L8567 Datasheet, PDF (1/42 Pages) Agere Systems – SLIC for Peoples Republic of China Applications

Data Sheet
August 1999
L8567 SLIC for
People’s Republic of China Applications
Features
s Low active power (typical 149 mW during on-hook
transmission)
s Sleep state for low idle power (47 mW typical)
s Quiet tip/ring polarity reversal
s Distortion-free on-hook transmission
s –35 V to –65 V battery operation
s Convenient operating states:
— Forward active
— Polarity reversal active
— Sleep
— Forward disconnect
s Supervision functions:
— Fixed threshold off-hook detector with
longitudinal rejection and hysteresis
— Ring trip detector
— Thermal shutdown indication
s Adjustable loop current limit
s Three driver outputs for relay driver
s LED driver output to indicate off-hook
s Latched parallel data interface
s Battery and +5 V required:
— Optional auxiliary lower voltage battery to
reduce short loop power
s –40 °C to +85 °C operational temperature range
s User-selectable power management techniques
s Thermal protection
s 32-pin PLCC or 44-pin PLCC packaging
Description
General
This electronic subscriber loop interface circuit
(SLIC) is optimized for low cost and low power con-
sumption while providing a full-feature set.
Included in the feature set is quiet reverse battery.
Quiet polarity reversal is possible because the ac
path is uninterrupted during transmission. The dc
loop current limit is user-adjustable via a single exter-
nal resistor. The maximum battery voltage is speci-
fied as –65 V for long loop applications. The L8567
supports on-hook transmission.
The total short loop off-hook power may be reduced
by use of a lower-voltage auxiliary battery supply. If,
when using the 32-pin PLCC, the user does not wish
to supply an auxiliary battery, the component of the
total short loop off-hook power that is dissipated on
the L8567 SLIC is controlled by use of an external
power resistor. With the 44-pin PLCC, a power resis-
tor is not necessary.
Included are both the loop closure and ring trip
supervision functions. The loop closure threshold is
fixed internally, which eliminates the need for an
external precision resistor to set the threshold. To
minimize noise at the supervision output, hysteresis
is included on the loop closure function. The loop clo-
sure and ring trip outputs are multiplexed into a sin-
gle NSTAT output. Also included is a thermal
shutdown mechanism. If device temperature exceeds
165 °C, as may be the case under an extended
power cross fault, the SLIC will shut down (i.e., enter
a high-impedance state) to provide protection against
the fault. A logic output will indicate the SLIC is in
thermal shutdown.