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

line CC

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

amb

operating ambient temperature −25 − +75 °C

Line loss compensation

∆G V R

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

SUPPLY AND REFERENCE

AGC

CIRCUIT

SLPESTABAGCREGV

CURRENT

REFERENCE

18 1912

17 1

6 5 4

11 20

MICL+ MICH+ MICH−

MICL−

DTMF

MUTE

TEA1066T

GAR

GAS1

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

20 19 18 17 16 15 14 13 12 11

MBH120

TEA1066T

GAS1 GAS2

QR− QR+

GAR

MICL−

MICH−

MICL+

SLPE AGC

REG V

DTMF

MUTE

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

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

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

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

handbook, halfpage

REG

MBA454

ref

R9 20 Ω

4.7 µF C1100 µF

Versatile telephone transmission circuit with dialler interface

The voltage regulator adjusts the average voltage on LN to:

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

SLPE

line

bal

R1 R2

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

handbook, full pagewidth

MSA501 - 1

SLPE

line

bal

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

LN(R)

LN(RM)

line

tot

stg

amb

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

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

+ 16 hidden pages