le9531cmqc Zarlink Semiconductor, le9531cmqc Datasheet - Page 5

• Manufacturer Part Number: le9531cmqc
• Description: Ringing Subscriber Line Interface Circuit
• Manufacturer: Zarlink Semiconductor

Le9531
Data Sheet
Product Description
The Le9531 device is a single-channel SLIC optimized to provide battery feed, ringing, and supervision on short
plain old telephone service (POTS) loops. This device is optimized to interface to Broadcom Cable Modem and
GPON devices. This device is equivalent of Le9530 channel 2.
This device provides power ringing to the subscriber loop through amplification of a low-voltage input. It also
provides forward and reverse battery feed states with a clamped T/R voltage during high battery application, a low-
power scan state also with a clamped T/R voltage during high battery application, ground start (tip open), and a
disconnect state. The active forward low dc current limit state is the default power up state.
The Le9531 device requires a Vcc and battery to operate. The ringing signal is derived from the high-voltage
battery. High voltage battery for ringing is graded for –100 V or –145 V. This device assumes use of a switching
power supply which will put out different voltages in different SLIC operation states; therefore, no battery switch is
included.
Loop closure, ring trip, and ground start detection are available. The loop closure detector has a fixed threshold with
hysteresis. The ring trip detector requires a single-pole filter, thus minimizing external components required.
The active forward/reverse low DC current limit SLIC operation states set the DC current limit to be 25 mA. The
active forward/reverse high DC current limit SLIC operation states set the DC current limit to be 40 mA. The DC
current limit is fixed in scan state.
The device is offered with differential ringing and receive inputs, but may be operated in single ended mode by
simply connecting the unused input to V
.
REF
This device is designed for ultra-low power in all operating states.
The Le9531 device offers eight operating states and assumes use of a single user adjusted battery for talk, ringing
and scanning. The battery amplitude to the SLIC device is expected to vary according to the operation state. A user
should carefully choose and provide the proper battery externally to the SLIC. The battery voltage is graded, up to
–100 V for scan and ring for the Le9531C device, and –100 V for scan and up to –145 V for ring for the Le9531D
device. For the Le9531D device, during ringing only the battery supply voltage may be extended to –145 V. The
supply has to be externally adjusted back to no more than -100 V for other operations. Also, when –145 V is used
for ringing special care should be taken to prevent certain faults from happening, such as tip to ring, tip or ring to
ground, or similar alike.
To minimize on-hook power, a low-power scan state is available. In this state, all functions except off-hook
supervision are turned off to conserve power. On-hook transmission is not allowed in the scan state. In the scan
state, with a primary battery whose magnitude is greater than a nominal 51 V, the magnitude of the tip-to-ground
and ring-to-ground voltage is clamped at less than 56.5 V.
Forward and Reverse Battery Active Transmission mode serve as both an off-hook talk mode and on-hook
transmission mode, as may be required during the quiet interval of ringing. The device depends on the switching
power supply to reduce the battery during off-hook conditions, to avoid potential thermal issues, and by doing so
may save overall operating power consumption.
Because on-hook transmission is not allowed in the scan state, during the on-hook transmission in the active state
the magnitude of the tip-to-ground and ring-to-ground voltage is clamped at less than 56.5 V, with a primary battery
whose magnitude is greater than a nominal 56.5 V. The magnitude of the overhead voltage for batteries whose
magnitude is less than 56.5 V has a typical default value of 6 to 8 V, allowing for an on-hook transmission of an
undistorted signal of 3.14 dBm into 900 . Additionally, this allows sufficient overhead for 500 mV of meter pulse if
desired. This overhead is fixed. The ring trip detector is turned off during Active states to conserve power.
A disconnect state is provided where all circuits are turned off and power is denied to the loop.
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Zarlink Semiconductor Inc.