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TEA7530
MONITOR AMPLIFIER
PRELIMINARY DATA
LOW VOLTAGE POWER: 100mW AT 5V ANTIDISTORTION SYSTEM FOR LOW CURRENT LINES
DESCRIPTION This 8 pins IC is designed for monitor telephone set and provides: a) Signal amplification for monitoring b) Antidistortion by automatic gain adaptation. ABSOLUTE MAXIMUM RATINGS
Symbol Top VLS ILS Temperature Range Supply Voltage Supply Current for T > 300ms for T 300ms Parameter
MINIDIP ORDERING NUMBERS: TEA7530DP
SO-8
TEA7530FP
Value Minidip -20 to +70 6 90 150 SO -20 to +70 6 75 120
Unit C V mA mA
BLOCK DIAGRAM
June 1993
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This is advanced information on a new product now in development or undergoing evaluation. Details are subject to change without notice.
TEA7530
PIN CONNECTION (top view)
PIN FUNCTION
N 1 2 3 4 5 6 7 8 Symbol GND ADS VLS INP LS1 VREF LS2 ADJ Ground Antidistortion Supply Input Signal Output Loudspeaker 1 Internal Reference Voltage Output Loudspeaker 2 Adjust Internal Reference VLS Description
FUNCTIONAL DESCRIPTION TEA7530 performs the following functions: The circuit amplifies the incoming signal and feeds it to the loudspeaker.
The Antidistortion system is incorporated for low current available from line. The maximum power available on a 50 impedance loudspeaker is 25mW at 3V and 100mW at 5V.
ELECTRICAL CHARACTERISTICS (Tamb = 25C, ILS = 30mA unless otherwise specified)
Symbol VLS1 VLSM VADJ G Parameter VLS1 Supply VLS Maximum Voltage Pin 8 Loudspeaker Amplifier V(5) - V(7) Gain = V(4) THD ZINPIN VOFFS GATT Distortion Earphone Input Output Offset [V(5) - V(7)] Loudspeaker Attenuated Gain = [V(5) - V(7)] / V(4) f = 300Hz to 2KHz V(5) - V(7) = 0.8Vrms; (fig. 6) (fig. 7) (fig. 6) V(2) = 0.7V; (fig. 8) V(2) = 0.4V; (fig. 8) 2.1 -80 20 -30 30 2.8 2 3.5 80 -20 % K mV dB dB Test Condition ILS = 2mA (fig. 5) ILS = 30mA (fig. 5) Ipin8 = 40A (fig. 5; So = closed) ILS = 2 to 30mA (fig. 5 ILS = 30mA (fig. 6) 1.0 30 1.25 32 Min. 2.7 Typ. 3 3.15 Max. 3.3 3.4 5.7 1.5 34 Unit V V V V dB
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TEA7530
Figure 1: Loudspeaker Gain vs. Voltage on Pin 2 Figure 2: Power Available on Loudspeakervs. VLS Typical Curve. (Voltage Mode
Figure 3: Distortion vs. Output Power
Figure 4: Output Power vs. Supply Current (Current Mode Supply)
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TEA7530
TEST CIRCUITS Figure 5: Shuntvoltage Regulator / Reference Voltage at Pin 8.
Figure 6: Loudspeaker Amplifier: Gain/Distortion/Output Offset
Figure 7: Impedance, ZINP
Figure 8: Anti-loading Feedback System at G = GATT
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TEA7530
CIRCUIT DESCRIPTION TEA7530 is a 8 pin DIP integrated circuit providing the following facilities: Loudspeaker amplifier Antidistortion feed-back system (limited line current compensation) 1.1. LOUDSPEAKER AMPLIFIER The amplifier is divided into 2 main sections. - Automatic Gain Control (AGC) - Push-pull amplifier (bridge structure) Figure 9 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 amplifier gain. When the required output level exceeds the capabilities of the available current, the AGC decreases the loudspeaker amplifier gain to avoids distortion. b) The output amplifier uses a double push-pull configuration (H bridge) to get maximum dynamic range under limited supply conditions.
Figure 10
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TEA7530
Amplifier DC 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 current source (see: supply considerations). An antidistortion system is embodied which provides AGC control to avoid loudspeaker distortion under current-limited conditions. AGC Circuit action When the supply VLS is insufficient, the voltage at 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 network on 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. Supply Considerations a) Current MODE - Pin 8 is open (VLS = VLS1) or Figure 11 connected to ground with an external resistor (Rext) higher than 16K. The typical value of VLS is : 40.5K + ( 27K REXT ) VLS = 1.2V . ( 27K REXT ) The AGC section is working as described in the previous paragraph. b) Voltage MODE - Pin 8 is shorted or connected to GND with a resistor (R EXT) lower than 16K. In this condition the circuit must be supplied with a DC voltage of 3 to 5.5V. In this case the AGC section is permanently ON. Pin 2 must be shorted to GND (in voltage mode only) to avoid permanent attenuation of the signal at audio input
PIN FUNCTIONS PIN 1: GND. PIN 2: AUTOMATIC GAIN CONTROL FILTER The antidistortion system response is adjusted by the R-C network on this pin. 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 supply voltage.
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TEA7530
THEORETICAL VOLTAGE ON PIN 2 Figure 12 - The value of R affects the system time constant and the charge/discharge duty cycle. - The value of C only affects the system time constant. - R should be greater or equal to 150K for correct AGC operation. PIN 3: CIRCUIT SUPPLY VOLTAGE With pin 8 open circuit, VLS is internally stabilized at 3V. When the TEA7530 is under AGC control, the voltage on this pin varies slightly (due to AGC action). PIN 4: EARPHONE INPUT Input for loudspeaker signal
Figure 13
Pin 2
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TEA7530
and loudspeaker outputs: 32dB. PIN 5-7: LOUDSPEAKER OUTPUTS Maximum outpt voltage: Vpp = 2VLS - 2.5V (with a gain of 32dB). Maximum output current: depending of the supply current. Figure 14 - "Asymmetrical" Mode This allows higher voltage operation, but at a lower supply current. Loudspeaker impedance recommended value: 25. Nominal gain available between earphone input and loudspeaker output: 32 - 6 = 26dB. Pin 6: Vref: INTERNAL REFERENCE Output which provides an internally regulated reference voltage. Vref = 1.2V typical MAXIMUM AVAILABLE CURRENT: 5A Pin 8: ADJUST VLS This pin is used to adjust the IC supply voltage. Figure 15
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 (between pins 5 and 7). - "Symmetrical" mode This is for low voltage working, but at a higher supply current. The highest output power is available in this mode, due to the 5.7V maximum supply voltage restriction, imposed by the TEA7530 Loudspeaker impedance recommended value: 50. Nominal gain available between earphone input
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TEA7530
MINIDIP PACKAGE MECHANICAL DATA
DIM Min. A a1 B b b1 D E e e3 e4 F i L Z 3.18 7.95 2.54 7.62 7.62 6.6 5.08 3.81 1.52 0.125 0.51 1.15 0.356 0.204 1.65 0.55 0.304 10.92 9.75 0.313 0.100 0.300 0.300 0260 0.200 0.150 0.060 mm Typ. 3.32 0.020 0.045 0.014 0.008 0.065 0.022 0.012 0.430 0.384 Max. Min. inch Typ. 0.131 Max.
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TEA7530
SO8 PACKAGE MECHANICAL DATA
DIM Min. A a1 a2 a3 b b1 C c1 D E e e3 F L M S 3.8 0.4 4.8 5.8 1.27 3.81 4.0 1.27 0.6 8 (max.)
o
mm Typ. Max. 1.75 0.1 0.25 1.65 0.65 0.35 0.19 0.25 0.85 0.48 0.25 0.5 45 (typ.) 5.0 6.2 0.189 0.228
o
inch Min. Typ. Max. 0.069 0.004 0.010 0.065 0.026 0.014 0.007 0.010 0.033 0.019 0.010 0.020
0.197 0.244 0.050 0.150
0.150 0.016
0.157 0.050 0.024
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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. (c) 1994 SGS-THOMSON Microelectronics - All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands Singapore - Spain - Sweden - Switzerland - Taiwan - Thaliand - United Kingdom - U.S.A.
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