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s Overview
The AN6425K is a high-function speech network IC with
speaker amplifier. It incorporates a transmitter-system non-lin-
ear circuit, receiver digital VRs, etc. and is suitable for realiz-
ing the multifunctional telephone sets.
s Features
Speech network IC for the multifunctional telephone sets
Capable of interfacing with the light-weight small receivers
and ECM transmitters
Built-in 2V REG constant voltage source (2V typ) for ECM
Built-in non-linear circuits in the transmitter and receiver
systems in order to eliminate ambient noises
Built-in speaker amplifier and capable of driving with a main
wire current
Built-in hold-tone amplifier, key-in-tone amplifier, and
DTMF transmitter, and capable of setting the mode with the
control pins
Automatic gain control (automatic pad function) according to
a circuit curret
Built-in tertiary active filter circuit and capable of sending a
DTMF circuit with much higher harmonic at a low distortion
factor
Built-in single touch receiver volume-up function (about
6dB)
AN6425K
Speech Network Circuit
Unit : mm
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
26.7
0.3
0.5
0.1
3 to 15
8.4
0.3
0.9
0.25
1.778
4.8
0.25
28-pin Shrunk DIL Plastic Package (SDIP028-P-0400B)
3.05
0.25
10.16
0.25
0.3
+0.1
0.05
1.05
0.25
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
TT
in
HT
KT
40k
80k
MIC
in
Filter
Amp.
SEND
Amp
MUTE
Logic
INV
NAND
DVR
4k
65k
30k
2k
2k
1V
30k
CLASS B
BTL
CLASS A
Push pull
+
+
+
REC
in
D6dB
D5dB
D3dB
D3dB
D12
dB
2V
1V
GND
VL
VL
2V REG
1V REFF
Battery
Selector
REC
DRIVER
REC
DRIVER
SP
Amp.
s Block Diagram
V
L
I
L
P
D
T
opr
T
stg
Supply voltage
Supply current
Power dissipation
Operating ambient temperature
Storage temperature
V
mA
mW
C
C
Parameter
Symbol
Rating
Unit
s Absolute Maximum Ratings (Ta=25C)
14.4 *
120 *
1200 *
20 to + 65
55 to +150
* V
CC
I
CC
<1200mW
Parameter
Symbol
Range
s Recommended Operating Range (Ta=25C)
Operating supply voltage range
V
L
3 to 12V
Parameter
Symbol
Condition
min
typ
max
s Electrical Characteristics (Ta=25C)
G
V
(REC)
Open between the Pins19 and 20. Measure the
output between the Pins22 and 23 when a sign-
al (55dBm) is input to the Pin18.
Receiver distortion factor
THD
(REC)
%
1
Open between the Pins19 and 20. Measure the out-
put distortion factor between the Pins 22 and 23
when a signal
(55dBm)
is input to the Pin18.
Receiver maximum output voltage
V
O
(REC)
dBm
+3
D Automatic pad
AP
(REC)
dB
Input a signal (45dBm) to the Pin18 and mea-
sure an output change between the Pins22 and
23 when I
L
changes from 80mA to 30mA.
MUTE
(REC)
Input a signal (45dBm) to the Pin18 and
measure an output change between the Pins
22 and 23 when the Pin12 changes from no
microphone input signal to 40dBm.
dB
Input a signal (45dBm) to the Pin18 and
measure an output change between the Pins
22 and 23 when the Pin12 is set from H to L.
Receiver D digital VR
DVR
dBm
50
Measure the output between the Pins22 and
23 when there is no signal at the Pin18.
3
Receiver noise output
V
no
(REC)
dB
42.5
Open bitween the Pins3 and 6. Measure
the output between the Pins28 and 1 when
a signal (45dBm) is input to the Pin12.
Transmitter gain
G
V
(SEND)
%
Transmitter distortion factor
THD
(SEND)
dBm
5
Open between the Pins3 and 6. Measure the
output distortion factor between the Pins28 and 1
when a signal
(45dBm)
is input to the Pin12.
Transmitter maximum transmission level
V
O
(SEND)
dB
3
1.5
60
29.5
45
5
1.5
5
8
45
6
2
40
Receiver gain
53
dB
50.5
48
0
6
D Receiver noise prevention
dB
5
3
7
4
Transmitter D automatic pad
AP
(SEND)
Input a signal (35dBm) to the Pin12 and
measure an output change between the Pins
28 and 1 when I
L
changes from 80mA.
dBm
65
Measure the output between the Pins28 and
1 when there is no signal at the Pin18.
Transmitter noise prevention
V
no
(SEND)
dB
26.5
HOLD TONE gain
G
V
(HOLD)
dB
41.5
Ground the Pin24. Input a signal
(30dBm) to the Pin17 and measure the
output change between the Pins 28 and 1.
TOUCH TONE gain
G
V
(TOUCH)
%
1
Ground a signal (45dBm) to
the Pin16 and measure the out-
put between the Pins28 and 1.
3
44
6
1.5
39
23.5
TOUCH TONE distortion factor
THD
(TOUCH)
Ground the Pin14. Input a signal (45dBm)
to the Pin16 and measure the output distor-
tion factor between the Pins 28 and 1.
Unit
Input a signal to the Pin18 and measure
the output between the Pins22 and 23 at
an output distortion factor of 5%.
Input a signal to the Pin12 and measure
the output between the Pins28 and 1 at
an output distortion factor of 5%.
* I
L
=30mA and Freq=1kHz unless otherwise specified.
Parameter
Symbol
Condition
min
typ
max
s Electrical Characteristics (cont.) (Ta=25C)
dB
3
1.5
6
TOUCH TONE D automatic pad
AP
(TOUCH)
Ground the Pin14. Input a signal (45
dBm) to the Pin16 and measure an out-
put change between the Pins 28 and 1
when I
L
changes from 80mA to 30mA.
dB
50
45
SP amplifier gain
G
V
(SP)
Ground the Pin15. Input a signal
(50dBm) to the Pin24 and measure
the output between the Pins 25 and 26.
%
10
SP distortion factor
THD
(SP)
Ground the Pin15. Input a signal (50dBm)
to the Pin24 and measure the output distor-
tion factor between the Pins 25 and 26.
Unit
* I
L
=30mA and Freq=1kHz unless otherwise specified.
s Pin Descriptions
1
2
3
4
5
6
7
GND
2V REG
1V REF
BT
1/2V
L
Ground pin.
Connect to the output of the diode
bridge.
2V internal stabillized power supply
output pin.
Connect to GND via 220
F. The current
obtainable from this pin is 5mA or less
(at I
L
=20mA).
1V reference coltage output pin.
Connect to GND via 47
F. No current
is allowed to be input/output from this
pin.
External battery connection pin.
Connect the 3 to 6V battery to GND.
Connect to GND directly when the BT
function is not used.
Transmitter output.
Transmitter gain control pin.
Controls the gain and frequency charac-
teristic of the transmitter system with
external C and R.
Automatic pad control pin.
Capable of controlling the pad operating
point with the external resistor.
Typical waveform
Description
Equivalent circuit
Pin No.
Pin name
SEND
OUTPUT
SEND
DRIVER
DC 0V
DC 2V
DC 1V
DC
0.3V
DC
0 to 6V
(Supplied from
Outside)
5/7
V
L
V
ref
2V
REG
2
3
+
V
CC
10k
1V
5
V
CC
V
L
Vref
65.3k
6
V
L
20k
47k
7
s Pin Descriptions (cont.)
8
9
10
11
12
13
14
15
16
Mute
LPF (1)
LPF (2)
LPF (3)
MIC input
HC
DMC
SPC
TT input
Microphone input pin.
Input pin for the microphone.
HOLD TONE control pin.
The HOLD TONE transmission mode
is set by setting this pin to Low.
DIAL MUTE control pin.
The DTMF transmission mode is set by
setting this pin to Low.
SPEAKER control pin.
The speaker mode is set by setting this
pin to Low.
DTMT signal input pin.
Inputs a DTMF signal. A signal is sent
to the circuit when the Pin14 is at Low.
Typical waveform
Description
Equivalent circuit
Pin No.
Pin name
0V
1V
1V
Hole Tone Mode
0V
DTMF
Transmission Mode
0V
Speaker Mode
V
CC
V
CC
10k
12
V
CC
V
CC
10k
13
V
CC
V
CC
10k
14
V
CC
V
CC
10k
15
V
CC
V
ref
10k
16
Transmitter filter pin.
Constitutes the tertiary active filter with the
external parts C and R, and capable of
controlling the high-pass transmitter fre-
quency characteristic.
Noise precentice peak hold pin.
Connect to GND via 10
F.
DC
W/o
External
Capafitor
W/External Capafitor
V
CC
V
CC
8
V
CC
V
CC
V
CC
9
10
11
+
+
40k
17
18
19
20
21
22
23
24
KT/HT input
DVR input
REC input
REC NFB
REC output
SP input
Receiver signal input pin.
Inputs a receiver signal from the side
tone preventive circuit network.
Receiver gain control pin,
Receiver signal output pin.
Capable of controlling the frequency
characteristic and gain of the receiver
system with the external parts C and F
of the Pins19 and 20. The receiver sig-
nal/HOLD TONE signal/KEY IN TONE
signal is output to the Pin20 by the
HC/DMC/SPC control.
Receiver amplifier signal input pin,
Receiver output (1) pin,
Receiver output (2) pin.
Inputs a receiver signal from the Pin20
to the Pin21. BTL output at the Pins20
and 23.
Speaker amplifier signal input pin.
Inputs a receiver signal from the Pin20.
Pin No.
1V
1V
1V
Driver
input
Driver
output (1)
Driver
output (2)
1V
1V
1V
1V
V
CC
Vref
18
V
CC
V
CC
V
CC
V
CC
+
82k
1
0
k
1
0
k
19
20
V
CC
Vref
Vref
V
CC
V
CC
+
+
2k
2k
2k
2k
22
23
21
V
CC
Vref
10k
24
KT/HT signal input pin,
Digital VR ON Pin.
Inputs a KEY IN TONE or HOLD
TONE signal. If the Pin14 is set to Low,
the KT signal is output to the receiver,
and if the Pin13 is set to Low, the HT
signal is output to the curcuit and speak-
er. The receiver gain is improved 6dB
by setting this pin to Low instantaneous-
ly.
Digital VR ON
1V
0V
KT/HT
4k
45k
V
CC
V
CC
Vref
30k
16
+
Typical waveform
Description
Equivalent circuit
Pin name
s Pin Descriptions (cont.)
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