Atmel U4091BM-R
Programmable Telephone Audio Processor
DATASHEET
Features
●
Speech circuit with anti-clipping
●
Tone-ringer interface with DC/DC converter
●
Speaker amplifier with anti-distortion
●
Power-supply management (regulated and unregulated) and a special supply for
electret microphone
●
Voice switch
●
Interface for answering machine and cordless phone
Applications
●
Feature phone
●
Answering machine
●
Fax machine
●
Speaker phone
●
Cordless phone
Benefits
●
No piezoelectric transducer necessary for tone ringing
●
Complete system integration of analog signal processing on one chip
●
Very few external components
4872C–CORD–09/12
1.
Description
The programmable telephone audio processor Atmel
®
U4091BM-R is a linear integrated circuit for use in feature phones,
answering machines and fax machines. It contains the speech circuit, tone-ringer interface with DC/DC converter, sidetone
equivalent and ear-protection rectifiers. The circuit is line-powered and contains all components necessary for signal
amplification and adaptation to the line. The Atmel U4091BM-R can also be supplied via an external power supply. An
integrated voice switch with loudspeaker amplifier enables hands-free or open-listening operation. With an anti-feedback
function, acoustic feedback during open listening can be reduced significantly. The generated supply voltage is suitable for a
wide range of peripheral circuits.
Figure 1-1. Block Diagram
Speech
circuit
Voice
switch
Audio
amplifier
Serial
bus
DTMF
Tone
ringer
Clock
Data
Reset
MCU
Atmel U4091BM-R [DATASHEET]
4872C–CORD–09/12
2
Table 2-1.
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
Note:
Pin Description
Symbol
RECIN
TXACL
MIC3
MIC2
MIC1
RECO2
RECO1
IND
VL
SENSE
GND
VB
SAO2
SAO1
VMPS
VMP
VMIC
TSACL
VRING
IMPA
COSC
SWOUT
INT
SCL
SDA
OSCIN
RESET
OSCOUT
ES
ADIN
BNMR
BNMT
CT
TLDR
INLDR
INLDT
TLDT
IMPSW
MICO
AMPB
Function
Receive amplifier input
(1)
Time constant adjustment for transmit anti-clipping
Microphone input for hands-free operation
Input of symmetrical microphone amplifier with high common-mode rejection ratio
Input of symmetrical microphone amplifier with high common-mode rejection ratio
Output of the receive amplifier
Output of the receive amplifier, also used for sidetone network
The internal equivalent inductance of the circuit is proportional to the value of the capacitor at this
pin. A resistor connected to ground may be used to adjust the DC mask
Positive supply-voltage input to the device in speech mode
Input for sensing the available line current
Ground, reference point for DC and AC signals
Unstabilized supply voltage for speech network
Negative output of speaker amplifier (push-pull only)
Positive output of speaker amplifier (single-ended and push-pull operation)
Unregulated supply voltage for the microcontroller (via series regulator to VMP)
Regulated output voltage for supplying the microcontroller (typically 3.3V/6mA in speech mode)
Reference node for microphone amplifier, supply for electret microphones
Time constant for speaker amplifier anti-clipping
Input for ringer supply
Input for adjusting the ringer input impedance
70-kHz oscillator for ringing power converter
Output for driving the external switch resistor
Interrupt line for serial bus
Clock input for serial bus
Data line for serial bus
Input for 3.58-MHz oscillator
Reset output for the microcontroller
Clock output for the microcontroller
Input for external supply indication
Input of A/D converter
Output of background-noise monitor receive
Output of background-noise monitor transmit
Time constant for mode switching of voice switch
Time constant of receive-level detector
Input of receive-level detector
Input of transmit-level detector
Time constant of transmit-level detector
Switch for additional line impedance
Microphone preamplifier output
Input for playback signal of answering machine
1. The protection device at pin RECIN is disconnected.
Atmel U4091BM-R [DATASHEET]
4872C–CORD–09/12
5
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