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參數(shù)資料
| 型號： | TEA1083AT |
| 廠商： | NXP SEMICONDUCTORS |
| 元件分類： | 通信及網(wǎng)絡(luò) |
| 英文描述： | Call progress monitor for line powered telephone sets |
| 中文描述： | SPECIALTY TELECOM CIRCUIT, PDSO16 |
| 封裝： | PLASTIC, SO-16 |
| 文件頁數(shù)： | 6/20頁 |
| 文件大?。?/td> | 139K |
| 代理商： | TEA1083AT |
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 V
BB
.
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 V
SS
whenever the instantaneous value of the
voltage at V
SUP
drops below the supply voltage V
BB
. V
BB
is
fixed to a typical value of 2.95 V.
The supply at V
BB
is decoupled with respect to V
SS
by a
220
μ
F capacitor (C20).
The DC voltage (V
SUP
V
SS
) is determined by the
transmission IC and V
int
; thus
V
SUP
V
SS
= V
LN
SLPE
+
V
int
.
The reference voltage of the transmission IC has to be
adjusted to a level where V
SUP
V
BB (max)
is greater than
400 mV. The minimum voltage space between SUP and
V
BB
(400 mV) is required to maintain a 'high' efficiency of
the internal supply for mean speech levels. V
BB (max)
is the
specified maximum level.
The internal current consumption of the TEA1083/83A
(I
SUP0
) is typically 2.5 mA (where V
SUP
V
SS
= 3.6 V).
The current I
SUP0
consists of currents I
BIAS
(approximately
0.4 mA) for the circuitry connected to SUP and I
BB0
(approximately 2.1 mA) for the internal circuitry connected
to V
BB
(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
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
V
O(p-p)
= 2.5 V (typical with 50
load). The input level
V
LSI
is approximately 16 mV(rms) and the supply current
I
SUP
>
11 mA. In this condition the signal is limited by the
available voltage space (V
BB
). 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:
V
O(p-p)
= 2
×
(I
SUP
I
SUPO
)
× π ×
R
LS
Where;
V
O(p-p)
= the peak-to-peak level of the loudspeaker
R
LS
= the loudspeaker impedance
I
SUPO
= 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 V
BB
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 I
BB0
(see Fig.5) is
reduced from 2.1 mA to 400
μ
A typically. Transistors TR1
and TR2 are inhibited during power-down and the bias
current is reduced from approximately 400
μ
A to
approximately 50
μ
A with V
SUP
= 3.6 V in the following
equation:
I
SUP(PD)
= I
BIAS(PD)
= (V
SUP
2V
d
)/Ra
Where 3.6
<
V
SUP
<
V
BB
+
3 V
2V
d
is the voltage drop across 2 internal diodes
(approximately 1.3 V)
Ra is an internal resistor (typical 50 k
)
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 V
SS
).
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