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
■
Applications
Central office
■
DLC
■
PBX
■
DAML
■
HFC/FITL
■
Description
The L7581 Ringing Access Switch is a monolithic
solid-state device that provides the switching functionality 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 analog 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-beforebreak switching, with simple logic level input control.
Because of the solid-state construction, voltage transients generated when switching into an inductive
ringing load during ring cadence or ring trip are minimized, 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 protection, to prevent breakdown in the presence of a transient fault condition (i.e., passing the transient on to
the ringing generator).
Incorporated into the L7581A
xx 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 currentlimiting and thermal shutdown circuits.
The L7581B
xx version provides only an integrated
diode bridge along with current limiting and thermal
shutdown, as shown in Figure 2. This will cause positive 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 mechanisms.
L7581 Ringing Access Switch
Data Sheet
November 1999
Description
(continued)
To protect the L7581 from an overvoltage fault condition, use of a secondary protector is required. The secondary 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 crowbartype 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
protection requirements.
UL*
The L7581 operates off of a 5 V supply only. This gives
the device extremely low idle and active power dissipation 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.
Pin Information
GND
1
F
2
NC
BAT
3
T
LINE
T
RINGING
T
DD
V
NC
SD
T
Note: Shown with A version protection. The 16-pin DIP is available
with either A or B version protection.
SW1
4
5
6
7
8
SCR
AND
TRIP
CKT
SW2
TEMPERATURE
SHUTDOWN
SW4SW3
Figure 1. 16-Pin, Plastic DIP
16
15
14
13
12
11
10
9
BAT
V
NC
BAT
R
LINE
R
RINGING
R
LATCH
INPUT
GND
D
12-2306.a (C)
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.
GND
1
F
BAT
2
T
LINE
T
NC
NC
RINGING
T
DD
V
SD
T
Note: Shown with B version protection. The 16-pin SOG is available
with either A or B version protection.
SW1
3
SW3
4
5
6
7
8
SW2
SW4
TEMPERATURE
SHUTDOWN
16
15
14
13
12
11
10
9
BAT
V
BAT
R
LINE
R
NC
RINGING
R
LATCH
INPUT
GND
D
12-2307.a (F)
Figure 2. 16-Pin, Plastic SOG
22Lucent Technologies Inc.
Data Sheet
November 1999
L7581 Ringing Access Switch
Pin Information
(continued)
Table 1. Pin Descriptions
DIP SOGSymbolDescriptionDIP SOGSymbolDescription
11 F
GND
Fault ground.1616V
BAT
Battery voltage. Used as a ref-
erence for protection circuit.
24NCNo connection.1513NCNo connection.
32 T
43 T
56T
BAT
LINE
RINGING
Connect to TIP on SLIC side.1415R
Connect to TIP on line side.1314R
Connect to return ground for
1212R
BAT
LINE
RINGING
Connect to RING on SLIC side.
Connect to RING on line side.
Connect to ringing generator.
ringing generator.
67 V
DD
5 V supply.1111LATCHData latch control, active-high,
transparent low.
75NCNo connection.1010INPUTLogic level input switch control.
88 T
SD
Temperature shutdown pin. Can
99 D
GND
Digital ground.
be used as a logic level input or
output. See Table 12, Truth
Table, and the Switching Behavior section of this data sheet for
input pin description. As an output, will read 5 V when device is
in its operational mode and 0 V
in the thermal shutdown mode.
In the L7581, the thermal shutdown mechanism cannot be disabled.
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
ParameterMinMaxUnit
Operating Temperature Range–40110°C
Storage Temperature Range–40150°C
Relative Humidity Range595%
Pin Soldering Temperature—10°C
5 V Power Supply—7V
Battery Supply—–85V
Logic Input Voltage—7V
Input-to-output Isolation—330V
Pole-to-pole Isolation—330V
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 Microelectronics Group employs a human-body model
(HBM) and a charged-device model (CDM) for ESDsusceptibility 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 standard HBM (resistance = 1500 Ω, capacitance = 100 pF)
is widely used and therefore can be used for comparison purposes. The HBM ESD threshold presented
here was obtained by using these circuit parameters.
Table 3. HBM ESD Threshold Voltage
DeviceRating
L75811000 V
Lucent Technologies Inc.3
L7581 Ringing Access Switch
Data Sheet
November 1999
Electrical Characteristics
TA = –40 °C to +85 °C, unless otherwise specified.
Minimum and maximum values are testing requirements. Ty pical values are characteristics of the device and are
the result of engineering evaluations. Typical v alues are for information purposes only and are not part of the testing requirements.
Table 4. Power Supply Specifications
SupplyMinTypMaxUnit
V
V
DD
BAT*
4.5 5 5.5 V
–19 —–72V
BAT
*V
is used only as a reference for internal protection circuitry. I f V
this state until the battery voltage drops below –15 V.
Table 5. Break Switches, 1 and 2
ParameterTest ConditionMeasureMin Typ Max Unit
OFF-state Leakage
Current:
+25 °C
Vswitch (differential) = –320 V to Gnd
Vswitch (differential) = –60 V to +260 V
+85 °C
Vswitch (differential) = –330 V to Gnd
Vswitch (differential) = –60 V to +270 V
–40 °C
Vswitch (differential) = –310 V to Gnd
Vswitch (differential) = –60 V to +250 V
ON-resistance
(SW1, SW2):
+25 °C
+85 °C
–40 °C
LINE
T
= ±10 mA, ±40 mA, T
LINE
T
= ±10 mA, ±40 mA, T
LINE
T
= ±10 mA, ±40 mA, T
ON-resistance MatchPer ON-resistance test
condition of SW1, SW2
LIMIT
ON-state Voltage*Iswitch = I
@ 50 Hz/60 HzV
dc Current Limit:
+85 °C
–40 °C
Dynamic Current Limit
(t = <0.5 µs)
Break switches in ON state; ringing
access switches off; apply ±1000 V at
Vswitch (on) = ±10 V
Vswitch (on) = ±10 V
10/1000 µs pulse; appropriate second-
ary protection in place
Isolation:
+25 °C
Vswitch (both poles) = ±320 V,
Logic inputs = Gnd
+85 °C
Vswitch (both poles) = ±330 V,
Logic inputs = Gnd
–40 °C
Vswitch (both poles) = ±310 V,
Logic inputs = Gnd
dV/dt Sensitivity
†
———200—V/µs
BA T
rises above –10 V, the device will enter an all OFF state and remain in
1
—
—
1
—
—
1
—
—
—
—
—
19.5
14.5
—
—
28
—
—0.21.0
——220V
80————
250mAmA
BAT
BAT
BAT
= –2 V
= –2 V
= –2 V
Iswitch
Iswitch
Iswitch
ON
V
∆
ON
V
∆
ON
V
∆
Magnitude
ON
R
SW1 – RON SW2
ON
Iswitch
Iswitch
Iswitch—2.5—A
1
—
Iswitch
Iswitch
Iswitch
—
—
—
—
—
1
1
µA
µA
µA
Ω
Ω
Ω
Ω
µA
µA
µA
* 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.
4Lucent Technologies Inc.
Data Sheet
November 1999
L7581 Ringing Access Switch
Electrical Characteristics
(continued)
Table 6. Ring Return Switch, 3
ParameterTest ConditionMeasure Min Typ Max Unit
OFF-state Leakage
Current (SW3):
+25 °C
Vswitch (differential) = –320 V to Gnd
Iswitch
—
—
1
Vswitch (differential) = –60 V to +260 V
+85 °C
Vswitch (differential) = –330 V to Gnd
Iswitch
—
—
1
Vswitch (differential) = –60 V to +270 V
–40 °C
Vswitch (differential) = –310 V to Gnd
Iswitch
—
—
1
Vswitch (differential) = –60 V to +250 V
dc Current LimitVswitch (on) = ±10 VIswitch—200—mA
Dynamic Current
Limit (t = <0.5 µs)
Break switches in ON state; ringing access switches
off; apply ±1000 V at 10/1000 µs pulse; appropriate
* 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
ParameterTest ConditionMeasureMin Typ Max Unit
OFF-state Leakage
Current (SW3):
+25 °C
Vswitch (differential) = –255 V to +210 V
Iswitch
—
1
—
Vswitch (differential) = +255 V to –210 V
+85 °C
Vswitch (differential) = –270 V to +210 V
Iswitch
—
1
—
Vswitch (differential) = +270 V to –210 V
–40 °C
Vswitch (differential) = –245 V to +210 V
Iswitch
—
1
—
Vswitch (differential) = +245 V to –210 V
ON-resistanceIswitch (on) = ±70 mA, ±80 mA
ON
V
∆
——12
ON VoltageIswitch (on) = ± 1 mA———3V
Ring Generator Current
* 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.5
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