ICs for Telephone
1
AN6215S
AGC IC for telephone speech network
s
Overview
The AN6215S is an AGC IC for telephone speech
network, and it incorporates an microphone input detec-
tion circuit and a receiver gain control circuit. It is espe-
cially best suited for cordless telephone thanks to a good
speech tone quality obtained by reducing howling and echo
sound.
s
Features
Operation with wide power supply voltage range from
2.1 V to 6.0 V
Enlargement of dynamic range by incorporating a
vari-
able V
REF
circuit that varies according to the supply
voltage
Possible to adjust the received voice attenuation amount
with an external resistor
Possible to adjust the AGC operating point with an ex-
ternal resistor
Possible to design with fewer external components
s
Block Diagram
SOP008-P-0225A
Unit: mm
1
2
3
4
8
7
6
5
0.4 0.25
0.6 0.3
1.27
5.0 0.3
0.1 0.1
0.3
4.2 0.3
6.5 0.3
0.15
0.65
1.5 0.2
V
REF
Det.
CC
Buff
1
2
3
4
8
V
CC
GND
7
6
5
2
AN6215S
ICs for Telephone
s
Pin Descriptions
s
Absolute Maximum Ratings
Parameter
Symbol
Rating
Unit
Supply voltage
V
CC
6.5
V
Supply current
I
CC
3.0
mA
Power dissipation
P
D
19.5
mW
Operating ambient temperature
*
T
opr
-
20 to
+
75
C
Storage temperature
*
T
stg
-
55 to
+
125
C
Note) *: Except for the operating ambient temperature and storage temperature, all ratings are for T
a
=
25
C.
s
Recommended Operating Range
Parameter
Symbol
Range
Unit
Supply voltage
V
CC
2.1 to 6.0
V
Pin No.
Symbol
Description
1
GND
Ground pin
2
GAIN
Variable gain adjustment pin
3
RX IN
Receiver signal input pin
4
RX OUT
Receiver signal output pin
5
TX DET
Transmitter signal detection pin
6
TX IN
Transmitter signal input pin
7
V
C
V
REF
control pin
8
V
CC
Supply voltage pin
s
Electrical Characteristics at T
a
=
25
C
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
Operating current
*1
I
CC
Operating time at no signal input
1.4
2.0
mA
Receiver amp. voltage gain
*1
G
RX
RX in
= -
20 dBm
1.5
3.5
5.5
dB
Receiver amp. output D range
*1
V
ORX
Output voltage at THD
=
5%
0
2
dBm
Receiver amp.
Gain
Receiver amp. gain variation between
-
10
-
8
-
6
dB
variable gain width
*1, *2
TX in
= -
50 dBm and TX in
= -
30 dBm
High-level V
REF
control sink current
I
CH
V
CH
=
3 V
25
50
A
High-level V
REF
control voltage
V
CH
Pin 7 voltage range in a base-set mode
1.5
V
CC
V
Low-level V
REF
control voltage
V
CL
Pin 7 voltage range in a hand-set mode
0
0.5
V
Note) 1. V
CC
=
5.0 V, f
=
1 kHz unless otherwise specified.
2. *1: Pin 7 DC voltage sets to V
CH
=
5.0 V
*2: ERO-25CKF6802 produced by Matsushita Electronic Components Co. is used for RX in
=
-
30 dBm.
(Refer to "
Application circuit example".)
3
ICs for Telephone
AN6215S
s
Electrical Characteristics at T
a
=
25
C (continued)
Design reference data
Note) 1. The characteristics listed below are theoretical values based on the IC design and are not guaranteed.
2. V
CC
=
5.0 V, f
=
1 kHz unless otherwise specified.
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
Detection circuit input impedance
Z
IDET
Pin 5 input impedance
50
Detection circuit gain
G
DET
R in
=
10 k
27
dB
Receiver amp. input impedance
Z
IRX
Pin 3 input impedance
25
k
Receiver amp. output wave
THD
V
ORX
= -
10 dBm (80 kHz LPF)
0.3
%
distortion factor
Receiver amp. output noise voltage
N
ORX
Wide band
-
65
dBm
Receiver amp. output impedance
Z
ORX
Pin 4 output impedance
1
k
Sidetone control operation voltage
V
DET
DC voltage of pin 5
0.3
V
when sidetone control operates
Sidetone control
Gain
R
RX out/
TX in
-
0.6
dB/dB
variation rate
at TX in
=
-
39 dBm
Base set mode V
REF
voltage
V
RB
Pin 4 DC voltage at pin 7
=
high
2
V
Hand set mode V
REF
voltage
V
RH
Pin 4 DC voltage at pin 7
=
low
1.15
V
Pin No.
Equivalent circuit
Description
Typical wave
1
GND: Ground pin
2
GAIN: Gain adjustment pin
Gain width of receiver amp. can be
changed by changing the external
resistance.
R1 to large
Gain width becomes
large.
R1 to small
Gain width becomes
small.
3
RX IN: Receiver signal input pin
Input receiver sound signal from line.
Input impedance is 25 k
.
4
RX OUT: Receiver signal output pin
Connect receiver amp. etc.
Output impedance is approximately
50
.
s
Terminal Equivalent Circuits
2
R1
1.15 V
68 k
17
A
Receiver amp.
I
2
3
4
25 k
V
REF
C1
C2
Receiver amp.
Receiver signal
To receiver amp.
0 V
DC
1.15 V
4
AN6215S
ICs for Telephone
Pin No.
Equivalent circuit
Description
Typical wave
5
TX DET:
Transmitter signal detection pin
Connect a smoothing capacitor and a
resister to adjust attack-recovery time
of transmitter signal detection.
Detection amp. gain is determined by
the following equation:
G
=
100 (k
)
3
R
4
(k
)
C3 large
Attack time becomes
long.
R3 small
Recovery time becomes
short.
6
TX IN: Transmitter signal input pin
Input transmitter sound signal
7
V
C
: Reference voltage control pin
Reference voltage V
REF
becomes 2 V
when voltage is high, and becomes
1.15 V when voltage is low.
Normally, reference voltage is set to
V
REF
=
2 V when it is used for a base-
set, and to V
REF
=
1.15 V when it is
used for a hand-set.
8
V
CC
: Supply voltage pin
Connect supply voltage.
s
Terminal Equivalent Circuits (continued)
5
100 k
R3
100 k
DC
C3
10
F
To receiver amp.
Full wave
detection
6
C4
R4
5
Detection
Transmitter
signal
10 k
180 k
100 k
V
H
/V
L
7
DC
Input
With capacitor
Without
capacitor
DC
DC
5
ICs for Telephone
AN6215S
s
Application Circuit Example
System configuration
Detects input of microphone and gives attenuation to a receiver system
Operating point and variable width of attenuator can be set with external resistor respectively.
1
2
3
4
8
7
6
5
R2
C1
C2
GND
BN
C3
Microphone
R3
C4
R1
VCSW
T
R
Circuit
I/F
Microphone
amp.
Receiver amp.
Receiver amp.
Speech amp.
VCSW: V
REF
control switch
SW on: V
REF
=
2.0 V
SW off: V
REF
=
1.15 V
R1: Detection circuit gain adjustment resistor
R2: Receiver
Gain width adjustment resistor
R3, C3: Resistor and capacitor to determine
attack-recovery time of transmitter
V
REF
V
CC
Det.
CC
Buff
Characteristics
RX out
TX in
Gain
= -
8 dB
(R2
=
68 k
)
RX out
TX in
Inclination:
R
= -
0.6 dB/dB
-
39 dBm
(R1
=
10 k
)
Figure 1. Variable width of attenuation
V
CC
V
REF
(V)
2.0
1.15
0.3
V
RB
(Base-set mode)
V
RH
(Hand-set mode)
V
DET
Reference voltage
Figure 3. Operation of variable V
REF
circuit
Figure 2. Operating point of attenuation
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