ⋅
- The sum of the losses is :
PTOTAL = ΣPi
= PVCEsat + PIBT1 + Pdesat + PIBT2 + PVZP
+ PRSU + Pcoil + PVLS + PµP + POLS + Pdiode
VI.4.3 - Output Power Adjustment
The optimization of the ouput power depends on the
system environment. It is therefore neccessary to
know the power which can be given by the system in
the best and worst loop line. Each country has a
different loop line system.
Figure 69 shows the system configuration.
t
2 ⋅ L ⋅ f ⋅ (VLS + VD)
(V − V ⋅ (V +
V )

√
E1
D
⇒
= VE ⋅ tD ⋅
Figure 69
TELEPHONE SET

√
2 ⋅ f⋅ IS ⋅ (VE1 − VLS) ⋅ (VLS + VD)
L ⋅ (VE1 + VD)
• T2 base current (IBT2) : PIBT2 =
(VE − 8.2)2
R32
- In the diode D7 :
IMax. ⋅ tOFF
⋅ VD
PDIODE =
2⋅t
VE1 − VS
⇒
= IS ⋅ VD ⋅
VE1 + VD
- At the primary ; The sum of these losses is equal
to : VE x IE0
• On Pin VZP (Pin 38) : VZP (Pin 38) = 2.55V ;
(VE − 2.55)2
PVZP =
R34 + R37
• On Pin RSU (Pin 40) :
(VE − 5.6)
⋅ VE
PRSU =
R35 + 300kΩ
- In the coil :
 IMax. 
2
 ⋅
 2 
Pcoil = Rcoil ⋅ 
⇒
= Rcoil ⋅ IS2 ⋅
tON2 + tOFF2
RL
Ring RC Network
Fixed by the Country
requirement
VRGENE
(20 to 60Hz)
PE
C
VE
The minimum power available, PE1 is for :
VRGENE(Min.) and RL(Max).
The maximum power available, PE2 is for :
VRGENE(Max.) and RL(Min).
Figure 70 gives the power available at the input of
the switch mode power supply.
Figure 70
VRGENE (Max.)
RL (Min.)
PE (mW)
2
R
AN848-70.EPS
LS)
E1
• tD, desaturationtime of T1 :
IMax. ⋅ tD
Pdesat = VE ⋅
25 ⋅ t
PE2
t
(VE1 − VLS) + (VLS + VD)
2
2
(VE1 + VD) 2
- At the secondary ; The sum of these losses is
equal to : VLS x IS0
• Current consumption of all the part powered on
Pin VLS (Pin 1) : PVLS = VLS x IPLS.
• Current consumption of the microcontroller :
PµP = VLS x IµP ; IS0 = IPLS + IµP.
• VCEsat of the loudspeakeramplifier output stage :
POLS = 0.2 x ISRL
VRGENE (Min.)
RL (Max.)
PE1
VE1
VE2
VE (V)
The output signal on Pin LSOUT (Pin 44) is controlled through the current information given on
Pin VZP (Pin 38) (see Figure 66).
53/57
AN848-71.EPS
= VE ⋅ IBT1 ⋅
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
VI - RINGER FEATURES (continued)
The 39µA current is the bias current of the internal
2.6V zener connected on Pin VZP (Pin 38).
I(VZP) =
VRING − 2.6
R37
(2)
- T h e c u rre nt I A g en erat es a vo lt a ge on
Pin RCO (Pin 41) equal to :
V(RCO) = R40 x IA (3)
- This input voltage, mixed with the ring frequency
is amplified to the loudspeaker connected on pin
LSOUT (Pin 44), and the peak to peak square
output voltage VPP(LSOUT) is :
VPP(LSOUT) = 16 x V(RCO) (4)
(1), (2), (3) & (4)
⇒
VPP(LSOUT) =
 VRING
16
2.6 
⋅ R40 ⋅ 
− 39µA −

9
R35//R38 
 R37
When the VRING input voltage is high enough
to
s a t u ra t e t h e o ut p u t st a ge on
Pin LSOUT (Pin 44), compared to Pin VLS (Pin 1),
(VLS (Pin 1) - VPP (LSOUT) < 0.2V), the switch in
serial with the current source on Pin LSSOF (Pin 6)
is a c t iva te d , a nd t h e in pu t v olt a ge o n
Pin LSSOF (Pin 6) is converted in current, with a
1/17.5kΩ transconductance. Finally this current
increases the voltage on Pin VLS (Pin 1) and allo ws t h e o u t pu t vo lt ag e, VPP(LSOUT) on
Pin LSOUT (Pin 44) to increase.
At low VRING input voltage, Pin VLS (Pin 1) is
clamped at a 3V minimum voltage, to maintain a
p ro p e r s u p ply t o t h e microc o n t ro lle r o n
Pin VRMC (Pin 8), and the output voltage on
Pin LSOUT(Pin 44) is progressively reduced.
When the VRING input voltage increases, the
Pin VLS (Pin 1) increases up to 6V and is clamped
to 6V by an internal zener.
54/57
VI.5 - Microcontroller Management (RI / RESET)
In ring mode, two pieces of information are given
to control the microcontroller :
- Pin RESET (Pin 11) which goes at level ”1” if Pin
VRMC (Pin 8) > 2.6V.
- Pin RI/VI (Pin 10) which goes at level ”1” if :
• Pin RSU (Pin 40) > 19V
• Pin VRMC (Pin 8) > 2.6V
• Current in Pin VZP (Pin 38) > 40µA
- After a ring mode, Pin RI/VI (Pin 10) goes back to
level ”0”, if Pin RSU (Pin 40) goes lower than 8V.
Figure 71
8
RCO (Pin 41)
VPP (LSOUT)
VLS (Pin 1)
7
6
5
4
3
NO
2 WORKING
AREA
1
0
0
10
20
30
VRING (V)
40
50
AN848-72.EPS
The principle is :
- From the current I(VZP) in the resistor R37, a
current IA is issued and equal to :
2.6
I(VZP) − 39µA −
R38
(1)
IA =
9
The Figure 71 gives the voltage on Pin VLS (Pin 1),
on Pin RCO (Pin 41) and the VPP(LSOUT) on
Pin LSOUT (Pin 44) versus the VRING input voltage
with : R37 = 200kΩ, R38 = 150kΩ, R40 = 47kΩ
The values of R37, R38 and R40 should be calculate to adapt the output power requested on
Pin LSOUT (Pin 44) to the available power, during
ring mode, on the terminal wire as described on
Figures 69 and 70 of this application note.
The recommended values for a ring network of,
CRING = 1µF, RRING = 1.5kΩ are :
- R37 = 200kΩ, R38 = 150kΩ
- P40 = 47kΩ,
if fRING = 25 or 50Hz / RLOUDSPEAKER = 50Ω
- R40 = 39kΩ, if fRING = 50Hz / RLOUDSPEAKER = 32Ω
- R40 = 33kΩ, if fRING = 25Hz / RLOUDSPEAKER = 32Ω
U (V)
VI.4 - Output Power Optimization (continued)
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
VI - RINGER FEATURES (continued)
VI.6 - Ring Software
To generate the ring on the loudspeaker, the flowchart is in Figure 72.
Figure 72
ON-HOOK
RI = 1
No
Yes
RING START
0010 001
RING MODE
GROUP LISTENING CODE
0110 001
Default : Gmax -28dB
(0 1 0 0 0 0 0)
VOLUME CONTROL CODE
0 1 0 0 X X X or 0 1 1 1 0 1 1
VOLUME
CHANGE
No
Yes
Fi1 Code
+ Divider 1 Code
0 0 0 XX X X + 1 XX XX XX
Fi2 Code
+ Divider 2 Code
0 0 0 XX X X + 1 XX XX XX
FiN Code + Divider N Code
0 0 0 XX X X + 1 XX XX XX
RI = 1
Yes
No
PON = 1
No
ON-HOOK
STEADY STATE
Yes
AN848-73.EPS
INIT CODE
0101 000
OFF-HOOK
WITH DEFAULT CONDITIONS
55/57
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
VII - APPLICATION DIAGRAM
CR1
VL1
D1
C8
R9
AGND
C14
R10
R11a
R11b
R27
R29
AGND
C28
RETURN
LOSS
C9
R28
C5
SIDETONE
R16
R13
C16
AGND
R15
R5
R6
DATA
R8
C25
C27 C12
CLK
HFIN
13
CLK
12
PON
14
DATA
ASC
15
SNSL
RECIN
16
23 MIC1
RESET 11
24 MIC2
RI/VI 10
25 VREF
OSC 9
26 VCC
VRMC 8
R21
C3
MIC-
R4
27 TSOFT
R2
R3
LSIN 5
30 VS
VREFL 4
GREC
VZP
SWP
RSU
RCO
DTMF2
GND
LSOUT
VLS 1
EAR-
33 ILL
I SL
VMC 2
34
35
36
37
38
39
40
41
42
43
44
C15
R31
C10
+
AGND
R35
R37
LS AMPLIFLIER
VREF
LS1
R17
C6
RING
R36
C30
R14
R32
R38
R40
C4
T1
Rx GAIN
L1
T2
D2
D3
GND
VLS
R23
D7
C26
W1
REOUT
LSIN
Part
56kΩ
30kΩ
2.7kΩ
820kΩ
0
39kΩ
1.62kΩ
680Ω
24Ω
6.2Ω
100kΩ
2.7kΩ
47kΩ
Ref.
R15
R16
R17
R18
R19
R21
R27
R28
R29
R31
R32
R33
R35
* (Ring frequency / LS impedance)
Part
2.2kΩ
330kΩ
75kΩ
18kΩ
6.8kΩ
1.5kΩ
3.3kΩ
33kΩ
18kΩ
560kΩ
220kΩ
1.5kΩ
56kΩ
Ref.
R36
R37
R38
R40
D1
D2
D3
D7
T1
T2
Part
4.7kΩ
200kΩ
150kΩ
47kΩ (50Hz/50Ω)*
47kΩ (25Hz/50Ω)*
39kΩ (50Hz/32Ω)*
33kΩ (25Hz/32Ω)*
13V
47V
8.2V
1N4148
BC556B
BC546B
Ref.
L1
Q1
C1
C2
C3
C4
C5
C6
C8
C10
C11
C12
C13
Part
1mH
3,58MHz
100µF
47µF
150nF
220nF
560pF
10µF (63V)
47µF
470µF
1µF
100nF
47nF
Ref.
C14
C15
C16
C17
C19
C20
C25
C26
C27
C28
C30
C31
C32
CR1
Part
47nF
4.7µF
1µF
330pF
470nF
47nF
470nF
47nF
100nF
1.8nF
1.2nF
10nF
2.7nF
10nF
AN848-74.EPS
RING1
56/57
VMC
+
C1
C2
C32
+
Ref.
R1
R2
R3
R4
R5
R6
R8
R10
R11a
R11b
R12
R13
R14
V RMC
+
+
C24
EAR-
C17
AGND
C13
VL 3
32 AGND
R19
RI/VI
3.58MHz
LSSOF 6
29 IREF
31 SLPE
R18
+
TEA7092
EAR+
+
C11
RESET
DTMF1 7
28 SOFTL
R1
R12
EAR+
17
ASQ
18
SNLL
19
C19
C31
20
C20
MIC+
21
GTR
HFIN
22
VREF
REOUT
PON
TEA7092 - TELEPHONE SET INTEGRATED CIRCUIT
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility
for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result
from its use. No licence is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics.
Specifications mentioned in this publication are subject to change without noti ce. This publication supersedes and replaces all
information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life
support devices or systems without express written approval of SGS-THOMSON Microelectronics.
 1996 SGS-THOMSON Microelectronics - All Rights Reserved
Purchase of I2C Components of SGS-THOMSON Microelectronics, conveys a license under the Philips
I2C Patent. Rights to use these components in a I2C system, is granted provided that the system confo rms to
the I2C Standard Specifications as defined by Philips.
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