Data Sheet
November 1999
L7581 Ringing Access Switch
Features
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Small size/surface-mount packaging
Monolithic IC reliability
Low impulse noise
Make-before-break, break-before-make operation
Clean, bounce-free switching
Low, matched ON-resistance
Built-in current limiting, thermal shutdown, and
SLIC protection
5 V only operation, very low power consumption
Battery monitor, all OFF state upon loss of battery
No EMI
Latched logic level inputs, no drive circuitry
Only one external protector required
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.
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Applications
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Central office
DLC
PBX
DAML
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
L7581 Ringing Access Switch
Data Sheet
November 1999
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.
Pin Information
F
GND
NC
T
BAT
T
LINE
T
RINGING
V
DD
NC
T
SD
1
2
3
4
5
6
7
8
SCR
AND
TRIP
CKT
16 V
BAT
15 NC
14 R
BAT
13 R
LINE
12 R
RINGING
11 LATCH
10 INPUT
SW1
SW2
SW3
SW4
TEMPERATURE
SHUTDOWN
9
D
GND
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
F
GND
*
UL
is a registered trademark of Underwriters Laboratories, Inc.
T
BAT
T
LINE
NC
NC
T
RINGING
V
DD
T
SD
1
2
SW1
3
SW3
4
5
6
7
8
TEMPERATURE
SHUTDOWN
SW2
SW4
16 V
BAT
15 R
BAT
14 R
LINE
13 NC
12 R
RINGING
11 LATCH
10 INPUT
9
D
GND
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
2
Lucent Technologies Inc.
Data Sheet
November 1999
L7581 Ringing Access Switch
Pin Information
(continued)
Table 1. Pin Descriptions
DIP SOG
1
1
2
3
4
5
6
7
8
4
2
3
6
7
5
8
Symbol
F
GND
NC
T
BAT
T
LINE
T
RINGING
V
DD
NC
T
SD
Description
Fault ground.
No connection.
Connect to TIP on SLIC side.
Connect to TIP on line side.
Connect to return ground for
ringing generator.
5 V supply.
DIP SOG
16
16
15
14
13
12
11
13
15
14
12
11
10
9
Symbol
V
BAT
NC
R
BAT
R
LINE
R
RINGING
LATCH
INPUT
D
GND
Description
Battery voltage. Used as a ref-
erence for protection circuit.
No connection.
Connect to RING on SLIC side.
Connect to RING on line side.
Connect to ringing generator.
Data latch control, active-high,
transparent low.
Logic level input switch control.
Digital ground.
No connection.
10
9
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.
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
Parameter
Operating Temperature Range
Storage Temperature Range
Relative Humidity Range
Pin Soldering Temperature
5 V Power Supply
Battery Supply
Logic Input Voltage
Input-to-output Isolation
Pole-to-pole Isolation
Min
–40
–40
5
—
—
—
—
—
—
Max
110
150
95
10
7
–85
7
330
330
Unit
°C
°C
%
°C
V
V
V
V
V
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
Ω,
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
Device
L7581
Rating
1000 V
Lucent Technologies Inc.
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L7581 Ringing Access Switch
Data Sheet
November 1999
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
Supply
V
DD
V
BAT*
Min
4.5
–19
Typ
5
—
Max
5.5
–72
Unit
V
V
* 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
Parameter
OFF-state Leakage
Current:
+25 °C
+85 °C
–40 °C
ON-resistance
(SW1, SW2):
+25 °C
+85 °C
–40 °C
ON-resistance Match
ON-state Voltage*
dc Current Limit:
+85 °C
–40 °C
Dynamic Current Limit
(t = <0.5 µs)
Test Condition
Measure
Min Typ Max
Unit
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
µA
µA
µA
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
Per ON-resistance test
condition of SW1, SW2
Iswitch = I
LIMIT
@ 50 Hz/60 Hz
Vswitch (on) = ±10 V
Vswitch (on) = ±10 V
Break switches in ON state; ringing
access switches off; apply ±1000 V at
10/1000 µs pulse; appropriate second-
ary protection in place
Vswitch (both poles) = ±320 V,
Logic inputs = Gnd
Vswitch (both poles) = ±330 V,
Logic inputs = Gnd
Vswitch (both poles) = ±310 V,
Logic inputs = Gnd
—
∆
V
ON
∆
V
ON
∆
V
ON
Magnitude
R
ON
SW1 – R
ON
SW2
V
ON
Iswitch
Iswitch
Iswitch
—
—
—
—
—
80
—
—
19.5
—
14.5
0.2
—
—
—
2.5
—
28
—
1.0
220
—
250
—
Ω
Ω
Ω
Ω
V
mA
mA
A
Isolation:
+25 °C
+85 °C
–40 °C
dV/dt Sensitivity
†
Iswitch
Iswitch
Iswitch
—
—
—
—
—
—
—
—
200
1
1
1
—
µA
µA
µA
V/µs
* 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.
4
Lucent Technologies Inc.
Data Sheet
November 1999
L7581 Ringing Access Switch
Electrical Characteristics
(continued)
Table 6. Ring Return Switch, 3
Parameter
OFF-state Leakage
Current (SW3):
+25 °C
+85 °C
–40 °C
dc Current Limit
Dynamic Current
Limit (t = <0.5 µs)
ON-resistance
ON-state Voltage*
Isolation:
+25 °C
+85 °C
–40 °C
dV/dt Sensitivity
†
Test Condition
Measure Min Typ Max Unit
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
Vswitch (on) = ±10 V
Break switches in ON state; ringing access switches
off; apply ±1000 V at 10/1000 µs pulse; appropriate
secondary protection in place
Iswitch (on) = 0 mA, ±10 mA
Iswitch = I
LIMIT
@ 50 Hz/60 Hz
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
Iswitch
Iswitch
—
—
—
—
—
—
—
—
200
2.5
1
1
1
—
—
µA
µA
µA
mA
A
∆
V
ON
V
ON
Iswitch
Iswitch
Iswitch
—
—
—
—
—
—
—
—
—
—
—
—
200
100
130
1
1
1
—
Ω
V
µA
µA
µA
V/µs
* 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
Parameter
OFF-state Leakage
Current (SW3):
+25 °C
+85 °C
–40 °C
Test Condition
Measure
Min Typ Max Unit
ON-resistance
∆
V
ON
ON Voltage
—
I
RINGSOURCE
Ring Generator Current
During Ring
Steady-state Current
†
—
Surge Current
†
—
Release Current
—
Isolation:
Iswitch
Vswitch (both poles) = ±320 V, Logic inputs = Gnd
+25 °C
Iswitch
Vswitch (both poles) = ±330 V, Logic inputs = Gnd
+85 °C
Iswitch
Vswitch (both poles) = ±310 V, Logic inputs = Gnd
–40 °C
—
—
dV/dt Sensitivity
‡
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 (on) = ±70 mA, ±80 mA
Iswitch (on) = ± 1 mA
V
CC
= 5 V
INPUT = 1
—
—
—
Iswitch
Iswitch
Iswitch
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
*
—
—
500
—
—
—
200
1
1
1
12
3
—
150
2
—
1
1
1
—
µA
µA
µA
Ω
V
mA
mA
A
µA
µA
µA
µA
V/µs
* 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.
Lucent Technologies Inc.
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