Data Sheet
November 1999
L7581 Ringing Access Switch
Features
s
Small size/surface-mount packaging
s
Monolithic IC reliability
s
Low impulse noise
s
Make-before-break, break-before-make operation
s
Clean, bounce-free switching
s
Low, matched ON-resistance
s
Built-in current limiting, thermal shutdown, and
SLIC protection
s
5 V only operation, very low power consumption
s
Battery monitor, all OFF state upon loss of battery
s
No EMI
s
Latched logic level inputs, no drive circuitry
s
Only one external protector required
Applications
s
Central office
s
DLC
s
PBX
s
DAML
s
HFC/FITL
Description
The L7581 Ringing Access Switch is a monolithic
solid-state device that provides the switching func-
tionality of a 2 form C switch.
The L7581 is designed to provide power ringing
access to tip and ring in central office, digital loop
carrier, private branch exchange, digitally added
main line, and hybrid fiber coax/fiber-in-the-loop ana-
log line card applications. The L7581 has three
states: the idle talk state (line break switches closed,
ringing access switches open), the power ringing
state (line break switches open, ringing access
switches closed), and an all OFF state.
The L7581 offers break-before-make or make-before-
break switching, with simple logic level input control.
Because of the solid-state construction, voltage tran-
sients generated when switching into an inductive
ringing load during ring cadence or ring trip are mini-
mized, possibly eliminating the need for external zero
cross switching circuitry. State control is via logic
level inputs, so no additional driver circuitry is
required.
The line break switch is a linear switch that has
exceptionally low ON-resistance and an excellent
ON-resistance matching characteristic. The ringing
access switch has a breakdown voltage rating
>480 V which is sufficiently high, with proper protec-
tion, to prevent breakdown in the presence of a tran-
sient fault condition (i.e., passing the transient on to
the ringing generator).
Incorporated into the L7581Axx is a diode bridge/
SCR clamping circuit, current-limiting circuitry, and a
thermal shutdown mechanism to provide protection
to the SLIC device and subsequent circuitry during
fault conditions (see Figure 1). Positive and negative
lightning is reduced by the current-limiting circuitry
and steered to ground via diodes and the integrated
SCR. Power cross is also reduced by the current-
limiting and thermal shutdown circuits.
The L7581Bxx version provides only an integrated
diode bridge along with current limiting and thermal
shutdown, as shown in Figure 2. This will cause pos-
itive faults to be directed to ground and negative
faults to battery. In either polarity, faults are reduced
by the current-limit and/or thermal shutdown mecha-
nisms.
2
2
Lucent Technologies Inc.
Data Sheet
November 1999
L7581 Ringing Access Switch
Description
(continued)
To protect the L7581 from an overvoltage fault condi-
tion, use of a secondary protector is required. The sec-
ondary protector must limit the voltage seen at the tip/
ring terminals to prevent the breakdown voltage of the
switches from being exceeded. To minimize stress on
the solid-state contacts, use of a foldback- or crowbar-
type secondary protector is recommended. With proper
choice of secondary protection, a line card using the
L7581 will meet all relevant ITU-T, LSSGR, FCC, or
UL*
protection requirements.
The L7581 operates off of a 5 V supply only. This gives
the device extremely low idle and active power dissipa-
tion and allows use with virtually any range of battery
voltage. This makes the L7581 especially appropriate
for remote power applications such as DAML or FOC/
FITL or other Bellcore TA 909 applications where
power dissipation is particularly critical.
A battery voltage is also used by the L7581, only as a
reference for the integrated protection circuit. The
L7581 will enter an all OFF state upon loss of battery.
During power ringing, to turn on and maintain the ON
state, the ring access switch will draw a nominal 2 mA
or 4 mA from the ring generator.
The L7581 device is packaged in a 16-pin, plastic DIP
package (L7581AC/BC) and a 16-pin, plastic SOG
package (L7581AAE/BAE). These devices are pin
compatible with the L7541 device.
*
UL
is a registered trademark of Underwriters Laboratories, Inc.
Pin Information
12-2306.a (C)
Note: Shown with A version protection. The 16-pin DIP is available
with either A or B version protection.
Figure 1. 16-Pin, Plastic DIP
12-2307.a (F)
Note: Shown with B version protection. The 16-pin SOG is available
with either A or B version protection.
Figure 2. 16-Pin, Plastic SOG
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
BAT
NC
R
BAT
LATCH
INPUT
D
GND
R
RINGING
F
GND
T
RINGING
V
DD
T
SD
SCR
NC
T
BAT
T
LINE
NC
R
LINE
AND
TRIP
CKT
TEMPERATURE
SHUTDOWN
SW1
SW2
SW4
SW3
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
BAT
R
BAT
R
LINE
LATCH
INPUT
D
GND
R
RINGING
F
GND
NC
T
RINGING
T
SD
T
BAT
T
LINE
NC
V
DD
NC
TEMPERATURE
SHUTDOWN
SW1
SW2
SW4
SW3
Data Sheet
November 1999
Lucent Technologies Inc.
3
L7581 Ringing Access Switch
Pin Information
(continued)
Table 1. Pin Descriptions
DIP SOG
Symbol
Description
DIP SOG
Symbol
Description
1
1
F
GND
Fault ground.
16
16
V
BAT
Battery voltage. Used as a ref-
erence for protection circuit.
2
4
NC
No connection.
15
13
NC
No connection.
3
2
T
BAT
Connect to TIP on SLIC side.
14
15
R
BAT
Connect to RING on SLIC side.
4
3
T
LINE
Connect to TIP on line side.
13
14
R
LINE
Connect to RING on line side.
5
6
T
RINGING
Connect to return ground for
ringing generator.
12
12
R
RINGING
Connect to ringing generator.
6
7
V
DD
5 V supply.
11
11
LATCH
Data latch control, active-high,
transparent low.
7
5
NC
No connection.
10
10
INPUT
Logic level input switch control.
8
8
T
SD
Temperature shutdown pin. Can
be used as a logic level input or
output. See Table 12, Truth
Table, and the Switching Behav-
ior section of this data sheet for
input pin description. As an out-
put, will read 5 V when device is
in its operational mode and 0 V
in the thermal shutdown mode.
In the L7581, the thermal shut-
down mechanism cannot be dis-
abled.
9
9
D
GND
Digital ground.
Absolute Maximum Ratings
Stresses in excess of the absolute maximum ratings
can cause permanent damage to the device. These are
absolute stress ratings only. Functional operation of the
device is not implied at these or any other conditions in
excess of those given in the operational sections of the
data sheet. Exposure to absolute maximum ratings for
extended periods can adversely affect device reliability.
Table 2. Absolute Maximum Ratings Parameters
Handling Precautions
Although protection circuitry has been designed into
this device, proper precautions should be taken to
avoid exposure to electrostatic discharge (ESD) during
handling and mounting. Lucent Technologies Micro-
electronics Group employs a human-body model
(HBM) and a charged-device model (CDM) for ESD-
susceptibility testing and protection design evaluation.
ESD voltage thresholds are dependent on the circuit
parameters used to define the model. No industry-wide
standard has been adopted for CDM. However, a stan-
dard HBM (resistance = 1500
, capacitance = 100 pF)
is widely used and therefore can be used for compari-
son purposes. The HBM ESD threshold presented
here was obtained by using these circuit parameters.
Table 3. HBM ESD Threshold Voltage
Parameter
Min
Max
Unit
Operating Temperature Range
40
110
C
Storage Temperature Range
40
150
C
Relative Humidity Range
5
95
%
Pin Soldering Temperature
--
10
C
5 V Power Supply
--
7
V
Battery Supply
--
85
V
Logic Input Voltage
--
7
V
Input-to-output Isolation
--
330
V
Pole-to-pole Isolation
--
330
V
Device
Rating
L7581
1000 V
4
Lucent Technologies Inc.
Data Sheet
November 1999
L7581 Ringing Access Switch
Electrical Characteristics
T
A
= 40 C to +85 C, unless otherwise specified.
Minimum and maximum values are testing requirements. Typical values are characteristics of the device and are
the result of engineering evaluations. Typical values are for information purposes only and are not part of the test-
ing requirements.
Table 4. Power Supply Specifications
* V
BAT
is used only as a reference for internal protection circuitry. If V
BAT
rises above 10 V, the device will enter an all OFF state and remain in
this state until the battery voltage drops below 15 V.
Table 5. Break Switches, 1 and 2
* This parameter is not tested in production. Choice of secondary protector should ensure this rating is not exceeded.
Applied voltage is 100 Vp-p square wave at 100 Hz.
Supply
Min
Typ
Max
Unit
V
DD
4.5
5
5.5
V
V
BAT*
19 --
72
V
Parameter
Test Condition
Measure
Min
Typ
Max
Unit
OFF-state Leakage
Current:
+25 C
+85 C
40 C
Vswitch (differential) = 320 V to Gnd
Vswitch (differential) = 60 V to +260 V
Vswitch (differential) = 330 V to Gnd
Vswitch (differential) = 60 V to +270 V
Vswitch (differential) = 310 V to Gnd
Vswitch (differential) = 60 V to +250 V
Iswitch
Iswitch
Iswitch
--
--
--
--
--
--
1
1
1
A
A
A
ON-resistance
(SW1, SW2):
+25 C
+85 C
40 C
T
LINE
= 10 mA, 40 mA, T
BAT
= 2 V
T
LINE
= 10 mA, 40 mA, T
BAT
= 2 V
T
LINE
= 10 mA, 40 mA, T
BAT
= 2 V
V
ON
V
ON
V
ON
--
--
--
19.5
--
14.5
--
28
--
ON-resistance Match
Per ON-resistance test
condition of SW1, SW2
Magnitude
R
ON
SW1 R
ON
SW2
--
0.2
1.0
ON-state Voltage*
Iswitch = I
LIMIT
@ 50 Hz/60 Hz
V
ON
--
--
220
V
dc Current Limit:
+85 C
40 C
Vswitch (on) = 10 V
Vswitch (on) = 10 V
Iswitch
Iswitch
80
--
--
--
--
250
mA
mA
Dynamic Current Limit
(t = <0.5 s)
Break switches in ON state; ringing
access switches off; apply 1000 V at
10/1000 s pulse; appropriate second-
ary protection in place
Iswitch
--
2.5
--
A
Isolation:
+25 C
+85 C
40 C
Vswitch (both poles) = 320 V,
Logic inputs = Gnd
Vswitch (both poles) = 330 V,
Logic inputs = Gnd
Vswitch (both poles) = 310 V,
Logic inputs = Gnd
Iswitch
Iswitch
Iswitch
--
--
--
--
--
--
1
1
1
A
A
A
dV/dt Sensitivity
--
--
--
200
--
V/s
Lucent Technologies Inc.
5
Data Sheet
November 1999
L7581 Ringing Access Switch
Electrical Characteristics
(continued)
Table 6. Ring Return Switch, 3
* This parameter is not tested in production. Choice of secondary protector should ensure this rating is not exceeded.
Applied voltage is 100 Vp-p square wave at 100 Hz.
Table 7. Ringing Access Switch, 4
* At the time of publication of this data sheet, the current device design will be a nominal 4 mA. Devices are being redesigned to reduce this
current to less than 2 mA nominally. Consult your Lucent Technologies Microelectronics Group account executive for additional details.
Choice of secondary protector and series current-limit resistor should ensure these ratings are not exceeded.
Applied voltage is 100 Vp-p square wave at 100 Hz.
Parameter
Test Condition
Measure Min
Typ Max Unit
OFF-state Leakage
Current (SW3):
+25 C
+85 C
40 C
Vswitch (differential) = 320 V to Gnd
Vswitch (differential) = 60 V to +260 V
Vswitch (differential) = 330 V to Gnd
Vswitch (differential) = 60 V to +270 V
Vswitch (differential) = 310 V to Gnd
Vswitch (differential) = 60 V to +250 V
Iswitch
Iswitch
Iswitch
--
--
--
--
--
--
1
1
1
A
A
A
dc Current Limit
Vswitch (on) = 10 V
Iswitch
--
200
--
mA
Dynamic Current
Limit (t = <0.5 s)
Break switches in ON state; ringing access switches
off; apply 1000 V at 10/1000 s pulse; appropriate
secondary protection in place
Iswitch
--
2.5
--
A
ON-resistance
Iswitch (on) = 0 mA, 10 mA
V
ON
--
--
100
ON-state Voltage*
Iswitch = I
LIMIT
@ 50 Hz/60 Hz
V
ON
--
--
130
V
Isolation:
+25 C
+85 C
40 C
Vswitch (both poles) = 320 V, Logic inputs = Gnd
Vswitch (both poles) = 330 V, Logic inputs = Gnd
Vswitch (both poles) = 310 V, Logic inputs = Gnd
Iswitch
Iswitch
Iswitch
--
--
--
--
--
--
1
1
1
A
A
A
dV/dt Sensitivity
--
--
--
200
--
V/s
Parameter
Test Condition
Measure
Min
Typ Max Unit
OFF-state Leakage
Current (SW3):
+25 C
+85 C
40 C
Vswitch (differential) = 255 V to +210 V
Vswitch (differential) = +255 V to 210 V
Vswitch (differential) = 270 V to +210 V
Vswitch (differential) = +270 V to 210 V
Vswitch (differential) = 245 V to +210 V
Vswitch (differential) = +245 V to 210 V
Iswitch
Iswitch
Iswitch
--
--
--
--
--
--
1
1
1
A
A
A
ON-resistance
Iswitch (on) = 70 mA, 80 mA
V
ON
--
--
12
ON Voltage
Iswitch (on) = 1 mA
--
--
--
3
V
Ring Generator Current
During Ring
V
CC
= 5 V
INPUT = 1
I
RINGSOURCE
--
*
--
mA
Steady-state Current
--
--
--
--
150
mA
Surge Current
--
--
--
--
2
A
Release Current
--
--
--
500
--
A
Isolation:
+25 C
+85 C
40 C
Vswitch (both poles) = 320 V, Logic inputs = Gnd
Vswitch (both poles) = 330 V, Logic inputs = Gnd
Vswitch (both poles) = 310 V, Logic inputs = Gnd
Iswitch
Iswitch
Iswitch
--
--
--
--
--
--
1
1
1
A
A
A
dV/dt Sensitivity
--
--
--
200
--
V/s
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