參數(shù)資料
型號： TEA1085
廠商： NXP SEMICONDUCTORS
元件分類： 通信及網(wǎng)絡(luò)
英文描述： Listening-in circuit for line-powered telephone sets
中文描述： SPECIALTY TELECOM CIRCUIT, PDIP24
封裝： 0.600 INCH, PLASTIC, DIP-24
文件頁數(shù)： 6/32頁
文件大?。?/td> 199K
代理商： TEA1085
March 1992
6
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
FUNCTIONAL DESCRIPTION
Figure 1 illustrates a block diagram of the
TEA1085/TEA1085A with external components and
connections to the transmission IC.
The TEA1085/TEA1085A are bipolar ICs which have been
designed for use in line-powered telephone sets and
provide a listening-in facility for the received line signal via
a loudspeaker. Nearly all the line current can be used for
powering the loudspeaker.
The loudspeaker amplifier consists of a preamplifier, to
amplify the earpiece signal from the transmission circuit
and, a double push-pull output stage to drive the
loudspeaker in the BTL (bridge tied load) or SE (single
ended) configuration. The gain of the preamplifier is
controlled by a dynamic limiter which prevents high
distortion of the loudspeaker signal. This is achieved by
preventing clipping of the loudspeaker signal, with respect
to the supply voltage, and at too low supply current. Two
logic inputs can be used to reduce the gain in 3 steps.
Because of acoustic feedback from the loudspeaker to the
microphone, howling signals (Larsen effect) can occur on
the telephone line and in the loudspeaker. When the
Larsen signal exceeds a voltage and time duration
threshold the Larsen level limiter (LLL) will reduce the
Larsen signal to a low level within a short period of time by
reducing the gain of the receiving preamplifier. This is
achieved by using the microphone signal as an input signal
which is processed in the LLL via a preamplifier and
3rd-order filter.
The MUTE input can be used to enable or disable the
loudspeaker amplifier.
The MUTE function of the TEA1085 has a toggle input to
permit the use of a simple push-button switch.
The MUTE function of the TEA1085A has a logic input to
operate with a microcontroller.
By activating the power-down input the current
consumption of the circuit will be reduced, this enables
pulse dialling or flash (register recall).
An internal start circuit ensures normal start-up of the
transmission IC and start-up of the listening-in IC in the
standby mode.
The TEA1085/TEA1085A are intended for use in
conjunction with a member of the TEA1060 family and
should be connected between LINE and SLPE of the
transmission IC. The transmission characteristics
(impedance, gain settings, for example) are not affected.
The interconnection between the two ICs is illustrated in
Fig.3.
Fig.3 Interconnection of the TEA1085/TEA1085A with the TEA1060.
handbook, full pagewidth
MGR033
TEA1060
VCC
LN
VEE
SLPE
QR
MIC
+
MIC
LAI
+
LAI
TEA1085
TEA1085A
SREF
SUP
VSS
LSI1
LSI2
QLS
LINE
to TEA1060
(SLPE)
相關(guān)PDF資料
PDF描述
TEA1085A Listening-in circuit for line-powered telephone sets
TEA1085AT Listening-in circuit for line-powered telephone sets
TEA1085T Listening-in circuit for line-powered telephone sets
TEA1093 Hands-free IC
TEA1093T Hands-free IC
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
TEA1085A 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Listening-in circuit for line-powered telephone sets
TEA1085AT 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Listening-in circuit for line-powered telephone sets
TEA1085T 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Listening-in circuit for line-powered telephone sets
TEA1088T 制造商:未知廠家 制造商全稱:未知廠家 功能描述:SMPS Battery Charger Control Circuit
TEA1093 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Hands-free IC
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