Philips TEA1112T-C1, TEA1112AT-C1, TEA1112A-C1, TEA1112-C1 Datasheet

INTEGRATED CIRCUITS

DATA SHEET

TEA1112; TEA1112A

Low voltage versatile telephone transmission circuits with dialler interface

Product specification

1997 Mar 26

Supersedes data of 1996 Feb 16

File under Integrated Circuits, IC03

Philips Semiconductors	Product specification

Low voltage versatile telephone

TEA1112; TEA1112A

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).

QUICK REFERENCE DATA

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.

Iline = 15 mA; VEE = 0 V; RSLPE = 20 Ω; AGC pin connected to VEE; Zline = 600 Ω; f = 1 kHz; Tamb = 25 °C; unless otherwise specified.

SYMBOL	PARAMETER	CONDITIONS	MIN.	TYP.	MAX.	UNIT
Iline	line current operating range	normal operation	11	−	140	mA
		with reduced performance	1	−	11	mA
ILED(max)	maximum supply current available	Iline = 18 mA	−	0.5	−	mA
		Iline > 76 mA	−	19.5	−	mA
VLN	DC line voltage		3.35	3.65	3.95	V
ICC	internal current consumption	VCC = 2.9 V	−	1.15	1.4	mA
VCC	supply voltage for peripherals	Ip = 0 mA	−	2.9	−	V
Gvtrx	typical voltage gain range
	microphone amplifier	VMIC = 2 mV (RMS)	38.8	−	51.8	dB
	receiving amplifier	VIR = 6 mV (RMS)	19.2	−	31.2	dB
Gvtrx	gain control range for microphone and	Iline = 85 mA	−	5.8	−	dB
	receiving amplifiers with respect to
	Iline = 15 mA
Gvtxm	microphone amplifier gain reduction		−	80	−	dB

1997 Mar 26

2

Philips Semiconductors	Product specification

Low voltage versatile telephone

TEA1112; TEA1112A

transmission circuits with dialler interface

ORDERING INFORMATION

TYPE		PACKAGE
NUMBER	NAME	DESCRIPTION	VERSION
TEA1112	DIP16	plastic dual in-line package; 16 leads (300 mil)	SOT38-4
TEA1112A	DIP16	plastic dual in-line package; 16 leads (300 mil)	SOT38-4
TEA1112T	SO16	plastic small outline package; 16 leads; body width 3.9 mm	SOT109-1
TEA1112AT	SO16	plastic small outline package; 16 leads; body width 3.9 mm	SOT109-1

BLOCK DIAGRAM

						MUTE
						or
				GAR	QR	MUTE
				15	14	8
IR	9	V−	I				VCC
						16
		V−	I			1
	7						LN
DTMF		ATT.			CURRENT
					REFERENCE
		V−	I
						5	GAS
MIC	12
						4	REG
		V−
			I
MIC	11
MMUTE	6	MICRO	AGC
or
		MUTE	CIRCUIT	LOW VOLTAGE
MMUTE
				CIRCUIT		TEA1112
				LED	TEA1112A
				DRIVER
		13	10	3		2	MBE793
						SLPE
	VEE		AGC	ILED
			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				PIN		DESCRIPTION
				TEA1112		TEA1112A
	LN			1		1	positive line terminal
	SLPE			2		2	slope (DC resistance) adjustment
	ILED			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
				−		6	microphone mute input (active LOW)
	MMUTE
	DTMF			7		7	dual-tone multi-frequency input
	MUTE			8		−	mute input to select speech or dialling mode
				−		8	mute input to select speech or dialling mode (active LOW)
	MUTE
	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
VEE				13		13	negative line terminal
	QR			14		14	receiving amplifier output
	GAR			15		15	receive gain adjustment
	VCC			16		16	supply voltage for speech circuit and peripherals

handbook, halfpage				VCC	handbook, halfpage
LN	1		16				LN		1		16	VCC
SLPE	2		15	GAR			SLPE		2		15	GAR
ILED	3		14	QR			ILED		3		14	QR
REG	4	TEA1112	13	VEE			REG		4	TEA1112A	13	VEE
GAS	5		12	MIC+			GAS		5		12	MIC+
				MIC−								MIC−
MMUTE	6		11		MMUTE				6		11
DTMF	7		10	AGC		DTMF			7		10	AGC
MUTE	8		9	IR		MUTE			8		9	IR
		MBE791								MBE790

Fig.2 Pin configuration (TEA1112).

Fig.3 Pin configuration (TEA1112A).

1997 Mar 26

4

Philips Semiconductors	Product specification

Low voltage versatile telephone

TEA1112; TEA1112A

transmission circuits with dialler interface

FUNCTIONAL DESCRIPTION

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

Supply (pins LN, SLPE, VCC and REG)

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

The ICs generate a stabilized reference voltage (Vref) 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 (CREG) which is connected to VEE. This capacitor, converted into an equivalent inductance (see Section “Set impedance”), realizes the set impedance

conversion from its DC value (RSLPE) to its AC value (RCC 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:

Where:

Iline = line current

ICC = current consumption of the IC

Ip = supply current for peripheral circuits

I* = current consumed between LN and VEE

ILED = supply current for the LED component

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

The preferred value for RSLPE is 20 Ω. Changing RSLPE will 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 CVCC. It may also be used to 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). RCCint is the internal impedance of the voltage supply point, and Irec is

the current consumed by the output stage of the earpiece amplifier.

VLN = Vref + RSLPE × ISLPE

VCC = VCC0 –RCCint × ( Ip –Irec)

I

SLPE

= I

line

–I

CC

–I

p

–I

= I

LED

+ I

VCC0 = VLN –RCC × ICC

sh

Rline

RCC

handbook, full pagewidth

619 Ω

Iline

ILED

LN

R

VCC

IP

TEA1112

p

from pre amp

CVCC

Rexch

TEA1112A

15.5 kΩ

RGASint

I

CC

I*

100 μF

Ish

69 kΩ

peripheral

ILED

LED

circuits

DRIVER

Vd

Vexch

Rd

SLPE

45.5 kΩ

REG

VEE

ISLPE

RSLPE

CREG

20

Ω

4.7 μF

MBE789

Fig.4

Supply configuration.

1997 Mar 26

5

Philips Semiconductors	Product specification

Low voltage versatile telephone

TEA1112; TEA1112A

transmission circuits with dialler interface

MGD176

6.0 handbook, halfpage

Vref

(V)

5.0

4.0

(1)

(2)

3.0

104 105 106 RVA (Ω) 107

(1)Influence of RVA on Vref.

(2)Vref without influence of RVA.

Fig.5 Reference voltage adjustment by RVA.

The DC line current flowing into the set is determined by the exchange supply voltage (Vexch), the feeding bridge

resistance (Rexch), the DC resistance of the telephone line (Rline) and the reference voltage (Vref). With line currents below 7.5 mA, the internal reference voltage (generating

Vref) is automatically adjusted to a lower value. This means 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 RCC resistor. The equivalent impedance of the circuits is illustrated in Fig.8.

LED supply (pin ILED)

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 ILED and LN. In the low voltage area, which corresponds to low line current

conditions, no current is available for this LED.

For line currents higher than a threshold, ILEDstart, the ILED current increases proportionally to the line current (with a

ratio of one third). The ILED current is internally limited to 19.5 mA (see Fig.9). If no LED device is used in the application, the ILED pin should be shorted to pin SLPE.

		Iline –17
For 17 mA < Iline < 77 mA: I		= ----------------------
	LED	3

This LED driver is referenced to SLPE. Consequently, all

the ILED supply current will flow through the RSLPE resistor. 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 RGAS between pins GAS and REG. The adjustment range is 13 dB. A capacitor CGAS connected between pins GAS and REG can be used to provide a first-order low-pass filter. The cut-off frequency corresponds to the time

constant CGAS × (RGASint // RGAS). RGASint is the internal resistor which sets the gain with a typical value of 69 kΩ.

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

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