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TEA1064BT/C1 View Datasheet(PDF) - Philips Electronics

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Description
Manufacturer
TEA1064BT/C1 Datasheet PDF : 32 Pages
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Philips Semiconductors
Low voltage versatile telephone transmission circuit
with dialler interface and transmit level dynamic limiting
Product specification
TEA1064B
Dynamic limiter (microphone) pin DLS/MMUTE
A low level at the DLS/MMUTE pin inhibits the microphone
inputs MIC+ and MICbut has no influence on the
receiving and DTMF amplifiers.
Removing the low level at the DLS/MMUTE pin provides
the normal function of the microphone amplifier after a
short time determined by the capacitor connected to
DLS/MMUTE pin. The microphone mute function can be
realised by a simple switch as shown in Fig.11.
To prevent distortion of the transmitted signal, the gain of
the sending amplifier is reduced rapidly when peaks of the
signal on the line exceed an internally-determined
threshold. The time in which gain reduction is effected
(attack time) is very short. The circuit stays in the
gain-reduced condition until the peaks of the sending
signal remain below the threshold level. The sending gain
then returns to normal after a a time determined by the
capacitor connected to DLS/MMUTE (release time).
The internal threshold adapts automatically to the DC
voltage setting of the circuit (VLN-SLPE). This means that
the maximum output swing on the line will be higher if the
DC voltage dropped across the circuit is increased.
Fig.12 shows the maximum possible output swing on the
line as a function of the DC voltage drop (VLN-SLPE) with
Iline Ip as a parameter.
The internal threshold level is lowered automatically if the
DC current in the transmit output stage is insufficient. This
prevents distortion of the sending signal in applications
using parallel-connected telephones or telephones
operating over long lines, for example.
Dynamic limiting also considerably improves sidetone
performance in over-drive conditions (less distortion;
limited sidetone level).
handbook, halfpage
R17
3.3 k
DLS/MMUTE
7
VEE1
11
MBA440
Fig.11 Microphone-mute function.
10
VLN(p-p)
(V)
8
6
4
2
MBA464
Iline-Ip
(mA)
25
23
21
19
17
15
13
11
0
3
3.5
4
4.5
5
5.5
VLN-VSLPE (V)
R16 = 392 .
Fig.12 Typical output swing on line as a function of
the DC voltage drop VLN-SLPE with
Iline Ip as a parameter.
March 1994
11
 

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