U4082B Datasheet, PDF (1/30 Pages) ATMEL Corporation – Low-voltage Voice-switched IC for Hands-free Operation

Features
• Low-voltage Operation 3V to 6.5V
• Attenuator Gain Range Between Transmit and Receive: 52 dB
• Four-point Signal Sensing for Improved Sensitivity
• Monitoring System for Background Noise Level
• Adjustable Microphone Amplifier Gain
• Mute Function
• Chip Disable for Active/Standby Operation
• On-board Filter
• Dial Tone Detector
• Compatible with U4083B Speaker Amplifier
Benefits
• Fast Channel Switching Allows Quasi-duplex Operation
• Proper Operation in Noisy Surroundings
1. Description
The low-voltage voice-switched speakerphone circuit, U4082B, incorporates a wide
range of functions. The versatility of the device is further enhanced by giving access to
internal circuit points. The block diagram (see Figure 1-1) shows amplifiers, level
detectors, transmit and receive attenuators operating in complementary functions,
background noise monitors, chip disable, dial tone detector and mute function. Due to
low-voltage operation, the device can be operated either by a low supply or via a tele-
phone line requiring 5.5 mA typically. Stand-alone operation is enabled by a coupling
transformer (Tip and Ring) or in conjunction with a handset speech network, as shown
in Figure 1-2 on page 2.
Figure 1-1. Block Diagram
MIC 11 MICO 10 17 TLI2
9 TI
8 TO 7 HTI 6 HTO-
12
MUTE
16
CPT
-
+
V_B
Background
Noise Monitor
18
TLO2
19
RLO2
4
V_S
28
GND
3
CD
Level
Detectors
400 Ω
T Attenuator
V_S
AGC
Attenuator
Control
Dial Tone
Detector _{+ -}
V_B
R Attenuator
-
+
V_B
-
+
V_B
Background
Noise Monitor
Level
Detectors
U4082B
Filter
+1
5
HTO+
27
CPR
23
TLI1
25
RLO1
24
TLO1
2
FI
Low-voltage
Voice-switched
IC for
Hands-free
Operation
U4082B
15 V_B 14 C_T
20 RLI2 _{RECO 22 21 RI 13 VCI 26 RLI1 1 PD}
Rev. 4743D–CORD–03/06