Datasheet ATTL7581AC, ATTL7581AAE, ATTL7581BC, ATTL7581BAE Datasheet (AGERE)

Data Sheet
November 1999

L7581 Ringing Access Switch

Features

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-resistan ce

■

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

■

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

22 Lucent Technologies Inc.

Data Sheet
November 1999

L7581 Ringing Access Switch

Pin Information

(continued)

Table 1. Pin Descriptions

DIP SOG Symbol Description DIP SOG Symbol Description

11 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.
32 T
43 T
56T

BAT

LINE

RINGING

Connect to TIP on SLIC side. 14 15 R
Connect to TIP on line side. 13 14 R
Connect to return ground for

12 12 R

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. 11 11 LATCH Data latch control, active-high,

transparent low.
7 5 NC No connection. 10 10 INPUT Logic 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

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

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

Device Rating

L7581 1000 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

Supply Min Typ Max Unit

V
V

DD
BAT*

4.5 5 5.5 V
–19 — –72 V

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

Parameter Test Condition Measure Min 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 Match Per ON-resistance test

condition of SW1, SW2

LIMIT

ON-state Voltage* Iswitch = I

@ 50 Hz/60 Hz V

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.

4 Lucent Technologies Inc.

Data Sheet
November 1999

L7581 Ringing Access Switch

Electrical Characteristics

(continued)

Table 6. Ring Return Switch, 3

Parameter Test Condition Measure 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 Limit Vswitch (on) = ±10 V Iswitch — 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

Iswitch — 2.5 — A

secondary protection in place

ON-resistance Iswitch (on) = 0 mA, ±10 mA

LIMIT

ON-state Voltage* Iswitch = I

@ 50 Hz/60 Hz V

ON

V

∆

ON

— — 100
— — 130 V

Isolation:

1

—

+25 °C
+85 °C
–40 °C

dV/dt Sensitivity

Vswitch (both poles) = ±320 V, Logic inputs = Gnd
Vswitch (both poles) = ±330 V, Logic inputs = Gnd
Vswitch (both poles) = ±310 V, Logic inputs = Gnd

†

— — — 200 — V/µs

Iswitch
Iswitch
Iswitch

—
—
—

—
—

1
1

µA
µA
µA

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.

Table 7. Ringing Access Switch, 4

Parameter Test Condition Measure Min 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-resistance Iswitch (on) = ±70 mA, ±80 mA

ON

V

∆

——12
ON Voltage Iswitch (on) = ± 1 mA — — — 3 V
Ring Generator Current

During Ring
Steady-state Current
Surge Current

†

†

CC

= 5 V

V

INPUT = 1

— — — — 150 mA
————2A

RINGSOURCE

I

—*—mA

Release Current — — — 500 — µA
Isolation:

1

—

+25 °C
+85 °C
–40 °C

dV/dt Sensitivity

Vswitch (both poles) = ±320 V, Logic inputs = Gnd
Vswitch (both poles) = ±330 V, Logic inputs = Gnd
Vswitch (both poles) = ±310 V, Logic inputs = Gnd

‡

— — — 200 — V/µs

Iswitch
Iswitch
Iswitch

—
—
—

—
—

1
1

µA
µA
µA

Ω

µA
µA
µA

* 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

L7581 Ringing Access Switch

Data Sheet

November 1999

Electrical Characteristics

(continued)

Table 8. Additional Electrical Characteristics

Parameter Test Condition Measure Min Typ Max Uni t

Digital Input Characteristics:

Input Low Voltage — — — — 1.5 V
Input High Voltage — — 3.5 — — V
Input Leakage Current (high) V

DD

= 5.5 V, V

BAT

= –75 V,

llogicin — — 1 µA

Vlogicin = 5 V

Input Leakage Current (low) V

DD

= 5.5 V, V

BAT

= –75 V,

llogicin — — 1 µA

Vlogicin = 0 V

Power Requirements:

DD

Power Dissipation V

= 5 V, V

Idle/talk state or all OFF state,

DD

V

Current VDD = 5 V,

Idle/talk state or all OFF state,

BAT

V

Current V

Idle/talk state or all OFF state,

BAT

= –48 V,

ringing state

ringing state

BAT

= –48 V,

ringing state

DD

BAT

I

I

I
I

I
I

, I

DD

DD
DD

BAT
BAT

—
—

3
6

——560

0.750

—
—

4
4

510mW

900

1.9

1010µA

Temperature Shutdown Requirements:*

Shutdown Activation Temperature — — 110 125 150 °C
Shutdown Circuit Hysteresis — — 10 — 25 °C

mW

µA

mA

µA

* Temperature shutdown flag (TSD) will be high during normal operation and low during temperature shutdown state.

Zero Cross Current Turn Off

The ring access switch (SW4) is designed to turn off on
the next zero current crossing after application of the
appropriate logic input control. This switch requires a
current zero cross to turn off. Switch 4, once on, will
remain in the ON state (regardless of logic input) until a
current zero cross. Therefore, to ensure proper opera­tion of switch 4, this switch should be connected, via
proper impedance, to the ringing generator or some
other ac source. Do not attempt to switch pure dc with
switch 4.

For a detailed explanation of the operation of switch 4,
please refer to the

Line Card Access Switches

An Introduction to L758X Series of

Application Note.

Switching Behavior

When switching from the power ringing state to the idle/
talk state via simple logic level input control, the L7581
is able to provide control with respect to the timing
when the ringing access contacts are released relative
to the state of the line break contacts.

Make-before-break operation occurs when the line
break switch contacts are closed (or made) before the
ringing access switch contact is opene d (or broken).
Break-before-make operation occurs when the ringing
access contact is opened (broke) before the line break
switch contacts are closed (made).

Using the logic level input pins INPUT and T
make-before-break or break-before-make operation of
the L7581 is easily achieved. The logic sequences for
either mode of operation are given in Table 9 and Table

10. See the Truth Table (Table 12) for an explanation of
the logic states.

SD

, either

6 Lucent Technologies Inc.

Data Sheet
November 1999

L7581 Ringing Access Switch

Switching Behavior

(continued)

and if current in excess of the SCR’s turn-on current is
also available, the SCR may turn on. Once the SCR is

When using an L7581 in the make-before-break mode,
during the ring-to-idle transit ion, for a period of up to
one-half the ringing frequency, the ring break switch
and the pnpn-type ring access switch can both be in
the ON state. This is the maximum time after the logic
signal at IN

RING

has transitioned that the ring access
switch is waiti ng f or the ne xt ze ro current c ross so it can
close. During this interval, current that is limited to the
dc break switch current-limit value will be sourced from

triggered on, if the SLIC is capable of supplying current
in excess of the holding current, the SCR may be
latched on by the SLIC.

The probability of this event depends on the character­istics of the given SLIC and of the holding current of the
L7581A device. The SCR hold current distribution is
designed to be safely away from the test limit of 80 mA.
The higher the distribution, the lower the probability of
the latch.

the ring node of the SLIC.

If this situation is of concern for a given board design,

This current is presented to the internal protection cir­cuit. If the SCR-type protector is used (A code), if by
random probability the ring-to-idle transition occurs

either use the A series device in the break-before-make
mode (eliminates the original 25 ms current pulse) or
use a B series device (eliminates the SCR).

during a portion of the ring cycle when the ringing volt­age exceeds the protection circuit SCR turn-on voltage,

Table 9. Make-Before-Break Operation

INPUT T

SD State Timing

5 V 5 V/Float Power

Break

Switches 1 & 2

— Open Closed Closed

Ring Return

Switch 3

Ring Access

Switch 4

Ringing

0 V 5 V/Float Make-

before-

break

SW4 waiting fo r next zero current
crossing to turn off, maximum
time—one-half of ringing. In this

Closed Open Closed

transition state, current that is lim­ited to the dc break switch cur­rent-limit value will be sourced
from the ring node of the SLIC.

0 V 5 V/Float Idle/Talk Zero cross current has occurred. Closed Open Open

Table 10. Break-Before-M ake Operation

INPUT T

SD State Timing

5 V 5 V/Float Power

Break

Switches 1 & 2

— Open Closed Closed

Ring Return

Switch 3

Ring Access

Switch 4

Ringing

5 V 0 V All Off Hold this state for ≤25 ms. SW4

Open Open Closed

waiting for zero current to turn off.

0 V 0 V All Off Zero current has occurred and

Open Open Open
SW4 has opened. Transition on
INPUT should occur during 25 ms
hold.

0 V 5 V/Float Idle/Talk Release break switch pair. Closed Open Open

Lucent Technologies Inc. 7

L7581 Ringing Access Switch

Data Sheet

November 1999

Power Supplies

Both the 5 V and battery supply are brought onto the
L7581. The L7581 requires only the 5 V supply for
switch operation; that is, state control is powered exclu­sively off of the 5 V supply. Because of this, the L7581
offers extremely low power dissipation, both in the idle
and active states.

The battery voltage is not used for switch state control.
The battery is used as a reference voltage by the inte­grated secondary protection circuit. When the voltage

BAT

at T
integrated SCR will trigger, thus preventing fault­induced overvoltage situations at the T

or R

BAT

drops 2 V to 4 V below the battery, the

BAT/RBAT

nodes.

Loss of Battery Voltage

As an additional protection feature, the L7581 monitors
the battery voltage. Upon loss of battery voltage, the
L7581 will automatically enter an all OFF state and
remain in that state until the battery voltage is restored.
The L7581 is designed so that the device will enter the
all OFF state if the battery rises above –10 V and will
remain off until the battery drops below –15 V.

Monitoring the battery for the automatic shutdown fea­ture will draw a small current from the battery, typically
4 µA. This will add slightly to the overall power dissipa­tion of the device.

Impulse Noise

Using the L7581 will minimize and possibly eliminate
the contribution to the overall system impulse noise
that is associated with ringing access switches.
Because of this characteristic of the L7581, it may not
be necessary to incorporate a zero cross switching
scheme. This ultimately depends upon the characteris­tics of the individual system and is best evaluated at
the board level.

Protection

Integrated SLIC Protection

Diode Bridge/SCR

In the L7581A
or other subsequent circuitry is provided by a combina­tion of current-limited break switches, a diode bridge/
SCR clamping circuit, and a thermal shutdown mecha­nism. In the L7581B
device or other subsequent circuitry is provided by a
combination of current-limited break switches, a diode
bridge, and a thermal shutdown mechanism.

In both versions, during a positive lightning event, fault
current is directed to ground via steering diodes in the
diode bridge. Voltage is clamped to a diode drop above
ground. In the A version, negative lightning causes the
SCR to conduct when the voltage goes 2 V to 4 V more
negative than the battery, and fault currents are
directed to ground via the SCR and steering diodes in
the diode bridge.

Note that for the SCR to foldback or crowbar, the ON
voltage (see Table 10) of the SCR must be less nega­tive than the battery reference voltage. If the battery
voltage is less negative than the SCR ON voltage, the
SCR will conduct fault currents to ground; however, it
will not crowbar.

In the B version, negative lightning is directed to battery
via steering diodes in the diode bridge.

For power cross and power induction faults, in both ver­sions, the positive cycle of the fault is clamped a diode
drop above ground and fault currents steered to
ground. In the A version, the negative cycle will cause
the SCR to trigger when the voltage exceeds the bat­tery reference voltage by 2 V to 4 V. When the SCR
triggers, fault current is steered to ground. In the B ver­sion, the negative cycle of the power cross is steered to
battery.

Current Limiting

xx version, protection to the SLIC device

xx version, protection to the SLIC

During a lightning event, the current that is passed
through the break switches and presented to the inte­grated protection circuit and subsequent circuitry is lim­ited by the dynamic current-limit response of the break
switches (assuming idle/talk state). When the voltage
seen at the T
an external secondary protector, upon application of a
1000 V 10 x 1000 pulse (LSSGR lightning), the current
seen at the T
magnitude 2.5 A and duration less than 0.5 µs.

88 Lucent Technologies Inc.

LINE/RLINE

BAT/RBAT

nodes is properly clamped by

nodes will typically be a pulse of

Data Sheet
November 1999

L7581 Ringing Access Switch

Protection

Integrated SLIC Protection

(continued)

(continued)

During a power cross event, the current that is passed
through the break switches and presented to the inte­grated protection circuit and subsequent circuitry is lim­ited by the dc current-limit response of the break
switches (assuming idle/talk state). The dc current limit
is specified over temperature between 100 mA and
250 mA.

Note that the current-limit circuitry has a negative tem­perature coefficient. Thus, if the device is subjected to
an extended power cross, the value of current seen at

BAT/RBAT

T

will decrease as the device heats due to the
fault current. If sufficient heating occurs, the tempera­ture shutdown mechanism will activate and the device
will enter an all off mode.

Temperature Shutdown Mechanism

When the device temperature reaches a minimum of
110 °C, the thermal shutdown mechanism will activate
and force the device into an all OFF state, regardless of
the logic input pins. Pin T

SD

, when used as an output,
will read 0 V when the device is in the thermal shut­down mode and +V

DD

during norm al operation.

During a lightning event, due to the relatively short
duration, the thermal shutdown will not typically acti­vate.

In the L7581, the thermal shutdown mechanism
cannot be disabled by logic control at the T
The functionality of T

SD

differs from the L7541, L7582,

SD

pin.

and L7583. For the proper use of and understanding of
any caveats related to T

SD

, please refer to the appropri-

ate data sheet specifications.
Electrical specifications relating to the overvoltage

clamping circuit are outlined in Table 11.

External Secondary Protector

With the above integrated protection features, only one
overvoltage secondary protection device on the loop
side of the L7581 is required. The purpose of this
device is to limit fault voltages seen by the L7581 so as
not to exceed the breakdown voltage or input-output
isolation rating of the device. To minimize stress on the
L7581, use of a foldback- or crowbar-type device is rec­ommended. A detailed explanation and design equa­tions on the choice of the external secondary
protection device are given in the

L758X Series of Line Card Access Switches

An Introduction to

Applica­tion Note. Basic design equations governing the choice
of external secondary protector are given below:

|

V

■

BATmax

|

V

■

ringingpeakmax

|

V

breakdownmin(ring)

|

V

■

ringingpeakmax

| + |V

breakovermax

| + |V

|

|

+ |V

BATmax

BATmax

|

< |V

breakdownmin(break)

|

+ |V

breakovermax

|

< |V

breakovermin

|

|

|

<

where:

During an extended power cross, the device tempera­ture will rise and cause the device to enter the thermal
shutdown mode. This forces an all off mode, and the
current seen at T

BAT/RBAT

drops to zero. Once in the
thermal shutdown mode, the device will cool and exit
the thermal shutdown mode, thus reentering the state it
was in prior to thermal shutdown. Current, limited to the
dc current-limit value, will again begin to flow and
device heating will begin again. This cycle of entering
and exiting thermal shutdown will last as long as the
power cross fault is present. The frequency of entering
and exiting thermal shutdown will depend on the mag­nitude of the power cross.

If the magnitude of the power cross is great enough,
the external secondary protector may trigger shunting
all current to ground.

V
V

—Maximum magnitude of battery voltage.

BATmax
breakovermax

—Maximum magnitude breakover voltage

of external secondary protector.
V

breakovermin

—Minimum magnitude breakover voltage

of external secondary protector.
V

breakdownmin(break)

—Minimum magnitude breakdown

voltage of L7581 break switch.
V

breakdownmin(ring)

—Minimum magnitude breakdown

voltage of L7581 ring access switch.
V

ringingpeakmax

—Maximum magnitude peak voltage of

ringing signal.
Series current-limiting fused resistors or PTCs should

be chosen so as not to exceed the current rating of the
external secondary protector. Refer to the manufac­turer’s data sheet for specifications.

Lucent Technologies Inc. 9

L7581 Ringing Access Switch

Data Sheet

November 1999

Protection

Integrated SLIC Protection

(continued)

(continued)

Table 11. Electrical Specifications, Protection Circuitry

Parameters Related to Diodes (in Diode Bridge)

Parameter Test Condition Measure Min Typ Max Unit

Voltage Drop @ Continuous Cur-

rent (50 Hz/60 Hz)

Voltage Drop @ Surge

Current

Apply ±dc cur rent lim it

of break switches

Apply ±dynamic cur-

rent limit of break

Forward

Voltage

Forward

Voltage

—— 3 V

—5 — V

switches

Parameters Related to Protection SCR

Surge Current — — — —
Gate Trigger Current*
Gate Trigger Current

†

†

Temperature

———2550mA
— — — –0.5 — %/°C

‡

Coefficient
Hold Current — — 70 — mA
Gate Trigger Voltage Trigger current — V
Reverse Leakage Current V
ON-State Voltage

§

0.5 A, t = 0.5 µs

2.0 A, t = 0.5 µs

BAT

———1.0µA

ON

V

—

– 4 — V

BAT

—
—

–3
–5

– 2 V

BAT

—
—

A

V
V

* Previous versions of this data sheet specified a Trigger Current of 50 mA minimum. Trigger Current is defined as the minimum current drawn

from tip and ring to turn on the SCR. The specification in this data sheet is Gate Trigger Current, which is defined as the maximum current

that can flow into the battery before the SCR turns on.

† Typical at 25 °C.
‡ Twice ± dynamic current limit of break switches.

§ In some instances, the typical ON-state voltage can range as low as –25 V.

10 Lucent Technologies Inc.

Data Sheet

+I

+V

–1.5 V

2/3 R

ON

CURRENT

LIMITING

–I

–V

CURRENT

LIMITING

I

LIMIT

I

LIMIT

R

ON

1.5 V

2/3 R

ON

R

ON

+I

+V

OS

+V

R

ON

–V

OS

–I

–V

November 1999

Typical Performance Characteristics

dc CURRENT-LIMIT

BREAK SWITCHES

BAT

V

– 2

BAT

V

– 4

BAT

V

ON

V

L7581 Ringing Access Switch

<1 µA

50 mA

Figure 3. Protection Circuit A Version

dc CURRENT-LIMIT

BREAK SWITCHES

BAT

– 3

V

BAT

V

<1 µA

3 V

dc CURRENT LIMIT
(OF BREAK SWITCHES)

H

I

12-2309.f (F)

3 V

12-2311 (F)

Figure 5. Switches 1—3

dc CURRENT LIMIT
(OF BREAK SWITCHES)

12-2309.b (F)

Figure 6. Switch 4

Figure 4. Protection Circuit B Version

Lucent Technologies Inc. 11

12-2312 (F)

L7581 Ringing Access Switch

Application

R1

TIP

CROWBAR

PROTECTION

SW3

SW1

SCR
AND

TRIP

CKT

BAT

V
(REFERENCE)

Data Sheet

November 1999

TIP

BATTERY

FEED

RING

R2

SW2

SW4

RING
GENERATOR

BATTERY

Figure 7. Typical RAS Application, A Version, Idle, or Talk State Shown

Table 12. Truth Table

INPUT T

0 V 5 V/Float
5 V 5 V/Float

Don’t Care 0 V

1. Thermal shutdown mechanism is active with TSD floating or equal to 5 V.

2. Forcing T

3. Idle/Talk state.

4. Power ringing state.

5. All OFF state.

SD

to ground overrides the logic input pins and forces an all OFF state.

SD Tip Break Switch Ring Break Switch Ringing Return Switch Ring Switch

1
1

2

On On Off Off
Off Off On On
Off Off Off Off

RING

12-3074.e (F)

3
4
5

A parallel in/parallel out data latch is integrated into the L7581. Operation of the data latch is controlled by the logic
level input pin LATCH. The data input to the latch is the INPUT pin of the L7581, and the output of the data latch is
an internal node used for state control.

When the LATCH control pin is at logic 0, the data latch is transparent and data control signals flow directly from
INPUT, through the data latch to state control. Any changes in INPUT will be reflected in the state of the switches.

When the LATCH control pin is at logic 1, the data latch is active—the L7581 will no longer react to changes at the
INPUT control pin. The state of the switches is now latched; that is, the state of the switches will remain as they
were when the LATCH input transitioned from logic 0 to logic 1. The switches will not respond to changes in INPUT
as long as LATCH is held high.

Note that the T

SD

input is not tied to the data latch. TSD is not affected by the LATCH input. TSD input will override

state control via INPUT and LATCH.
12 Lucent Technologies Inc.

Data Sheet
November 1999

L7581 Ringing Access Switch

Outline Diagrams

16-Pin, Plastic SOG (L7581AAE/BAE)

Note: The dimensions in this outline diagram are intended for informational purposes only. F or detailed schematics

to assist your design efforts, please contact your Lucent Technologies Sales Representative.

L

N

B

1

PIN #1 IDENTIFIER ZONE

H

SEATING PLANE

1.27 TYP

Number

of Pins

(N)

0.51 MAX

Maximum

Length

(L)

0.28 MAX

Maximum Width

Without Leads

(B)

0.10

Maximum Width
Including Leads

(W)

0.61

Maximum Height

16 10.49 7.62 10.64 2.67

W

Above Board

(H)

5-4414r2 (C)

Lucent Technologies Inc. 13

L7581 Ringing Access Switch

Data Sheet

November 1999

Outline Diagrams

(continued)

16-Pin, Plastic DIP (L7581AC/BC)

Note: The dimensions in this outline diagram are intended for informational purposes only. For detailed schematics

to assist your design efforts, please contact your Lucent Technologies Sales Representative.

N

1

PIN #1 IDENTIFIER ZONE

L

B

W

H

SEATING PLANE

0.38 MIN

Number

of Pins

(N)

2.54 TYP

Maximum

Length

(L)

0.58 MAX

Maximum Width

Without Leads

(B)

Maximum Width
Includi n g Leads

(W)

Maximum Height

Above Board

16 20.57 6.48 7.87 5.08

(H)

5-4410 (F)

14 Lucent Technologies Inc.

Data Sheet
November 1999

L7581 Ringing Access Switch

Ordering Information

Device Part No. Description Package Comcode

ATTL7581AAE Ringing Access Switch 16-Pin SOG 107338469
ATTL7581AAE-TR* Ringing Access Switch 16-Pin SOG (Tape & Reel) 107338493
ATTL7581AC Ringing Access Switch 16-Pin DIP 107338436
ATTL7581BAE Ringing Access Switch 16-Pin SOG 107392839
ATTL7581BAE-TR* Ringing Access Switch 16-Pin SOG (Tape & Reel) 107392953
ATTL7581BC Ringing Access Switch 16-Pin DIP 107392995

*Devices on tape and reel must be ordered in 1000-piece increments.

Lucent Technologies Inc. 15

For additional information, contact your Microelectronics Group Account Manager or the following:
INTERNET:
E-MAIL:
N. AMERICA:Microelectronics Group, Lucent Technologies In c., 55 5 Uni on Boulevard, Room 30L-15P-BA, Allentown, PA 1 81 03

ASIA PACIFIC:Microelectronics Group, Lucent Technologies Singapore Pte. Ltd . , 77 Science Park Drive, #03-18 Cintech III, Singapore 118256
CHINA: Microelectronics Group, Lucent Technologies (China) Co., Ltd., A-F2, 23/F, Zao Fong Universe Building, 1800 Zhong Shan Xi Road, Shanghai
JAPAN: Microelectronics Group, Lucent Technologies Japan Ltd., 7-18, Higashi-Gotanda 2-chome, Shinagawa-ku, Tokyo 141, Japan
EUROPE: Data Requests: MICROELECTRONICS GROUP DATALINE:

Lucent Technologies Inc. reserves the right to make changes to the product(s) or information contained herein without notice. No liability is assumed as a result of their use or application. No
rights under any patent accompany the sale of any such product(s) or information.

http://www.lucent.com/micro
[e-mail]

1-800-372-2447
Tel. [phone]

200233 P. R. China

Tel. [phone]

Technical Inquiries:GERMANY:

, FAX [phone] (In CANADA:

, FAX [phone]

Tel. [phone], ext. 316

, FAX [phone]

FRANCE:
ITALY:

(39) 02 6608131

(49) 89 95086 0

(33) 1 40 83 68 00

(Milan), SPAIN:

1-800-553-2448

, FAX [phone]

(Munich), UNITED KINGDOM:

(Paris), SWEDEN:

, FAX [phone])

Tel. [phone]

(46) 8 594 607 00

(34) 1 807 1441

(Madrid)

, FAX [phone]

(44) 1344 865 900

(Stockholm), FINLAND:

(Ascot),

(358) 9 4354 2800

(Helsinki),

Copyright © 1999 Lucent Technologies Inc.
All Rights Reserved

November 1999
DS00-050ALC (Replaces DS99-014ALC)