HC55121IM Intersil, HC55121IM Datasheet - Page 18

• Manufacturer Part Number: HC55121IM
• Manufacturer: Intersil

Specifications of HC55121IM

• Number Of Channels: 1
• On-hook Transmission: Yes
• Polarity Reversal: Yes
• On-chip Ring Relay Driver: Yes
• Longitudinal Balanced: 53
• Operating Supply Voltage (typ): 5V
• Operating Temp Range: -40C to 85C
• Package Type: PLCC
• Loop Current Limit: 30mA
• Operating Temperature Classification: Industrial
• Pin Count: 28
• Mounting: Surface Mount
• Operating Current: 2.7mA
• Operating Supply Voltage (max): 5.25V
• Operating Supply Voltage (min): 4.75V
• Lead Free Status / RoHS Status: Not Compliant

V
protection resistors.
Z
Z
protection resistors.
(AC) 4-Wire to 2-Wire Gain
The 4-wire to 2-wire gain is equal to V
(AC) 2-Wire to 4-Wire Gain
The 2-wire to 4-wire gain is equal to V
From Equation 18 with V
Substituting Equation 24 into Equation 23 and simplifying.
By design, VTX = -VTX´, therefore
A more useful form of the equation is rewritten in terms of
V
from E
Loop Equation
–
V
G
V
E
E
L
TR
TR
TX
G
TX
TR
2-4
G
= The line impedance.
=
′
/V
+
=
= The tip to ring voltage including the voltage across the
= The input impedance of the SLIC including the
=
=
Z
⎛
⎜
⎝
I
TR
G
V
---------- =
M
L
E
----------------------- -
Z
–
TX
I
TR
+
(
G
to V
I
-
M
E
I
. A voltage divider equation is written to convert
M
Z
-
Z
M
G
L
TR
+
(
+
Z
+
2R
Z
TR
I
--------------------------------------- -
Z
TR
L
M
Z
I
L
M
HC55120, HC55121, HC55130, HC55140, HC55142, HC55143, HC55150
TR
P
(
⎞
⎟
⎠
as shown in Equation 27.
Z
(
–
E
I
Z
M
TR
Z
)
G
2R
L
V
TR
–
TR
+
–
RING
P
V
TIP
Z
)
2R
TX
TR
+
-
RX
P
′
)
+
)
-
=
=
R
= 0
R
I
I
0
18
M
M
P
P
(
-------------------------------- -
Z
(
V
+
Z
-
TR
TX
L
´
+
+
-
–
Z
2R
TR
TR
TX
FIGURE 17. SIMPLIFIED AC TRANSMISSION CIRCUIT
P
)
/E
/V
)
R
S
RX
20Ω
R
20Ω
G
S
with V
.
+
-
R
500K
R
500K
20Ω
I
INT
INT
X
I
X
20Ω
RX
+
-
(EQ. 27)
(EQ. 23)
(EQ. 24)
(EQ. 25)
(EQ. 26)
UniSLIC14
= 0
+
+
-
-
1/80K
Z
T
= 200 (Z
From Equation 21 and the relationship Z
Notice that the phase of the 4-wire to 2-wire signal is 180°out
of phase with the input signal.
Rearranging Equation 27 in terms of E
into Equation 26 results in an equation for 2-wire to 4-wire
gain, that’s a function of the synthesized input impedance of
the SLIC (Z
Notice that the phase of the 2-wire to 4-wire signal is in
phase with the input signal.
(AC) 4-Wire to 4-Wire Gain
The 4-wire to 4-wire gain is equal to V
From Equation 18.
Substituting -V
Equation 30.
G
G
V
V
TX
TX
4-2
2-4
TR
I
′
X
=
- 2R
=
=
5
=
V
---------- - = -2
V
V
---------- - =
V
– V
–
2
TR
RX
P
TX
TR
I
V
X
)
TX
RX
TR
500K
500K
Z
-----------------------------
=
–
) and the protection resistors (R
TR
TR
V
-------------------------------------------- -
-------------------------
Z
– V
Z
L
2
TR
/Z
TR
- 2R
+ Z
Z
V
(
RX
A
L
L
Z
= I
TR
into Equation 29 for I
TR
Z
P
I
+
X
500K
L
M
2
–
I
(Z
=
M
500K
2R
+
-
TR
(
A = 1
–
Z
2
-2R
P
TR
--------------------------------------------- -
Z
)
L
P
–
)
+
2R
⎛
⎝
--------- -
200
Z
P
Z
T
V
V
PTG
)
L
TX
G
TX
RX
+
, and substituting
T
/V
2R
= 200(Z
M
RX
P
⎞
⎠
results in
, E
P
).
V
G
V
TX
RX
TR
+
= 0.
-
+
June 1, 2006
-
(EQ. 29)
(EQ. 30)
(EQ. 22)
FN4659.13
-2R
(EQ. 28)
P
).