Philips TEA1098TV-C2, TEA1098TV-C1, TEA1098H-C2, TEA1098H-C1 Datasheet

INTEGRATED CIRCUITS

DATA SHEET

TEA1098

Speech and handsfree IC

Product specification

1999 Oct 14

Supersedes data of 1999 May 20

File under Integrated Circuits, IC03

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

ORDERING INFORMATION

∙Dynamic limiter on loudspeaker amplifier to prevent distortion

∙Logarithmic volume control on loudspeaker amplifier 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 telephony applications. It includes a 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.

TYPE		PACKAGE
NUMBER	NAME	DESCRIPTION	VERSION
TEA1098TV	VSO40	plastic very small outline package; 40 leads	SOT158-1
TEA1098H	QFP44	plastic quad flat package; 44 leads (lead length 1.3 mm);	SOT307-2
		body 10 × 10 × 1.75 mm
TEA1098UH	−	bare die; on foil	−

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Philips Semiconductors	Product specification
Speech and handsfree IC	TEA1098

QUICK REFERENCE DATA

Iline = 15 mA; RSLPE = 20 Ω; Zline = 600 Ω; f = 1 kHz; Tamb = 25 °C for TEA1098H and TEA1098TV; Tj = 25 °C for

TEA1098UH; AGC pin connected to LN; PD = HIGH; HFC = LOW; MUTE = HIGH; measured according to test circuits; unless otherwise specified.

SYMBOL	PARAMETER			CONDITIONS	MIN.	TYP.	MAX.	UNIT
Iline	line current operating range		normal operation		11	−	130	mA
			with reduced performance		1	−	11	mA
VSLPE	stabilized voltage between SLPE		Iline = 15 mA		3.4	3.7	4.0	V
	and GND		Iline = 70 mA		5.7	6.1	6.5	V
VBB	regulated supply voltage for		Iline = 15 mA		2.75	3.0	3.25	V
	internal circuitry		Iline = 70 mA		4.9	5.3	5.7	V
VDD	regulated supply voltage on pin		VBB > 3.35 V + 0.25 V (typ.)		3.1	3.35	3.6	V
	VDD		otherwise		−	VBB − 0.25	−	V
IBB	current available on pin VBB		in speech mode		−	11	−	mA
			in handsfree mode		−	9	−	mA
IBB(pd)	current consumption on VBB			= LOW	−	460	−	μA
			PD
	during power-down phase
Gv(MIC-LN)	voltage gain from pin MIC+/MIC−		VMIC = 5 mV (RMS)		43.3	44.3	45.3	dB
	to LN
Gv(IR-RECO)	voltage gain from pin IR		VIR = 8 mV (RMS)		28.7	29.7	30.7	dB
	(referenced to LN) to RECO
Gv(QR)	gain voltage range between pins				−3	−	+15	dB
	RECO and QR
Gv(TXIN-TXOUT)	voltage gain from pin TXIN to		VTXIN = 3 mV (RMS);		12.7	15.2	17.7	dB
	TXOUT		RGATX = 30.1 kΩ
Gv(HFTX-LN)	voltage gain from pin HFTX to LN		VHFTX = 15 mV (RMS)		33.5	34.7	35.9	dB
Gv(HFRX-LSAO)	voltage gain from pin HFRX		VHFRX = 30 mV (RMS);		25.5	28	30.5	dB
	to LSAO		RGALS = 255 kΩ; Iline = 70 mA
SWRA	switching range				−	40	−	dB
SWRA	switching range adjustment		with RSWR referenced to		−40	−	+12	dB
			365 kΩ
Gv(trx)	gain control range for transmit and		Iline = 70 mA		5.45	6.45	7.45	dB
	receive amplifiers affected by the
	AGC; with respect to Iline = 15 mA

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Philips Semiconductors	Product specification
Speech and handsfree IC	TEA1098

BLOCK DIAGRAM

				REG	SLPE
				19	17
LN	18	(15)	STARTER	(16)	(14)
								(10) 13	VBB
					R1
								(19) 22	VDD
			LINE CURRENT DETECTION			SWITCH	SUPPLY	(20) 23	MICS
			LOW VOLTAGE BEHAVIOUR				MANAGEMENT
AGC	21	(18)	AGC				POWER-DOWN	(38) 1	PD
							CURRENT SOURCES
GND	16	(13)	Tail currents for preamps
HFTX	39	(36)					LOGIC	(37) 40	HFC
						TEA1098	INPUTS	(39) 2	MUTE
							DECODING
DTMF	35	(32)	ATTENUATOR
MIC+	34	(31)
MIC−	33	(30)						(27) 30	GATX
								(26) 29	TXOUT
TXIN	31	(28)						(29) 32	GNDTX
								(24) 27	SWT
TSEN	8 (4)							(25) 28	IDT
TENV	7 (3)
TNOI	6 (2)		TX AND RX		BUFFERS	DUCO LOGIC	VOICE	(21) 24	STAB
RNOI	9 (5)		ENVELOPE AND NOISE		AND
						SWT STATUS	SWITCH	(22) 25	SWR
RENV			DETECTORS	COMPARATORS
	11	(7)
RSEN	10	(6)
							VOLUME	(23) 26	VOL
							CONTROL
GALS	14	(11)						(1) 5	HFRX
LSAO	15	(12)
DLC	12	(8)	DYNAMIC
			LIMITER
								(17) 20	IR
RECO	38	(35)
GARX	37	(34)					ATTENUATOR
QR	36	(33)
								MGL317

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

Fig.1 Block diagram.

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Philips Semiconductors								Product specification
		Speech and handsfree IC						TEA1098
PINNING
		SYMBOL			PIN		PAD	DESCRIPTION
					TEA1098TV	TEA1098H	TEA1098UH
					1	38	41	power-down input (active LOW)
		PD
					2	39	42	logic input (active LOW)
	MUTE
	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
	VBB				13	10	10	stabilized supply for internal circuitry
	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
	VDD				22	19	21	3.35 V regulated voltage supply for microcontrollers
	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

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	Philips Semiconductors				Product specification
	Speech and handsfree IC				TEA1098
	SYMBOL	PIN		PAD	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

handbook, halfpage

	PD		1			40			HFC
	MUTE		2				39		HFTX
	n.c.		3				38		RECO
	n.c.		4				37		GARX
	HFRX		5				36		QR
	TNOI		6				35		DTMF
									MIC+
	TENV		7				34
									MIC−
	TSEN		8				33
	RNOI		9				32		GNDTX
	RSEN		10				31		TXIN
					TEA1098TV
	RENV		11				30		GATX
	DLC		12				29		TXOUT
	VBB		13				28		IDT
	GALS		14				27		SWT
	LSAO		15				26		VOL
	GND		16				25		SWR
	SLPE		17				24		STAB
	LN		18				23		MICS
	REG		19				22		VDD
	IR		20				21		AGC
					MGL341

Fig.2 Pin configuration (TEA1098TV).

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Philips Semiconductors	Product specification
Speech and handsfree IC	TEA1098

			n.c.		n.c.		n.c.		n.c.		n.c.		MUTE			PD		HFC		HFTX		RECO		GARX
			44		43		42		41		40		39		38			37		36		35		34
HFRX	1																									33	QR
TNOI	2																									32	DTMF
																											MIC+
TENV	3																									31
																											MIC−
TSEN	4																									30
RNOI	5																									29	GNDTX
RSEN	6										TEA1098H															28	TXIN
RENV																											GATX
	7																									27
DLC																											TXOUT
	8																									26
n.c.																											IDT
	9																									25
VBB	10																									24	SWT
GALS																											VOL
	11																									23

12		13		14		15		16		17		18		19		20		21		22
LSAO		GND		SLPE		LN		REG		IR		AGC		V		MICS		STAB		SWR
														DD

FCA020

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)

The supply for the TEA1098 and its peripherals is obtained from the line. The IC generates a stabilized reference voltage (Vref) between pins SLPE and GND.

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, Vref is automatically adjusted to a 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.

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

conversion from its DC value (RSLPE) to its AC value (done by an external impedance).

The IC regulates the line voltage at pin LN which can be calculated as follows:

VLN = Vref + RSLPE × ISLPE

ISLPE = Iline –Ix

where:

Iline = line current.

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

ISLPE = current flowing through the RSLPE resistor.

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Philips Semiconductors	Product specification
Speech and handsfree IC	TEA1098

The preferred value for RSLPE is 20 Ω. Changing this value not only affects the DC characteristics, it also influences

the transmit gains to the line, the gain control characteristic, the sidetone level, and the maximum 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 RSLPE is sunk by the VBB voltage stabilizer, and is suitable for supplying a

loudspeaker amplifier or any peripheral IC. Voltage VBB is 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.

The current switch TR1-TR2 is intended to reduce distortion of large AC line signals. Current ISLPE is supplied to VBB via TR1 when the voltage on pin SLPE is above VBB + 0.25 V. When the voltage on pin SLPE is below this value, ISLPE is shunted to GND via TR2.

Voltage Vref can be increased by connecting an external resistor between pins REG and SLPE. For large line currents, this increase can slightly affect some dynamic performances such as maximum signal level on the line at 2% Total Harmonic Distortion (THD). The external resistor does not affect the voltage on pin VBB; see Fig.5 for the main DC voltages.

handbook, full pagewidthLN				TR2
		RSLPE		GND
		20 Ω
			TR1
SLPE				VBB
CREG	TP1	E1		E2
4.7 μF
	J1	D1
	R3
REG				D1
	R1			TN2
	R2
	from	J2
	preamp
	TN1
GND				MGM298
			GND

Fig.4 Line interface principle.

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Philips Semiconductors	Product specification
Speech and handsfree IC	TEA1098

FCA049

8

LN

voltages

(V)

SLPE

6

VBB

4

VDD

MICS

2

0

0	0.01	0.02	0.03	0.04	0.05	0.06	Iline (A)	0.07

Fig.5 Main DC voltages.

VDD SUPPLY FOR MICROCONTROLLERS (PIN VDD)

The voltage on the VDD supply point follows the voltage on VBB with a difference typically of 250 mV, internally limited 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 consumption on VDD (typically 100 μA). This voltage source should not be below 3.5 V or above 6 V.

VBB and VDD can supply current to external circuits within the line limits, taking into account the internal current consumption.

SUPPLY FOR MICROPHONE (PINS MICS AND GNDTX)

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.

LOW VOLTAGE BEHAVIOUR

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 LSAO and is continuously activated, discharging the capacitor connected to pin DLC. In the DC condition, the loudspeaker is then automatically disabled below this voltage.

When VBB falls below 2.5 V, the TEA1098 is forced into a low voltage mode irrespective of the logic input levels. This is a speech mode with reduced performance which only enables the microphone channel (between the MIC inputs 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.

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Philips Semiconductors	Product specification
Speech and handsfree IC	TEA1098

108				FCA050
IDD
(pA)
107
106
105
104
103
102
10	1.5		2.5	3.0
1.0		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 CREG is internally disconnected.

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

typically 70 kΩ. The voltage gain between pins MIC+/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).

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)

The TEA1098 has an asymmetrical 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 at a low level. This is called the confidence tone. The voltage attenuation 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.

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Philips Semiconductors	Product specification
Speech and handsfree IC	TEA1098
HANDSFREE TRANSMIT AMPLIFIER (PINS HFTX AND LN)	AGC (pin AGC)

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 kW. 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 kW 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 kW. This output is biased at a voltage of two diodes.

Automatic gain control is provided for line loss compensation.

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 resistors which set the required gain or attenuation from -3 to +15 dB compared to the receive gain.

Two external capacitors CGAR (connected between GAR

and QR) and CGARS (connected between GAR and GND) ensure stability. The CGAR capacitor provides a first-order

low-pass filter. The cut-off frequency corresponds to the time constant CGAR ´ Re2. The relationship

CGARS ³ 10 ´ CGAR must be satisfied.

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

The TEA1098 performs automatic line loss 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 control range is 6.45 dB for Gv(MIC-LN) and Gv(IR-RECO), and 6.8 dB for Gv(HFTX-LN), which corresponds 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 for compensation 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 kW). 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.

Therefore in the handsfree application, the circuit can have three stable modes:

1.Transmit mode (Tx mode).

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

2.Receive mode (Rx mode).

The microphone amplifier 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.

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Philips Semiconductors	Product specification
Speech and handsfree IC	TEA1098

handbook, full pagewidth

acoustic coupling

	telephone	HYBRID	DUPLEX
	line		CONTROL
		sidetone

MGM299

Fig.7 Handsfree telephone set principles.

HANDSFREE MICROPHONE CHANNEL: PINS TXIN, GATX,

TXOUT AND GNDTX (see Fig.8)

The TEA1098 has an asymmetrical handsfree microphone input (TXIN) with an input resistance of 20 kΩ.

The input DC bias is 0 V. The gain of the input 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.

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 RGATX and equals 15.2 dB when RGATX is 30.1 kΩ. Without output limitation, the microphone input stage can accept signals of up to

18 mV (RMS) at 2% THD (room temperature).

VBB	RGATX
	GATX 30
	(27)

RMIC

CMIC	31	TXIN		TXOUT	29
			V I
	(28)			I V	(26)
		to	from	GNDTX	32
					(29)
		envelope	voice
		detector	switch
				MGL342

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

Fig.8 Handsfree microphone channel.

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