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Moteur de recherche de fiches techniques de composants électroniques |
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Moteur de recherche de fiches techniques de composants électroniques |
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TEA1083A Fiches technique(PDF) 6 Page - NXP Semiconductors |
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TEA1083A Fiches technique(HTML) 6 Page - NXP Semiconductors |
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6 / 20 page  March 1994 6 Philips Semiconductors Product specification Call progress monitor for line powered telephone sets TEA1083; TEA1083A The circuit stabilizes its own supply voltage at VBB. Transistor TR1 provides the supplies for the internal circuits. Transistor TR2 is used to minimize signal distortion on the line by momentarily diverting the input current to VSS whenever the instantaneous value of the voltage at VSUP drops below the supply voltage VBB. VBB is fixed to a typical value of 2.95 V. The supply at VBB is decoupled with respect to VSS by a 220 µF capacitor (C20). The DC voltage (VSUP − VSS) is determined by the transmission IC and Vint; thus VSUP − VSS = VLN−SLPE + Vint. The reference voltage of the transmission IC has to be adjusted to a level where VSUP − VBB (max) is greater than 400 mV. The minimum voltage space between SUP and VBB (400 mV) is required to maintain a 'high' efficiency of the internal supply for mean speech levels. VBB (max) is the specified maximum level. The internal current consumption of the TEA1083/83A (ISUP0) is typically 2.5 mA (where VSUP − VSS = 3.6 V). The current ISUP0 consists of currents IBIAS (approximately 0.4 mA) for the circuitry connected to SUP and IBB0 (approximately 2.1 mA) for the internal circuitry connected to VBB (see Fig.6). LOUDSPEAKER AMPLIFIER (LSI1/LSI2 and QLS) The TEA1083/83A has symmetrical inputs at LSI1 and LSI2. The input signal is normally taken from the earpiece output of the transmission circuit (see Fig.5) and/or from the signal output of the DTMF generator via a resistive attenuator. The attenuation factor must be chosen in accordance with the output levels from the transmission IC and/or DTMF generator and, in accordance with the required output power and permitted signal distortion from the loudspeaker signal. The output QLS drives the loudspeaker as a single-ended load. The output stage has been optimized for use with a 50 Ω loudspeaker (e.g. Philips type AD2071). The loudspeaker amplifier is enabled when the LSE input goes HIGH. The gain of the amplifier is fixed at 35 dB. Volume control of the loudspeaker signal can be obtained by using a level control at the input (see Fig.5). The maximum voltage swing at the QLS output is VO(p-p) = 2.5 V (typical with 50 Ω load). The input level VLSI is approximately 16 mV(rms) and the supply current ISUP > 11 mA. In this condition the signal is limited by the available voltage space (VBB). Higher input levels and/or lower supply currents will result in an increase of the harmonic distortion due to signal clipping. With a limit of 2.5 V (p-p), the maximum output swing is dependent on the supply current and loudspeaker impedance. It can be approximated, for low distortions, by the following equation: VO(p-p) =2 × (ISUP − ISUPO) ×π× RLS Where; • VO(p-p) = the peak-to-peak level of the loudspeaker • RLS = the loudspeaker impedance • ISUPO = 2.5 mA (typ.) POWER-DOWN INPUT (PD) During pulse dialling or register recall (timed loop break) the telephone line is interrupted, thereby breaking the supply current to the transmission IC. The capacitor connected to VBB provides the supply for the TEA1083/83A during the supply breaks. By making the PD input HIGH during the loop break, the requirement on the capacitor is eased and, consequently, the internal current consumption IBB0 (see Fig.5) is reduced from 2.1 mA to 400 µA typically. Transistors TR1 and TR2 are inhibited during power-down and the bias current is reduced from approximately 400 µA to approximately 50 µA with VSUP = 3.6 V in the following equation: ISUP(PD) = IBIAS(PD) = (VSUP − 2Vd)/Ra Where 3.6 < VSUP < VBB + 3V 2Vd is the voltage drop across 2 internal diodes (approximately 1.3 V) Ra is an internal resistor (typical 50 k Ω) LOUDSPEAKER ENABLE INPUT (LSE) The LSE input has a pull-down structure. It switches the loudspeaker amplifier, in the monitoring condition, by applying a HIGH level at the input. The amplifier is in the standby condition when LSE is LOW (input open-circuit or connected to VSS). |
Numéro de pièce similaire - TEA1083A |
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Description similaire - TEA1083A |
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