tea1110auh NXP Semiconductors, tea1110auh Datasheet - Page 8

• Manufacturer Part Number: tea1110auh
• Description: Low Voltage Versatile Telephone Transmission Circuit With Dialler Interface
• Manufacturer: NXP Semiconductors

Philips Semiconductors
SIDETONE SUPPRESSION
The TEA1110A anti-sidetone network comprising
R
suppresses the transmitted signal in the earpiece.
Maximum compensation is obtained when the following
conditions are fulfilled:
The scale factor k is chosen to meet the compatibility with
a standard capacitor from the E6 or E12 range for Z
In practice, Z
the line length. Therefore, the value of Z
average line length which gives satisfactory sidetone
suppression with short and long lines. The suppression
also depends on the accuracy of the match between Z
and the impedance of the average line.
2000 Feb 15
Z
R
handbook, full pagewidth
k
CC
bal
SLPE
Low voltage versatile telephone
transmission circuit with dialler interface
=
//Z
=
------------------------------------------------------------------ -
line
R
k
ast2
, R
R
ast1
Z
R
ast1
line
line
ast1
R
, R
=
varies considerably with the line type and
ast3
ast2
R
R
CC
SLPE
+
, R
R
ast3
SLPE
R
Fig.8 Equivalent circuit of TEA1110A family anti-sidetone bridge.
, R
ast2
SLPE
+
Z line
V EE
R
ast3
and Z
bal
bal
should be for an
R SLPE
R CC
(see Fig.8 )
bal
SLPE
LN
.
bal
I m
R ast3
8
The anti-sidetone network for the TEA1110A (as shown in
Fig.13) attenuates the receiving signal from the line by
32 dB before it enters the receiving amplifier. The
attenuation is almost constant over the whole audio
frequency range.
A Wheatstone bridge configuration (see Fig.9) may also
be used.
More information on the balancing of an anti-sidetone
bridge can be obtained in our publication “Applications
Handbook for Wired Telecom Systems, IC03b” , order
number 9397 750 00811.
R ast1
Z bal
R ast2
IR
MBE787
Z ir
Product specification
TEA1110A