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參數(shù)資料
| 型號： | HC5517CM |
| 廠商： | HARRIS SEMICONDUCTOR |
| 元件分類： | 模擬傳輸電路 |
| 英文描述： | 3 REN Ringing SLIC For ISDN Modem/TA and WLL |
| 中文描述： | TELECOM-SLIC, PQCC28 |
| 文件頁數(shù)： | 9/18頁 |
| 文件大?。?/td> | 175K |
| 代理商： | HC5517CM |
68
Therefore to match the HC5517, with R
S
equal to 50
, to a
600
load:
and:
To prevent loading of the V
TX
output, the value of R
8
and R
9
are typically scaled by a factor of 100:
Since the impedance matching is a function of the voltage
gain, scaling of the resistors to achieve a standard value is
recommended.
For complex impedances the above analysis is the same.
Reference application note AN9607 (“Impedance Matching
Design Equations for the HC5509 Series of SLICs”) for the
values of KR
9
and KR
8
for several worldwide Typical line
impedances.
Tip-to-Ring Open-Circuit Voltage
The tip-to-ring open-circuit voltage, V
OC
, of the HC5517 is
programmable to meet a variety of applications. The design
of the HC5517 defaults the value of V
OC
to:
The HC5517 application circuit overrides the default V
OC
operation when operating from a -80V battery. While operat-
ing from a -80V battery, the SLIC will be in either the ringing
mode or on-hook standby mode. In the ringing mode, V
OC
is
designed to switch from 0V (centering voltage) to -47V
(Maintenance Termination Unit voltage). The centering volt-
age is active during the ringing portion of the ringing wave-
form and the Maintenance Termination Unit (MTU) voltage is
active during the silent portion of the ringing signal. In the
on-hook standby mode, the application circuit is designed to
maintain V
OC
at the MTU voltage.
Centering Voltage Application Circuit Overview
The centering voltage is used during ringing to center the
DC outputs of the tip feed and ring feed amplifiers. Centering
the amplifier outputs allows for the maximum undistorted
voltage swing of the ringing signal. Without centering, the
output of each amplifier would saturate at ground or V
BAT
,
minimizing the ringing capability of the HC5517. The
required centering voltage, V
C
, is +1.8V
DC
when operating
from a -80V battery.
Centering Voltage Application Circuit Operation
The circuit used to generate the centering voltage is shown
in Figure 5.
The circuitry within the dotted lines is internal to the
HC5517. The value of the resistor designated as R is 108k
and the resistor R/20 is 5.4k
. The tip amplifier gain of
20V/V amplifies the +1.8V
DC
at V
C
to +36V
DC
and adds it to
the internal 4V
DC
offset, generating -40V
DC
at the tip
amplifier output. The -40V
DC
offset also sums into the ring
amplifier, adding to the battery voltage, achieving -40V at the
ring amplifier output.
Centering Voltage Design Equations
The centering voltage (V
C
) is dependent on the battery
voltage. A battery voltage of -80V requires a +1.8V
DC
centering voltage. The equation used to calculate the
centering voltage is shown below.
The DC voltage at the outputs of the centered tip and ring
amplifiers can be calculated from Equation 28 and
Equation 29.
The shunt resistor of the divider network, R
18
, is not
determined from a design equation. It is selected based on
the trade-off of power dissipation in the voltage divider (low
value of R
18
) and loading affects of the internal R/20 resistor
(high value of R
18
). The suggested range of R
18
is between
1.0k
and 2.0k
. The application circuit design equation
used to calculate the value of R
19
of the divider network is
as follows:
R
9
8R
S
8 50
)
400
=
=
=
(EQ. 23)
R
8
R
L
4
–
R
S
600
200
–
400
=
=
=
(EQ. 24)
KR
8
40k
=
KR
9
40k
=
(EQ. 25)
KR
9
40k
=
KR
8
100 Resistive
200
–
)
--------------------------
+
=
(EQ. 26)
V
OC
V
BAT
8
–
FIGURE 5. CENTERING VOLTAGE APPLICATION CIRCUIT
RING FEED
AMPLIFIER
RF
90k
90k
90k
TIP FEED
AMPLIFIER
TF
R
R/20
R/2
T
2
+5V
R
24
R
19
+
-
RC
R
18
D
13
D
6
V
RING
+2V
V
C
TO ZENER
DIODE D
11
V2
+
-
+
-
V
C
V
--------------
4
–
20
=
(EQ. 27)
V
TC
20V
C
4
+
(
)
–
=
(EQ. 28)
V
RC
V
BAT
20V
C
4
+
(
)
+
=
(EQ. 29)
HC5517
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| HC5517CM96 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
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| HC5517IM | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| HC5517IM96 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| HC55180 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Extended Reach Ringing SLIC Family |
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