loop impedance.
The device offers the reverse battery function. Using
anced power ring signal to tip and ring. In this
lower-voltage battery during the talk and idle states.
power ringing. In addition, dc overhead voltage is
reduced during the ring state. With the battery and
鈩?/div>
+ 40
碌F.
The device offers ring trip and loop closure supervi-
sion with 0.3 V and 2 mA hysteresis, respectively. It
also includes the ground start state and ring ground
detection. A summing node for meter pulse injection
to 2.2 Vrms is also included. The 44-pin PLCC ver-
sion also has a spare uncommitted op amp, which
may be used for ac gain setting or meter pulse filter-
ing.
Full-feature set for central office applications
Also ideal for ISDN terminal adapters, pair gain,
and cable telephony applications
Auxiliary input for second battery, and internal
switch to enable its use to save power in short tele-
phone loops
5 V only operation or optional 鹵5 V operation for
reduced power consumption
Low active power (85 mW typical) and scan power
(61 mW typical) with 5 V only operation
Low active power (68 mW typical with auxiliary bat-
tery) and scan power (45 mW typical) with 鹵5 V
operation
Quiet tip/ring polarity reversal
Per-line ringing available for short loops
Reduced overhead and increased current limit dur-
ing ring mode for lower-battery operation or
increased ring loop length
Supports meter pulse injection
Distortion-free full duplex from 0 mA dc loop cur-
rent on-hook transmission
Convenient operating states:
鈥?Forward powerup
鈥?Polarity reversal powerup
鈥?Forward sleep
鈥?Ground start
鈥?Disconnect
Adjustable supervision functions:
鈥?Off-hook detector with longitudinal rejection
鈥?Ground key detector with longitudinal rejection
鈥?Ring trip detector
Independent, adjustable dc and ac parameters:
鈥?dc feed resistance (44-pin PLCC version)
鈥?Loop current limit
鈥?Termination impedance
Thermal protection
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