PANASONIC AN6175K

ICs for Telephone
AN6175K
Hands-free Speech Network IC
AN6175K
0.9±0.25
0.5±0.1
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
0.96±0.25
13.7±0.3
4.76±0.25
3.3±0.25
+0.1 5
0.0
3 ∼ 15°
■ Features
Unit : mm
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
1.778
The AN6175K is a speech network IC incorporating a
hands-free function. It provides for a high-quality handsfree telephone or handset telephone. The hands-free
telephone function(HF)includes :
• MIC amplifier capable of mute and gain control
• Background noise monitoring
• Voice switching attenuation control
• Symmetrical transmitter/receiver attenuators
• Dynamic loudspeaker amplifier
The handset telephone function(HF)includes:
• Automatic pad capable of detecting transmission
distance
• MIC amplifier
• Receiver preamplifier
• Dynamic loudspeaker amplifier
36.8±0.3
■ Overview
15.3±0.25
0.3 −
SDIP package with 42 pins (SDIP042-P-0600A)
• Provides all the functions required of a hands-free or
handset telephone.
• Can operate on line voltage (requiring no external
power supply).
• Consumes minimal current.
• Provides for an external filter ensuring a wide range of
howling suppression.
• Mute mode for hands-free operation
• Background noise monitoring to improve transmission
quality
• 100 mW loudspeaker output (at IL=100mA)
• Built-in power supply and low-voltage regulator
• DIP package with 42-pins or QFH package with 44-pins
1
1
3
MAI
(HS)
−
MAO
(HF)
+
−
Vr
MAI
(HF)
BGR
40
BGR
VCC1
+
2
41
Vr
SOUT
42
+
VCC1
4
MAO
(HS)
5
37
TND
6
HFI
36
TVR
7
TLI1
LOG1
TND
VCC2
LOG5
Vr
TRB
38
TAPC
INT
TRE
39
8
ST
ATT
CONT
VCC
34
TLI2
LOG2
9
RLI1
10
RLI2
11
LOG3
TLO1
CONT
HS/HF
32
COUNT1
Vr
Vr
33
LOG4
COUNT2
MFI
35
12
31
30
+
−
13
TLO2
RAPC
RPO
29
14
15
41
REC−
CONT
Vr
VSP
28
Vr
RLO1 RLO2
HS,HF RPI
/MF
33
16
40
RVR
SP Pre
−
+
SPI
27
17
26
FB
40
ATC
18
TATT
TAO
SP
SPO1
25
19
RAO
20
−
+
GND
Vr
23
SPO2
RATT
24
41
APC
+
IL
+
2
−
VL
DO
DI
21
−
22
AN6175K
ICs for Telephone
■ Block Diagram
ICs for Telephone
AN6175K
■ Pin Descriptions
Pin No. Symbol
MAO
1
(HF)
MAI
2
(HF)
MAI
3
(HS)
MAO
4
(HS)
Description
Pin No. Symbol
Description
MIC amp. output (hands-free mode)
22
DO
MIC amp. input (hands-free mode)
23
GND
Ground
MIC amp. input (handset mode)
24
SPO2
Loudspeaker amp. (2) output
MIC amp. output (handset mode)
25
SPO1
Loudspeaker amp. (1) output
Receiver amp. output
5
TND
Hands-free mode transmission noise detection
26
FB
Loudspeaker amp. input (–)
6
TVR
Noise detection reference
27
SPI
Loudspeaker amp. input (+)
7
TLI1
LOG amp. (1) input (from MIC amp. output)
28
VSP
Loudspeaker amp. power input
8
TLI2
29
RPO
Receiver preamp. output
9
RLI1
30
RPI
Receiver preamp. input
10
RLI2
LOG amp. (2) input
(from hands-free control output)
LOG amp. (4) input
(from receiver preamp. output)
LOG amp. (3) input
(from loudspeaker amp. output)
11
TLO1
12
31
HS,
Mode switching (handset or hands-free/MF)
HF/MF
LOG amp. (1) output
32
HS/HF
TLO2
LOG amp. (2) output
33
Vr
Reference for handset or hands-free mode
13
RLO1
LOG amp. (3) output
34
ST
To the base of the power supply transistor
14
RLO2
LOG amp. (4) output
35
MFI
MF input
15
REC–
Receiver switching (hands-free mode)
CONT
36
HFI
From transmitter att. output (hands-free mode)
16
RVR
Receiver att. gain control
37
VCC2
Transmission amp. AC impedance setting
17
ATC
Receiver att. switching control
38
TRB
To the base of the transmission transistor
18
TAO
Transmitter att. output (hands-free mode)
39
TRE
To the emitter of the transmission transistor
19
RAO
Receiver att. output (hands-free mode)
40
BGR
Band-gap ref. voltage output
20
APC
Auto. PAD current control
(handset mode, MF)
41
VCC1
Power output to the handset and hands-free
circuits
21
DI
Receiver amp. input (–)
42
SOUT
Mode switching (handset/hands-free)
Hands-free control output
■ Absolute Maximum Ratings (Ta=25°C)
Parameter
Supply voltage
Symbol
Rating
VCC2
12.0
Unit
V
Supply current
IL
120
mA
Power dissipation Note)
PD
1016
mW
Operating ambient temperature
Topr
–20 to + 75
°C
Tstg
–55 to + 150
°C
Storage temperature
Note) In an open condition with Ta=25°C
3
ICs for Telephone
AN6175K
■ Electrical Characteristics (Ta=25±2°C)
Parameter
Symbol
Condition
min
typ
max
Unit
HS power supply
HS mode line voltage (1)
VLS1
HS mode line voltage (2)
VLS2
HS mode VCC2 voltage (1)
VCS21
HS mode VCC2 voltage (2)
VCS22
HS mode VCC1 voltage (1)
VCS11
HS mode VCC1 voltage (2)
VCS12
SW1,2 : a
IL= 20mA, VL voltage
SW1/2 : a/a
IL= 120mA, VL voltage
SW1/2 =a/a,
IL= 20mA, DC voltage at pin37
SW1/2 =a/a,
IL= 120mA, DC voltage at pin37
SW1/2 =a/a,
IL= 20mA, DC voltage at pin41
SW1/2 =a/a,
IL= 120mA, DC voltage at pin41
3.6
4.0
4.4
V
9.5
10.5
11.5
V
3.3
3.7
4.1
V
8.3
9.3
10.3
V
1.6
2.0
2.4
V
4.4
4.8
5.2
V
3.6
4.0
4.4
V
9.5
10.5
11.5
V
3.3
3.7
4.1
V
8.3
9.3
10.3
V
HF power supply
HF mode line voltage (1)
VLF1
HF mode line voltage (2)
VLF2
HF mode VCC2 voltage (1)
VCF21
HF mode VCC2 voltage (2)
VCF22
HF mode VCC1 voltage (1)
VCF11
HF mode VCC1 voltage (2)
VCF12
SW1/2=a/b,
IL= 20mA, VL voltage
SW1/2=a/b,
IL= 120mA, VL voltage
SW1/2=a/b,
IL= 20mA, DC voltage at pin37
SW1/2=a/b,
IL= 120mA, DC voltage at pin37
SW1/2=a/b,
IL= 20mA, DC voltage at pin41
SW1/2=a/b,
IL= 120mA, DC voltage at pin41
1.6
2.0
2.4
V
4.4
4.8
5.2
V
27
29
31
dB
0.3
2.0
HS transmitter
Trans. amp. gain
GHS
Vin1= –30dBm
Trans. amp. distortion
THS
Vin1= –30dBm
Trans. amp. max output
VHS
THS= 5%
Trans. amp. noise
NHS
Trans. level auto. PAD
APS
Rg= 2kΩ with a CCITT filter
Gain Difference with
Vin1= –30dBm, IL= 20 to 120mA
MF trans. amp. gain
GMF
Vin2= –30dBm
MF trans. amp. distortion
TMF
Vin2= –30dBm
MF trans. amp. max output
VMF
MF trans. amp. auto. PAD
APMF
TMF= 5%
Gain Difference with
Vin2= –30dBm, IL= 20 to 120mA
– 0.5
4
27
2.5
%
dBm
–65
dBm
8
dB
29
31
dB
0.3
2.0
6
%
0
3.0
dBm
4
6
8
dB
17
19
21
dB
1.5
5
HS receiver
Rec. amp. gain
GHR
Vin3= –35dBm
Rec. amp. distortion
THR
Vin3= –35dBm
Rec. amp. max output
VHR
THR= 5%
Rec. amp. noise
NHR
Rec. amp. auto. PAD
APR
Rg=2kΩ with a CCITT filter
Gain Difference with
Vin3= –35dBm, IL= 20 to 120mA
Note: Unless otherwise specified, IL=20 mA and fin=1 kHz.
4
–10
4
–7
6
%
dBm
–75
dBm
8
dB
ICs for Telephone
AN6175K
■ Electrical Characteristics (cont.) (Ta=25±2°C)
Parameter
Symbol
Condition
min
typ
max
Unit
HF transmitter
Trans. gain (1)
GFS1
Trans. gain (2)
GFS2
Trans. noise
NFS
Trans. att. gain (1)
GTA MAX1
Trans. att. gain range (1)
GTA MIN1
Trans. att. idling gain (1)
GTA IDL1
Trans. att. gain (2)
GTA MAX2
Trans. att. gain range (2)
GTA MIN2
Trans. att. idling gain (2)
GTA IDL2
Vin4= –65dBm
IL=20mA
Vin4= –65dBm
IL=120mA
Rg=2kΩ,
IL=20mA with a CCITT filter
Vin4= –60dBm
IL=20mA
Vin4= –60dBm
IL=20mA
Vin4= –60dBm
IL=20mA
Vin4= –60dBm
IL=20mA
Vin4= –60dBm
IL=20mA
Vin4= –60dBm
IL=20mA
57
60
63
dB
63
66
69
dB
–58
dBm
34
dB
28
31
45
48
1
4
7
dB
33
36
39
dB
47
50
3
6
9
dB
34
37
40
dB
40
43
46
dB
1.5
5.0
%
dB
dB
HF receiver
Rec.gain (1)
GFR1
Rec. gain (2)
GFR2
Rec. distortion
TSP
Vin3= –50dBm
IL=20mA
Vin3= –50dBm
IL=120mA
Vin3= –50dBm
IL=20mA
Rec. max output (1)
VSP1
TSP=5%, IL=20mA
Rec. max output (2)
VSP2
TSP=5%, IL=120mA
Rec. noise
NFR
Rec. att. gain (1)
GRA MAX1
Rec. att. gain range (1)
GRA MIN1
Rec. att. idling gain (1)
GRA IDL1
Rec. att. gain (2)
GRA MAX2
Rec. att. gain range (2)
GRA MIN2
Rec. att. idling gain (2)
GRA IDL2
Rec. att. volume characteristics
GRA VRM
Rg=2kΩ,
IL=20mA with a CCITT filter
Vin3= – 40dBm
IL=20mA
Vin3= – 40dBm
IL=20mA
Vin3= – 40dBm
IL=20mA
Vin3= – 40dBm
IL=120mA
Vin3= – 40dBm
IL=120mA
Vin3= – 40dBm
IL=120mA
Vin3= – 40dBm
IL=20mA
–10
–7
dBm
4
7
dBm
–60
dBm
15
dB
9
12
49
52
–15
–12
–9
dB
14
17
20
dB
53
56
–13
–10
–7
dB
–4
–2
0
dB
dB
dB
■ Electrical Characteristics (Design Values for Reference) (Ta=25±2°C)
Parameter
Symbol
Condition
Design value
Unit
HS power supply
HS mode internal reference voltage (1)
Vrs
HS mode internal reference voltage (2)
VSPS
HS mode internal reference voltage (3)
VBGS
HS mode AC impedance
ZACS
Pin31 high, Pin32 high,
IL=20mA
Pin31 high, Pin32 high,
IL=20mA
Pin31 high, Pin32 high,
IL=20mA
Pin31 high, Pin32 high,
IL=20mA
1.0
V
2.0
V
1.17
V
610
Ω
5
ICs for Telephone
AN6175K
■ Electrical Characteristics (Design Values for Reference) (cont.) (Ta=25±2°C)
Parameter
Symbol
Condition
Design value
Unit
HF power supply
HF mode internal reference voltage (1)
VrF
HF mode internal reference voltage (2)
VSPF
HF mode internal reference voltage (3)
VBGF
HF mode AC impedance
ZACF
Pin31 high, Pin32 low,
IL=20mA
Pin31 high, Pin32 low,
IL=20mA
Pin31 high, Pin32 low,
IL=20mA
Pin31 high, Pin32 low,
IL=20mA
1.0
V
2.0
V
1.17
V
610
Ω
Control voltage
Low level
VC (L)
– 0.3 to + 0.5
V
High level
VC (H)
1.0 to 5.0
V
Note) These values are for reference only (not guaranteed values).
■ Mode Control
Pin No.
31
32
15
HF, HS/MF
HS/MF
REC– CONT
0
0
0
Transmit MF in the hands-free mode. Trans./rec. att. can be changed according to input level.
0
0
1
Transmit MF in the hands-free mode. Trans./rec. att. is available only in the receiver mode.
0
1
0
Transmit MF in the handset mode.
0
1
1
Transmit MF in the handset mode.
1
0
0
Speech in the hands-free mode
1
0
1
Speech in the hands-free mode. Trans./rec. att. is available only in the receiver mode.
1
1
0
Speech in the handset mode
1
1
1
Speech in the handset mode
Description
Where 0 means connection to GND, and 1 means connection to Pin41(VCC1).
■ ES-42D Package Power Dissipation
PD  Ta
(mW)
1,800
Power Dissipation (PD)
1,600
Open condition
Rthj— a=123°C/W
PD=1016mW(25°C)
1,400
1,200
1016
1,000
800
600
400
200
0
0
25
50
75
100
Ambient Temperature (Ta)
6
125
150
(°C)
ICs for Telephone
AN6175K
■ Operation in the Hand-free Mode
• Block Diagram
Trans. Attenuator
MIC
MIC Level
Monitor
TLOG1
Noise Level
Monitor
Trans. Level
Monitor
Attenuator Control
C1
Line Interface
C2
Rec. Level
Monitor
SP Level
Monitor
RLOG1
TLOG2
RLOG1
SP
Rec. Attenuator
■ Attenuator Control
Input signal
C1
C2
Operation mode
Trans. noise REC– CONT
TX
TX
TX
0
Transmitter mode
TX
RX
TX
0
High-speed switching idle mode
RX
TX
TX
0
High-speed switching idle mode
RX
RX
—
0
Receiver mode
TX
TX
noise
0
Low-speed switching idle mode
TX
RX
noise
0
Low-speed switching idle mode
RX
TX
noise
0
Low-speed switching idle mode
—
—
—
1
Receiver mode
C1 : Output comparison between TLOG1 and RLOG1.
C2 : Output comparison between TLOG2 and RLOG2.
■ Trans./Rec. Switching Characteristics
Idle Mode
Transmitter Gain
Gain
Receiver Gain
7
ICs for Telephone
AN6175K
1.Setting
(1) Setting the Line Path
1—1 Setting the DC Characteristics
The AN6175K can be made compatible with local telephone regulations by setting the following characteristics :
1. Gradient of the IL—VL characteristics
2. Degree of shifting of the IL—VL characteristics
How to set the above characteristics is described below.
1. Setting the gradient of the IL-VL characteristics
Referring to Fig.1—1, the resistance of R34 is 27Ω(standard)as with the current application board.
• If R34's resistance is decreased, the gradient decreases.
• If R34's resistance is increased, the gradient increases.
Also see Fig.1—2.
VCC1
VCC2
C38
37
R33
VL
TRB
Q3
38
ZL= 600Ω
MIC amp.
TRE
VCC1
39
R34
AN6175K
Fig.1—1 Line Output Block Diagram
12
R34=33Ω
11.8V
VL (V)
Higher than
standard
Lower than
standard
4.2V
R34=27Ω
10.6V (standard)
R34=20Ω
8.7V
3.95V
3.6V
0
0
20
120
IL (mA)
Fig.1—2 IL—VL Characteristics
As shown in Fig.1—2, the resistance of R34 determines the gradient of the IL—VL characteristics. R34 also affects the gain of
the line output. Also see 1—2, Setting the AC Characteristics.
8
ICs for Telephone
AN6175K
2. Setting the degree of shifting of the IL—VL characteristics
12
VL (V)
R33=1.3kΩ
R33=820Ω(standard)
R33=330Ω
0
0
20
120
IL (mA)
Fig.1—3 IL—VL Characteristics
Referring to Figs.1—1 and 1—3, the resistance of R33 is now set to 820Ω(standard).
• If R33's resistance is decreased, the curve shifts downward.
• If R33's resistance is increased, the curve shifts upward.
As shown in Fig.1—3, the resistance of R33 determines the degree of vertical shifting of the IL—VL characteristics. R33 also
affects the AC characteristics of the line interface.
VCC2
VCC1
Referring to Fig.1—4, the AC impedance(ZAC)of the line interface is calculated as follows :
VL
ZAC= R33/ZQ3
If the impedance of transistor Q3 is 2 kΩ(ZQ3=2 k), and the
resistance of R33 is 820Ω, then ZAC is determined as follows :
ZAC= 820//2k
= 600Ω
C38
37
R33
TRB
Q3
38
MIC amp.
TRE
VCC1
39
R34
AN6175K
Fig.1—4 Line Output
1—2 Setting the AC Characteristics
1. Line output gain adjustment
VCC1
VCC2
C38
37
R33
VL
TRB
Q3
38
ZL=300Ω
MIC amp.
TRE
Use R34 to adjust the line output gain as shown in Fig.1—1.
The line output amplifier gain, G(38), as seen from Pin38, is
calculated as follows :
G(38)= 20 log (ZL/R34)
If R34 is 27Ω, G(38) is 21dB.
VCC1
39
R34
AN6175K
Fig.1—5 Line Output Block Diagram
9
ICs for Telephone
AN6175K
Automatic PAD control adjustment
Automatic PAD control, or APC, is such a function as to automatically adjust transmission gain according to line current (IL).
The gain range of the APC of the AN6175K is 6 dB. The adjustment of the APC means setting the IL at which the APC starts
functioning. The adjustment is done by changing the R24/R25 ratio as shown in Fig.2—1.
Under the standard condition(R24=18 kΩ, R25=12 kΩ), the IL at which the APC starts functioning(the APC start point)is 45 mA
as shown in Fig.2—2.
Standard R24/R25 ratio
DG (dB)
2.
Referring to Fig. 1—6, the APC start point depends on the R24/R25
ratio as follows :
• If the ratio increases, the point becomes higher.
• If the ratio decreases, the point becomes lower.
Larger R24/R25 ratio
Smaller R24/R25 ratio
0
20
45
120
Line Current IL (mA)
Fig.1—6 Automatic PAD Control
3.
Balance network adjustment
The balance network of the AN6175K application board is shown below. Its constants can be adjusted to application needs.
From line
VL pin connecting to the transmission transistor
R1
3.9kΩ
R3
3.3kΩ
R2
12kΩ
C3
0.039µF
To the receiver preamplifier
R4
330Ω
From the emitter of the transmission transistor
Fig.1—7 Balance Network
(2) Handset(HS)Mode
2—1 Setting the Transmitter System
The block diagram of the transmitter system in the HS mode is shown below.
Vr
VL
AN6175K
TRE
+
38
–
ZL=300Ω
Q3
R34
TAPC
VCC1
3
MAI
4
18
MAO
APC
C42
R12
R13
R25
R14
C45
R24
C6
VCC1
ECM
Fig.2—1 HS Mode Transmitter System Block Diagram
As seen from the above diagram, the gain of the transmitter system from ECM to VL in the HS mode is determined by the gain of
the MIC preamplifier and the gain of the line output amplifier(21dB). How to adjust the gain/frequency characteristics of the MIC
preamplifier is described below.
10
ICs for Telephone
AN6175K
MIC Preamplifier Gain/Frequency Characteristics Adjustment
The external components, R12, R13, C6, and C45, determine the MIC preamplifier gain/frequency characteristics in the HS mode
as shown in Fig. 2—2. R12 and C6 form a low-pass filter, and R13 and C45 form a high-pass filter.
AN6175K
Vr
To APC
+
Referring to Fig.2—2, the MIC preamplifier gain, G(HSMIC), is cal-
–
culated as follows :
3
MAI
4
G (HSMIC) = 20log
MAO
R12
VCC1
R13
(dB)
In the standard condition, R12=R13=10 kΩ, C6=102 pF, and C45
= 0.1µF.
R14
C45
{1/ (2π f C6)}// R12
{1/ (2π f C45)} + R13
C6
ECM
Fig.2—2 MIC Preamplifier
The HS mode transmitter frequency characteristics are calculated as follows :
• High-band cutoff frequency, fHC=1/(2πC6 · R12)
Gain (dB)
• Low-band cutoff frequency, fLC=1/(2πC45 · R13)
Referring to the above calculations :
• For the low-pass filter, the larger the C6 capacitance, the lower the cutoff frequency, or the smaller the capacitance, the
higher the frequency.
• For the high-pass filter, the larger the C45 capacitance, the lower the cutoff frequency, or the smaller the capacitance, the
higher the frequency. See Fig.2—3.
Larger C45
Smaller C45 Larger C6
Smaller C6
Standard C45
Standard C6
300
1k
4k
Input Frequency (Hz)
Fig.2—3 HS Mode Transmitter Frequency Characteristics
11
ICs for Telephone
AN6175K
2–2 Setting the Receiver System
The block diagram of the receiver system in the HS mode is shown below.
To LOG4amp.
BN
Handset receiver
VCC1
C32
Vr
C20
R31
C31
R24
C22
R25
R27 C21
R26
R32
30
29
RPI
RPO
20
22
APC
DO
21
DI
Receiver amplifier
RAPC
–
+
Receiver
preamplifier
AN6175K
Fig.2–4 HS Mode Receiver System Block Diagram
There are two adjustments for the HS mode receiver system as follows :
1. Set the frequency characteristics of the receiver preamplifier.
2. Adjust the receiver amplifier.
1. Receiver Preamplifier Frequency Characteristics Setting
Fig.2–5 is the block diagram for the receiver preamplifier.
To LOG4amp.
BN
C32
Vr
0
R31
C31
R32
30
RPI
29
RPO
20
Gain (dB)
–3
Receiver preamplifier
To receiver amplifier
FN
AN6175K
Frequency (Hz)
Fig.2–5 Receiver Preamplifier Block Diagram
Fig.2–6 HPF Frequency Characteristics
A high-pass filter(HPF)consisting of R31, R32, C31, and C32 blocks external hum noise. The frequency characteristics of the
HPF are calculated as follows(see Fig. 2-6) :
FN =
1
2π
1
1
×
C31 ⋅ C32
R31 ⋅ R32
In the standard condition, R31=56 kΩ, R32=220 kΩ, and C31=C32= 0.0047µF.
12
ICs for Telephone
AN6175K
2. Receiver Amplifier Gain Adjustment
Use R26, R27, and C21 to adjust the receiver amplifier gain as shown in Fig.2–7.
Handset receiver
C22
R26 C21
R27
22
Referring to Fig.2–7, the receiver amplifier gain, G(REC), is calculated as
follows :
21
DO
R27
R26 + {1/(2π f C21)}
G(REC) = 20log
(dB)
DI
In the standard condition, R26=1 kΩ, R27=100 kΩ, and C21=10µF.
Receiver amplifier
AN6175K
Fig.2–7 Receiver Amplifier
(3) Hands-Free (HF) Mode
3–1 Setting the Transmitter System
The block diagram of the transmitter system in the HF mode is shown below.
Vr
AN6175K
VL
TATT
TRB
+
38
–
2
R9
MAO
1
TAO
18
36
20
HFI
VCC1
VCC1
R24
VCC1
Q3
R34=27Ω
TAPC
MAI
ZL=300Ω
C42
R10
C5
R11
C37
C44
C22
R25
ECM
Fig.3–1 HF Mode Transmitter System Block Diagram
As seen from the above diagram, the gain of the transmitter system from ECM to VL in the HF mode is determined by the gains
of the MIC preamplifier, transmitter attenuator(T ATT), and line output amplifier. The gain of the T ATT is 0 dB, and the gain of
the line output amplifier is 21 dB(see 1-2, Setting the AC Characteristics). How to adjust the gain of the MIC preamplifier is the
same as that in the HS mode. The gain, G(HSMIC), is calculated as follows :
G (HSMIC) = 20log
{1/(2πf C5)}// R9
{1/(2πf C44)} + R10
(dB)
In the standard condition, R9=26 kΩ, R10=10 kΩ, C5=102 pF, and C44=0.1 µF.
13
ICs for Telephone
AN6175K
3–2 Setting the Receiver System
The block diagram of the receiver system in the HF mode is shown below.
Loudspeaker
To LOG4amp.
C27
BN
C32
C25
C23
R29
C29
C24
Vr
R31
C31
R32
R31
RPI
C28
SPI
RPO
30
R28
29
19
FB C26
27
SPO1
26
25
–
SP Pre.
Vr
+
+
+
SPO2
24
–
–
RATT
2k
Vr
20k
AN6175K
Fig.3–2 HF Mode Receiver System Block Diagram
There are two settings for the HF mode receiver system as follows :
⋅ Set the gain of the receiver preamplifier.
⋅ Set the gain of the loudspeaker amplifier.
Setting of the receiver preamplifier gain is the same as that in the HS mode. How to set the loudspeaker amplifier gain is described
below.
The loudspeaker amplifier gain, G(SP), is calculated as follows :
G(SP)=20log
R28// {1/(2πf C26)}
+6
R29+ {1/(2πf C27)}
(dB)
Note : 6 dB is added for the purpose of BTL configuration.
In the standard condition, R28=R29=20 kΩ, C26=100 pF, and C27=47µF.
(4) MF Mode
4–1 Setting the MF Signal Gain
Fig. 4–1 shows how the MF signal flows.
VL
AN6175K
ZL=600Ω
TRE
38
TAPC
35
18
Q3
R34
VCC1
APC
C42
MFI
C35
R25
R24
VCC1
Fig.4–1 MF Signal Flow
In the standard condition, the MF signal gain, G(MF), is equal to the line output gain, that is, 21 dB. To adjust the MF signal gain,
use a proper resistor combination as indicated in a dotted box in Fig. 4–1.
14
ICs for Telephone
AN6175K
■ Detailed Pin Descriptions
Symbol
Pin No.
Equivalent circuit
Description
VCC1
[MIC preamplifier output in the HF mode]
1
MAO(HF)
Amplified HF mode transmitter signals
are output from this pin through C7(0.1
µF)and R15(5.1 kΩ)to pin 7 to become
the LOG amp.1 input. The output impedance, Zout=50Ω.
To the transmitter
attenuator
HF mode MIC +
preamplifier
−
40Ω
1
40Ω
[MIC preamplifier input in the HF mode]
2
MAI(HF)
HF mode transmitter signals are input
from ECM. Use R9 and R10 to adjust the
transmitter signal gain, and use C3 and
C44 to adjust the frequency characteristics.
2
−
+
−
+
[MIC preamplifier input in the HS mode]
3
MAI(HS)
HS mode transmitter signals are input
from the handset MIC. Use R12 and R13
to adjust the transmitter signal gain, and
use C6 and C45 to adjust the frequency
characteristics.
3
[MIC preamplifier output in the HS mode]
MAO(HS)
VCC1
To the line driver
HS mode MIC
preamplifier
+
4
Amplified HS mode transmitter signals
are output from this pin. The output
impedance, Zout = 1 kΩ.
4
−
[Noise detecting circuit control]
VCC1
5
TND
Turns ON or OFF the background-noise
detecting circuit in the HS mode. The
circuit turns ON if this pin is grounded
through C7(SW7 to a), and turns OFF if
this pin is grounded directly(SW7 to b).
5
15
ICs for Telephone
AN6175K
■ Detailed Pin Descriptions(cont.)
Symbol
Pin No.
Equivalent circuit
Description
TVR
6
hands-free
[LOG amp.(4)input(from receiver
preamp. output)]
This pin connects through C11(0.1 µF)and
R17(5.1 kΩ)to the receiver preamp. output.
RLI2
–
9
–
+
[LOG amp.(3)input(from loudspeaker
amp. output)]
10
8
This pin connects through C10(0.1 µF)and
R16(5.1 kΩ)to the HF control output.
+
RLI1
–
+
9
TLI2
7
This pin connects through C9(0.1 µF)and
R15(5.1 kΩ)to the MIC amp. output.
[LOG amp.(2)input(from
control output)]
8
+
TLI1
–
This pin must be grounded through C8
(22µF).
[LOG amp.(1)input(from MIC amp. output)]
7
+
[Noise detecting circuit reference]
6
10
–
This pin connects through C12(0.1 µF)and
R18(5.1 kΩ)to the loudspeaker amp. output.
VCC1
11
16
TLO1
[LOG amp.(1)output]
Outputs amplified MIC amp. output.
Grounded through C13(2.2 µF). The
attack recovery time of the attenuator
changes with the capacitance of C13.
11
ICs for Telephone
AN6175K
■ Detailed Pin Descriptions(cont.)
Symbol
Pin No.
Equivalent circuit
Description
VCC1
[LOG amp.(2)output]
12
TLO2
Outputs the amplified hands-free control
output. Grounded through C14(2.2 µF).
The attack recovery time of the attenuator
changes with the capacitance of C14.
12
VCC1
[LOG amp.(3)output]
13
RLO1
Outputs the amplified receiver preamp.
output. Grounded through C15(2.2 µF).
The attack recovery time of the attenuator
changes with the capacitance of C15.
13
VCC1
[LOG amp.(4)output]
14
RLO2
Outputs the amplified loudspeaker amp.
output. Grounded through C16(2.2 µF).
The attack recovery time of the attenuator
changes with the capacitance of C16.
14
[Receiver switching]
15
16
REC–CONT
RVR
Determines whether the attenuator is to
be in the receiver mode or normal mode.
If this pin is connected to VCC1(SW3 to
b), the receiver mode is selected. If connected to GND(SW3 to a), the normal
mode is selected.
15
100kΩ
100kΩ
[Receiver att. gain control]
An external rheostat circuit connects to
this pin to control the receiver attenuator
gain.
16
[Receiver att. switching control]
ATC
R22(51 kΩ)and C18(4.7 µF)connect to
this pin to adjust the attenuator switching
time.
+
17
–
17
17
ICs for Telephone
AN6175K
■ Detailed Pin Descriptions(cont.)
Symbol
Pin No.
[Transmitter
mode)]
18
TAO
Equivalent circuit
Description
att.
output(hands-free
The transmitter attenuator outputs transmitter signals in the HF mode from this
pin to Pin36 through C37(0.1 µF). The
output impedance, Zout=1 kΩ.
18
[Receiver att. output(hands-free mode)]
19
RAO
The receiver attenuator outputs receiver
signals in the HF mode from this pin
through C29(0.1 µF)and R30(10 kΩ)to
Pin27 as the loudspeaker preamplifier
non-inverse input. The output impedance,
Zout=1 kΩ.
[Auto. PAD current control(handset
mode, MF)]
20
21
APC
DI
The ratio of R24 to R25 as connected to
this pin controls the operation point of the
automatic PAD.
[Receiver amp. input(–)]
Combined R26, R27, and C21 as connected to this pin determine the gain of
the receiver amplifier.
19
APC 20
1.2V
VGR 40
BGR
21
[Receiver amp. output]
18
22
DO
23
GND
Connects through C22(22µF)to the handset receiver. The output impedance,
Zout=100 Ω.
[Ground]
This is the ground pin of the IC.
22
ICs for Telephone
AN6175K
■ Detailed Pin Descriptions(cont.)
Symbol
Pin No.
Equivalent circuit
Description
25
[Loudspeaker amp.(2)output]
Pins24 and 25 form a BTL configuration.
The output impedance, Zout=10 Ω.
24
25
SPO2
SPO1
24
VCC1
[Loudspeaker amp.(1)output]
Pins24 and 25 form a BTL configuration.
Connects through R18 and C12 to pin 10
as the LOG amp.(3)input. The output
impedance, Zout=10 Ω.
+
+
–
–
26
[Loudspeaker amp. input(–)]
26
FB
Combined R28, R29, C26, and C27 connect to this pin to adjust the gain and the
frequency characteristics of the loudspeaker amplifier. The loudspeaker
amplifier is added with another gain of 6
dB because of its BTL configuration.
26
VCC1
[Loudspeaker amp. input(+)]
27
27
SPI
The receiver attenuator output signal is
sent from pin 19 to this pin through C28
(coupling capacitor).
+
–
[Loudspeaker amp. power input]
28
VSP
The power supply pin for the loudspeaker
amplifiers and other output circuits.
[Receiver preamp. output]
RPO
To rec. amp. for
HS mode
Rec. preamp.
+
29
Amplified receiver signals are output
from this pin through C30(coupling
)to Pin9 as the LOG amp.(4)input. Within
the IC, the receiver preamplifier output
also connects to the receiver amplifier for
the HS mode and to the receiver attenuator for the HF mode.
VCC1
40Ω
29
–
40Ω
To rec. att. for
HF mode
[Receiver preamp. input]
30
RPI
Receiver signals are input from line to
this pin through a high-pass filter consisting of R31, C31, and C32. The filter
removes hum from receiver signals.
30
19
ICs for Telephone
AN6175K
■ Detailed Pin Descriptions(cont.)
Symbol
Pin No.
Equivalent circuit
Description
[Mode switching(handset or hands-free
/MF)]
31
HS, HF/MF
50kΩ
31
This pin must be connected to VCC1 for
the HS or HF mode(SW2 to a), or to
GND for the MF mode (SW2 to b).
100kΩ
[Mode switching(handset/hands-free)]
32
HS/HF
50kΩ
32
This pin must be connected to VCC1 for
the HS mode (SW1 to a), or to GND for
the HF mode (SW1 to b).
100kΩ
VCC1
33
34
Vr
ST
+
[Reference for the handset or hands-free
mode]
33
The voltage equal to half the VCC1 voltage is output.
–
[Input to the base of the power supply
transistor]
34
This pin connects to the base of Q4.
[MF input]
35
MFI
MF signals are input to this pin through
C35(0.1µF). The input impedance,
Zin=20 kΩ.
[From transmitter att. output(hands-free
mode)]
20kΩ
35
VCC1
+
36
37
20
HF1
VCC2
The transmitter attenuator output is sent
from Pin18 to this pin through C37(0.1
µF). The input impedance, Zin=20 kΩ.
[Transmission amp. AC impedance setting]
This pin connects to VCC1 through C38
(100µF)and to the collector of Q3 (transmission transistor)through R38(330 Ω).
36
–
ICs for Telephone
AN6175K
■ Detailed Pin Descriptions(cont.)
Symbol
Pin No.
Description
Equivalent circuit
[To the base of the transmission transistor]
38
TRB
38
This pin connects to the base of Q3
(transmission transistor).
[To the emitter of the transmission transistor]
39
TRE
This pin connects to the emitter of Q3
(transmission transistor)and R33 to adjust
the Q3 gain.
39
+
40
[Band-gap ref. voltage output]
40
BGR
–
BGR
Connects to GND through C39(47 µF).
BGR
[Power output to the handset and handsfree circuits]
41
VCC1
The power supply pin for the signal processing circuits.
+
[Hands-free control output]
42 SOUT
–
42
SOUT
Outputs transmitter monitor signals in the
HF mode. Connects through R16 and
C10 to LOG amp.(2)input at Pin8.
21