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参数资料
| 型号： | ATTL7554BP |
| 英文描述： | L7554 Low-Power SLIC |
| 中文描述： | L7554低功耗用户接口 |
| 文件页数： | 23/28页 |
| 文件大小： | 486K |
| 代理商： | ATTL7554BP |
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Lucent Technologies Inc.
23
Data Sheet
March 1997
L7554 Low-Power SLIC
Applications
(continued)
dc Applications
(continued)
Ring Trip Detection
The ring trip circuit is a comparator that has a special in-
put section optimized for this application. The equiva-
lent circuit is shown in Figure 31, along with its use in an
application using unbalanced, battery-backed ringing.
12-3014 (C)
Figure 31. Ring Trip Equivalent Circuit and
Equivalent Application
The comparator input voltage compliance is V
CC
to
V
BAT
, and the maximum current is 240
μ
A in either
direction. Its application is straightforward. A resistance
(R
TSN
+ R
TS2
) in series with the R
TSN
input establishes a
current that is repeated in the R
TSP
input. A slightly
lower resistance (R
TSP
) is placed in series with the R
TSP
input. When ringing is being injected, no dc current
flows through R
TS1
, so the R
TSP
input is at a lower
potential than R
TSN
. When enough dc loop current
flows, the R
TSP
input voltage increases to trip the com-
parator. In Figure 31, a low-pass filter with a double
pole at 2 Hz was implemented to prevent false ring trip.
The following example illustrates how the detection cir-
cuit of Figure 31 will trip at 12.5 mA dc loop current us-
ing a –48 V battery.
The current I
N
is repeated as I
P
in the positive compar-
ator input. The voltage at comparator input R
TSP
is:
V
RTSP
V
BAT
I
LOOP dc
+
=
Using this equation and the values in the example, the
voltage at input R
TSP
is –12 V during ringing injection
(I
LOOP(dc)
= 0). Input R
TSP
is, therefore, at a level of 5 V
below R
TSN
. When enough dc loop current flows
through R
TS1
to raise its dc drop to 5 V, the comparator
will trip. In this example,
Ring Ground Detection
Pin ICM sinks a current proportional to the longitudinal
loop current. It is also connected to an internal compar-
ator whose output is pin RGDET. In a ground start
application where Tip is open, the ring ground current
is half differential and half common mode. In this case,
to set the ring ground current threshold, connect a
resistor R
ICM
from pin ICM to V
CC
. Select the resistor
according to the following relation:
The above equation is shown graphically in Figure 18.
It applies for the case of Tip open. The more general
equation can be used in ground key application to
detect a common-mode current I
CM
:
+
–
R
TSP
R
LOOP
–
+
15 k
7 V
I
P
= I
N
R
TSN
R
TS2
2 M
2 M
C
RTS1
0.022 μF
C
RTS2
0.27 μF
274 k
V
RING
PHONE
HOOK SWITCH
RC PHONE
V
BAT
NRDET
R
TS1
402
R
TSP
I
N
R
TSN
I
N
2.289 k
–7 – (–48)
=
17.9
μ
A
=
)
R
TS1
I
P
R
TSP
×
+
×
I
LOOP dc
)
402
--5 V
=
12.5 mA
=
R
ICM
k
(
)
(
)
----------------------
=
R
ICM
k
(
)
(
60
×
)
-------------------
=
相关PDF资料 |
PDF描述 |
|---|---|
| ATTL7554BP-TR | L7554 Low-Power SLIC |
| ATTL7554P-TR | L7554 Low-Power SLIC |
| ATTL7554AP | LH1263 E&M Signaling Circuit |
| AU01Z | Fast-Recovery Rectifier Diodes |
| AU02Z | Fast-Recovery Rectifier Diodes |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ATTL7554BP-TR | 制造商:AGERE 制造商全称:AGERE 功能描述:L7554 Low-Power SLIC |
| ATTL7554P-TR | 制造商:AGERE 制造商全称:AGERE 功能描述:L7554 Low-Power SLIC |
| ATTL7556AAU | 制造商:未知厂家 制造商全称:未知厂家 功能描述:LH1263 E&M Signaling Circuit |
| ATTL7556AAU-TR | 制造商:AGERE 制造商全称:AGERE 功能描述:Low-Power SLICs with Battery Switch |
| ATTL7557AAU | 制造商:AGERE 制造商全称:AGERE 功能描述:Low-Power SLICs with Battery Switch |
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