LUCL8567AAU-D AGERE [Agere Systems], LUCL8567AAU-D Datasheet - Page 36

• Manufacturer Part Number: LUCL8567AAU-D
• Description: SLIC for Peoples Republic of China Applications
• Manufacturer: AGERE [Agere Systems]

L8567 SLIC for
People’s Republic of China Applications
dc Applications
Ring Trip Detection
The ring trip circuit is a comparator that has a special input section optimized for this application. The equivalent
circuit is shown in Figure 28, along with its use in an application using unbalanced, battery-backed ringing.
The comparator input voltage compliance is V
V
direction. Its application is straightforward. A resistance
(R
current that is repeated in the R
lower resistance (R
input. When ringing is being injected, no dc current
flows through R
potential than R
flows, the R
parator. In Figure 28, 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 28 will trip at 12.5 mA dc loop current
using a –48 V battery.
The current I
ator input. The voltage at comparator input R
Using this equation and the values in the example, the
voltage at input R
(I
below R
through R
will trip. In this example,
36
BAT
LOOP(dc)
TSN
, and the maximum current is 240 µA in either
+ R
V
TSN
RTSP
= 0). Input R
TS2
TS1
. When enough dc loop current flows
TSP
) in series with the R
N
= V
to raise its dc drop to 5 V, the comparator
is repeated as I
PHONE HOOK
input voltage increases to trip the com-
TS1
TSN
BAT
I
TSP
I
N
, and so the R
LOOP dc
TSP
. When enough dc loop current
SWITCH
+ I
= 17.9 µA
=
is –12 V during ringing injection
TSP
Figure 28. Ring Trip Equivalent Circuit and Equivalent Application
) is placed in series with the R
(continued)
LOOP(dc)
–7 V – (–48 V)
------------------------------------- -
2.289 M
is, therefore, at a level of 5 V
=
= 12.5 mA
RC PHONE
P
---------------- -
402
x R
TSP
in the positive compar-
5 V
TSN
TSP
TS1
V
input. A slightly
RING
input establishes a
402
input is at a lower
R
R
+ I
LOOP
TS1
P
x R
V
274 k
BAT
TSP
TSP
R
CC
TS2
is:
to
TSP
C
0.27 µF
RTS2
2 M
2 M
R
R
TSN
TSP
Other Supervision Functions
The L8567 has on-chip thermal shutdown circuitry. If
the silicon die temperature exceeds a nominal
165 C temperature, the SLIC will sense this tempera-
ture and enter the thermal shutdown mode, regardless
of the logic inputs. The thermal shutdown mode is func-
tionally similar to the disconnect state. When the die
temperature cools, the SLIC will return to the reshut-
down state. A hysteresis is included in the thermal
shutdown mechanism.
The L8567 also has a logic input pin, NEXTSD, whose
status is transferred to the serial output data bus. This
pin may be connected to an external monitoring device.
An example is the thermal shutdown output pin of the
L7583. If the L7583 enters the thermal shutdown
mode, this is reflected in the TSD output pin of this
device. The L8567 SLIC can accept this status pin and
transfer the information on this pin to the serial output
data bus.
C
0.022 µF
RTS1
RTSP
RTSN
+
–
I
P
15 k
= I
I
N
N
+
–
7 V
Lucent Technologies Inc.
NRDET
August 1999
Data Sheet
12-3014 (F)