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Электронный компонент: ILA1062

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ILA1062/ILA1062A
1
T
ELEPHONE SPEECH NETWORK WITH DIALER INTERFACE
DESCRIPTION
The ILA1062 and ILA1062A are integrated circuits that perform all speech and line interface
functions required in fully
electronic telephone sets. They perform electronic switching between dialing and speech. The ICs
operates at line voltage down
to 1.6 V DC (with reduced performance) to facilitate the use of more telephone sets connected in
parallel.
All statements and values refer to all versions unless otherwise specified. The ILA1062(ILA1062A)
is packaged in a standard
16-pin plastic DIP and special plastic DIP with internal heatsink is also available.
FEATURES
Low DC line voltage; operates down to 1.6V
(excluding
polarity guard)
Voltage regulator with adjustable static resistance
Provides a supply for external circuits
Symmetrical high-impedance inputs (64 k
) for
dynamic, magnetic or piezo-electric microphones
Asymmetrical high-impedance input (32 k
) for
electret
microphones
DTMF signal input with confidence tone
Mute input for pulse or DTMF dialing
- ILA1062: active HIGH (MUTE)
- ILA1062A: active LOW (MUTE)
Receiving amplifier for dynamic, magnetic or
piezo-electric earpieces
Large gain setting range on microphone and
earpiece
amplifiers
Line loss compensation (line current dependent) for
microphone and earpiece amplifiers
Gain control curve adaptable to exchange supply
DC line voltage adjustment facility
PIN CONNECTION


BT1062A
LN
GAS1
GAS2
OR
GAR
MIC-
MIC+
STAB
SLPE
AGC
REG
V
CC
MUTE
DTMF
IR
V
EE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
ILA1062A
ILA1062/ILA1062A
2
QUICK REFERENCE DATA
Characteristic
Symbol
Test Condition
Min
Typ
Max
Unit
Line Voltage
V
LN
I
line
= 15mA
3.55
4.0
4.25
V
Operating Line Current
I
line
2.0
V
dc
Normal Operation
11
140
mA
with Reduced Performance
1
11
mA
Internal Supply Current
I
CC
V
CC
= 2.8V
0.9
1.35
mA
Supply Voltage for Peripherals
V
CC
I
line
= 15mA
I
p
= 1.2mA
I
p
= 0mA
2.2
2.2
2.7
3.4
V
Voltage Gain
G
V
microphone amplifier
44
52
dB
receiving amplifier
20
31
dB
Line loss compensation
Gain Control
D
G
V
5.8 dB
Exchange Supply Voltage
V
exch
36
60
V
Exchange Feeding bridge
Resistance
R
exch
0.4
1
k
W

BLOCK DIAGRAM
SUPPLY AND
REFERENCE
CURRENT
REFERENCE
LOW VOLTAGE
CIRCUIT
CONTROL
CURRENT
ILA1062A
13
10
7
6
12
11
(1)
9
14
15
8
16
3
2
-
+
-
+
+
-
+
-
4
5
1
LN
V
CC
IR
MIC+
dB
MIC-
DTMF
MUTE
V
EE
REG AGC
STAB
SLPE
GAS2
GAS1
QR
GAR
(1) Pin 12 is active HIGH (MUTE) for ILA1062.
Fig.1 Block diagram for ILA1062A
ILA1062/ILA1062A
3
FUNCTIONAL DESCRIPTION
Supplies V
CC
, LN, SLPE, REG and STAB

Power for the IC and its peripheral circuits is usually obtained from the telephone line. The supply voltage is
delivered from the line via a dropping resistor and regulated by the IC. The supply voltage V
CC
may also be
used to supply external circuits e.g. dialing and control circuits.

Decoupling of the supply voltage is performed by a capacitor between V
CC
and V
EE
. The internal voltage
regulator is decoupled by a capacitor between REG and V
EE.
The DC current flowing into the set is determined by the exchange supply voltage V
exch
, the feeding bridge
resistance R
exch
and the DC resistance of the telephone
line R
line
.

The circuit has internal current stabilizer operating at a level determined by a 3.6 k
?
resistor connected
between STAB and V
EE
(see Fig.6). When the line current (I
line
) is more than 0.5mA greater than the sum of
the IC supply current (I
CC
) and the current drawn by the peripheral circuitry connected to V
CC
(I
p
) the excess
current is shunted to V
EE
via LN.

The regulated voltage on the line terminal (V
LN
) can be calculated as:
V
LN
= V
ref
+ I
SLPE
x R9
V
LN
= V
ref
+ {(I
line
- I
CC
- 0.5 x 10
-3
A) - I
p
} x R9

V
ref
is an internally generated temperature compensated reference voltage of 3.7V and R9 is an external
resistor connected between SLPE and V
EE.
In normal use the value of R9 would be 20
?
.

Changing the value of R9 will also affect microphone gain, DTMF gain, gain control characteristics, sidetone
level, maximum output swing on LN and the DC characteristics (especially at the lower voltages).
Fig.2 Equivalent impedance circuit

Under normal conditions, when I
SLPE
>>I
CC
+ 0.5mA + I
p
, the static
behaviour of the circuit is that of a 3.7V regulator diode with an
internal resistance equal to that of R9. In the audio frequency
range the dynamic impedance is largely determined by R1. Fig.2
show the equivalent impedance of the circuit.
At line currents below 9mA the internal reference voltage is
automatically adjusted to a lower value (typically 1.6V at 1mA).
This means that more sets can be operated in parallel with DC
line voltage (excluding the polarity guard) down to an absolute
minimum voltage of 1.6V. At line currents below 9mA the circuit
has limited sending and receiving levels. The internal reference
voltage can be adjusted by means of an external resistor (R
VA
).
This resistor when connected between LN and REG will decrease
the internal reference voltage and when connected between REG
and SLPE will increase the internal reference voltage.

Microphone inputs MIC+ and MIC- and gain pins GAS1 and GAS2

The circuit has symmetrical microphone inputs. Its input impedance is 64 k
?
(2 x 32k
?
) and its voltage gain is
typically 52 dB (when R7 = 68k
?
; see Fig.6).
Dynamic, magnetic, piezo-electric or electret (with built-in FET source followers) can be used.

The gain of the microphone amplifier can be adjusted between 44 dB and 52 dB to suit the sensitivity of the
transducer in use. The gain is proportional to the value of R7 which is connected between GAS1 and GAS2.

Stability is ensured by two external capacitors, C6 connected between GAS1 and SLPE and C8 connected
between GAS1 and VEE. The value of C6 is 100pF but this may be increased to obtain a first-order low-pass
R1
LN
R
p
R = 16.2 k
p
L
eq
L = C3 x R9 x R
eq
p
V
ref
REG
V
CC
V
EE
C1
100 F
C3
4.7 F
R9
20
ILA1062/ILA1062A
4
filter. The value of C8 is 10 times the value of C6. The cut-off frequency corresponds to the time constant R7
x C6.

Input MUTE (ILA1062)

When MUTE is LOW or open-circuit, the DTMF input is enable and the microphone and receiving amplifier
inputs are inhibited. The reverse is true when MUTE is HIGH.
MUTE switching causes only negligible clicking on the line and earpiece output. If the number of parallel sets
in use causes a drop in line current to below 6 mA the DTMF amplifier becomes active independent to the
DC level applied to the MUTE input.

Dual-tone multi-frequency input DTMF

When the DTMF input is enable dialing tones may be sent on to the line. The voltage gain from DTMF to LN
is typically 25.5 dB (when R7=68k
?
) and varies with R7 in the same way as the microphone gain. The
signalling tones can be heard in the earpiece at a low level (confidence tone).

Receiving amplifier IR, QR and GAR

The receiving amplifier has one input (IR) and a non-inverting output (QR). The IR to QR gain is typically
31dB (when R4 = 100k
?
). It can be adjusted between 20 and 31dB to match the sensitivity of the transducer
in use. The gain is set with the value of R4 which is connected between GAR and QR. The overall receive
gain, between LN and QR, is calculated by subtracting the anti-sidetone network attenuation (32dB) from the
amplifier gain. Two external capacitors, C4 and C7, ensure stability. C4 is normally 100pF and C7 is 10
times the value of C4. The value of C4 may be increased to obtain a first-order low-pass filter. The cut-off
frequency will depend on the time constant R4 x C4.

The output voltage of the receiving amplifier is specified for continuous-wave drive. The maximum output
voltage will be higher under speech conditions where the peak to RMS ratio is higher.

Automatic gain control input AGC

Automatic line loss compensation is achieved by connecting a resistor (R6) between AGC and V
EE
.
The automatic gain control varies the gain of the microphone amplifier and the receiving amplifier in
accordance with the DC line current. The control range is 5.8 dB which corresponds to a line length of 5 km
for a
0.5mm diameter twisted-pair copper cable with a DC resistance of 176
?
/km and average attenuation of
1.2dB/km. Resistor R6 should be chosen in accordance with the exchange supply voltage and its feeding
bridge resistance. The ratio of start and stop currents of the AGC curve is independent of the value of R6. If
no automatic
line-loss compensation is required the AGC pin may be left open-circuit. The amplifiers, in this condition, will
give their maximum specified gain.

Sidetone suppression
The anti-sidetone network, R1//Z
line
, R2, R3, R8, R9 and Z
bal
suppresses the transmitted signal in the
earpiece. Maximum compensation is obtained when the following conditions are fulfilled:
R9 x R2 = R1 x
R 3
R 8
Z
R 8
Z
bal
bal
+
+


x
(1)
Z
Z
R 8
bal
bal
+
=
Z
Z
R 1
line
line
+
(2)

If fixed values are chosen for R1, R2, R3 and R9, then condition (1) will always be fulfilled when
To obtain optimum sidetone suppression, condition (2) has to be fulfilled which results in:
ILA1062/ILA1062A
5
Z
bal
=
R 8
R 1
x Z
line
= k x Z
line
Where k is scale factor; k =
R 8
R 1
The scale factor k, dependent on the value of R8, is chosen to meet the following criteria:
compatibility with a standard capacitor from the E6 or
E12 range for Z
bal
|
Z
bal
//R8
|
<<R8 fulfilling condition (a) and thus
ensuring correct
anti-sidetone bridge operation
|
Z
bal
+ R8
|
>>R9 to avoid influencing the transmit gain.
In practise Z
line
varies considerably with the line type and length. The value chosen for Z
bal
should therefore
be for an average line thus giving optimum setting for short or long lines.
ABSOLUTE MAXIMUM RATING
Characteristic
Symbol
Test Condition
Min
Typ
Max
Unit
Positive Continuous Line
Voltage
V
LN
12
V
Repetitive Line Voltage During
Switch-on or Line Interruption
V
LN(R)
13.2
V
Repetitive Peak Line Voltage
for a 1ms Pulse per 5s
V
LN(RM)
R9 = 20
W
; R10 = 13
W
;
see Fig.6
28
V
Line Current
I
line
R9 = 20
W
; note 1
140
mA
Input Voltage on all other Pins
V
I
-0.7
V
CC
+0.7
V
Total
Power
Standard DIP
P
tot
R9 = 20
W
; note 2
0.58
W
Dissipation
DIP with heatsink
0.67
Operating Ambient
Temperature
T
A
-25 +75
o
C
Storage Temperature
T
stg
-40 +125
o
C
Junction Temperature
T
j
+125
o
C
Notes
1. Mostly dependent on the maximum required T
A
and on the voltage between LN and SLPE.
2. Calculated for the maximum ambient temperature specified and a maximum junction temperature of
125
o
C.
(Thermal Resistance R
JA
= 85
o
C/W for standard DIP and R
JA
= 75
o
C/W for special DIP with heatsink).
(1) T
A
=45
o
C; P
tot
=0.94W
(2) T
A
=55
o
C; P
tot
=0.82W
(3) T
A
=65
o
C; P
tot
=0.71W
(4) T
A
=75
o
C; P
tot
=0.58W
2
30
4
6
8
10
12
70
90
50
110
130
150
V - V
(V)
LN
SLPE
I (mA)
LN
(1)
(2)
(3)
(4)
(1) T
A
=45
o
C; P
tot
=1.07W
(2) T
A
= 55
o
C; P
tot
=0.93W
(3) T
A
=65
o
C; P
tot
=0.80 W
(4) T
A
=75
o
C; P
tot
=0.67 W
2
30
4
6
8
10
12
70
90
50
110
130
150
V - V
(V)
LN
SLPE
I (mA)
LN
(1)
(2)
(3)
(4)
Fig.3a Safe operating area(Standard DIP)
Fig.3b Safe operating area (DIP with HS)