Philips TEA1067-C2 Datasheet

DATA SH EET

Product speciﬁcation File under Integrated Circuits, IC03A

June 1990

INTEGRATED CIRCUITS

TEA1067

Low voltage versatile telephone transmission circuit with dialler interface

June 1990 2

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone transmission circuit with dialler interface

TEA1067

GENERAL DESCRIPTION

The TEA1067 is a bipolar integrated circuit performing all speech and line interface functions required in fully electronic telephone sets. It performs electronic switching between dialling and speech. The circuit is able to operate down to a DC line voltage of 1.6 V (with reduced performance) to facilitate the use of more telephone sets in parallel.

Features

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

• Voltage regulator with adjustable static resistance

• Provides supply with limited current for external circuitry

• Symmetrical high-impedance inputs (64 kΩ) for

dynamic, magnetic or piezoelectric microphones

• Asymmetrical high-impedance input (32 kΩ) for electret microphone

• DTMF signal input with confidence tone

• Mute input for pulse or DTMF dialling

• Power down input for pulse dial or register recall

• Receiving amplifier for magnetic, dynamic or

piezoelectric earpieces

• Large gain setting range on microphone and earpiece amplifiers

• Line current dependent line loss compensation facility for microphone and earpiece amplifiers

• Gain control adaptable to exchange supply

• DC line voltage adjustment capability

QUICK REFERENCE DATA

PACKAGE OUTLINES

PARAMETER CONDITIONS SYMBOL MIN. TYP. MAX. UNIT

Line voltage I

line

= 15 mA V

3.65 3.9 4.15 V

Line current operating range normal operation

TEA1067 I

line

11 − 140 mA

TEA1067T I

line

11 − 140 mA

with reduced performance I

line

1 − 11 mA

Internal supply current power down

input LOW I

− 1 1.35 mA

input HIGH I

− 55 82 µA

Supply voltage for peripherals I

line

= 15 mA; Ip= 1.4 mA;

mute input HIGH V

2.2 2.4 − V

line

= 15 mA; Ip= 0.9 mA;

mute input HIGH V

2.5 −− V

Voltage gain range

microphone amplifier G

44 − 52 dB

receiving amplifier G

20 − 45 dB

Line loss compensation

gain control range ∆G

5.5 5.9 6.3 dB

Exchange supply voltage range V

exch

36 − 60 V

Exchange feeding bridge

resistance range R

exch

0.4 − 1kΩ

TEA1067: 18-lead DIL; plastic (SOT102). SOT102-1; 1998 Jun 18. TEA1067T: 20-lead mini-pack; plastic (SO20; SOT163A). SOT163-1; 1998 Jun 18.

June 1990 3

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone transmission circuit with dialler interface

TEA1067

Fig.1 Block diagram.

Figures in parenthesis refer to TEA1067T.

handbook, full pagewidth

MGR082

CURRENT

REFERENCE

LOW

VOLTAGE

CIRCUIT

AGC

CIRCUIT

SUPPLY AND REFERENCE

16 (18)10 (11)

REG AGC STAB SLPE

GAS2

GAS1

QR−

QR+

GAR

12 (14)

14 (16)

13 (15)

(1)

7 (7)

8 (9)

−

17 (19) 9 (10) (20)18

11 (12)

MIC+ MIC−

DTMF

MUTE

−

+−+

−

(1)1

15 (17)

TEA1067 TEA1067T

(6) 6

(5) 5 (4) 4

(2) 2

(3) 3

June 1990 4

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone transmission circuit with dialler interface

TEA1067

PINNING

Fig.2 Pinning diagram for TEA1067 18-lead DIL

version.

handbook, halfpage

LN GAS1 GAS2

QR− QR+

GAR MIC− MIC+

STAB

SLPE AGC REG

DTMF PD

MUTE

IR V

1 2 3 4 5 6 7 8 9

18 17 16 15 14 13

TEA1067

MGR084

1 LN positive line terminal 2 GAS1 gain adjustment; transmitting ampliﬁer 3 GAS2 gain adjustment; transmitting ampliﬁer 4QR− inverting output; receiving ampliﬁer 5QR+ non-inverting output receiving ampliﬁer 6 GAR gain adjustment; receiving ampliﬁer 7 MIC− inverting microphone input 8 MIC+ non-inverting microphone input 9 STAB current stabilizer

10 V

negative line terminal 11 IR receiving ampliﬁer input 12 PD power-down input 13 DTMF dual-tone multi-frequency input 14 MUTE mute input 15 V

positive supply decoupling 16 REG voltage regulator decoupling 17 AGC automatic gain control input 18 SLPE slope (DC resistance) adjustment

Fig.3 Pinning diagram for TEA1067T 20-lead

mini-pack version.

handbook, halfpage

1 2 3 4 5 6 7 8 9

20 19 18 17 16 15 14 13

TEA1067T

MGR083

LN GAS1 GAS2

QR− QR+

GAR

MIC−

MIC+

STAB

SLPE AGC REG

DTMF

n.c. n.c.

MUTE

IR V

1 LN positive line terminal 2 GAS1 gain adjustment; transmitting ampliﬁer 3 GAS2 gain adjustment; transmitting ampliﬁer 4QR− inverting output; receiving ampliﬁer 5QR+ non-inverting output receiving ampliﬁer 6 GAR gain adjustment, receiving ampliﬁer 7 MIC− inverting microphone input 8 n.c. not connected

9 MIC+ non-inverting microphone input 10 STAB current stabilizer 11 V

negative line terminal 12 IR receiving ampliﬁer input 13 n.c. not connected 14 PD power-down input 15 DTMF dual-tone multi-frequency input 16 MUTE mute input 17 V

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

June 1990 5

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone transmission circuit with dialler interface

TEA1067

FUNCTIONAL DESCRIPTION Supply: V

, LN, SLPE, REG and STAB

Power for the TEA1067 and its peripheral circuits is usually obtained from the telephone line. The IC develops its own supply at V

and regulates its voltage drop. The supply voltage VCCmay also be used to supply external circuits e.g. dialling and control circuits.

Decoupling of the supply voltage is performed by a capacitor between VCCand VEEwhile the internal voltage regulator is decoupled by a capacitor between REG and VEE.

The DC current drawn by the device will vary in accordance with varying values of the exchange voltage (V

exch

), the feeding bridge resistance (R

exch

), and the DC

resistance of the telephone line (R

line

The TEA1067 has an internal current stabilizer working at a level determined by a 3.6 kΩ resistor connected between STAB and VEE(see Fig.7). When the line current (I

line

) is more than 0.5 mA greater than the sum of the IC supply current (ICC) and the current drawn by the peripheral circuitry connected to VCC(Ip) the excess current is shunted to VEEvia LN. The regulated voltage on the line terminal (VLN) can be calculated as:

VLN=V

ref

+ I

SLPE

× R9; or

VLN= V

ref

+ [(I

line

− ICC− 0.5 × 10−3A) − Ip] × R9

Where V

ref

is an internally generated temperature compensated reference voltage of 3.6 V and R9 is an external resistor connected between SLPE and VEE.

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, side-tone level and 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 3.6 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.4 shows the equivalent impedance of the 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 the operation of more sets in parallel is possible with DC line voltages (excluding the polarity guard) down to an absolute minimum voltage of

1.6 V. With 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 (RVA). This resistor connected between LN and REG will decrease the internal reference voltage, connected between REG and SLPE it will increase the internal reference voltage.

Current (Ip) available from VCCfor peripheral circuits depends on the external components used. Fig.10 shows this current for VCC> 2.2 V. If MUTE is LOW when the receiving amplifier is driven the available current is further reduced. Current availability can be increased by connecting the supply IC (TEA1081) in parallel with R1, as shown in Fig.17 (c), or by increasing the DC line voltage by means of an external resistor (RVA) connected between REG and SLPE.

June 1990 6

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone transmission circuit with dialler interface

TEA1067

Microphone inputs (MIC+ and MIC−) and gain adjustment pins (GAS1 and GAS2)

The TEA1067 has symmetrical microphone inputs. Its input impedance is 64 kΩ (2 × 32 kΩ) and its voltage gain is typically 52 dB (when R7 = 68 kΩ, see Fig.14). Dynamic, magnetic, piezoelectric or electret (with built-in FET source followers) microphones can be used. Microphone arrangements are shown in Fig.11.

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 the external capacitor C6 which is connected between GAS1 and SLPE. The value of C6 is 100 pF but this may be increased to obtain a first-order low-pass filter. The cut-off frequency corresponds to the time constant R7 × C6.

Mute input (MUTE)

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

Fig.4 Equivalent impedance circuit.

Rp= 16.2 kΩ L

= C3 × R9 × R

handbook, halfpage

MBA454

R9 20 Ω

REG

4.7 µF

ref

C1 100 µF

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 (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+, QR− and GAR)

The receiving amplifier has one input (IR), one non-inverting complementary output (QR+) and an inverting complementary output (QR−). These outputs may be used for single-ended or differential drive depending on the sensitivity and type of earpiece used (see Fig.12). IR to QR + gain is typically 31 dB (when R4 = 100 kΩ), this is sufficient for low-impedance magnetic or dynamic microphones which are suited for single-ended drive. Using both outputs for differential drive gives an additional gain of 6 dB. This feature can be used when the earpiece impedance exceeds 450 Ω (high-impedance dynamic or piezoelectric types).

The receiving amplifier gain can be adjusted between 20 and 39 dB with single-ended drive and between 26 and 45 dB with differential drive, 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+. Overall receive gain between LN and QR+ is calculated by substracting the anti-sidetone 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 × 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 × 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.

June 1990 7

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone transmission circuit with dialler interface

TEA1067

Automatic gain control input (AGC)

Automatic line loss compensation is achieved by connecting a resistor (R6) between AGC and VEE. 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 5.9 dB. This corresponds to 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 1.2 dB/km. Resistor R6 should be chosen in accordance with the exchange supply voltage and its feeding bridge resistance (see Fig.13 and Table 1). 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 may be left open-circuit. The amplifiers, in this condition, will give their maximum specified gain.

Power-down input (PD)

During pulse dialling or register recall (timed loop break) the telephone line is interrupted. During these interruptions the telephone line provides no power for the transmission circuit or circuits supplied by V

. The charge held on C1 will bridge these gaps. This bridging is made easier by a HIGH level on the PD input which reduces the typical supply current from 1 mA to 55 µA and switches off the voltage regulator preventing discharge through LN. When PD is HIGH the capacitor at REG is disconnected with the effect that the voltage stabilizer will have no switch-on delay after line interruptions. This minimizes the 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-circuit.

Side-tone suppression

The anti-sidetone network, R1//Z

line

, R2, R3, R9 and Z

bal

, (see Fig.5) suppresses transmitted signal in the earpiece. Compensation is maximum when the following conditions are fulfilled:

(a) R9 × R2 = R1 (R3 + [R8//Z

bal

]);

(b) (Z

bal

/ [Z

bal

+ R8]) = (Z

line

/ [Z

line

+ R1])

If fixed values are chosen for R1, R2, R3, and R9 then condition (a) will always be fulfilled whenR8//Z

bal

 << R3. To obtain optimum side-tone suppression condition (b) has to be fulfilled resulting in:

bal

= (R8/R1) Z

line

= k.Z

line

where k is a scale factor;

k = (R8/R1) The scale factor (k), dependent on the value of R8, is

chosen to meet the following criteria: (a) Compatibility with a standard capacitor from the E6 or

E12 range for Z

bal

(b)  Z

bal

//R8 << R3 to fulfil condition (a) and thus

ensuring correct anti-sidetone bridge operation (c)  Z

bal

+ R8 >> R9 to avoid influencing the transmitter

gain In practice 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.

June 1990 8

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone transmission circuit with dialler interface

TEA1067

Example

The line balance impedance (Z

bal

) at which the optimum suppression is present can be calculated by: suppose Z

line

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

bal

= 130 Ω+ (820 Ω//220 nF).

The anti-sidetone network for the TEA1060 family shown in Fig.5 attenuates the signal received from the line by 32 dB before it enters the receiving amplifier. The attenuation is almost constant over the whole audio frequency range. Fig.6 shows a conventional Wheatstone bridge anti-sidetone circuit that can be used as an alternative. Both bridge types can be used with either resistive or complex set impedances.

More information can be found in the designer guide; 9398 341 10011

Fig.5 Equivalent circuit of TEA1060 anti-sidetone bridge.

handbook, full pagewidth

MSA500

SLPE

line

bal

Fig.6 Equivalent circuit of an anti-sidetone network in a Wheatstone bridge configuration.

handbook, full pagewidth

MSA501

SLPE

line

bal

June 1990 9

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone transmission circuit with dialler interface

TEA1067

RATINGS

Limiting values in accordance with the Absolute Maximum System (IEC 134)

Notes

1. Mostly dependent on the maximum required T

amb

and on the voltage between LN and SLPE. See Figs 7 and 8 to determine the current as a function of the required voltage and the temperature.

2. Calculated for the maximum ambient temperature specified T

amb

= 75 °C and a maximum

junction temperature of 125 °C.

THERMAL RESISTANCE

PARAMETER CONDITIONS SYMBOL MIN. MAX. UNIT

Positive continuous line voltage V

− 12 V

Repetitive line voltage during

switch-on line interruption V

− 13.2 V

Repetitive peak line voltage for a

1 ms pulse per 5 s R9 = 20 Ω;

R10 = 13 Ω (Fig.16) V

− 28 V

Line current TEA1067 (note 1) R9 = 20 Ω I

line

− 140 mA

Line current TEA1067T (note 1) R9 = 20 Ω I

line

− 140 mA

Voltage on all other pins V

− VCC+ 0.7 V

−V

− 0.7 V

Total power dissipation (note 2) R9 = 20 Ω

TEA1067 P

tot

− 769 mW

TEA1067T P

tot

− 550 mW

Storage temperature range T

stg

−40 + 125 °C

Operating ambient temperature range T

amb

−25 + 75 °C

Junction temperature T

−+ 125 °C

From junction to ambient in free air

TEA1067 R

th j-a

typ. 65 K/W

TEA1067T mounted on glass epoxy board 41 × 19 × 1.5 mm R

th j-a

typ. 90 K/W

+ 19 hidden pages