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U4087B Datasheet, PDF (1/8 Pages) TEMIC Semiconductors – Low Voltage Voice Switch Interface Circuit for Hands-free Operation in Telephone
U4087B
Low Voltage Voice Switch Interface Circuit for Hands-free
Operation in Telephone
Description
The voice switch interface circuit U4087B is a linear
integrated circuit for improvement of handsfree
performance of U4090B system.
The U4087B provides an optimized interface to U4090B,
the necessary level detectors and switching control for a
properly operating speakerphone. The detection
sensitivity and timing are externally controllable.
Additionally, the U4087B provides a back- ground noise
monitor which makes the circuit insensitive to room
noise.
The Block diagram shows level detectors, back ground
noise monitor.
Due to low voltage operation it can be operated via power
supply management of U4090B requiring 1.0 mA typ.
Features
D Low voltage operation: 3.0 to 7.0 V
D Four point signal sensing
D Monitoring system for background noise level
D Case: SO 16
D Chip Disable for active/standby operation
Benefits
D Fast channel switching allows quasi duplex operation
D Low current consumption
Block Diagram
TLO2
16
15
TLI2
Logic
CPT
14
Noise
detector
VB VM CD GND
7 13 6 5
Bias
TLO1
2
Logic
1
TLI1
9
RLI2
Logic
– TS
=
+
Logic
DIRE
–
+
+
DIRA
–
Charge
Discharge
C.T.
Generator
4
Logic
RLI1
8
RLO2
12
10
11
3
CT TLDR TLDT
RLO1
12610
Figure 1. Block diagram with external circuit
TELEFUNKEN Semiconductors
1 (8)
Rev. A1, 09-Sep-96
Preliminary Information