Philips TEA1098 Technical data

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TEA1098

Speech and handsfree IC

Product speciﬁcation Supersedes data of 1999 May 20 File under Integrated Circuits, IC03

1999 Oct 14

Philips Semiconductors Product speciﬁcation

Speech and handsfree IC TEA1098

FEATURES Line interface

• Low DC line voltage

• Voltage regulator with adjustable DC voltage

• Symmetrical high impedance inputs (70 kΩ) for

dynamic, magnetic or electret microphones

• DTMF input with confidence tone on earphone and/or loudspeaker

• Receive amplifier for dynamic, magnetic or piezo-electric earpieces(with externally adjustable gain)

• Automatic Gain Control (AGC) for true line loss compensation.

Supplies

• Provides a strong 3.35 V regulated supply for microcontrollers or diallers

• Provides filtered power supply, optimized according to line current

• Filtered 2.0 V power supply output for electret microphone

• PD logic input for power-down.

Handsfree

• Asymmetrical high input impedance for electret microphone

• Loudspeaker amplifier with single-ended rail-to-rail output and externally adjustable gain

• Dynamic limiter on loudspeaker amplifier to prevent distortion

• Logarithmic volume controlon loudspeakeramplifier via linear potentiometer

• Duplex controller consisting of: – Signal and noise envelope monitors for both

channels (with adjustable sensitivities and timing)

– Decision logic (with adjustable switch-over and Idle

mode timing)

– Voice switch control (with adjustable switching range

and constant sum of gain during switching).

APPLICATIONS

• Line powered telephone sets.

GENERAL DESCRIPTION

The TEA1098 is an analog bipolar circuit dedicated to telephonyapplications. It includesa line interface,handset (HS) microphone and earpiece amplifiers, handsfree (HF) microphone and loudspeaker amplifiers and a duplex controller with signal and noise monitors on both channels.

This IC provides a 3.35 V supply for a microcontroller or dialler and a 2.0 V filtered voltage supply for an electret microphone.

ORDERING INFORMATION

TYPE

NUMBER

TEA1098TV VSO40 plastic very small outline package; 40 leads SOT158-1 TEA1098H QFP44 plastic quad ﬂat package; 44 leads (lead length 1.3 mm);

TEA1098UH − bare die; on foil −

1999 Oct 14 2

NAME DESCRIPTION VERSION

body 10 × 10 × 1.75 mm

PACKAGE

SOT307-2

Philips Semiconductors Product speciﬁcation

Speech and handsfree IC TEA1098

QUICK REFERENCE DATA

= 15 mA; R

line

TEA1098UH; AGC pin connected to LN; unless otherwise speciﬁed.

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

line

SLPE

BB(pd)

v(MIC-LN)

v(IR-RECO)

∆G

v(QR)

v(TXIN-TXOUT)

v(HFTX-LN)

v(HFRX-LSAO

SWRA switching range − 40 − dB

∆SWRA switching range adjustment with R

∆G

v(trx)

SLPE

=20Ω; Z

= 600 Ω; f = 1 kHz; T

line

=25°C for TEA1098H and TEA1098TV; Tj=25°C for

amb

PD = HIGH; HFC = LOW; MUTE = HIGH; measured according to test circuits;

line current operating range normal operation 11 − 130 mA

with reduced performance 1 − 11 mA

stabilized voltage between SLPE and GND

regulated supply voltage for internal circuitry

regulated supply voltage on pin V

current available on pin V

= 15 mA 3.4 3.7 4.0 V

line

= 70 mA 5.7 6.1 6.5 V

line

= 15 mA 2.75 3.0 3.25 V

line

= 70 mA 4.9 5.3 5.7 V

line

VBB> 3.35 V + 0.25 V (typ.) 3.1 3.35 3.6 V otherwise − V

− 0.25 − V

in speech mode − 11 − mA in handsfree mode − 9 − mA

current consumption on V

PD = LOW − 460 −µA

during power-down phase voltage gain from pin MIC+/MIC−

= 5 mV (RMS) 43.3 44.3 45.3 dB

MIC

to LN voltage gain from pin IR

VIR= 8 mV (RMS) 28.7 29.7 30.7 dB

(referenced to LN) to RECO gain voltage range between pins

−3 − +15 dB

RECO and QR voltage gain from pin TXIN to

TXOUT voltage gain from pin HFTX to LN V

) voltage gain from pin HFRX

to LSAO

= 3 mV (RMS);

TXIN

= 30.1 kΩ

GATX

= 15 mV (RMS) 33.5 34.7 35.9 dB

HFTX

= 30 mV (RMS);

HFRX

GALS

= 255 kΩ; I

referenced to

SWR

=70mA

line

12.7 15.2 17.7 dB

25.5 28 30.5 dB

−40 − +12 dB

365 kΩ

gain control range for transmitand

= 70 mA 5.45 6.45 7.45 dB

line

receive ampliﬁers affected by the AGC; with respect to I

=15mA

line

1999 Oct 14 3

Philips Semiconductors Product speciﬁcation

Speech and handsfree IC TEA1098

BLOCK DIAGRAM

REG

SLPE

LN 18 (15)

STARTER

LINE CURRENT DETECTION LOW VOLTAGE BEHAVIOUR

(16)17(14)

SWITCH

SUPPLY

MANAGEMENT

(10) 13

(19) 22

(20) 23

MICS

AGC

GND

HFTX

DTMF

MIC+ MIC−

TXIN

TSEN TENV

TNOI

RNOI RENV RSEN

GALS

LSAO

21 (18)

16 (13)

39 (36)

35 (32)

34 (31) 33 (30)

31 (28)

8 (4) 7 (3) 6 (2) 9 (5) 11 (7) 10 (6)

14 (11)

15 (12)

AGC

Tail currents for preamps

ATTENUATOR

TX AND RX

ENVELOPE AND NOISE

DETECTORS

BUFFERS

AND

COMPARATORS

TEA1098

DUCO LOGIC

SWT STATUS

POWER-DOWN

CURRENT SOURCES

LOGIC

INPUTS

DECODING

VOICE

SWITCH

VOLUME

CONTROL

(38) 1

(37) 40

(39) 2

(27) 30 (26) 29

(29) 32

(24) 27 (25) 28

(21) 24

(22) 25

(23) 26

(1) 5

HFC MUTE

GATX TXOUT

GNDTX

SWT IDT

STAB

SWR

VOL

HFRX

12 (8)

DLC

RECO GARX

38 (35) 37 (34)

36 (33)

DYNAMIC

LIMITER

Pin numbers in parenthesis apply to the TEA1098H. Pin numbers not in parenthesis apply to the TEA1098TV.

Fig.1 Block diagram.

1999 Oct 14 4

ATTENUATOR

(17) 20

MGL317

Philips Semiconductors Product speciﬁcation

Speech and handsfree IC TEA1098

PINNING

SYMBOL

PD 1 38 41 power-down input (active LOW) MUTE 2 39 42 logic input (active LOW) n.c. 3 40 43 not connected n.c. 4 41 44 not connected n.c. − 42 45 not connected n.c. − 43 46 not connected n.c. − 44 47 not connected HFRX 5 1 1 receive input for loudspeaker ampliﬁer TNOI 6 2 2 transmit noise envelope timing adjustment TENV 7 3 3 transmit signal envelope timing adjustment TSEN 8 4 4 transmit signal envelope sensitivity adjustment RNOI 9 5 5 receive noise envelope timing adjustment RSEN 10 6 6 receive signal envelope sensitivity adjustment RENV 11 7 7 receive signal envelope timing adjustment DLC 12 8 8 dynamic limiter capacitor for the loudspeaker ampliﬁer n.c. − 9 9 and 13 not connected V

GALS 14 11 11 loudspeaker ampliﬁer gain adjustment LSAO 15 12 12 loudspeaker ampliﬁer output GND 16 13 14 and 15 ground reference SLPE 17 14 16 line current sense LN 18 15 17 positive line terminal REG 19 16 18 line voltage regulator decoupling IR 20 17 19 receive ampliﬁer input AGC 21 18 20 automatic gain control/line loss compensation V

MICS 23 20 22 microphone supply STAB 24 21 23 reference current adjustment SWR 25 22 24 switching range adjustment VOL 26 23 25 loudspeaker volume adjustment SWT 27 24 26 switch-over timing adjustment IDT 28 25 27 Idle mode timing adjustment TXOUT 29 26 28 HF microphone ampliﬁer output GATX 30 27 29 HF microphone ampliﬁer gain adjustment TXIN 31 28 30 HF microphone ampliﬁer input GNDTX 32 29 31 to 32 ground reference for microphone ampliﬁers MIC− 33 30 33 negative HS microphone ampliﬁer input MIC+ 34 31 34 positive HS microphone ampliﬁer input

TEA1098TV TEA1098H TEA1098UH

PIN PAD

DESCRIPTION

13 10 10 stabilized supply for internal circuitry

22 19 21 3.35 V regulated voltage supply for microcontrollers

1999 Oct 14 5

Philips Semiconductors Product speciﬁcation

Speech and handsfree IC TEA1098

SYMBOL

DESCRIPTION

TEA1098TV TEA1098H TEA1098UH

DTMF 35 32 35 dual tone multi-frequency input QR 36 33 36 earpiece ampliﬁer output GARX 37 34 37 earpiece ampliﬁer gain adjustment RECO 38 35 38 receive ampliﬁer output HFTX 39 36 39 transmit input for line ampliﬁer HFC 40 37 40 logic input

PIN PAD

handbook, halfpage

MUTE

n.c. n.c.

HFRX

TNOI TENV TSEN

RNOI RSEN RENV

DLC V

GALS LSAO

GND

SLPE

REG

1 2 3 4 5 6 7 8

9 10 11 12 13 14 15 16 17 18 19 20

TEA1098TV

MGL341

40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21

HFC HFTX RECO GARX QR DTMF MIC+ MIC− GNDTX TXIN GATX TXOUT IDT SWT VOL SWR STAB MICS V

AGC

Fig.2 Pin configuration (TEA1098TV).

1999 Oct 14 6

Philips Semiconductors Product speciﬁcation

Speech and handsfree IC TEA1098

handbook, full pagewidth

n.c.

n.c. 42

n.c. 41

n.c. 40

MUTE 39

PD 38

HFC 37

HFTX 36

RECO 35

GARX 34

HFRX

TNOI

TENV

TSEN

RNOI

RSEN RENV

DLC

n.c.

GALS

7 8

9 10 11

GND

LSAO

SLPE

TEA1098H

Fig.3 Pin configuration (TEA1098H).

FUNCTIONAL DESCRIPTION

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

Supplies

LINE INTERFACE AND INTERNAL SUPPLY (PINS LN, SLPE, REG AND VBB)

Thesupply for theTEA1098 and itsperipheralsis obtained from the line. The IC generates a stabilized reference voltage (V

) between pins SLPE and GND.

ref

This reference voltage is equal to 3.7 V for line currents below 18 mA. When the line current rises above 45 mA, the reference voltage rises linearly to 6.1 V. For line currents below 9 mA, V

is automatically adjusted to a

ref

lower value. The performance of the TEA1098 in this so-called low voltage area is limited (see Section “Low voltage behaviour”). The reference voltage is temperature compensated.

QR DTMF

32 31

MIC+

MIC− GNDTX

29 28

TXIN GATX

TXOUT

IDT

25 24

SWT VOL

REG

AGC

MICS

STAB

SWR

FCA020

The voltage between pins SLPE and REG is used by the internal regulator to generate the stabilized reference voltage and is decoupled by a capacitor connected between pins LN and REG. This capacitor, converted into an equivalent inductance realizes the set impedance conversionfrom its DC value(R

)to its AC value(done

SLPE

by an external impedance). The IC regulates the line voltage at pin LN which can be

calculated as follows:

SLPEIline

refRSLPEISLPE

×+=

Ix–=

where: I

= line current.

line

Ix= current consumed on pin LN (approximately a few µA).

= current flowing through the R

SLPE

resistor.

1999 Oct 14 7

Philips Semiconductors Product speciﬁcation

Speech and handsfree IC TEA1098

The preferred value for R

is 20 Ω. Changing this value

SLPE

not only affects the DC characteristics, it also influences the transmit gains to the line, the gain control characteristic,the sidetonelevel, and themaximum output swing on the line.

Figure 4 shows that the internal circuit is supplied by pin VBB, which combined with the line interface is a strong supply point.

The line current through resistor R

is sunk by the V

SLPE

voltage stabilizer, and is suitable for supplying a loudspeaker amplifier or any peripheral IC. Voltage VBBis

3.0 V at line currents below 18 mA and rises linearly to

5.3 V when the line current rises above 45 mA. It is temperature compensated.

handbook, full pagewidth

REG

4.7 µF

SLPE

TP1

SLPE

20 Ω

The current switch TR1-TR2 is intended to reduce distortionof large AC linesignals. Current I

SLPE

issupplied to VBB via TR1 when the voltage on pin SLPE is above VBB+ 0.25 V. Whenthe voltage on pin SLPE is below this value, I

Voltage V

is shunted to GND via TR2.

SLPE

can be increased by connecting an external

ref

resistor between pins REG and SLPE. For large line currents, this increase can slightly affect some dynamic performances such as maximumsignal level on the line at 2% Total Harmonic Distortion(THD). Theexternal resistor does not affect the voltage on pin VBB; see Fig.5 for the main DC voltages.

TR2

GND

TR1

REG

GND

from

preamp

TN1

Fig.4 Line interface principle.

TN2

GND

MGM298

1999 Oct 14 8

Philips Semiconductors Product speciﬁcation

Speech and handsfree IC TEA1098

handbook, full pagewidth

voltages

(V)

0 0.01

0.02 0.05

Fig.5 Main DC voltages.

SUPPLY FOR MICROCONTROLLERS (PIN V

The voltage on the V

supply point follows the voltage on

)

VBBwith a difference typically of 250 mV, internallylimited to 3.35 V. This voltage is temperature compensated. This supply point can provide a current of up to typically 3 mA. Its internal consumption stays low (a few 10 nA) as long as VDD does not exceed 1.5 V (see Fig.6).

An external voltage can be connected to VDD with limited extra consumptionon VDD(typically 100 µA).This voltage source should not be below 3.5 V or above 6 V. VBBand VDDcan supply current to external circuits within the line limits, taking into account the internal current consumption.

UPPLY FOR MICROPHONE (PINS MICS AND GNDTX)

S The MICS output can be used as a supply for an electret

microphone. Its voltage is equal to 2.0 V; it can source a current of up to 1 mA and has an output impedance equal to 200 Ω.

FCA049

SLPE

MICS

0.040.03

OW VOLTAGE BEHAVIOUR

line

(A)

0.070.06

For line currents below 9 mA, the reference voltage is automatically adjusted to a lower value; the VBB voltage follows the SLPE voltage with a difference of 250 mV. Any excess current available, other than for the purposes of DC biasing the IC, will be small. At low reference voltage, the IC has limited performance.

When voltage VBB falls below 2.7 V, it is detected by the receive dynamic limiter circuit connected to pin LSAOand is continuously activated, discharging the capacitor connected to pin DLC. In the DC condition, the loudspeaker is then automatically disabled below this voltage.

When VBBfalls below 2.5 V, the TEA1098 is forced into a lowvoltage mode irrespectiveof the logicinput levels. This is a speech mode with reduced performance which only enables the microphone channel (between the MICinputs and pin LN) and the earpiece amplifier. These two channels are able to deliver signals for line currents as small as 3 mA. The HFC input is tied to GND sinking a current of typically 300 µA.

1999 Oct 14 9

Philips Semiconductors Product speciﬁcation

Speech and handsfree IC TEA1098

handbook, full pagewidth

(pA)

1.0

FCA050

1.5 2.5 3.0

2.0 VDD (V)

Fig.6 Current consumption on VDD.

POWER-DOWN MODE (PIN PD) To reduce consumption during dialling or register recall

(flash), the TEA1098 is provided with a power-down input (PD). When the voltage on pin PD is LOW, the current consumption from VBB and VDD is reduced to typically 460 µA. Therefore a capacitor of 470 µF on VBB is sufficient to power the TEA1098 during pulse dialling or flash. The PD input has a pull-up structure. In this mode, the capacitor C

is internally disconnected.

REG

Transmit channels (pins MIC+, MIC−, DTMF, HFTX and LN)

HANDSET MICROPHONE AMPLIFIER (PINS MIC+, MIC−

AND LN)

The TEA1098 has symmetrical microphone inputs. The input impedance between pins MIC+ and MIC− is typically70 kΩ.The voltage gainbetweenpinsMIC+/MIC− and LN is set to 44.3 dB. Without output limitation, the microphone input stage can accept signals of up to 18 mV (RMS) at 2% THD (room temperature).

1999 Oct 14 10

The microphone inputs are biased at a voltage of one diode.

Automatic gain control is provided for line loss compensation.

DTMF AMPLIFIER (PINS DTMF, LN AND RECO) TheTEA1098 has anasymmetrical DTMF input.The input

impedance between DTMF and GND is typically 20 kΩ. The voltage gain between pins DTMF and LN is set to

25.35 dB. Without output limitation, the input stage can accept signals of up to 180 mV (RMS) at 2% THD (room temperature).

When the DTMF amplifier is enabled, dialling tones may be sent on the line. These tones can be heard in the earpiece or in the loudspeaker ata lowlevel. This is called theconfidence tone. Thevoltageattenuation between pins DTMF and RECO is typically −16.5 dB. This input is DC biased at 0 V.

The automatic gain control has no effect on these channels.

Philips Semiconductors Product speciﬁcation

Speech and handsfree IC TEA1098

HANDSFREE TRANSMIT AMPLIFIER (PINS HFTX AND LN) The TEA1098 has an asymmetrical HFTX input, which is

mainly intended for use in combination with the TXOUT output. The input impedance between HFTX and GND is typically 20 kΩ. The voltage gain between pins HFTX and LN is set to 34.7 dB. Without output limitation, the input stage can accept signals of up to 95 mV (RMS) at 2% THD (room temperature). The HFTX input is biased at a voltage of two diodes.

Automatic gain control is provided for line loss compensation.

Receive channels (pins IR, RECO, GARX and QR)

RX AMPLIFIER (PINS IR AND RECO) The receive amplifier has one input (IR) which is

referenced to the line. The input impedance between pins IR and LN is typically 20 kΩ and the DC bias between these pins is equal to the voltage of one diode. The gain between pins IR(referenced to LN) and RECO is typically

29.7 dB. Without output limitation, the input stage can accept signals of up to 50 mV (RMS) at 2% THD (room temperature).

The receive amplifier has a rail-to-rail output (RECO), which is designed for use with high ohmic (real) loads of more than 5 kΩ. This output is biased at a voltage of two diodes.

Automatic gain control is provided for line loss compensation.

AGC (pin AGC)

The TEA1098 performsautomatic lineloss compensation, which fits well with the true line attenuation. The automatic gain control varies the gain of some transmit and receive amplifiers in accordance with the DC line current. The controlrange is6.45 dB for G and 6.8 dB for G

v(HFTX-LN)

, which corresponds

v(MIC-LN)

andG

v(IR-RECO),

approximately to a line length of 5.5 km for a 0.5 mm twisted-pair copper cable.

To enable this gain control, the pin AGC must be shorted to pin LN. The start current forcompensation corresponds to a line current of typically 23 mA and a stop current of 57 mA. The start current can be increased by connecting an external resistor between pins AGC and LN. It can be increased by up to 40 mA (using a resistor of typically 80 kΩ). The start and stop current will be maintained at a ratio of 2.5. By leaving the AGC pin open, the gain control is disabled and no line loss compensation occurs.

Handsfree application

Figure 7 shows a loop is formed by the sidetone network in the line interface section, and by the acoustic coupling between loudspeaker and microphone in the handsfree section. A loop-gain of greater than 1 causes howl. To prevent howl in full duplex applications, the loop-gain must be set much lower than 1. This is achieved by the duplex controller which detects the channel with the ‘largest’ signal and controls the gains of the microphone and the loudspeaker amplifiers so that the sum of their

gains remains constant. EARPIECE AMPLIFIER (PINS GARX AND QR) The earpiece amplifier is an operational amplifier which

has an output (QR) and an inverting input (GARX). Its input signal is fed by a decoupling capacitor from the receive amplifier output (RECO) to two resistorswhich set the required gain or attenuation from −3 to +15 dB compared to the receive gain.

Two external capacitors C and QR) and C ensure stability. The C

(connected between GAR and GND)

GARS

GAR

(connected between GAR

GAR

capacitor provides a first-order low-pass filter. The cut-off frequency corresponds to the time constant C C

≥ 10 × C

GARS

× Re2. The relationship

GAR

must be satisfied.

GAR

The earpiece amplifierhas arail-to-rail output(QR) biased at a voltage of two diodes. It is designed for use with low ohmic (real) loads of 150 Ω, or capacitive loads of 100 nF in series with 100 Ω.

1999 Oct 14 11

Thereforein the handsfreeapplication,thecircuit can have three stable modes:

1. Transmit mode (Tx mode). The microphone amplifieris atmaximum gain, andthe

loudspeaker amplifier is at minimum gain.

2. Receive mode (Rx mode). The microphoneamplifier is at minimum gain, and the

loudspeaker amplifier is at maximum gain.

3. Idle mode. The microphone amplifier and the loudspeaker

amplifier are both midway between maximum and minimum gain.

The difference between the maximum and minimum gain is called the switching range.

Philips Semiconductors Product speciﬁcation

Speech and handsfree IC TEA1098

handbook, full pagewidth

acoustic coupling

telephone

line

sidetone

HYBRID

Fig.7 Handsfree telephone set principles.

HANDSFREE MICROPHONE CHANNEL: PINS TXIN, GATX, TXOUT AND GNDTX (see Fig.8)

TheTEA1098 has an asymmetricalhandsfreemicrophone input (TXIN) with an input resistance of 20 kΩ. The input DCbias is 0 V.Thegain oftheinput stage varies according to the TEA1098 mode. In Tx mode, it has maximum gain; in Rx mode, it has minimum gain, and in Idle mode, it is midway between maximum and minimum gain.

DUPLEX

CONTROL

MGM299

Switch-over from one mode to the other is smooth and click-free. The output (TXOUT) is biased at a voltage of two diodes and has a current capability of 20 µA (RMS). In Tx mode, the overall gain of the microphone amplifier (from pins TXIN to TXOUT) can be adjusted from 0 up to 31 dB to suit specific application requirements. The gain is proportional to the value of R

15.2 dB whenR

is 30.1 kΩ. Withoutoutput limitation,

GATX

and equals

the microphone input stage can accept signals of up to 18 mV (RMS) at 2% THD (room temperature).

handbook, full pagewidth

MIC

Pin numbers in parenthesis apply to the TEA1098H. Pin numbers not in parenthesis apply to the TEA1098TV.

MIC

(28)

TXIN

envelope

detector

V I I V

from

voice

switch

GATX

TXOUT

GNDTX

MGL342

Fig.8 Handsfree microphone channel.

1999 Oct 14 12

30 (27)

29 (26)

32 (29)

GATX

+ 28 hidden pages