Philips TEA1112T, TEA1112AT, TEA1112A Datasheet

INTEGRATED CIRCUITS

DATA SH EET

TEA1112; TEA1112A

Low voltage versatile telephone transmission circuits with dialler interface

Product speciﬁcation Supersedes data of 1996 Feb 16 File under Integrated Circuits, IC03

1997 Mar 26

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone transmission circuits with dialler interface

FEATURES

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

• Voltage regulator with adjustable DC voltage

• Provides a supply for external circuits

• Symmetrical high impedance inputs (64 kΩ) for

dynamic, magnetic or piezo-electric microphones

• Asymmetrical high impedance input (32 kΩ) for electret microphones

• DTMF input with confidence tone

• Mute input for pulse or DTMF dialling (MUTE for

TEA1112 and MUTE for TEA1112A)

• Receiving amplifier for dynamic, magnetic or piezo-electric earpieces

• AGC line loss compensation for microphone and earpiece amplifiers

• LED on-hook/off-hook status indication

• Microphone mute function (MMUTE for TEA1112 and

MMUTE for TEA1112A).

APPLICATION

• Line powered telephone sets, cordless telephones, fax machines and answering machines.

GENERAL DESCRIPTION

The TEA1112; TEA1112A are bipolar integrated circuits that perform all speech and line interface functions required in fully electronic telephone sets. They perform electronic switching between speech and dialling. The ICs operate at a line voltage down to 1.6 V DC (with reduced performance) to facilitate the use of telephone sets connected in parallel.

A current (proportional to the line current and internally limited to a typical value of 19.5 mA) is available to drive an LED which indicates the on-hook/off-hook status.

The microphone amplifier can be disabled during speech condition by means of a microphone mute function.

All statements and values refer to all versions unless otherwise specified.

TEA1112; TEA1112A

QUICK REFERENCE DATA

= 15 mA; VEE=0V; R

line

=20Ω; AGC pin connected to VEE; Z

SLPE

= 600 Ω; f = 1 kHz; T

line

amb

=25°C;

unless otherwise speciﬁed.

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

line

line current operating range normal operation 11 − 140 mA

with reduced performance 1 − 11 mA

LED(max)

vtrx

∆G

vtrx

maximum supply current available I

=18mA − 0.5 − mA

line

>76mA − 19.5 − mA

line

DC line voltage 3.35 3.65 3.95 V internal current consumption VCC= 2.9 V − 1.15 1.4 mA supply voltage for peripherals Ip=0mA − 2.9 − V typical voltage gain range

microphone amplifier V receiving amplifier V

gain control range for microphone and

= 2 mV (RMS) 38.8 − 51.8 dB

MIC

= 6 mV (RMS) 19.2 − 31.2 dB

=85mA − 5.8 − dB

line

receiving ampliﬁers with respect to I

=15mA

line

∆G

vtxm

microphone ampliﬁer gain reduction − 80 − dB

1997 Mar 26 2

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone transmission circuits with dialler interface

ORDERING INFORMATION

TYPE

NUMBER

TEA1112 DIP16 TEA1112A DIP16 TEA1112T SO16 TEA1112AT SO16

BLOCK DIAGRAM

handbook, full pagewidth

NAME DESCRIPTION VERSION

plastic dual in-line package; 16 leads (300 mil) plastic dual in-line package; 16 leads (300 mil) plastic small outline package; 16 leads; body width 3.9 mm plastic small outline package; 16 leads; body width 3.9 mm

V− I

PACKAGE

GAR

15 14 8

MUTE

TEA1112; TEA1112A

SOT38-4

SOT38-4 SOT109-1 SOT109-1

DTMF

MMUTE MMUTE

MIC

V− I

ATT.

V− I

MICRO

MUTE

AGC

CIRCUIT

AGC

LOW VOLTAGE

CIRCUIT

DRIVER

LED

CURRENT

REFERENCE

TEA1112

TEA1112A

231013 SLPE

GAS

REG

MBE793

Fig.1 Block diagram.

1997 Mar 26 3

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone

TEA1112; TEA1112A

transmission circuits with dialler interface

PINNING

SYMBOL

TEA1112 TEA1112A

LN 1 1 positive line terminal SLPE 2 2 slope (DC resistance) adjustment I

LED

3 3 available output current to drive a LED REG 4 4 line voltage regulator decoupling GAS 5 5 sending gain adjustment MMUTE 6 − microphone mute input MMUTE − 6 microphone mute input (active LOW) DTMF 7 7 dual-tone multi-frequency input MUTE 8 − mute input to select speech or dialling mode MUTE − 8 mute input to select speech or dialling mode (active LOW) IR 9 9 receiving ampliﬁer input AGC 10 10 automatic gain control/line loss compensation MIC− 11 11 inverting microphone ampliﬁer input MIC+ 12 12 non-inverting microphone ampliﬁer input V

13 13 negative line terminal QR 14 14 receiving ampliﬁer output GAR 15 15 receive gain adjustment V

16 16 supply voltage for speech circuit and peripherals

DESCRIPTION

handbook, halfpage

SLPE

LED

REG GAS

MMUTE

DTMF MUTE

1 2 3 4 5 6 7 8

TEA1112

MBE791

GAR

MIC+

MIC−

AGC

Fig.2 Pin configuration (TEA1112).

1997 Mar 26 4

handbook, halfpage

Fig.3 Pin configuration (TEA1112A).

SLPE

LED

REG

GAS

MMUTE

DTMF MUTE

1 2 3 4

TEA1112A

5 6 7 8

MBE790

GAR

MIC+

MIC−

AGC

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone transmission circuits with dialler interface

FUNCTIONAL DESCRIPTION

All data given in this chapter are typical values, except when otherwise specified.

Supply (pins LN, SLPE, V

The supply for the TEA1112; TEA1112A and their peripherals is obtained from the telephone line.

The ICs generate a stabilized reference voltage (V between pins LN and SLPE. This reference voltage is equal to 3.35 V, is temperature compensated and can be adjusted by means of an external resistor (RVA). It can be increased by connecting the RVA resistor between pins REG and SLPE (see Fig.5), or decreased by connecting the RVA resistor between pins REG and LN. The voltage at pin REG is used by the internal regulator to generate the stabilized reference voltage and is decoupled by a capacitor (C

) which is connected to VEE. This

REG

capacitor, converted into an equivalent inductance (see Section “Set impedance”), realizes the set impedance conversion from its DC value (R in the audio-frequency range). The voltage at pin SLPE is proportional to the line current. Figure 4 illustrates the supply configuration.

The ICs regulate the line voltage at pin LN, and can be calculated as follows:

SLPEIlineICC

refRSLPEISLPE

×+=

– Ip– I∗– I

and REG)

SLPE

LED

)

ref

) to its AC value (R

I+

TEA1112; TEA1112A

Where:

= line current

line

ICC= current consumption of the IC Ip= supply current for peripheral circuits I* = current consumed between LN and V I

= supply current for the LED component

LED

Ish= the excess line current shunted to SLPE (and VEE) via LN.

The preferred value for R

is 20 Ω. Changing R

SLPE

affect more than the DC characteristics; it also influences the microphone and DTMF gains, the LED supply current characteristic, the gain control characteristics, the sidetone level and the maximum output swing on the line.

The internal circuitry of the TEA1112; TEA1112A is supplied from pin VCC. This voltage supply is derived from the line voltage by means of a resistor (RCC) and must be decoupled by a capacitor C

. It may also be used to

VCC

supply peripheral circuits such as dialling or control circuits. The VCC voltage depends on the current consumed by the IC and the peripheral circuits as shown by the formula (see also Figs.6 and 7). R internal impedance of the voltage supply point, and I the current consumed by the output stage of the earpiece amplifier.

CC0

CC0RCCintIpIrec

VLNR

×–=

CCICC

–()×–=

CCint

is the

SLPE

rec

will

line

handbook, full pagewidth

line

exch

LED

TEA1112

TEA1112A

LED

DRIVER

SLPE

20 Ω

15.5 kΩ

45.5 kΩ

Fig.4 Supply configuration.

1997 Mar 26 5

619 Ω

GASint

69 kΩ

from pre amp

REG

4.7 µF

VCC

100 µF

peripheral

circuits

MBE789

Philips Semiconductors Product speciﬁcation

Low voltage versatile telephone transmission circuits with dialler interface

RVA (Ω)

MGD176

6.0

handbook, halfpage

ref

(V)

5.0

4.0

(1)

(2)

3.0

(1) Influence of RVA on V (2) V

without influence of RVA.

ref

Fig.5 Reference voltage adjustment by RVA.

TEA1112; TEA1112A

For line currents higher than a threshold, I current increases proportionally to the line current (with a ratio of one third). The I

current is internally limited to

LED

19.5 mA (see Fig.9). If no LED device is used in the application, the I

For 17 mA < I

pin should be shorted to pin SLPE.

LED

17–

line

< 77 mA:

line

LED

---------------------3

This LED driver is referenced to SLPE. Consequently, all the I

supply current will flow through the R

LED

The AGC characteristics are not disturbed (see Fig.4).

Microphone ampliﬁer (pins MIC+, MIC− and GAS)

The TEA1112; TEA1112A have symmetrical microphone inputs. The input impedance between pins MIC+ and MIC− is 64 kΩ (2 × 32 kΩ). The voltage gain from pins MIC+/MIC− to pin LN is set at 51.8 dB (typ). The gain can be decreased by connecting an external resistor R between pins GAS and REG. The adjustment range is 13 dB. A capacitor C

connected between pins GAS

GAS

and REG can be used to provide a first-order low-pass filter. The cut-off frequency corresponds to the time constant C

GAS

× (R

GASint

// R

GAS

). R

GASint

resistor which sets the gain with a typical value of 69 kΩ.

, the I

LEDstart

resistor.

SLPE

is the internal

LED

GAS

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

) and the reference voltage (V

line

), the DC resistance of the telephone line

exch

), the feeding bridge

exch

). With line currents

ref

below 7.5 mA, the internal reference voltage (generating V

) is automatically adjusted to a lower value. This means

ref

that more sets can operate in parallel with DC line voltages (excluding the polarity guard) down to an absolute minimum voltage of 1.6 V. At currents below 7.5 mA, the circuit has limited sending and receiving levels. This is called the low voltage area.

Set impedance

In the audio frequency range, the dynamic impedance is mainly determined by the R

resistor. The equivalent

impedance of the circuits is illustrated in Fig.8.

LED supply (pin I

LED

)

The TEA1112; TEA1112A give an on-hook/off-hook status indication. This is achieved by a current made available to drive an LED connected between pins I

and LN. In the

LED

low voltage area, which corresponds to low line current conditions, no current is available for this LED.

Automatic gain control is provided on this amplifier for line loss compensation.

Microphone mute (pin MMUTE; TEA1112)

The microphone amplifier can be disabled by activating the microphone mute function. When MMUTE is LOW, the normal speech mode is entered, depending on the level on MUTE (see Table 1). When MMUTE is HIGH, the microphone amplifier inputs are disabled while the DTMF input is enabled (no confidence tone is provided). The voltage gain between LN and MIC+/MIC− is attenuated; the gain reduction is 80 dB (typ).

Microphone mute (pin

MMUTE; TEA1112A)

The microphone amplifier can be disabled by activating the microphone mute function. When MMUTE is LOW, the microphone amplifier inputs are disabled while the DTMF input is enabled (no confidence tone is provided). The voltage gain between LN and MIC+/MIC− is attenuated; the gain reduction is 80 dB (typ). When MMUTE is HIGH, the normal speech mode is entered, depending on the level on MUTE (see Table 1).

1997 Mar 26 6

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