Philips TEA1066T Datasheet

INTEGRATED CIRCUITS

DATA SH EET

TEA1066T

Versatile telephone transmission
circuit with dialler interface

Product specification
Supersedes data of September 1990
File under Integrated Circuits, IC03

1996 Apr 04

Philips Semiconductors Product specification

Versatile telephone transmission circuit

TEA1066T

with dialler interface

FEATURES

• Voltage regulator with adjustable static resistance

• Provides supply for external circuitry

• Symmetrical low-impedance inputs for dynamic and

magnetic microphones

• Symmetrical high-impedance inputs for piezoelectric
microphone

• Asymmetrical high-impedance input for electret
microphone

• Dual-tone multi-frequency (DTMF) signal input with
confidence tone

• Mute input for pulse or DTMF dialling

• Power down input for pulse dial or register recall

QUICK REFERENCE DATA

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

V
I
I

V

G

LN

line
CC

CC

v

line voltage I
line current normal operation 10 − 140 mA
internal supply current power down input LOW − 0.96 1.3 mA

supply voltage for peripherals I

voltage gain range for microphone amplifier

low impedance inputs (pins 7 and 9) 44 − 60 dB
high impedance inputs (pins 8 and 10) 30 − 46 dB
receiving amplifier 17 − 39 dB

T

amb

operating ambient temperature −25 − +75 °C

Line loss compensation

∆G
V
R

v

exch

exch

gain control 5.5 5.9 6.3 dB
exchange supply voltage 24 − 60 V
exchange feeding bridge resistance 400 − 1000 Ω

• Receiving amplifier for magnetic, dynamic or
piezoelectric earpieces

• Large gain setting range on microphone and earpiece
amplifiers

• Line loss compensation facility, line current dependent
(microphone and earpiece amplifiers)

• Gain control adaptable to exchange supply

• DC line voltage adjustment facility.

GENERAL DESCRIPTION

The TEA1066T is a bipolar integrated circuit that performs
all speech and line interface functions required in fully
electronic telephone sets. The circuit performs electronic
switching between dialling and speech.

= 15 mA 4.25 4.45 4.65 V

line

power down input HIGH − 55 82 µA

= 15 mA; MUTE

line

2.8 3.05 − V

input HIGH; Ip= 1.2 mA
I

= 15 mA; MUTE

line

2.5 − − V

input HIGH; Ip= 1.7 mA

ORDERING INFORMATION

TYPE

NUMBER

TEA1066T SO20

NAME DESCRIPTION VERSION

plastic small outline package; 20 leads; body width 7.5 mm SOT163-1

1996 Apr 04 2

PACKAGE

Philips Semiconductors Product specification

Fig.1 Block diagram.

The blocks marked ‘dB’ are attenuators.

handbook, full pagewidth

MEA009 - 1

dB

dB

SUPPLY AND
REFERENCE

AGC

CIRCUIT

SLPESTABAGCREGV

EE

CURRENT

REFERENCE

14

18 1912

16

15

7

8

10

9

13

17 1

6
5
4

11 20

IR

MICL+
MICH+
MICH−

MICL−

DTMF

MUTE

PD

V

CC

TEA1066T

LN

GAR

2

GAS1

3

GAS2

QR+
QR−

Versatile telephone transmission circuit
with dialler interface

BLOCK DIAGRAM

TEA1066T

1996 Apr 04 3

Philips Semiconductors Product specification

Fig.2 Pin configuration.

handbook, halfpage

1
2
3
4
5
6
7
8
9

10

20
19
18
17
16
15
14
13
12
11

MBH120

TEA1066T

LN

GAS1
GAS2

QR−
QR+

GAR

MICL−

MICH−

MICL+

SLPE
AGC

REG
V

CC

IR

DTMF

V

EE

MUTE

PD

STAB

MICH+

Versatile telephone transmission circuit
with dialler interface

PINNING

SYMBOL PIN DESCRIPTION

LN 1 positive line terminal
GAS1 2 gain adjustment transmitting

amplifier

GAS2 3 gain adjustment transmitting

amplifier
QR− 4 inverting output receiving amplifier
QR+ 5 non-inverting output receiving

amplifier
GAR 6 gain adjustment receiving amplifier
MICL− 7 inverting microphone input, low

impedance
MICH− 8 inverting microphone input, high

impedance
MICL+ 9 non-inverting microphone input, low

impedance
MICH+ 10 non-inverting microphone input,

high impedance
STAB 11 current stabilizer
V

EE

IR 13 receiving amplifier input
PD 14 power-down input
DTMF 15 dual-tone multi-frequency input
MUTE 16 mute input
V

CC

REG 18 voltage regulator decoupling
AGC 19 automatic gain control input
SLPE 20 slope (DC resistance) adjustment

FUNCTIONAL DESCRIPTION
Supplies: VCC, LN, SLPE, REG and STAB

Power for the TEA1066T and its peripheral circuits is
usually obtained from the telephone line. The TEA1066T
develops its own supply voltage at V
voltage drop. The supply voltage VCC may also be used to
supply external peripheral circuits, e.g. dialling and control
circuits.

The supply has to be decoupled by connecting a
smoothing capacitor between VCC and VEE; the internal
voltage regulator has to be decoupled by a capacitor from
REG to VEE. An internal current stabilizer is set by a
resistor of 3.6 kΩ between STAB and VEE.

12 negative line terminal

17 supply voltage decoupling

and regulates its

CC

TEA1066T

The DC current flowing into the set is determined by the
exchange supply voltage (V
resistance (R
(R

) and the DC voltage on the subscriber set

line

), the DC resistance of the telephone line

exch

(see Fig.7).
If the line current I

exceeds the current ICC+ 0.5 mA

line

required by the circuit itself (approximately 1 mA) plus the
current Ip required by the peripheral circuits connected to
VCC, then the voltage regulator diverts the excess current
via LN.

), the feeding bridge

exch

1996 Apr 04 4

Philips Semiconductors Product specification

Fig.3 Equivalent impedance circuit.

Rp= 17.5kΩ
Leq= C3× R9 × R

p

handbook, halfpage

REG

V

EE

V

CC

LN

MBA454

L

eq

R

p

R1

V

ref

R9
20 Ω

C3

4.7 µF C1100 µF

Versatile telephone transmission circuit
with dialler interface

The voltage regulator adjusts the average voltage on
LN to:

VLN= V

or

VLN= V

where V
compensated reference voltage of 4.2 V and R9 is an
external resistor connected between SLPE and VEE.

The preferred value for R9 is 20 Ω. Changing the value of
R9 will also affect microphone gain, DTMF gain, gain
control characteristics, side-tone level and the maximum
output swing on LN.

Under normal conditions, when I
the static behaviour of the circuit is that of a 4.2 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 (see Fig.3).

+ I

ref

+ (I

ref

is an internally generated temperature

ref

× R9

SLPE

− ICC− 0.5 × 10−3A − Ip) × R9

line

>> ICC+ 0.5 mA + Ip,

SLPE

TEA1066T

and > 3 V, this being the minimum supply voltage for most
CMOS circuits, including voltage drop for an enable diode.
If MUTE is LOW, the available current is further reduced
when the receiving amplifier is driven.

Microphone inputs MICL+, MICH+, MICL− and MICH−
and amplification adjustment connections GAS1 and
GAS2

The TEA1066T has symmetrical microphone inputs.
The MICL+ and MICL− inputs are intended for
low-sensitivity, low-impedance dynamic or magnetic
microphones. The input impedance is 8.2 kΩ (2 × 4.1 kΩ)
and its voltage gain is typically 52 dB. The MICH+ and
MICH− inputs are intended for a piezoelectric microphone
or an electret microphone with a built-in FET source
follower. Its input impedance is 40.8 kΩ (2 × 20.4 kΩ) and
its voltage gain is typical 38 dB.

The arrangements with the microphone types mentioned
are shown in Fig.9.

The internal reference voltage can be adjusted by means
of an external resistor RVA. This resistor, connected
between LN and REG (pins 1 and 18), will decrease the
internal reference voltage; when connected between REG
and SLPE (pins 18 and 20) it will increase the internal
reference voltage.

Current Ip, available from VCC for supplying peripheral
circuits, depends on external components and on the line
current. Figure 8 shows this current for VCC> 2.2 V

The gain of the microphone amplifier in both types can be
adjusted over a range of ±8 dB to suit the sensitivity of the
transducer used. The gain is proportional to external
resistor R7 connected between GAS1 and GAS2.

An external capacitor C6 of 100 pF between GAS1 and
SLPE is required to ensure stability. A larger value may be
chosen to obtain a first-order low-pass filter. The cut-off
frequency corresponds with the time constant R7 × C6.

Mute input MUTE

A HIGH level at MUTE enables the DTMF input and
inhibits the microphone inputs and the receiving amplifier;
a LOW level or an open circuit has the reverse effect.
Switching the mute input will cause negligible clicks at the
earpiece outputs and on the line.

Dual-tone multi frequency input DTMF

When the DTMF input is enabled, dialling tones may be
sent onto the line. The voltage gain from DTMF to LN is
typically 25.5 dB and varies with R7 in the same way as
the gain of the microphone amplifier. The signalling tones
can be heard in the earpiece at a low level (confidence
tone).

Receiving amplifier: IR, QR+, QR− and GAR

The receiving amplifier has one input IR and two
complementary outputs, a non-inverting output QR+ and
an inverting output QR−.

1996 Apr 04 5

Philips Semiconductors Product specification

× R1 R3 R8//Z

bal

[ ]+( )=

( )⁄ Z

lineZline

R1+( )⁄=

Versatile telephone transmission circuit
with dialler interface

These outputs may be used for single-ended or for
differential drive, depending on the sensitivity and type of
earpiece used (see Fig.10). Gain from IR to QR+ is
typically 25 dB. This will be sufficient for low-impedance
magnetic or dynamic earpieces, which are suited for
single-ended drive. By using both outputs (differential
drive), the gain is increased by 6 dB and differential drive
becomes possible. This feature can be used when the
earpiece impedance exceeds 450 Ω (high-impedance
dynamic, magnetic or piezoelectric earpieces).

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 ratio of peak
to RMS value is higher.

The receiving amplifier gain can be adjusted over a range
of ±8 dB to suit the sensitivity of the transducer used.
The gain is set by the external resistor R4 connected
between GAR and QR+.

Two external capacitors, C4 = 100 pF and
C7 = 10 × C4 = 1 nF, are necessary to ensure stability.
A larger value of C4 may be chosen to obtain a first-order,
low-pass filter. The ‘cut-off’ frequency corresponds with
the time constant R4 × C4.

Automatic gain control input AGC

Automatic line loss compensation is obtained by
connecting a resistor R6 between AGC and VEE. This
automatic gain control varies the microphone amplifier
gain and the receiving amplifier gain in accordance with
the DC line current.

The control range is 6 dB. This corresponds with a line
length of 5 km for a 0.5 mm diameter copper twisted-pair
cable with a DC resistance of 176 Ω/km and an 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 Fig.11 and Table 1). Different values of R6 give the
same ratio of line currents for start and end of the control
range.

If automatic line loss compensation is not required, AGC
may be left open. The amplifiers then all give their
maximum gain as specified.

Power-down input PD

During pulse dialling or register recall (timed loop break)
the telephone line is interrupted, as a consequence it
provides no supply for the transmission circuit and the
peripherals connected to VCC. These gaps have to be

TEA1066T

bridged by the charge in the smoothing capacitor C1.
The requirements on this capacitor are relaxed by applying
a HIGH level to the PD input during the time of the loop
break, which reduces the supply current from typically
1 mA to typically 55 µA.

A HIGH level at PD further disconnects the capacitor at
REG, with the effect that the voltage stabilizer will have no
switch-on delay after line interruptions. This results in no
contribution of the IC to the current waveform during pulse
dialling or register recall. When this facility is not required
PD may be left open.

Side-tone suppression

Suppression of the transmitted signal in the earpiece is
obtained by the anti-side-tone network consisting of
R1//Z
compensation is obtained when the following conditions
are fulfilled:

R9 R2
Z

If fixed values are chosen for R1, R2, R3, and R9, then
condition (1) will always be fulfilled, provided that
R8//Z
suppression, condition (2) has to be fulfilled, resulting in:

Z
k = (R8/R1).

Scale factor k (dependent on the value of R8) must be
chosen to meet the following criteria:

1. Compatibility with a standard capacitor from the E6 or

2. Z

3. Z
In practice, Z

type; consequently, an average value has to be chosen for
Z
with which Z

Example: The balanced line impedance Z
the optimum suppression is preset can be calculated by:

Assume Z
5 km line of 0.5 mm diameter, copper, twisted-pair cable
matched to 600 Ω (176 Ω/km; 38 nF/km). When k = 0.64,
then R8 = 390 Ω; Z

The anti-side-tone network for the TEA1060 family shown
in Fig.4 attenuates the signal received from the line by
32 dB before it enters the receiving amplifier.

, R2, R3, R8, R9 and Z

line

balZbal

= (R8/R1) Z

bal

E12 range for Z

. The suppression further depends on the accuracy

bal

R8+

 < R3. To obtain optimum side-tone

bal

= k × Z

line

bal

//R8 << R3

bal

+ R8 >> R9.

bal

varies greatly with line length and cable

line

/k equals the average line impedance.

bal

= 210 Ω + (1265 Ω/140 nF), representing a

line

= 130 Ω + (820 Ω//220 nF).

bal

(see Fig.14). Maximum

bal

, where k is a scale factor:

line

 at which

bal

(1)
(2)

1996 Apr 04 6

Philips Semiconductors Product specification

Fig.4 Equivalent circuit of TEA1060 family anti-side-tone bridge.

handbook, full pagewidth

MSA500 - 1

IR

R3

R8

SLPE

R9

Z

line

V

EE

Z

bal

i

m

R

t

R1 R2

LN

Fig.5 Equivalent circuit of an anti-side-tone network in a Wheatstone bridge configuration.

handbook, full pagewidth

MSA501 - 1

IR

R8

SLPE

R9

R1

LN

Z

line

V

EE

Z

bal

R

A

i

m

R

t

Versatile telephone transmission circuit
with dialler interface

The attenuation is almost constant over the whole audio
frequency range. Figure 5 shows a conventional
Wheatstone bridge anti-side-tone circuit that can be used
as an alternative. Both bridge types can be used with
either resistive or complex set impedances.

The anti-side-tone network as used in the standard
application (see Fig.13) attenuates the signal from the line

TEA1066T

with 32 dB. The attenuation is nearly flat over the
audio-frequency range.

Instead of the previously-described special TEA1066
bridge, the conventional Wheatstone bridge configuration
can be used as an alternative anti-side-tone circuit. Both
bridge types can be used with either a resistive set
impedance or a complex set impedance.

1996 Apr 04 7

Philips Semiconductors Product specification

Versatile telephone transmission circuit

TEA1066T

with dialler interface

LIMITING VALUES

In accordance with the Absolute Maximum Rating System (IEC 134).

SYMBOL PARAMETER CONDITIONS MIN. MAX. UNIT

V

LN

V

LN(R)

V

LN(RM)

I

line

V

n

P

tot

T

stg

T

amb

T

j

Notes

1. Mostly dependent on the maximum required T

2. Calculated for the maximum ambient temperature specified, T
125 °C.

positive continuous line voltage − 12 V
repetitive line voltage during switch-on or

− 13.2 V

line interruption
repetitive peak line voltage for a 1 ms pulse

per 5 s

R9 = 20 Ω;
R10 = 13 Ω; (Fig.10)

− 28 V

line current R9= 20 Ω; note 1 − 140 mA
voltage on any other pin VEE− 0.7 VCC+ 0.7 V
total power dissipation R9= 20 Ω; note 2 − 555 mW
IC storage temperature −40 +125 °C
operating ambient temperature −25 +75 °C
junction temperature − 125 °C

and on the voltage between LN and SLPE (see Fig.6).

amb

= 75 °C and a maximum junction temperature of

amb

THERMAL CHARACTERISTICS

SYMBOL PARAMETER VALUE UNIT

R

th j-a

thermal resistance from junction to ambient in free air mounted on glass epoxy

90 K/W

board 41 × 19 × 1.5 mm

1996 Apr 04 8