L7581 Ringing Access Switch
Data Sheet
November 1999
Electrical Characteristics
(continued)
Table 8. Additional Electrical Characteristics
Parameter
Digital Input Characteristics:
Input Low Voltage
Input High Voltage
Input Leakage Current (high)
Input Leakage Current (low)
Power Requirements:
Power Dissipation
Test Condition
—
—
V
DD
= 5.5 V, V
BAT
= –75 V,
Vlogicin = 5 V
V
DD
= 5.5 V, V
BAT
= –75 V,
Vlogicin = 0 V
V
DD
= 5 V, V
BAT
= –48 V,
Idle/talk state or all OFF state,
ringing state
V
DD
= 5 V,
Idle/talk state or all OFF state,
ringing state
V
BAT
= –48 V,
Idle/talk state or all OFF state,
ringing state
—
—
Measure
—
—
llogicin
llogicin
Min
—
3.5
—
—
Typ
—
—
—
—
Max Unit
1.5
—
1
1
V
V
µA
µA
I
DD
, I
BAT
I
DD
I
DD
I
DD
I
BAT
I
BAT
—
—
—
—
—
—
—
—
110
10
3
6
5
10
mW
mW
µA
mA
µA
µA
°C
°C
V
DD
Current
560 900
0.750 1.9
4
4
125
—
10
10
150
25
V
BAT
Current
Temperature Shutdown Requirements:*
Shutdown Activation Temperature
Shutdown Circuit Hysteresis
* 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 opera-
tion 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
An Introduction to L758X Series of
Line Card Access Switches
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 opened (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
SD
, either
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
the logic states.
6
Lucent Technologies Inc.
AGERE [ AGERE SYSTEMS ]
