Datasheet TEA7530 Datasheet (SGS Thomson Microelectronics)

LOW VOLTAGE
POWER:100mW AT 5V
ANTIDISTORTION SYSTEM FOR LOW CUR-

RENTLINES

TEA7530

MONITORAMPLIFIER

PRELIMINARY DATA

DESCRIPTION

This 8 pins IC is designed for monitor telephone
set andprovides:

a) Signal amplification for monitoring
b) Antidistortionby automaticgain adaptation.

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter

T

V

I

Temperature Range -20 to +70 -20 to +70 °C

op

Supply Voltage 6 6 V

LS

Supply Current for T > 300ms

LS

for T ≤ 300ms

BLOCK DIAGRAM

MINIDIP SO-8

ORDERING NUMBERS:

TEA7530DP TEA7530FP

Value

Minidip SO

90

150

75

120

Unit

mA
mA

June 1993

This is advanced information on anew product now in development or undergoing evaluation. Details are subject to change without notice.

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TEA7530

PIN CONNECTION (top view)

PIN FUNCTION

N° Symbol Description

1 GND Ground
2 ADS Antidistortion
3V

LS

4 INP Input Signal
5 LS1 Output Loudspeaker 1
6V

REF

7 LS2 Output Loudspeaker 2
8 ADJ Adjust Internal Reference V

Supply

Internal Reference Voltage

LS

FUNCTIONAL DESCRIPTION

TEA7530performsthe followingfunctions:
The circuit amplifies the incoming signal and

feeds it to the loudspeaker.

ELECTRICAL CHARACTERISTICS (T

=25°C,ILS= 30mA unless otherwise specified)

amb

♦ The Antidistortion system is incorporated for
lowcurrent availablefromline.

♦ The maximum power available on a 50Ω im-
pedanceloudspeakeris 25mW at 3V and 100mW
at5V.

Symbol Parameter Test Condition Min. Typ. Max. Unit

V

LS1

V

LSM

V

ADJ

G Loudspeaker Amplifier

THD Distortion f = 300Hz to 2KHz

Z

INPIN

V

OFFS

GATT Loudspeaker Attenuated

V

Supply ILS = 2mA (fig. 5)

LS1

VLSMaximum I

I

= 30mA (fig. 5)

LS

=40µA (fig. 5; So = closed) 5.7 V

pin8

2.7 3

3.15

3.3

3.4

Voltage Pin 8 ILS= 2 to 30mA (fig. 5 1.0 1.25 1.5 V

ILS= 30mA (fig. 6) 30 32 34 dB

V

− V

(5)

Gain =

(7)

V

(4)

2%

V

(5)-V(7)

= 0.8Vrms; (fig. 6)
Earphone Input (fig. 7) 2.1 2.8 3.5 KΩ
Output Offset [V

Gain = [V

(5)-V(7)

] (fig. 6) -80 80 mV

(5)-V(7)

V

]/V

= 0.7V; (fig. 8)

(2)

V

(4)

= 0.4V; (fig. 8) 20

(2)

-30
30

-20 dB

V
V

dB

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TEA7530

Figure1: LoudspeakerGainvs. Voltage on Pin 2 Figure 2: Power Available on Loudspeakervs.

TypicalCurve. (VoltageMode

V

LS

Figure3: Distortion vs. OutputPower Figure4:

OutputPower vs. SupplyCurrent

(CurrentMode Supply)

3/11

TEA7530

TEST CIRCUITS
Figure5: ShuntvoltageRegulator/ Reference

Voltageat Pin 8.

Figure6: LoudspeakerAmplifier:

Gain/Distortion/OutputOffset

Figure7: Impedance, ZINP

Figure8: Anti-loadingFeedbackSystemat

G = GATT

4/11

TEA7530

CIRCUITDESCRIPTION

TEA7530 is a 8 pin DIP integrated circuit provid­ing the followingfacilities:

♦ Loudspeakeramplifier
♦ Antidistortion feed-back system (limited line

currentcompensation)

1.1. LOUDSPEAKERAMPLIFIER
The amplifier is divided into 2 main sections.

- Automatic Gain Control (AGC)

- Push-pull amplifier(bridge structure)

Figure9

a) The AGC section is used for the antidistortion
system.

♦When used in a telephone set to avoid larsen

effect the AGC automatically decreases loud­speaker amplifiergain.

♦When the required output level exceeds the

capabilities of the available current, the AGC
decreases the loudspeaker amplifier gain to
avoidsdistortion.

b) The output amplifier uses a double push-pull
configuration(H bridge) to get maximum dynamic
rangeunder limitedsupply conditions.

Figure10

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TEA7530

AmplifierDC Supply

In transmission mode, the supply voltage is con­trolled by the internal shunt DC regulator. For this
reason, the TEA7530 should be supplied from a
currentsource (see:supply considerations).
An antidistortion system is embodied which pro­vides AGC control to avoid loudspeakerdistortion
under current-limitedconditions.

AGC Circuit action

When the supply V

isinsufficient, the voltage at

LS

pin 8, falls below the reference voltage 1.2V, re­sulting in transistor (TR) being switched off, re­sulting zero current flow in resistor R. This state
enables the gain control system. Under these
conditions, the shunt DC supply will switch at a
rate determined by the time constant of the RC
networkon pin 2.
This switching action accomodates normal
speech characteristic under low supply condi­tions.
The AGC will be switched ON when the level on
Pin 2 is greater than a reference voltage of 0.4V.

SupplyConsiderations

a) Current MODE - Pin 8 is open (V

LS=VLS1

)or

connected to ground with an external resistor

) higher than 16KΩ. The typical value of V

(R

ext

is:
V

= 1.2V

LS

The AGC section is working as described in the

40.5KΩ+(27K

( 27KΩ⁄⁄R

Ω⁄⁄R

EXT

)

EXT

)

.

LS

previousparagraph.
b) Voltage MODE - Pin 8 isshorted or connected

to GND with a resistor(R

) lower than 16KΩ.In

EXT

this condition the circuit must be supplied with a
DC voltage of 3 to 5.5V. In this case the AGC
sectionis permanentlyON. Pin 2 must be shorted
to GND (in voltage mode only) to avoid perma­nent attenuationof the signal at audioinput

PIN FUNCTIONS
PIN1: GND.
PIN2: AUTOMATICGAIN CONTROL FILTER

The antidistortion system response is adjusted by
the R-C networkon thispin.

The AGC will be switched ON when the level on
pin 2 is greater than a reference voltage of 0.4V,
the RC-network charges (current source ON) or
discharges (current source OFF) according to
supplyvoltage.

Figure11

6/11

TEA7530

THEORETICALVOLTAGE ON PIN 2
Figure12

Figure13

- The value of R affects the system time con­stant and the charge/dischargedutycycle.

- The value of C only affects the system time
constant.

- R should be greateror equal to 150KΩfor cor­rect AGC operation.

PIN3: CIRCUIT SUPPLYVOLTAGE
With pin 8 open circuit, V

is internally stabilized

LS

at3V.
When the TEA7530 is under AGC control, the
voltage on this pin varies slightly (due to AGC ac­tion).

PIN4: EARPHONEINPUT
Inputfor loudspeakersignal

Pin 2

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TEA7530

PIN 5-7: LOUDSPEAKEROUTPUTS

Maximum outpt voltage: V
gain of 32dB).

Maximum output current: depending of the supply
current.

Figure14

=2VLS- 2.5V (with a

pp

and loudspeakeroutputs: 32dB.

- ”Asymmetrical”Mode

This allows higher voltage operation, but at a
lowersupply current.

Loudspeaker impedance recommended value:
25Ω.

Nominal gain available between earphone input
and loudspeakeroutput: 32 - 6 = 26dB.

Two loudspeaker connection methods are possi­ble, using the amplifier in either symmetrical or
asymmetrical mode.

Note:

It is advisable to connect a 47nF capacitor in par­allel with the loudspeaker(betweenpins5 and7).

- ”Symmetrical”mode

This is for low voltage working, but at a higher
supply current. The highest output power is avail­able in thismode, due to the 5.7V maximum sup­ply voltage restriction,imposedby the TEA7530

Loudspeaker impedance recommended value:
50Ω.

Nominal gain available between earphone input

Pin6: V

: INTERNALREFERENCE

ref

Output which provides an internallyregulated ref­erencevoltage.

V

=1.2V typical

ref

MAXIMUM AVAILABLECURRENT: 5µA

Pin8: ADJUSTV

LS

Thispin is used to adjust the IC supply voltage.

Figure15

8/11

MINIDIP PACKAGE MECHANICAL DATA

TEA7530

DIM

Min. Typ. Max. Min. Typ. Max.

A 3.32 0.131

a1 0.51 0.020

B 1.15 1.65 0.045 0.065
b 0.356 0.55 0.014 0.022

b1 0.204 0.304 0.008 0.012

D 10.92 0.430
E 7.95 9.75 0.313 0.384

e 2.54 0.100
e3 7.62 0.300
e4 7.62 0.300

F 6.6 0260

i 5.08 0.200
L 3.18 3.81 0.125 0.150
Z 1.52 0.060

mm inch

9/11

TEA7530

SO8 PACKAGE MECHANICAL DATA

DIM

mm inch

Min. Typ. Max. Min. Typ. Max.

A 1.75 0.069

a1 0.1 0.25 0.004 0.010
a2 1.65 0.065
a3 0.65 0.85 0.026 0.033

b 0.35 0.48 0.014 0.019

b1 0.19 0.25 0.007 0.010

C 0.25 0.5 0.010 0.020

o

c1 45

(typ.)
D 4.8 5.0 0.189 0.197
E 5.8 6.2 0.228 0.244
e 1.27 0.050

e3 3.81 0.150

F 3.8 4.0 0.150 0.157
L 0.4 1.27 0.016 0.050

M 0.6 0.024

o

S8

(max.)

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TEA7530

Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the
consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No
license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifications men­tioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied.
SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without ex­press written approval of SGS-THOMSON Microelectronics.

 1994 SGS-THOMSON Microelectronics - All RightsReserved

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