le75282 Zarlink Semiconductor, le75282 Datasheet - Page 9

• Manufacturer Part Number: le75282
• Description: Dual Intelligent Line Card Access Switch
• Manufacturer: Zarlink Semiconductor

ZERO CROSS CURRENT TURN OFF
The ringing access switch (SW4x) 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. This switch, once on, will remain in the ON state
(regardless of logic input) until a current zero cross. Therefore, to ensure proper operation, 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 the ringing access
switch.
SWITCHING BEHAVIOR
When switching from the Ringing state to the Idle/Talk state via simple logic level input control, the Le75282 device is able to
provide timing control 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 (broken) before
the line break switch contacts are closed (made).
Using the logic level input pins P1’ and P2’, either make-before-break or break-before-make operation of the Le75282 device is
easily achieved. The logic sequences are presented in Tables 7 and 8. See
for an explanation of the logic states.
When using an Le75282 device in the make-before-break mode during the ring-to-idle transition, for a period of up to one-half
the ringing frequency, the B break switch and the pnpn-type ringing access switch can both be in the ON state. This is the
maximum time after the logic signal at RD2 has transitioned, where the ringing access switch is waiting to open at the next zero
current cross. During this interval, current that is limited to the DC break switch current-limit value will be sourced from the BD
node of the SLIC device.
1. Combined power or current of both channels, both channels in same state.
3. Temperature shutdown flag (TSDx) will be high during normal operation and low during temperature shutdown state.
2. Controlled via OFFx pin.
Table 6. Additional Electrical Characteristics (Continued)
Table 7. Make-Before-Break Operation
Power Requirements
Temperature Shutdown Requirements
Shutdown Activation Temperature
Shutdown Circuit Hysteresis
Loss of Battery Detector Threshold:
Loss of Battery
Resumption of Battery
CFG=0, RD3=0
RD2
Power Dissipation
V
V
1
0
0
DD
BH
Current
Current
RD1
0
0
0
OFFx
1
:
1
1
1
Idle/Talk
Ringing
before-
Make-
break
State
3
:
—
SW4 waiting for next zero current
crossing to turn off, maximum
time—one-half of ringing. In this
transition state, current that is
limited to the dc break switch
current-limit value will be sourced
from the BD node of the SLIC.
Zero cross current has occurred.
V
V
V
—
—
—
—
Idle/Talk state
All Off state
Ringing or Test Access state
Idle/Talk state
All Off state
Ringing or Test Access state
DD
DD
BH
Zarlink Semiconductor Inc.
= –48 V, All states
= 5 V, V
= 5 V,
2
BH
Timing
9
= –48 V,
Table 9,
Switches
1x & 2x
Break
Operating States: CFG =
OFF
ON
ON
I
I
I
I
I
I
I
—
—
—
—
DD
DD
DD
DD
DD
DD
V
BH
, I
, I
, I
V
V
V
BH
BH
BH
Ringing
Return
Switch
OFF
OFF
ON
3x
110
–19
–19
—
—
—
—
—
—
—
10
Ringing
Access
Switch
OFF
–14
ON
ON
125
–12
4x
—
—
—
—
—
—
—
4
0, on page 17
150
7.5
2.0
1.5
4.0
10
20
10
25
–5
–5
Switches
Access
5x & 6x
Test
OFF
OFF
OFF
mW
mW
mW
mA
mA
mA
µA
°C
°C
V
V