(SLIC) is optimized for low-power consumption while
providing an extensive set of features.
Quiet polarity reversal is possible because the ac
path is uninterrupted during transition.
The L7554 includes the ground start state and a
summing node for meter pulse injection to 2.2 Vrms.
A spare, uncommitted op amp is included for meter
pulse filtering.
The device is being offered in two versions, based
upon maximum battery. The L7554AP is guaranteed
to –60 V, and the L7554BP is guaranteed to –72 V.
The device is available in a 44-pin PLCC package. It
is built by using a 90 V complementary bipolar
(CBIC) process.
Low active power (typical 165 mW during on-hook
transmission)
Sleep state for low idle power (76 mW)
Quiet Tip/Ring polarity reversal
Supports meter pulse injection
Spare op amp for meter pulse filtering
–24 V to –72 V power supply operation
Distortion-free on-hook transmission
Convenient operating states:
— Forward powerup
— Polarity reversal powerup
— Forward low-power scan
— Polarity reversal low-power scan
— Ground start
— Disconnect (high impedance)
Adjustable supervision functions:
— Off-hook detector with longitudinal rejection
— Ground key detector
— Ring trip detector
Independent, adjustable, dc and ac parameters:
— dc feed resistance
— Loop current limit
— Termination impedance
Thermal protection
s
s
s
s
s
s
s
s
s
s
L7554 Low-Power SLIC
Data Sheet
March 1997
Table of Contents
Content
Page
Features .................................................................................................................................................................. 1
Pin Information ......................................................................................................................................................... 4
Absolute Maximum Ratings ..................................................................................................................................... 6
Ring Trip Requirements ..................................................................................................................................... 11
Test Configurations ............................................................................................................................................... 12
dc Applications ................................................................................................................................................... 20
Overhead Voltage .......................................................................................................................................... 20
Adjusting Overhead Voltage ........................................................................................................................... 21
Adjusting dc Feed Resistance......................................................................................................................... 22
Adjusting Overhead Voltage and dc Feed Resistance Simultaneously .......................................................... 22
Ring Trip Detection......................................................................................................................................... 23
Ring Ground Detection................................................................................................................................... 23
ac Design ........................................................................................................................................................... 24
PCB Layout Information ......................................................................................................................................... 26
Ordering Information ........................................................................................................................................... 28
2
Lucent Technologies Inc.
Data Sheet
March 1997
L7554 Low-Power SLIC
Description
(continued)
BGND
AGND
I
PROG
V
REG
V
BAT
CF1
CF2
FB1
V
CC
FB2
POWER CONDITIONING & REFERENCE
RECTIFIER
3
DCOUT
–
–1 V/24 mA
V
TX
0.1 µF
T
XI
C
EXTERNAL
9.6
VITR
+
SN
PT
A=4
SPARE
OP AMP
–
XMT
+
–
PR
A = –4
1
RCVN
RCVP
+
DCR
dc RESISTANCE
ADJUST
BATTERY FEED
STATE CONTROL
B0
B1
B2
LCTH
LOOP CLOSURE DETECTOR
+
NLC
–
RTSP
RTSN
RING TRIP DETECTOR
+
NRDET
–
RGDET
ICM
RING GROUND
DETECTOR
12-2569 (C)
Figure 1. Functional Diagram
Lucent Technologies Inc.
3
L7554 Low-Power SLIC
Data Sheet
March 1997
Pin Information
I
PROG
FB2
6
7
V
CC
RCVP
RCVN
TXI
LCTH
V
REG
DCOUT
V
BAT
PR
8
9
10
11
12
13
14
15
16
17
18
CF2
5
4
3
2
1
44
43
42
41
40
39
38
37
36
35
FB1
SN
XMT
B1
B2
NLC
NRDET
RTSP
RTSN
PT
VTX
L7554
34
33
32
31
30
29
19
CF1
20
VITR
21
I
CM
22
R
GDET
23
B0
24
AGND
25
AGND
26
DCR
27
BGND
28
12-2571 (C)
Figure 2. Pin Diagram (PLCC Chip)
Table 1. Pin Descriptions
Pin
3
8
9
10
11
12
13
14
15
16
18
19
Symbol Type
I
PROG
V
CC
RCVP
RCVN
TXI
LCTH
V
REG
DCOUT
V
BAT
PR
CF2
CF1
I
—
I
I
—
I
I
O
—
I/O
—
—
Description
Current-Limit Program Input.
A resistor to DCOUT sets the dc current limit of the
device.
+5 V Power Supply.
Receive ac Signal Input (Noninverting).
This high-impedance input controls the ac
differential voltage on Tip and Ring.
Receive ac Signal Input (Inverting).
This high-impedance input controls the ac differen-
tial voltage on Tip and Ring.
ac/dc Separation.
Connect a 0.1
µ
F capacitor from this pin to VTX
.
Loop Closure Threshold Input.
Connect a resistor to DCOUT to set off-hook threshold.
Regulated Negative dc Battery Voltage.
Can be connected to an external regulator.
Otherwise, connect to V
BAT
.
dc Output Voltage.
This output is a voltage that is directly proportional to the absolute
value of the differential Tip/Ring current.
Battery Supply.
Negative high-voltage power supply.
Protected Ring.
The output of the ring driver amplifier and input to loop sensing circuitry.
Connect to loop through overvoltage protection.
Filter Capacitor 2.
Connect a 0.1
µ
F capacitor from this pin to AGND.
Filter Capacitor 1.
Connect a 0.47
µ
F capacitor from this pin to pin CF2.
4
Lucent Technologies Inc.
Data Sheet
March 1997
L7554 Low-Power SLIC
Pin Information
(continued)
Table 1. Pin Descriptions
(continued)
Pin Symbol Type
20
21
VITR
I
CM
O
I
Description
Transmit ac Output Voltage.
This output is a voltage that is directly proportional to the
differential ac Tip/Ring current.
Common-Mode Current Sense.
To program ring ground sense threshold, connect a
resistor to V
CC
and connect a capacitor to AGND to filter 50/60 Hz. If unused, the pin can
be left unconnected.
Ring Ground Detect.
When high, this open-collector output indicates the presence of a
ring ground. To use, connect a 100 k
Ω
resistor to V
CC
.
State Control Input.
B0, B1, and B2 determine the state of the SLIC. See Table 2.
Analog Signal Ground
.
Analog Signal Ground.
dc Resistance for Low Loop Currents.
Leave open for dc feed resistance of 118
Ω
, or
short to DCOUT for 618
Ω
. Intermediate values can be set by a simple resistor divider
from DCOUT to ground with the tap at DCR.
Battery Ground.
Ground return for the battery supply.
This output is a voltage that is directly proportional to the differential Tip/Ring current.
Protected Tip
. The output of the tip driver amplifier and input to loop sensing. Connect to
loop through overvoltage protection.
Ring Trip Sense Negative
. Connect this pin to the ringing generator signal through a
high-value resistor.
Ring Trip Sense Positive
. Connect this pin to the ring relay and the ringer series resistor
through a high-value resistor.
Ring Trip Detector Output
. When low, this logic output indicates that ringing is tripped.
Loop Detector Output
. When low, this logic output indicates an off-hook condition.
State Control Input
. B0, B1, and B2 determine the state of the SLIC. See Table 2.
State Control Input
. B0, B1, and B2 determine the state of the SLIC. See Table 2.
Transmit ac Output Voltage
. The output of the uncommitted operational amplifier.
Summing Node
. The inverting input of the uncommitted operational amplifier. A resistor
or network to XMT sets the gain.
Forward Battery Slowdown.
A 0.1
µ
F capacitor from FB1 to AGND and from FB2 to
AGND will ramp the polarity reversal transition for added flexibility in applications requiring
quiet polarity reversal. If not needed, the pin can be left open.
Forward Battery Slowdown.
A 0.1
µ
F capacitor from FB2 to AGND and from FB1 to
AGND will ramp the polarity reversal transition for added flexibility in applications requiring
quiet polarity reversal. If not needed, the pin can be left open.
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