SL34118
Voice Switched Speakerphone Circuit
The SL34118 Voice Switched Speakerphone Circuit incorporates
the necessary amplifiers, attenuators, level detectors, and control
algorithm to form the heart of a high quality hands-free speakerphone
system. Included are a microphone amplifier with adjustable gain and
MUTE control, Transmit and Receive attenuators which operate in a
complementary manner, level detectors at both input and output of
both attenuators, and background noise monitors for both the transmit
and receive channels. A Dial Tone Detector prevents the dial tone
from being attenuated by the Receive background noise monitor
circuit. Also included are two line driver amplifiers which can be used
to form a hybrid network in conjunction with an external coupling
transformer. A high pass filter can be used to filter out 60 Hz noise in
the reseive channel, or for other filtering functions. A Chip Disable pin
permits powering down the entire circuit to conserve power on long
loops where loop current is at a minimum.
The SL34118 may be operated from a power supply, or it can be
powered from the telephone line, requiring typically 5.0 mA. The
SL34118 can be interfaced directly to Tip and Ring (through a coupling
transformer) for stand-alone operation, or it can be used in
conjunction with a handset speech network and or other features of a
featurephone.
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Improved Attenuator Gain Range: 52 dB Between Transmit and
Receive
Low Voltage Operation for Line-Powered Applications (3.0-6.5 V)
4 Point Signal Sensing for Improved Sensitivity
Background Noise Monitors for Both Transmit and Receive Paths
Microphone Amplifier Gain Set by External Resistors - Mute
Function Included
Chip Disable for Active Standby Operation
On Board Filter Pinned-Out for User Deined Function
Dial Tone Detector to Inhibit Receive Idle Mode During Dial Tone
Presence
ORDERING INFORMATION
SL34118N Plastic
SL34118D SOIC
T
A
= -25° to 70° C for all packages
PIN ASSIGNMENT
SLS
System Logic
Semiconductor
SLS [ SYSTEM LOGIC SEMICONDUCTOR ]
