Philips TEA1094T-C1, TEA1094AT-C1, TEA1094AM-C1, TEA1094A-C1, TEA1094T-C2 Datasheet

INTEGRATED CIRCUITS

DATA SHEET

TEA1094; TEA1094A

Hands free IC

Product specification

1996 Jul 15

Supersedes data of 1996 Mar 11

File under Integrated Circuits, IC03

Philips Semiconductors	Product specification
Hands free IC	TEA1094; TEA1094A

FEATURES

∙Low power consumption

∙Power-down function (TEA1094A only)

∙Microphone channel with:

–externally adjustable gain

–microphone mute function.

∙Loudspeaker channel with:

–externally adjustable gain

–dynamic limiter to prevent distortion

–rail-to-rail output stage for single-ended load drive

–logarithmic volume control via linear potentiometer

–loudspeaker mute function.

∙Duplex controller consisting of:

–signal envelope and noise envelope monitors for both channels with:

externally adjustable sensitivity

externally adjustable signal envelope time constant externally adjustable noise envelope time constant

–decision logic with:

externally adjustable switch-over timing externally adjustable idle mode timing

externally adjustable dial tone detector in receive channel

–voice switch control with: adjustable switching range

constant sum of gain during switching

constant sum of gain at different volume settings.

ORDERING INFORMATION

APPLICATIONS

∙Mains, battery or line-powered telephone sets with hands-free/listening-in functions

∙Cordless telephones

∙Answering machines

∙Fax machines.

GENERAL DESCRIPTION

The TEA1094 and TEA1094A are bipolar circuits intended for use in mains, battery or line-powered telephone sets, cordless telephones, answering machines and Fax machines. In conjunction with a member of the TEA106X, TEA111X families of transmission circuits, the devices offer a hands-free function. They incorporate a microphone amplifier, a loudspeaker amplifier and a duplex controller with signal and noise monitors on

both channels.

	TYPE NUMBER		PACKAGE
		NAME	DESCRIPTION	VERSION
	TEA1094	DIP28	plastic dual in-line package; 28 leads (600 mil)	SOT117-1
	TEA1094A	DIP24	plastic dual in-line package; 24 leads (600 mil)	SOT101-1
	TEA1094T	SO28	plastic small outline package; 28 leads; body width 7.5 mm	SOT136-1
	TEA1094AT	SO24	plastic small outline package; 24 leads; body width 7.5 mm	SOT137-1
	TEA1094AM	SSOP24	plastic shrink small outline package; 24 leads; body width 5.3 mm	SOT340-1

1996 Jul 15

2

Philips Semiconductors	Product specification
Hands free IC	TEA1094; TEA1094A

QUICK REFERENCE DATA

VBB = 5 V; VGND = 0 V; f = 1 kHz; Tamb = 25 °C; MUTET = LOW; PD = LOW (TEA1094A only); RL = 50 Ω; RVOL = 0 Ω; measured in test circuit of Fig.12; unless otherwise specified.

SYMBOL	PARAMETER	CONDITIONS	MIN.	TYP.	MAX.	UNIT
VBB	supply voltage		3.3	−	12.0	V
IBB	current consumption from pin VBB		−	3.1	4.4	mA
Gvtx	voltage gain from pin MIC to	VMIC = 1 mV (RMS);	13	15.5	18	dB
	pin MOUT in transmit mode	RGAT = 30.1 kΩ
Gvtxr	voltage gain adjustment with RGAT		−15.5	−	+15.5	dB
Gvrx	voltage gain in receive mode; the	VRIN = 20 mV (RMS);	16	18.5	21	dB
	difference between RIN1 and RIN2	RGAR = 66.5 kΩ;
	to LSP	RL = 50 Ω
Gvrxr	voltage gain adjustment with RGAR		−18.5	−	+14.5	dB
VO(p-p)	output voltage (peak-to-peak value)	VRIN = 150 mV (RMS);	−	7.5	−	V
		RGAR = 374 kΩ;
		RL = 33 Ω; VBB = 9.0 V;
		note 1
SWRA	switching range		−	40	−	dB
SWRA	switching range adjustment with RSWR		−40	−	+12	dB
	referenced to RSWR = 365 kΩ
Tamb	operating ambient temperature		−25	−	+75	°C

Note

1. Corresponds to 200 mW output power.

1996 Jul 15

3

Philips Semiconductors	Product specification
Hands free IC	TEA1094; TEA1094A

BLOCK DIAGRAM

	10									8
	(7)	VBB				TEA1094
										(6)
									GND
	(13)	PD(1)				TEA1094A
VBB	19				MICROPHONE CHANNEL					21	RGAT
	(15)	MUTET							GAT	(17)
CMIC	22									20
	(18)	MIC							MOUT	(16)
				V	I		I	V
											to TEA106x
RMIC										18
								MICGND		(14)
										16	RIDT
	28								IDT	(12)
RTSEN			LOG
	(24)	TSEN			DUPLEX
								Vref
CTSEN					CONTROLLER					14
			BUFF
									SWT	(11)
											CSWT
	27
	(23)	TENV			13 mV
CTENV			BUFF
	26				ATTENUATOR
	(22)	TNOI								13	RSTAB
CTNOI	23								STAB	(10)
	(19)	RNOI
CRNOI							VOICE
						LOGIC
							SWITCH
			BUFF
	24	RENV
	(20)
CRENV										12	RSWR
					13 mV				SWR	(9)
			BUFF
RRSEN	25
	(21)	RSEN
CRSEN			LOG		Vdt
RGAR	5
	(4)	GAR						2		2
	6				VBB				RIN1	(2)
	(5)	LSP			V	I	I	V		3	from
											TEA106x
									RIN2	(3)
CLSP
	1									11
	(1)	DLC/MUTER		DYNAMIC				VOLUME	VOL	(8)
				LIMITER				CONTROL			RVOL
CDLC					LOUDSPEAKER CHANNEL

MGE436

The pin numbers given in parenthesis are for the TEA1094A.

(1) TEA1094A only.

Fig.1 Block diagram.

1996 Jul 15

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	Philips Semiconductors					Product specification
	Hands free IC					TEA1094; TEA1094A
	PINNING
	SYMBOL			PINS		DESCRIPTION
				TEA1094	TEA1094A
				1	1	dynamic limiter timing adjustment; receiver channel mute input
	DLC/MUTER
	RIN1			2	2	receiver amplifier input 1
	RIN2			3	3	receiver amplifier input 2
	n.c.			4	−	not connected
	GAR			5	4	receiver gain adjustment
	LSP			6	5	loudspeaker amplifier output
	n.c.			7	−	not connected
	GND			8	6	ground reference
	n.c.			9	−	not connected
	VBB			10	7	supply voltage
	VOL			11	8	receiver volume adjustment
	SWR			12	9	switching range adjustment
	STAB			13	10	reference current adjustment
	SWT			14	11	switch-over timing adjustment
	n.c.			15	−	not connected
	IDT			16	12	idle mode timing adjustment
	PD			−	13	power-down input
	n.c.			17	−	not connected
	MICGND			18	14	ground reference for the microphone amplifier
	MUTET			19	15	transmit channel mute input
	MOUT			20	16	microphone amplifier output
	GAT			21	17	microphone gain adjustment
	MIC			22	18	microphone input
	RNOI			23	19	receive noise envelope timing adjustment
	RENV			24	20	receive signal envelope timing adjustment
	RSEN			25	21	receive signal envelope sensitivity adjustment
	TNOI			26	22	transmit noise envelope timing adjustment
	TENV			27	23	transmit signal envelope timing adjustment
	TSEN			28	24	transmit signal envelope sensitivity adjustment

1996 Jul 15

5

Philips Semiconductors	Product specification
Hands free IC	TEA1094; TEA1094A

handbook, halfpage
DLC/MUTER			1		28	TSEN
	RIN1					TENV
			2		27
	RIN2		3			TNOI
					26
	n.c.		4			RSEN
					25
	GAR					RENV
			5		24
	LSP		6		23	RNOI
	n.c.					MIC
			7	TEA1094	22
			8
	GND				21	GAT
	n.c.		9			MOUT
					20
	VBB		10			MUTET
					19
	VOL		11			MICGND
					18
	SWR		12			n.c.
					17
	STAB		13			IDT
					16
	SWT		14		15	n.c.
				MGE434

Fig.2 Pin configuration (TEA1094).

FUNCTIONAL DESCRIPTION

General

The values given in the functional description are typical values unless otherwise specified.

A principle diagram of the TEA106X is shown on the left side of Fig.4. The TEA106X is a transmission circuit of the TEA1060 family intended for hand-set operation.

It incorporates a receiving amplifier for the earpiece, a transmit amplifier for the microphone and a hybrid.

For more details on the TEA1060 family, please refer to “data Handbook IC03”. The right side of Fig.4 shows a principle diagram of the TEA1094 and TEA1094A, hands-free add-on circuits with a microphone amplifier, a loudspeaker amplifier and a duplex controller.

As can be seen from Fig.4, a loop is formed via the sidetone network in the transmission circuit and the acoustic coupling between loudspeaker and microphone of the hands-free circuit. When this loop gain is greater than 1, howling is introduced. In a full duplex application, this would be the case.

The loop-gain has to be much lower than 1 and therefore

handbook, halfpage
DLC/MUTER			1		24	TSEN
	RIN1					TENV
			2		23
	RIN2		3			TNOI
					22
	GAR		4			RSEN
					21
	LSP					RENV
			5		20
	GND		6	TEA1094A	19	RNOI
	VBB					MIC
			7		18
			8
	VOL				17	GAT
	SWR		9			MOUT
					16
	STAB		10			MUTET
					15
	SWT		11			MICGND
					14
	IDT		12			PD
					13
				MGE435

Fig.3 Pin configuration (TEA1094A).

has to be decreased to avoid howling. This is achieved by the duplex controller. The duplex controller of the TEA1094 and TEA1094A detects which channel has the ‘largest’ signal and then controls the gain of the microphone amplifier and the loudspeaker amplifier so that the sum of the gains remains constant.

As a result, the circuit can be in three stable modes:

1.Transmit mode (Tx mode).

The gain of the microphone amplifier is at its maximum and the gain of the loudspeaker amplifier is at its minimum.

2.Receive mode (Rx mode).

The gain of the loudspeaker amplifier is at its maximum and the gain of the microphone amplifier is at its minimum.

3.Idle mode.

The gain of the amplifiers is halfway between their maximum and minimum value.

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

1996 Jul 15

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Philips Semiconductors	Product specification
Hands free IC	TEA1094; TEA1094A

handbook, full pagewidth

acoustic coupling

telephone		HYBRID			DUPLEX
line					CONTROL

sidetone

TEA106x	TEA1094	MGE438
	TEA1094A

Fig.4 Hands-free telephone set principles.

Supply: pins VBB, GND and PD

The TEA1094 and TEA1094A must be supplied with an external stabilized voltage source between pins VBB and GND. In the idle mode, without any signal, the internal supply current is 3.1 mA at VBB = 5 V.

To reduce the current consumption during pulse dialling or register recall (flash), the TEA1094A is provided with a power-down (PD) input. When the voltage on PD is HIGH the current consumption from VBB is 180 μA.

Microphone channel: pins MIC, GAT, MOUT, MICGND and MUTET (see Fig.5)

The TEA1094 and TEA1094A have an asymmetrical microphone input MIC with an input resistance of 20 kΩ. The gain of the input stage varies according to the mode of the TEA1094 and TEA1094A. In the transmit mode, the gain is at its maximum; in the receive mode, it is at its minimum and in the idle mode, it is halfway between maximum and minimum.

Switch-over from one mode to the other is smooth and click-free. The output capability at pin MOUT is

20 μA (RMS).

In the transmit mode, the overall gain of the microphone amplifier (from pins MIC to MOUT) can be adjusted from 0 dB up to 31 dB to suit specific application requirements. The gain is proportional to the value of RGAT and equals 15.5 dB with RGAT = 30.1 kΩ.

A capacitor must be connected in parallel with RGAT to ensure stability of the microphone amplifier. Together with RGAT, it also provides a first-order low-pass filter.

By applying a HIGH level on pin MUTET, the microphone amplifier is muted and the TEA1094 and TEA1094A are automatically forced into the receive mode.

1996 Jul 15

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Philips Semiconductors	Product specification
Hands free IC	TEA1094; TEA1094A

		19	MUTET					GAT	21	RGAT
VBB	(15)								(17)	CGAT
	CMIC	22	MIC					MOUT	20
				V	I		I			to TEA106X
	(18)							V	(16)
RMIC
			to	from		to		MICGND	18
									(14)
			envelope	voice		logic
			detector	switch
										MGD343

The pin numbers given in parenthesis refer to the TEA1094A.

Fig.5 Microphone channel.

Loudspeaker channel

handbook, full pagewidth

to

to

5

to/from

envelope

RGAR

logic

voice switch

detector

(4) GAR

2

2

6

VBB

RIN1

(2)

CGAR

(5) LSP

3

from

V I

I

V

TEA106x

CLSP

RIN2

(3)

1

11

(1) DLC/MUTER

DYNAMIC

VOLUME

VOL (8)

CDLC

LIMITER

CONTROL

RVOL

MGE437

The pin numbers given in parenthesis refer to the TEA1094A.

Fig.6 Loudspeaker channel.

1996 Jul 15

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Philips Semiconductors	Product specification
Hands free IC	TEA1094; TEA1094A

LOUDSPEAKER AMPLIFIER: PINS RIN1, RIN2, GAR AND LSP

The TEA1094 and TEA1094A have symmetrical inputs for the loudspeaker amplifier with an input resistance of 40 kΩ between RIN1 and RIN2 (2 × 20 kΩ). The input stage can accommodate signals up to 390 mV (RMS) at room temperature for 2% of total harmonic distortion (THD). The gain of the input stage varies according to the mode of the TEA1094 and TEA1094A. In the receive mode, the gain is at its maximum; in the transmit mode, it is at its minimum and in the idle mode, it is halfway between maximum and minimum. Switch-over from one mode to the other is smooth and click-free. The rail-to-rail output stage is designed to power a loudspeaker connected as a single-ended load (between LSP and GND).

In the receive mode, the overall gain of the loudspeaker amplifier can be adjusted from 0 dB up to 33 dB to suit specific application requirements. The gain from

RIN1 and RIN2 to LSP is proportional to the value of RGAR and equals 18.5 dB with RGAR = 66.5 kΩ. A capacitor connected in parallel with RGAR can be used to provide a first-order low-pass filter.

VOLUME CONTROL: PIN VOL

The loudspeaker amplifier gain can be adjusted with the potentiometer RVOL. A linear potentiometer can be used to obtain logarithmic control of the gain at the loudspeaker amplifier. Each 950 Ω increase of RVOL results in a gain loss of 3 dB. The maximum gain reduction with the volume control is internally limited to the switching range.

DYNAMIC LIMITER: PIN DLC/MUTER

The dynamic limiter of the TEA1094 and TEA1094A prevents clipping of the loudspeaker output stage and protects the operation of the circuit when the supply voltage at VBB falls below 2.9 V.

Hard clipping of the loudspeaker output stage is prevented by rapidly reducing the gain when the output stage starts to saturate. The time in which gain reduction is effected (clipping attack time) is approximately a few milliseconds. The circuit stays in the reduced gain mode until the peaks of the loudspeaker signals no longer cause saturation. The gain of the loudspeaker amplifier then returns to its normal value within the clipping release time (typically 250 ms). Both attack and release times are proportional to the value of the capacitor CDLC. The total harmonic distortion of the loudspeaker output stage, in reduced gain mode, stays below 5% up to 10 dB (minimum) of input voltage overdrive [providing VRIN is below 390 mV (RMS)].

When the supply voltage drops below an internal threshold voltage of 2.9 V, the gain of the loudspeaker amplifier is rapidly reduced (approximately 1 ms). When the supply voltage exceeds 2.9 V, the gain of the loudspeaker amplifier is increased again.

By forcing a level lower than 0.2 V on pin DLC/MUTER, the loudspeaker amplifier is muted and the TEA1094 (TEA1094A) is automatically forced into the transmit mode.

Duplex controller

SIGNAL AND NOISE ENVELOPE DETECTORS: PINS TSEN,

TENV, TNOI, RSEN, RENV AND RNOI

The signal envelopes are used to monitor the signal level strength in both channels. The noise envelopes are used to monitor background noise in both channels. The signal and noise envelopes provide inputs for the decision logic. The signal and noise envelope detectors are shown in Fig.7.

For the transmit channel, the input signal at MIC is 40 dB amplified to TSEN. For the receive channel, the differential signal between RIN1 and RIN2 is 0 dB amplified to RSEN. The signals from TSEN and RSEN are logarithmically compressed and buffered to TENV and RENV respectively. The sensitivity of the envelope detectors is

set with RTSEN and RRSEN. The capacitors connected in series with the two resistors block any DC component and

form a first-order high-pass filter. In the basic application,

see Fig.13, it is assumed that VMIC = 1 mV (RMS) and VRIN = 100 mV (RMS) nominal and both RTSEN and RRSEN have a value of 10 kΩ. With the value of CTSEN and CRSEN at 100 nF, the cut-off frequency is at 160 Hz.

The buffer amplifiers leading the compressed signals to TENV and RENV have a maximum source current of 120 μA and a maximum sink current of 1 μA. Together with

the capacitor CTENV and CRENV, the timing of the signal envelope monitors can be set. In the basic application, the

value of both capacitors is 470 nF. Because of the logarithmic compression, each 6 dB signal increase means 18 mV increase of the voltage on the envelopes TENV or RENV at room temperature. Thus, timings can be expressed in dB/ms. At room temperature, the 120 μA sourced current corresponds to a maximum rise-slope of the signal envelope of 85 dB/ms. This is sufficient to track normal speech signals. The 1 μA current sunk by TENV or RENV corresponds to a maximum fall-slope of 0.7 dB/ms. This is sufficient for a smooth envelope and also eliminates the effect of echoes on switching behaviour.

1996 Jul 15

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