le75282 Zarlink Semiconductor, le75282 Datasheet - Page 15

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

Le75282
Data Sheet
For option 3, LCAS CFG = 1 and LCAS P3’ = 0, wire SLAC P1 to LCAS P2’, and wire SLAC P3 to LCAS P1’, do not wire SLAC
P2 to the LCAS device. The test load (if enabled) can then be applied independent of the LCAS operating state. When SLAC P1
= 1, the Ringing and All Off state will be activated when the external ringing signal is at zero cross (assuming CCR4 RMODE is
set for external ringing (1) and ZXR is set for enable zero cross ringing relay operation (0)). For the Ringing state this is the desired
operation. For the All Off state, the delay in activation needs to be considered in the firmware. An immediate All Off state can
always be asserted by controlling OFFx or by writing the ZXR bit to disable zero cross ringing relay operation prior to writing the
All Off state.
For option 4, LCAS CFG = 0, wire SLAC P1 to LCAS P2’, wire SLAC P2 to LCAS P1’, and wire SLAC P3 to LCAS P3’. The test
load (if enabled) will be applied when the LCAS device is in the Test, Test/Monitor, and Test Ringing states. When SLAC P1 =
1, the Ringing, Test Ringing, and Test/Monitor state will be activated when the external ringing signal is at zero cross (assuming
CCR4 RMODE is set for external ringing (1) and ZXR is set for enable zero cross ringing relay operation (0)). For the Ringing
and Test Ringing state this is the desired operation. For the Test/Monitor state, the delay in activation needs to be considered in
the firmware. An immediate Test/Monitor state can always be asserted by writing the ZXR bit to disable zero cross ringing relay
operation prior to writing the Test/Monitor state.
For option 5, LCAS CFG = 1, wire SLAC P1 to LCAS P2’, wire SLAC P2 to LCAS P1’, and wire SLAC P3 to LCAS P3’. The test
load (if enabled) will be applied when the LCAS device is in the Test, All Off, Test/Monitor, and Test Ringing states. When SLAC
P1 = 1, the Ringing, Test Ringing, and All Off states will be activated when the external ringing signal is at zero cross (assuming
CCR4 RMODE is set for external ringing (1) and ZXR is set for enable zero cross ringing relay operation (0)). For the Ringing
and Test Ringing state this is the desired operation. For the All Off state, the delay in activation needs to be considered in the
firmware. An immediate All Off state can always be asserted by controlling OFFx or by writing the ZXR bit to disable zero cross
ringing relay operation prior to writing the All Off state.
A sixth option is to use the option 4 states but use the P1 relay driver in the ISLIC device to drive an electromechanical DPDT
test-out relay. The relay would be wired between the protection and the ALINE/BLINE LCAS device pins. The relay, when
actuated, would disconnect the LCAS device and apply an alternate test bus to the loop. For this option, LCAS CFG = 0, wire
SLAC P1 to LCAS P3’, wire SLAC P2 to LCAS P2’, and wire SLAC P3 to LCAS P1’. The R1 relay driver drives the test-out
electromechanical relay. When SLAC P1 = 0 the loop is connected, Idle/Talk, Test, Ringing, and Test/Monitor states are available.
When SLAC P1 = 1 the loop is disconnected, and Idle/Talk, Test/Monitor, Ringing, and Test Ringing states are available. When
SLAC P2 = 1, the Ringing, Test Ringing, and Test/Monitor states are activated when the external ringing signal is at zero crossing
(assuming CCR4 RMODE is set for external ringing (1) and ZXR is set for enable zero cross ringing relay operation (0) and I/O
Register RD2IO (Le792284 only) is set to automatically set and clear RD2 during external ringing). For the Ringing and Test
Ringing state this is the desired operation. For the Test/Monitor state, the delay in activation needs to be considered in the
firmware. An immediate Test/Monitor state can always be asserted by writing the ZXR bit to disable zero cross ringing relay
operation prior to writing the Test/Monitor state. Since SLAC P1 is used to drive the electromechanical test-out relay, and SLAC
P2 is used to activate the LCAS device ringing states at zero crossing, the per-channel test load is not used with this scenario.
Reset
There are two possible ways to control reset of the Le75282 device.
If the OFFx pin is used, it can provide a power-up reset and an active device reset. When using a SLAC with the general purpose
I/O pins, the I/O pins can be used to control OFFx. At power-up the I/O pins default to high impedance inputs. The internal pull-
down in the OFFx pin will clear the P1’-P3’ inputs and set the Le75282 device into its All Off state at power-up. After the I/O pins
are configured as outputs, they can be set high to allow programming of the Le75282 device. During operation, the RD1-RD3
control data can be cleared by bringing OFFx low.
If OFFx is not used, a power-up reset can be achieved by placing a 0.1 µf capacitor on each TSDx pin to ground. The Le75282
device will then power-up in the All Off state and remain in that state until an operating state is programmed.
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