HC5513_03 INTERSIL [Intersil Corporation], HC5513_03 Datasheet - Page 10

• Manufacturer Part Number: HC5513_03
• Description: TR909 DLC/FLC SLIC with Low Power Standby
• Manufacturer: INTERSIL [Intersil Corporation]

Substituting in Equation 12 for V
Therefore
Equation 16 can now be used to match the SLIC’s
Example:
Calculate Z
R
Z
(AC) 2-Wire to 4-Wire Gain
The 2-wire to 4-wire gain is equal to V
From Equations 9 and 10 with V
(AC) 4-Wire to 2-Wire Gain
Transhybrid Circuit
The purpose of the transhybrid circuit is to remove the
receive signal (V
preventing an echo on the transmit side. This is
accomplished by using an external op amp (usually part of
the CODEC) and by the inversion of the signal from the
4-wire receive port (RSN) to the 4-wire transmit port (V
Figure 17 shows the transhybrid circuit. The input signal will
impedance to any known line impedance (Z
Z
Z
T
TR
T
F
= 560kΩ in series with 2.16nF.
= 20Ω:
=
=
1000
V
------------ -
1000
TR
Z
T
Z
•
T
+
-
T
(
+
Z
=
to make Z
2R
TR
Z
1000
L
F
RX
–
+
-
E
2R
G
) from the transmit signal (V
Z
•
TR
F



RING
600
)
TR
TIP
+
= 600Ω in series with 2.16µF.
---------------------------------------- - 2 20
jω 2.16
10
R
R
I
I
•
M
M
F
F
RX
TX
V
1
TX
= 0:
+
-
•
10
TX
FIGURE 16. SIMPLIFIED AC TRANSMISSION CIRCUIT
–
/ V
6
HC5513
–
TR
TR
•
.
).
TX



), thereby
(EQ. 15)
(EQ. 16)
+
-
TX
1
).
HC5513
A = 250
A = 250
The 4-wire to 2-wire gain is equal to V
From Equations 9, 10 and 11 with E
For applications where the 2-wire impedance (Z
Equation 15) is chosen to equal the line impedance (Z
expression for A
(AC) 4-Wire to 4-Wire Gain
The 4-wire to 4-wire gain is equal to V
From Equations 9, 10 and 11 with E
be subtracted from the output signal if I
analysis yields the following equation:
A
A
A
A
V
---------- -
R
2 4
4 2
4 4
4 2
TX
TX
–
–
–
–
+
=
=
=
=
V
-----------
Z
RX
–
V
---------- -
V
-----------
V
V
-----------
V
B
V
---------- -
Z
TX
TR
RX
TR
RX
TX
Z
RX
=
T
=
=
=
0
•
1
-- -
2
----------------------------------------- -
Z
–
–
4-2
---------- -
Z
T
---------- -
Z
Z
Z
A = 4
RX
RX
⁄
Z
T
T
1000
simplifies to:
T
•
•
⁄
1000
------------------------------------------- -
------------ -
1000
------------------------------------------- -
------------ -
1000
Z
Z
+
T
T
2R
Z
L
+
+
F
+
Z
2R
2R
V
RSN
L
2R
TX
1000
I
F
F
M
F
+
+
Z
Z
G
G
L
L
Z
TR
= 0:
TX
= 0:
T
1
/V
/V
equals I
RX
RX
Z
RX
V
.
.
TX
+
TR
-
2
. Node
,
V
RX
(EQ. 17
(EQ. 18)
(EQ. 19)
(EQ. 20)
(EQ. 21)
+
-
L
), the