Datasheet ILA1062AN Datasheet (INTEGRAL)

TECHNICAL DATA

1

Low Voltage Transmission Circuit
with Dialler Interface

The ILA1062A is an integrated circuit that perform all speech and line
interface functions required in fully electronic telephone sets. They
perform electronic switching between dialling and speech. The ICs
operate at line voltage down to 1.6 V DC (with reduced performance)
to facilitate the use of more telephone sets connected in parallel.

•

Low DC line voltage: operates down to 1.6 V (excluding polarity
guard)

•

Voltage regulator with adjustable static resistance

•

Provides a supply for external circuits

•

Symmertical high-impedance inputs (64 KΩ) for dynamic,
magnetic or piezo-electric microphones

•

Asymmetrical high-impedance input (32 KΩ) for electret
microphones

•

DTMF signal input with confidence tone

•

Mute input for pulse or DTMF dialing:
active LOW (MUTE)

•

Receiving amplifier for dynamic, magnetic or piezo-electric
earpieces

•

Large gain setting ranges 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

ILA1062A

ORDERING INFORMATION

ILA1062AN Plastic

TA = -25° to 75° C

for package

PIN ASSIGNMENT

BLOCK DIAGRAM

ILA1062A

2

PIN DESCRIPTION

Pin No Designation Description

1 LN positive line terminal
2 GAS1 gain adjustment; transmitting amplifier
3 GAS2 gain adjustment; transmitting amplifier
4 QR non-inverting output; receiving amplifier
5 GAR gain adjustment; receiving amplifier
6 MIC- inverting microphone input
7 MIC+ non-inverting microphone input
8 STAB current stabilizer

9VEEnegative line terminal
10 IR receiving amplifier input
11 DTMF dual-tone multi-frequency input
12 MUTE mute input
13 V

CC

possitive supply decoupling
14 REG voltage regulator decoupling
15 AGC automatic gain control input
16 SLPE slope (DC resistance) adjustment

FUNCTIONAL DESCRIPTION

Supplies VCC, LN, SLPE, REG and STAB

Power for the IC and its peripheral circuits is usually
obtained from the telephone line. The supply voltage
is derived 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. dialling
and control circuits.

Decoupling of the supply voltage is performed by a
capacitor between V

CC

and VEE. 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 an internal current stabilizer
operating at a level determined by a 3.6 KΩ resistor
connected between STAB and V

EE

(see Fig.1).

Figure 1. Supply arrengement

When the line current (I

line

) is more than 0.5 mA

greater than the sum of the IC supply current (I

CC

)
and the current draw by the peripheral circuitry
connected to V

CC

(Ip) the excess curre nt is shunt ed 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

- ICC - 0.5 x 10-3 A)-Ip) x R9

ILA1062A

3

V

ref

is an internally generated temperature
compensated reference voltage of 3.7 V and R9 is
an external resistor connected between SLPE and
V

EE

.
In normal use the value of R9 would be 20Ω.
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).

Under normal conditions, when
I

SLPE

>>ICC + 0.5 mA + Ip, the static behaviour of the
circuit is that of a 3.7 V 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 shows the equivalent
impedance of the circuit.

Leq = C3 x R9 x R

P

RP = 16.2 K

Ω

Figure 2. Equivalent impedance circuit

At line currents below 9 mA the internal reference
voltage is automatically adjusted to a lower value
(typically 1.6 V at 1 mA) This means that more sets
can be operated in parallel with DC line voltages
(excluding the polarity guard) down to an absolute
minimum voltage of 1.6 V.

At line currents below 9 mA 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 KΩ (2 x 32 KΩ) and its
voltage gain is typically 52 dB (when R7 = 68 KΩ,
see Figure 3). 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 V

EE

. The value of C6
is 100 pF but this may be increased to obtain a first­order low-pass filter. The value of C8 is 10 limes the
value of C6. The cut-off frequency corresponds to
the time constant R7 x C6.

Input MUTE

When MUTE is LOW or open circuit, the DTMF
input is enabled 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.

Dial-tone multi-frequency input DTMF

When the DTMF input is enabled dialling tones may
be sent on to the line. The voltage gain from DTMF
to LN is typically 25.5 dB (when R7 = 68 KΩ) 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 31 dB (when R4 = 100 KΩ). It can be
adjusted between 20 and 31 dB 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 anti­sidetone network attenuation (32 dB) from the
amplifier gain. Two external capacitors, C4 and C7,
ensure stability. C4 is normally 100 pF 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.

ILA1062A

4

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 0.5 mm diameter twisted-pair copper
cable with a DC resistance of 176 Ω/km and average
attenuation of 1.2 dB/km. Resistor R6 should be
chosen in accordance with the exchange supply
voltage and its feeding bridge resistance (see
Table 1).

Table 1

Values of resistor R6 for optimum line-loss
compensation at various values of exchange supply
voltage (V

exch

) and exchange feeding bridge

resistance (R

exch

); R9 = 20 Ω.

V

exch

(V)

400

R

exch

(Ω)

600

R

exch

(Ω)

800

R

exch

(Ω)

1000

R

exch

(Ω)

R6(KΩ)
36 100 78.7 - ­48 140 110 93.1 82
60 - - 120 102

The ratio of start and stop currents of the AGS curve
is independent of the value of R6. If no automatic
line-loss compensation is required the AGS 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

(see Fig4) suppresses the transmitted
signal in the earpiece. Maximum compensation is
obtained when the following conditions are fulfilled:

R9 x R2 = R1 x

(

R3 +

)

(1)

=

(2)

It fixed values are chosen for R1, R2, R3 and R9,
then condition (1) will always be fulfilled when



R8//Z

bal



<<R3.

To obtain optimum sidetone suppression, condition
(2) has to be fulfilled which results in:

Z

bal

= x Z

line

= k x Z

line

Where k is a scale factor; k =

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<<R3 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 length thus giving
optimum setting for short or long lines.

MAXIMUM RATINGS

*

Symbol Parameter Condition Min Max Unit

V

LN

Positive continuous line voltage - 12 V

V

LN(R)

Repetitive line voltage during
switch-on or line interruption

- 13.2 V

V

LN(RM)

Repetitive peak line voltage for
a 1 ms pulse per 5 s

R9 = 20 Ω; R10 = 13 Ω;
see Fig.5

-28V

I

line

Line current

R9 = 20

Ω

- 140 mA

V

IN

positive input voltage - VCC+0.7 V
negative input voltage - -0.7 V

P

D

Total power dissipation

R9 = 20 Ω; note 1

- 666 mW

Tstg Storage temperature -40 +125

°

C

*

Maximum Ratings are those values beyond which damage to the device may occur.

Functional operation should be restricted to the Recommended Operating Conditions.
Note 1. Calculated for the maximum operating temperature specified (T

amb

= 75°C) and a maximum j unction

temperature of 125°C.

R8 x Z

bal

R8 +Z

bal

R8
R1

Z

bal

Z

bal

+ R8

R8
R1

Z

line

Z

line

+ R1

Input voltage on all other pins

ILA1062A

5

RECOMMENDED OPERATING CONDITIONS

Symbol Parameter Conditions Min Typ Max Unit

I

line

Operating line current
normal operation
with reduced performance

11

1

-

-

140

11

mA
mA

V

CC

Supply voltage for
peripherals

I

line

= 15 mA

I

p

= 1.2 mA; MUTE = LOW

I

p

= 0 mA; MUTE = LOW

2.2

-

-

3.4

-

-

V
V

G

V

Voltage gain
microphone amplifier
receiving amplifier

44
20

-

-

52
31

dB
dB

T

amb

Operating ambient
temperature

-25 - +75

°

C

Line loss compensation

∆

G

V

Gain control - 5.8 - dB

V

exch

Exchange supply volt age 36 - 60 V

R

exch

Exchange feedi ng bridge
resistance

0.4 - 1

K

Ω

This device c ontains p rote ction ci rcuitr y to guard a gainst damage d ue to high st atic voltages or electr ic
fields. However, precautions must be taken to avoid applications of any voltage higher than maximum rated
voltages to this high-impedance circuit. For proper operation, V

IN

and V

OUT

should be constrained to the range

GND≤(V

IN

or V

OUT

)≤VCC.

Unused inputs must always be tied to an appropriate logic voltage level (e.g., either GND or V

CC

).

Unused outputs must be left open.

ELECTRICAL CHARACTERISTICS

(I

line

= 11 to 140 mA; VEE = 0 V; f = 800 Hz;T

amb

= 25°C;

unless other specified)

Symbol Parameter Test Conditions Guaranteed Limits Unit

Min Typ Max

Supplies LN and VCC (pins 1 and 13)

V

LN

Voltage Drop Over Circuit
between LN and V

EE

MIC Inputs Open-Circuit
I

line

= 1 mA

I

line

= 4 mA

I

line

= 15 mA

I

line

= 100 mA

I

line

= 140 mA

-

-

3.56

4.9

-

1.6

1.9

-

-

-

-

-

4.25

6.5

7.5

V

∆

V

LN

/∆T

Variation with Temperature I

line

= 15 mA - -0.3 - mV/K

V

LN

Voltage Drop Over Circuit
between LN and V

EE

with

External Resistor R

VA

I

line

= 15 mA

R

VA

(LN to REG)=68K

Ω

R

VA

(LN to SLPE)=39K

Ω

3.5

4.5

V

I

CC

Supply Current VCC = 2.8 V 1.35 mA

(continued)

ILA1062A

6

ELECTRICAL CHARACTERISTICS

(I

line

= 11 to 140 mA; VEE = 0 V; f = 800 Hz;T

amb

= 25°C;

unless other specified)

Symbol Parameter Test Conditions Guaranteed Limits Unit

Min Typ Max

Microphone inputs MIC- and MIC+ (pins 6 and 7)



Z

i



Input Impedance
differential
single-ended

between MIC- and MIC+
MIC- or MIC+ to V

EE

-

-

64
32

-

-

K

Ω

CMRR Common Mode Rejection

Ratio

-82-dB

G

v

Voltage Gain MIC+ or MIC­to LN

I

line

= 15 mA

R7 = 68 K

Ω

50.5 53.5 dB

∆

G

vf

Gain Variation with
Frequency Referenc e to 800
Hz

f = 300 and 3400 Hz -

±

0.2

-dB

∆

G

vT

Gain Variation with
Temperature Referenced to
25°C

without R6; I

line

=50 mA;

T

amb

= -25 and +75°C

-

±

0.2

-dB

DTMF input (pin 11)



Z

i



Input Impedance - 20.7 -

K

Ω

G

v

Voltage Gain from DTMF to
LN

I

line

15 mA; R7 = 68 K

Ω

24.0 - 27.0 dB

∆

G

vf

Gain Variation with
Frequency Referenc e to
800 Hz

f = 300 and 3400 Hz -

±

0.2

-dB

∆

G

vT

Gain Variation with
Temperature Referenced to
25°C

I

line

=50 mA;

T

amb

= -25 and +75°C

-

±

0.2

-dB

Gain Adjustment Inputs GAS1 and GAS2 (pins 2 and 3)

∆

G

v

Transmitting Amplifier Gain
Variation by Adjustment of
R7 between GAS1 and
GAS2

-8 - 0 dB

Sending Amplifier Output LN (pin 1)

V

LN(rms)

Output Voltage (RMS value) THD = 10%

I

line

= 4 mA

I

line

= 15 mA

-

1.7

0.8

-

-

-

V

V

no(rms)

Noise Output Voltage (RMS
value)

I

line

= 15 mA; R7 =68K

Ω

200 Ω between MIC- and
MIC+

--69-dBmp

Receiving Amplifier Input IR (pin 10)



Z

i



Input Impedance - 21 -

K

Ω

Receiving amplifier output QR (pin 4)



Z

o



Output Impedance - 4 -

Ω

G

v

Voltage Gain from IR to QR

I

line

15 mA; RL = 300

Ω

(from pin 9 to pin 4)

29.5 - 32.5 dB

(continued)

ILA1062A

7

ELECTRICAL CHARACTERISTICS

(I

line

= 11 to 140 mA; VEE = 0 V; f = 800 Hz;T

amb

= 25°C;

unless other specified)

Symbol Parameter Test Conditions Guaranteed Limits Unit

Min Typ Max

∆

G

vf

Gain Variation with
Frequency Referenc e to
800 Hz

f = 300 and 3400 Hz -

±

0.2

-dB

∆

G

vT

Gain Variation with
Temperature Referenced to
25°C

without R6; I

line

=50 mA;

T

amb

= -25 and +75°C

-

±

0.2

-dB

V

o(rms)

Output Voltage (RMS value) THD = 2%; sine wave

drive: R4 = 100 KΩ;
I

line

= 15 mA; Ip = 0 mA

R

L

= 150

Ω

R

L

= 450

Ω

0.22

0.3

-

-

-

-

V

V

o(rms)

Output Voltage (RMS value)

THD=10%; R4=100 KΩ;
I

line

= 4 mA; RL = 150

Ω

-15-mV

V

no(rms)

Noise Output Voltage (RMS
value)

I

line

= 15 mA; R4=100K

Ω

IR open-circuit
psophometrically weighted;
R

L

=300

Ω

-50-

µ

V

Gain Adjustment Input GAR (pin 5)

∆

G

v

Receiving Amplifier Gain
Variation by Adjustment of
R4 between GAR and OR

-11 - 0 dB

Mute Input (pin 12)

V

IH

HIGH Level Input Voltage 1.5 - V

CC

V

V

IL

LOW Level Input Voltage - - 0.3 V

I

MUTE

Input Current - - 15

µ

A

Raduction of Gain

∆

G

v

MIC+ or MIC- to LN MUTE = LOW - 70 - dB

G

v

Voltage Gain from DTMF to
QR

R4 = 100 K

Ω

R

L

= 300

Ω

--17-dB

Automatic Gain Control Input AGC (pin 15)

∆

G

v

Controlling the Gain from IR
to QR and the Gain from
MIC+, MIC- to LN
Gain Control Range

R6 = 110 K

Ω

(between AGC and V

EE

)

I

line

= 70 mA

- -5.8 - dB

I

lineH

Highest Line Curre nt for
Maximum Gain

-23-mA

I

lineL

Lowest Line Current for
Minimum Gain

-61-mA

ILA1062A

8

Voltage gain is defined as GV = 20 log

For measuring gain from MIC+ and MIC- the MUTE input should be HIGH.
For measuring the DTMF input, the MUTE input should be LOW or open-circuit.
Inputs not being tested should be open-circuit.

Figure 3. Test circuit for defining ILA1062A voltage gain of MIC+, MIC- and DTMF inputs.

Figure 4. Equivalent circuit of ILA1062A anti-sidetone bridge

V

O

V

I

ILA1062A

9

The diode bridge, the Zener diode and R10 limit the current into, and the voltage across, the circuit during
line transients.
A different protaction arrangement is required for pulse dialling or register recall.
The DC line voltage can be set to a higher value by the resistor R

VA

(REG to SLPE).

Figure 5. Typical application of ILA1062A, with piezo-electric earpiece and DTMF dialling.