TEA7089A
LOW-RANGE PHONE DEDICATED CHIP
.
.
.
.
.
.
.
RING
- GENERATION OF 8 MELODY TONES
(Including the 3 German Melody Tones)
- 4 STEPS DIGITAL CONTROL ON THE AM-
PLIFIER OUTPUT LEVEL
SPEECH
- TRANSMIT GAINEXTERNALLY ADJUSTABLE
- RECEIVINGGAINEXTERNALLYADJUSTABLE
- AGCSLOPEEXTERNALLYPROGRAMMABLE
- SOFTCLIPPING ON SENDING CHANNEL
- RECEIVE AMPLIFIER FOR PIEZO OR
ELECTRODYNAMIC TRANSDUCER
- +6dB MODE ON RECEIVE CHANNEL
- LINE POWER MANAGEMENT
DIALING
- DTMF GENERATOR
- LOW DC MASK DURING MAKE PERIOD
THROUGH MICROCONTROLLER SERIAL
BUS INTERFACE
MICROCONTROLLER INTERFACE
- 1.79MHz CLOCK OR 3.58MHz OSCILLATOR
INPUT
MICROCONTROLLER POWER SUPPLY
MICROCONTROLLER CONTROL INTER-
FACE INCLUDING SERIAL BUS
LINE CURRENT EXTRACTOR FOR SUPPLY
OF EXTERNAL PERIPHERALS
SO28
(Plastic Package)
ORDER CODE :
TEA7089AFP
PIN CONNECTIONS
S OFT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
DTMF
RECIN
SN
AGC
MIC1
MIC2
V
REF
V
RMC
DCL
DATA
MSK
OSC
RI
P ON
GTR
DESCRIPTION
The TEA7089A is a Telephone Analog Front End
device, TAFE, which integrates the three basic
functions of a standard telephone set :
- Speech network,
- DTMF generator,
- Ringer generator on buzzer.
A complete telephone set can be designed using
TEA7089A associated with a low cost microcon-
troller.
June 1998
V
CC
GND
IVLS
V
S
RES
V
RING
BUZ
7089A-01.EPS
V
L
V
MC
GREC
EAR+
EAR-
1/17
TEA7089A
SPEECH
The speech network includes :
- a low noise transmit channel suitable for any kind
of microphone transducer. Softclipping on trans-
mit line signal is provided by the chip.
- a low noise receive channel with symmetrical
outputs to be compatible with both piezoceramic
and electrodynamic earpiece. An additional 6dB
gain can be inserted in the receive channel
through software control.
- a line length gain control (AGC) with starting point
of gain regulation fixed at 25mAline current ; slope
of gain regulationis externallyadjustablewith one
resistor.AGC can be removedby hardware (maxi-
mum gain flat) or by software (-2dB flat).
The phone impedance and sidetone can be tuned
through external networks.
DTMF GENERATOR
The onboard DTMF generator fullfils the CEPT
requirements with an external single pole filter.
PIN DESCRIPTION
Name
SOFT
RECIN
SN
AGC
MIC1
MIC2
GTR
V
CC
GND
IVLS
V
S
V
L
V
MC
GREC
EAR-
EAR+
BUZ
VRING
RES
PON
RI
OSC
MSK
DATA
DCL
V
RMC
V
REF
DTMF
2/17
Pin N°
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Description
Transmit Softclipping Time Constant
Receiving Input
Sidetone Network Input
Line Current Regulation Stop Value
Microphone Input
Microphone Input
Transmit Gain Adjustment
Transmit and Receive Part Power Supply
Ground
Line Current Source Power Supply
Voltage Stabilizer
Positive Line
Unregulated Microcontroller Power Supply
Receive Gain Adjustment
Negative Earphone Output
Positive Earphone Output
Ringer Buzzer Output
Ring Power Supply
Reset
Power On
Ring Indicator
Oscillator Input
Mask, Ring Melody Input
Data Input
Data Clock Input
Microcontroller Stabilized Power Supply
Reference Voltage (V
CC
/2)
DTMF Filter
RINGER
Up to 8 different tones can be generated by the
TEA7089Aringer. The digital volume control of the
ringer can be performed through a specific com-
mand (4 steps). A ring indication signal is provided
to the microcontroller by the TEA7089A.If more
tones are requested the input RM/MSK allows to
inject tones generated by the microcontroller.
FURTHER ADVANTAGES
The microcontroller power supply is provided by the
TEA7089A.The power supply is specifically designed
to copewitha longflash or a long groundkey duration.
The TEA7089A is able to supply the necessary
current to an external speakerphone circuit
TEA7540 and loudspea ker amplifier TEA7532
without any additional circuitry.
Line current and reset indications are provided to
the microcontroller by the TEA7089A.
The microcontroller drives the TEA7089A through
a 2 wires serial interface.
7089A-01.TBL
To Line
C8
C30
To
µP
To Line
C1
C12
V
L
RI
21
12
8
10
2
3
R10
R13
V
CC
Sidetone
R11
R12
V
CC
IVLS
RECIN
SN
C11
Figure 1 :
Block Diagram
V
S
11
TEA7089A
18
26
17
R40 + R15
C16
C15
V
REF
VSTAB
RING POWER
SUPPLY
LOGIC POWER
SUPPLY
BUZZER
AMPLIFIER
LINE CURRENT
POWER SUPPLY
27
V
REF
C14
R14
V
RING
V
RMC
BUZ
GREC
14
R17
MUTE
AGC
MUTE
CONTROL
SIDETONE
& AGC
EAR+
16
Earphone
Earphone
Amplifier
-1
SERIAL
REGULATOR
EAR-
15
RING
GENERATOR
13
V
MC
C10
C3
KVL
R4
SOFT
1
R8
V
IN
GTR
DTMF
GENERATOR
µP
INTERFACE
AGC
V
REF
PON & RESET
CONTROL
OSCILLATOR
/2
7
23
MSK
25
DCL
24
DATA
MIC1
5
To
µP
Microphone
MIC2
6
4
9
28
20
19
22
C3
AGC
DTMF
GND
PON
To
µP
RES
OSC
V
CC
R25
TEA7089A
3/17
7089A-02.EPS
TEA7089A
ELECTRICAL CHARACTERISTICS
The block diagram is given in Figure 1.
The values of the different networks used in this datasheet are defined as followed :
- The return loss is adjusted by R10 of 600
Ω
.
- The transmit adjust gain network R8 is calculated in order to have a gain of 46dB typical with I
LS
= 22mA.
- The sidetone network ZST is set to be lower than 20dB (Vear/Vmic) on a 600
Ω
load on line.
- The DC characteristics are set by a resistor of 82kΩ between V
L
and V
S
.
Absolute Maximum Ratings
Symbol
Authorized Voltage on
Pin 2 - RECIN
Pin 3 - SN
Pin 8 - V
CC
Pin 10 - IVLS
Pin 12 - V
L
Pin 13 - V
MC
Pin 17 - BUZ
Pin 18 - V
RING
Pin 19 - RES
Pin 20 - PON
Pin 21 - RI
Pin 22 - OSC
Pin 23 - MSK
Pin 24 - DATA
Pin 25 - DCL
Pin 26 - V
RMC
I
LINE
I
RING
T
oper
T
stg
T
j
Line Current
Ring Current
Operating Temperature
Storage Temperature
Junction Temperature
Parameter
Value
13
12
11
6
12
6
V
RING
+0.3, GND -0.3
27
V
RMC
+0.3, GND -0.3
V
RMC
+0.3, GND -0.3
V
RMC
+0.3, GND -0.3
V
RMC
+0.3, GND -0.3
V
RMC
+0.3, GND -0.3
V
RMC
+0.3, GND -0.3
V
RMC
+0.3, GND -0.3
5
120
50
-25, +70
-55, +150
-25, +150
Unit
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
mA
mA
°C
°C
7089A-02.TBL
°C
DC Characteristics
(T
amb
= 25°C ; Logic in Default Mode unless otherwise noted)
Symbol
V
L
Parameter
Line Voltage
- In Speech and DTMF Mode
- In Mask Mode
I
VRMC
V
RMC
I
VMC
Stabilized Supply Voltage
- Output Current
- Output Voltage
Unstabilized Supply Voltage
- Start up Current
- Output Current
Line Current Source Supply
Test Conditions
Test 1
I
L
= 22mA
I
L
= 90mA
I
L
= 22mA
Test 1, I
L
= 22mA
1.5
IRMC = 1.5mA
Test 1, I
L
= 22mA
V
MC
= 2.5V, I
VRMC
= 1.5mA
V
MC
= 3.6V, I
VRMC
= 0mA
Test 1, V
LS
= 0V ; V
MC
= 3.6V
I
L
= 22mA
I
L
= 90mA
3.15
10
3.35
15
3
14
75
18
82
3.55
mA
V
mA
mA
mA
mA
Min.
4
6.7
Typ.
4.6
7.5
Max.
5.2
8.3
3
Unit
V
V
V
I
LS
10
67
The line current source supply depends of I
L
:
- For I
L
< 20mA : I
LS
(mA) = 0.765 x I
L
(mA) - 1.4mA
- For I
L
> 20mA : I
LS
(mA) = 0.92 x I
L
(mA) - 4.5mA
On this pin the maximum output level is : V
10
= V
12
- (1.2 + 10 x I
LS
) and V
10
< 6V
4/17
TEA7089A
ELECTRICAL SPECIFICATIONS
(continued)
AC Characteristics
(T
amb
= 25°C ; R
L
= 600Ω ; Logic in Default Mode unless otherwise noted)
Symbol
R1
Parameter
Return Loss
Test Conditions
Test 2, I
L
= 22mA
f = 300/3400Hz, V
AC
= -10dBV
Min.
17
Typ.
Max.
Unit
dB
Transmit Characteristics
(T
amb
= 25°C ; R
L
= 600Ω ; f = 1kHz ; Logic in Default Mode unless otherwise noted)
Symbol
Gtx
Gtxl
Gtxs
Zmic
Ntx
Mmic
Dtx
V
L
Max.
Microphone Input Impedance
Noise
Microphone Mute
Soft Clipping
- Distortion
- Maximum Level on Line
Parameter
Microphone Gain
Test Conditions
Test 3, V
m
= -55dBV
R8 = 1.3kΩ, R25 = 3.9kΩ
I
L
= 22mA
I
L
= 90mA
between MIC1 & MIC2
Test 3, 2kΩ on microphone inputs,
I
L
= 22mA
Test 3, V
m
= -55dBV, I
L
= 22mA
Test 3, I
L
= 22mA, see Figure 2
V
m
= -41dBV
V
m
= -34dBV
60
2
1.5
Min.
Typ.
Max.
Unit
45
38
32
46
40
40
-76
47
42
48
dB
dB
kΩ
dBmp
dB
%
Vp
Figure 2 :
Softclipping
10
Thres hold
Level
The maximum gain Gtl is adjustable between 44
and 56dB with R8 :
R10 // R
L
+
R11
Gtxl
=
20log
820
⋅
R8 // 50k
Ω
The AGC variation is programmed with one resistor
connected on Pin AGC. I
SL
is the line current at
which the gain must be decreased by 6dB.
R25
(Ω) =
7089A-03.EPS
V
AC
peak on line (V)
1
-15
-10
-5
-2
1
10
V
microphon e
pe a k (mV)
100
0.1
300
(R25 > 2.6kΩ)
I
SL
−
5mA
0.1
For line current lower than I
LL
or higher than I
SL
,
The transmit and receive gains have a constant
value.
If no resistor or a resistor higher than 300k
Ω
is
connected on Pin AGC, the gain is constant and
equal to Gtxl and Grxl.
±
0.5dB.
Figure 3
10
8
V
AC
pe a k
V
L
(Pin 12) (V)
6
4
2
0
0
AGC can be inhibited also through MCU code
”010100”. In this case Tx and Rx gains are fixed
2dB lower than the maximum gain.
The minimum saturation voltage of the TEA7089A
respect to ground is 2.2V. On long line, when the
voltage over TEA7089A is low, the softclipping
function automatically limits the AC dynamic to
avoid to reach the 2.2V limit on TEA7089A respect
to ground.
V
AC
pe a k
20
40
60
I
L
(mA)
80
10 0
7089A-04.EPS
5/17
京公网安备 11010802033920号
EEWORLD
