hc5523 Intersil Corporation, hc5523 Datasheet - Page 11

• Manufacturer Part Number: hc5523
• Description: Lssgr/tr57 Co/loop Carrier Slic With Low Power Standby
• Manufacturer: Intersil Corporation

Z
Substituting in Equation 9 for V
Substituting in Equation 12 for V
Therefore
Equation 16 can now be used to match the SLIC’s
impedance to any known line impedance (Z
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
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
Z
Z
A
A
A
Z
A
Z
Z
TR
T
TR
T
F
2 4
4 2
4 4
TR
TR
4 2
T
= 560kΩ in series with 2.16nF
–
–
–
= 20Ω.
–
=
=
is defined as:
=
=
=
1000
1000
=
=
=
=
V
---------- -
V
---------- -
------------ -
1000
I
TR
I
M
Z
–
V
---------- -
V
-----------
V
V
-----------
V
TX
V
M
---------- -
Z
T
TX
TR
RX
TR
RX
TX
Z
•
RX
T
•
+
T
(
+


Z
to make Z
2R
---------------------- -
600
=
=
=
TR
2R
•
1
-- -
2
----------------------------------------- -
Z
–
–
4-2
F
I
---------- -
Z
M
F
–
T
---------- -
Z
+
Z
Z
•
RX
RX
2R
⁄
Z
T
---------------------------------------- - 2 20
jω 2.16
T
I
1000
simplifies to:
M
T
F
•
•
•
⁄
)
1000
------------------------------------------- -
------------ -
1000
------------------------------------------- -
------------ -
1000
TR
Z
Z
+
T
T
1
2R
Z
= 600Ω in series with 2.16µF.
•
L
+
+
11
10
F
+
Z
2R
2R
L
2R
TR
–
RX
TX
6
F
F
F
–
+
+
= 0
Z
Z
G
G
•
L
L
TX
TR
TX
= 0
= 0
/ V
/V


/V
RX
RX
TR
TR
).
TR
,
(EQ. 13)
(EQ. 14)
(EQ. 15)
(EQ. 16)
(EQ. 17)
(EQ. 18)
(EQ. 19)
(EQ. 20)
L
), the
HC5523
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
be subtracted from the output signal if I
analysis yields the following equation:
The value of Z
Where V
Therefore
Example:
Given: R
value), R
The value of Z
Supervisory Functions
The loop current, ground key and the ring trip detector
outputs are multiplexed to a single logic output pin called
DET. See Table 1 to determine the active detector for a
given logic input. For further discussion of the logic circuitry
see section titled “Digital Logic Inputs”.
V
---------- -
R
Z
Z
B
B
TX
TX
HC5523
=
=
+
–
R
V
-----------
R
Z
TX
RX
B
TX
RX
F
TX
•
= 20Ω and Z = 600Ω
•
=
/V
Z
---------- -
= 20kΩ, Z
FIGURE 17. TRANSHYBRID CIRCUIT
Z
V
-----------
V
RX
V
RSN
0
TX
T
B
RX
TX
B
TX
is then
•
= 18.7kΩ
RX
equals 1/ A
------------------------------------------- -
------------ -
1000
Z
Z
) from the transmit signal (V
T
T
Z
L
RX
+
+
R
2R
TX
2R
Z
= 280kΩ, Z
RX
F
4-4
F
+
Z
I
I
2
1
L
Z
B
T
1
= 562kΩ (standard
equals I
R
FB
CODEC/
V
FILTER
-
+
RX
TX
+
-
2
), thereby
. Node
(EQ. 21)
(EQ. 22)
(EQ. 23)
V
TX
TX
+
-
).