tea1069n NXP Semiconductors, tea1069n Datasheet - Page 13

• Manufacturer Part Number: tea1069n
• Description: Versatile Speech/dialler/ringer With Music-on-hold
• Manufacturer: NXP Semiconductors

Philips Semiconductors
S
Suppression of the transmitted signal in the earpiece is
obtained by the anti-sidetone network comprising R1//Z
R2, R3, R8, R9 and Z
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 series for Z
In practice, Z
length. Therefore, the value chosen for Z
an average line length thus giving optimum setting for
short or long lines.
Example: the balance impedance Z
optimum suppression is present can be calculated as
1998 Jan 08
R9 R2
k
Z
handbook, full pagewidth
IDETONE SUPPRESSION
bal
Versatile speech/dialler/ringer with
music-on-hold
=
R3
=
k Z
=
---------------------------- -
R8
R2 R9
R1
line
line
+
varies considerably with the line type and
R9
R3
bal
Fig.10 Equivalent circuit of TEA1069 and TEA1069A anti-sidetone bridge.
+
R8
(see Fig.10). The maximum
Z line
V EE
bal
at which the
bal
should be for
R1
R9
SLPE
line
LN
line
.
(1)
(2)
(3)
,
i m
13
R8
follows:
suppose Z
5 km line of 0.5 mm diameter, copper, twisted-pair cable
matched to 600
When k = 0.64 then R8 = 390 ;
Z
The anti-sidetone network for the TEA1069 and
TEA1069A shown in Fig.10 attenuates the signal received
from the line by 32 dB before it enters the receiving
amplifier.
The attenuation is almost constant over the whole
audio-frequency range. Figure 11 shows a conventional
Wheatstone bridge anti-sidetone circuit that can be used
as an alternative. Both bridge types can be used with
either resistive or complex set impedances. More
information on the balancing of anti-sidetone bridges can
be found in our publication “Applications Handbook for
Wired telecom systems, IC03b” , order number
9397 750 00811.
R2
bal
R3
Z bal
= 130
IR
line
+ (820 //220 nF).
= 210
MSA500 - 1
R t
(176 /km; 38 nF/km).
+ (1265 //140 nF) representing a
TEA1069; TEA1069A
Product specification