NJW1124
– 1
–
Voice Switched Speakerphone circuit
!
!!
! GENERAL DESCRIPTION !
!!
! PACKAGE OUTLINE
The NJW1124 is a Voice Switched Speakerphone Circuit.
NJW1124 includes all of functions processing a high quality hands–free
speakerphone system, such as the necessary amplifiers ( Microphone ,
Receive ,Line), attenuators, level detectors functions.
All external capacitors are sufficient small so that ceramic capacitors are
applied.
!
!!
! APPLICATION
•Video Door Phone
•Conference System
•Wireless Application
•Security System
!
!!
! FEATURES
• Operating voltage range 2.9 to 4.5V
• Force to Receive, Transmit, or Idle modes
• Mode –watching monitor
• Attenuator gain range between Transmit and Receive 52dB
• Microphone amplifier with mute function
• Background noise monitor for each path
• Volume control range 40dB
• 4-point signal sensing
• Microphone and Receive Amplifiers pinned out for flexibility
• Package Outline SSOP32
!
!!
! BLOCK DIAGRAM
NJW1124V
BIAS
Tx Attenuator
Attenuator
Control
Level
Detector
Backgro und
N oi seM o ni to r
Monitor
Speaker
Microphone
-1
Rx Attenuator
Level
Detector
Background
NoiseMonitor
V
+
IC2
NJU7084
Power Amp lifier
Line Amplifier
V
+
Line Out
VLC
V
+
MCI MCO TLI2 TLI1 TXO LII LiO- LiO+
V
+
RT SW
CPR
TLO1
RL O1
GND
FIRLI1
RLI2RXO
V
REF2
VREF
CPT
RL O2
TLO2
MUT
CT
Recive In
VREF
C3
470n
C4
470n
C2
1u
C23
1µ
µµ
µ
R9
22k
R8
11k
C17
100n
R11
10k
C6
100n
R2
5.1k
R3
51k
C7
100n
R4
51k
R5
10k
C8
100n
R6
5.1k
R7
51k
R12
51k C18
100n
R13
5.1k
C12
100n
R14
5.1k
C21
470n
C20
470n
C22
1µ
µµ
µ
C5
1µ
µµ
µ
C11
1µ
µµ
µ
C19
100n
C9
100n
C1
1µ
µµ
µ
R1
300k
Mic
Am
p
lifie
r
R eceiv e
A
m
p
lifier
1.2µ
µµ
µA
C10
VREF
VREF
R
VLC
5.0V
+
10µ
µµ
µ
C14 1 µ
1 µ 1 µ
1 µ
1µ
1µ1µ
1µ
FO
C16
C13
IC1
NJW1124
V
+
C15
1µ
µµ
µ
R10
15k
NJW1124
– 2 –
!PIN CONFIGURATION
1
VREF2
32
MON
2
MUT
31
RTSW
3
NC
30
VREF
4
CPT
29
CPR
5
TLO2
28
RLO1
6
RLO2
27
TLO1
7
CT
26
VLC
8
MCI
25
FI
9
MCO
24
FO
10
TLI2
23
RLI1
11
TLI1
22
RLI2
12
TXO
21
RXO
13
LII
20
NC
14
LIO-
19
NC
15
LIO+
18
NC
16
GND
17
V+
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
NJW1124
1
NJW1124
– 3 –
!
!!
! ABSOLUTE MAXIMUM RATING
(Ta=25°C)
PARAMETER SYMBOL RATING UNIT
Power Supply Voltage V
+
5.5 V
Power Dissipation P
D
800 (Note1) mW
Operating Temperature Range Topr -40 ~ +85 °C
Storage Temperature Range Tstg -40 ~ +125 °C
Maximum Input Voltage V
IMAX
0 ~ V
+
V
(Note1) EIA/JEDEC STANDARD Test board (76.2x114.3x1.6mm, 2layer, FR-4) mounting
(Note2) Don’t apply the input voltage that exceeds supply voltage.
!
!!
! OPERATING VOLTAGE
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Operating Voltage
V
+
- 2.9 4.0 4.5 V
!
!!
! ELECTRICAL CHARACTERISTICS
(Ta=25°C,V
+
=4V,MUT=ACTIVE,RTSW=OPEN,R
VLC
=0Ω,G
VM
=0dB,ReceiveAmplifierG
V
=0dB)
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Operating Current 1
I
CC1
RX-mode (Receive) 0.7 2.0 4.0 mA
Operating Current 2
I
CC2
TX-mode (Transmit) 0.7 2.0 4.0 mA
Operating Current 3
I
CC3
Idle-mode 0.7 2.0 4.0 mA
Reference Voltage
V
REF
Idle-mode 1.7 2.0 2.3 V
●Receive Attenuator
(RxIN=100Vrms,Receive Amplifier Gv=0dB)
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Receive Attenuator Gain 1
G
R1
RX-mode (Receive) 3.0 6.0 9.0 dB
Receive Attenuator Gain 2
G
R2
TX-mode (Transmit) -43 -46 -50 dB
Receive Attenuator Gain 3
G
R3
Idle-mode (Standby),CPT=CPR=V
+
-17 -20 -23 dB
Range R to T mode
∆G
R
RX-mode – TX-mode 47 52 57 dB
Dynamic DC offset
G
RDC
RX-mode – TX-mode (DC) -50 - 50 mV
Volume control range
G
RVR
RX-mode,R
VLC
=0
Ω
-100k
Ω
30 40 50 dB
Maximum DetecterSink Current I
RSINKMAX
RLI1,TLI1,Maximum Sink Current
- - 200 µA
●Transmit Attenuator
(TxIN=100Vrms,Mic.amplifier Gv=0dB)
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Transmit Attenuator Gain 1
G
T1
TX-mode (Transmit) 3.0 6.0 9.0 dB
Transmit Attenuator Gain 2
G
T2
RX-mode (Receive) -43 -46 -50 dB
Transmit Attenuator Gain 3
G
T3
Idle-mode CPT=CPR=V
+
-17 -20 -23 dB
Range R to T mode
∆G
T
TX-mode – RX-mode 47 52 57 dB
Dynamic DC offset
G
TDC
TX-mode – RX-mode (DC) -50 - 50 mV
Volume control range
G
TVR
RX-mode,R
VLC
=0
Ω
-100k
Ω
31 40 46 dB
Maximum DetecterSink Current I
RSINKMAX
RLI1,TLI1,Maximum Sink Current
- - 200 µA
NJW1124
– 4 –
●MIC Amplifier
(TxIN=1mVrms,Gv=40dB,R
L
=5.1kΩ)
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Output Offset Voltage V
MOS
R5=300kΩ,V
MOS
=V
MCI
-V
MCO
-30 0.0 30 mV
Input Bias Current I
MBIAS
- - 0.0 - nA
Voltage Gain 1 G
VM1
f=1kHz - 40 - dB
Voltage Gain 2 G
VM2
f=20kHz - 38 - dB
Maximum Output Voltage V
MMAX
THD=1% 0.9 - - Vrms
Maximum Output Current I
MOMAX
- - 1.5 - mA
Maximum Attenuation G
MMUTE
R5=300kΩ 70 73 - dB
●Receive Amplifier
(RxIN=1mVrms,Gv=40dB,R
L
=5.1kΩ)
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Output Offset Voltage V
ROS
RF=300kΩ,V
FOS
=V
FI
-V
FO
-30 0.0 30 mV
Input Bias Current I
RBIAS
- - 30 - nA
Voltage Gain 1 G
VR1
f=1kHz - 40 - dB
Voltage Gain 2 G
VR2
f=20kHz - 38 - dB
Maximum Output Voltage V
RMAX
THD=1% 0.9 - - mVrms
Maximum Output Current I
ROMAX
- - 1.5 - mA
●Line Amplifier
(LINEIN=50mVrms, G
V
=26dB,R
L
=1.2kΩ)
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Output Offset Voltage V
LOS
R9=51kΩ 20 0.0 20 mV
Input Bias Current I
LBIAS
- - 0.0 - nA
Voltage Gain 1 G
VL1
f=1kHz - 26 - dB
Voltage Gain 2 G
VL2
f=20kHz - 25 - dB
Closed Loop Gain G
LC
LIO- to LIO+ -0.5 0 0.5 dB
Maximum Output Voltage V
LMAX
THD=1% 1.5 - - Vrms
Total Harmonic Distortion THD
LN
f=1kHz - - 0.5 %
Maximum Output Current I
LOMAX
-
- 4.0 - mA
●Monitor Terminal (32Pin) Output Voltage
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
R
X
-mode Rx - V
+
-0.3 - - V
T
X
-mode Tx - - - 0.3 V
Idle-mode Idle No Signal - V
+
/2 - V
Maximum Output Current I
MON
Rx-mode / Tx-mode - 1.0 - mA
NJW1124
– 5 –
!
!!
!
CONTROL CHARACTERISTICS (MUT)
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Low Level Input Voltage V
IL1
- - - 0.3 V
High Level Input Voltage V
IH1
- 1.5 - - V
!
!!
!
CONTROL CHARACTERISTICS (RTSW)
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Low Level Input Voltage V
IL2
- - - 0.3 V
High Level Input Voltage V
IH2
- V
+
-0.3 - - V
!
!!
!
FUNCTION
●MUT (2pin)
INPUT VOLTAGE STATUS OPERATION
V
IH
MUTE The microphone input is made a mute.
V
IL
ACTIVE The microphone input is active.
●RTSW (31pin)
INPUT VOLTAGE STATUS OPERATION
V
IH
Receive Force to Receive mode.
OPEN AUTO
Receive mode and Transmit mode are automatically
switched.
V
IL
Transmit Force to Transmit mode.
●R
VLC
(26pin)
IMPEDANCE STATUS OPERATION
0 Vol
MAM
The Receive attenuator Volume is maximum.
100k
Ω
Vol
MIN
The Receive attenuator Volume is minimum.
NJW1124
– 6 –
!
!!
!
MEASUREMENT CIRCUIT
1u
100n
100n
1u
300k
300k
100n 5.1k
1u
1u
100n
100n
300k
100n
1u
100n
5.1k
51k
100n
V+
1u
47p
V
IH
100
V
IL
3k
1u
TxI N
MC OU T
0dB
40dB
Tx OU T
LINEIN
LINEOUT 1.2k(R
LL
)
4.7k 4.7k
V
IH
V
IL
100
RxIN
FilterOUT
RxOUT
300k
3k
40dB
0dB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
FI
TLI1
TLI2
MCO
MCI
F
O
RLI1
RLI2
V
+
GND
LIO
+
LIO-
NC
NC
NC
RX
O
LII
MUT
NC
TXO
CT
CPT
TLO2
RL O2 TLO1
V
LC
CP
R
RL O1
RT S
W
VREF
MO
N
V
REF2
NJW1124
OPEN
Icc
M ONOUT
100k
100
k
0ohm
V
+
OPEN
1k
S2
S4
S5
S6
1k
V
+
OPEN
S7
S8
S9
V
re
f
R
LMH
R
LML
OPEN V+ OPEN
S12 S13
1u
5.1k
5.1k5.1k
NJW1124
– 7 –
!
!!
!
APPLICATION CIRCUIT
Speaker Out
+
-
4
3
2
1
1µ
µµ
µ
470n
470n
1u
100n 5.1k
51k
100n 51k
1µ
µµ
µ
1µ
µµ
µ
470n
470n
5.1k
100n
51k
5.1k 100n
100n
10k
100n
5.1k
51k
10k
100n
Receive In
LINE
OUT
V+ (1)
1µ
µµ
µ
47p
V
+
1µ
µµ
µ
300k
V+ :MUTE
GND :ACTIVE
Mic I n
V+
V+ :Recive
GND :Trensmit
Open :Auto
Rx-Mode :V+
Tx-Mo de :GND
Idle :HI-Z
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
FI
TLI1
TLI2
MCO
MCI
F
O
RLI1
RLI2
V+
GND
LIO
+
LIO-
NC
NC
NC
RX
O
LII
MUT
NC
TXO
CT
CPT
TLO2
RLO2 TLO1
V
LC
CP
R
RLO1
RTS
W
V
RE
F
MON
V
REF2
NJW1124
100k
8
7
6
5
OUT
A
V+
GN
D
OUT
B
-IN
+
++
+IN
SDTC
SD
V+ (2)
10u
NJU7084
11k
0.1u
22k
1
µ
µµ
µ
1
µ
µµ
µ
V+
15k
V+ :ACTIVE
GND :Shut Down
1µ
µµ
µ
TR1
V+
LED1
Monitor Out
TX
OUT
+
-
Recei ve Out
2.2k
56k 0.47µ
µµ
µ
NJW1124
– 8 –
!
!!
!
TYPICAL CHARACTERISTICS
Volume control range vs ambient temperature
( VLC=0Ω/100kΩ)
25.0
30.0
35.0
40.0
45.0
50.0
-50 -30 -10 10 30 50 70 90 110
Ambient temperature [℃]
Volume Control range [dB]
V+=3.3V
V+=4.0V
Tx ATT Gain vs ambient temperature
(V+=3.3V , Receive Amp Gain = 0dB , VLC=0Ω)
-50.0
-40.0
-30.0
-20.0
-10.0
0.0
10.0
-50 -30 -10 10 30 50 70 90 110
Ambient temperature [℃]
Tx ATT Gain [dB
]
Tx-Mode
Idle-Mode
Rx-Mode
Tx ATT Gain vs ambient temperature
(V+=4.0V , Receive Amp Gain = 0dB , VLC=0Ω)
-50.0
-40.0
-30.0
-20.0
-10.0
0.0
10.0
-50 -30 -10 10 30 50 70 90 110
Ambient temperature [℃]
Tx ATT Gain [dB
]
Tx-Mode
Idle-Mode
Rx-Mode
Detector Max Sink Current vs ambient temperature
(TLI1,TLI2,RLI1,RLI2 Max Sink Current)
0
100
200
300
400
500
600
700
-50 -30 -10 10 30 50 70 90 110
Ambient temperature [℃]
Max Sink Current [
∪
A]
V+=3.3V
V+=4.0V
Monitor Out
vs ambient temperature
(V+=3.3V , RLMH=RLML=4.7kΩ)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
-50 -30 -10 10 30 50 70 90 110
Ambient temperature [℃]
Monitor output Voltage [V]
Rx-Mode
Idle-Mode
Tx-Mode
note : The MONITOR OUT(@Idole-mode) is Hi-Z when there are neither RLMH and RLML.
Monitor Out
vs ambient temperature
(V+=4.0V , RLMH=RLML=4.7kΩ)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
-50 -30 -10 10 30 50 70 90 110
Ambient temperature [℃]
Monitor output Voltage [V]
Rx-Mode
Idle-Mode
Tx-Mode
note : The MONITOR OUT(@Idole-mode) is Hi-Z when there are neither RLMH and RLML.
NJW1124
– 9 –
!
!!
!
TYPICAL CHARACTERISTICS
MUTE Pin Voltage vs MUTE ATT Ratio
(V+=3.3V , MICAMP GAIN=40dB, Rf=300kΩ, Ri=3kΩ, A-weighted)
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
0 0.5 1 1.5 2 2.5
MUT PIN Voltage [V]
MUTE ATT Ratio [dB]
85℃
-40℃
25℃
MUTE Pin Voltage vs MUTE ATT Ratio
(V+=4.0V , MICAMP GAIN=40dB, Rf=300kΩ, Ri=3kΩ, A-weighted)
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
0 0.5 1 1.5 2 2.5
MUT PIN Voltage [V]
MUTE ATT Ratio [dB]
85℃
-40℃
25℃
MUTE Pin Voltage vs MUTE ATT Ratio
(V+=3.3V , MICAMP GAIN=0dB, Rf=3kΩ, Ri=3kΩ, A-weighted)
-60
-50
-40
-30
-20
-10
0
10
00.511.522.5
MUT PIN Voltage [V]
MUTE ATT Ratio [dB]
85℃
-40℃
25℃
MUTE Pin Voltage vs MUTE ATT Ratio
(V+=4.0V , MICAMP GAIN=0dB, Rf=3kΩ, Ri=3kΩ, A-weighted)
-60
-50
-40
-30
-20
-10
0
10
00.511.522.5
MUT PIN Voltage [V]
MUTE ATT Ratio [dB]
85℃
-40℃
25℃
MICAMP Gain vs Frequency
(V+=3.3V , RL=5.1kΩ, Cin=1µF, Rin=3kΩ)
-10
0
10
20
30
40
50
10 100 1000 10000 100000
Frequency [Hz]
Gain [dB]
85℃
25℃
-40℃
85℃
25℃
-40℃
Gv=40dB, Rf=300kΩ, Vin=1mV
Gv=0dB, Rf=3kΩ, Vin=100mV
MICAMP Gain vs Frequency
(V+=4.0V , RL=5.1kΩ, Cin=1µF, Rin=3kΩ)
-10
0
10
20
30
40
50
10 100 1000 10000 100000
Frequency [Hz]
Gain [dB]
85℃
25℃
-40℃
85℃
25℃
-40℃
Gv=40dB, Rf=300kΩ, Vin=1mV
Gv=0dB, Rf=3kΩ, Vin=100mV
NJW1124
– 10 –
!
!!
!
TYPICAL CHARACTERISTICS
Receive AMP THD+N vs Input Voltage
(V+=3.3V, RL=5.1kΩ , Gain=40dB , Rf=300kΩ, Ri=3kΩ, BW:400Hz-30kHz)
0.1
1
10
0.0001 0.001 0.01 0.1
Input Voltage [Vrms]
THD+N [%]
85℃
25℃
-40℃
Receive AMP THD+N vs Input Voltage
(V+=4.0V, RL=5.1kΩ , Gain=40dB , Rf=300kΩ, Ri=3kΩ, BW:400Hz-30kHz)
0.1
1
10
0.0001 0.001 0.01 0.1
Input Voltage [Vrms]
THD+N [%]
85℃
25℃
-40℃
Receive AMP Gain vs Frequency
(V+=3.3V , RL=5.1kΩ, Cin=1µF, Rin=3kΩ)
-10
0
10
20
30
40
50
10 100 1000 10000 100000
Frequency [Hz]
Gain [dB]
Gv=40dB, Rf=300kΩ, Vin=1mV
Gv=0dB, Rf=3kΩ, Vin=100mV
Receive AMP. Gain vs Frequency
(V+=4.0V , RL=5.1kΩ, Cin=1µF, Rin=3kΩ
-10
0
10
20
30
40
50
10 100 1000 10000 100000
Frequency [Hz]
Gain [dB]
Gv=40dB, Rf=300kΩ,Vin=1mV
Gv=0dB, Rf=3kΩ, Vin=100mV
LINEAMP Gain vs Frequency
(V+=3.3V , RL=1.2kΩ, Cin=1µF, Rf=51kΩ, Rin=5.1kΩ, Cf=47pF)
10
12
14
16
18
20
22
24
26
28
30
10 100 1000 10000 100000
Frequency [Hz]
Gain [dB]
Gv=26dB, Vin=50mV
LINE AMP Gain vs Frequency
(V+=4.0V , RL=1.2kΩ, Cin=1µF, Rf=51kΩ, Rin=5.1kΩ, Cf=47pF)
10
12
14
16
18
20
22
24
26
28
30
10 100 1000 10000 100000
Frequency [Hz]
Gain [dB]
Gv=26dB, Vin=50mV
NJW1124
– 11 –
!
!!
!
TYPICAL CHARACTERISTICS
Receive AMP THD+N vs Input Voltage
(V+=3.3V, RL=5.1kΩ , Gain=0dB , Rf=3kΩ, Ri=3kΩ, BW:400Hz-30kHz)
0.01
0.1
1
10
0.01 0.1 1 10
Input Voltage [Vrms]
THD+N [%]
85℃
25℃
-40℃
Receive AMP THD+N vs Input Voltage
(V+=4.0V, RL=5.1kΩ , Gain=0dB , Rf=3kΩ, Ri=3kΩ, BW:400Hz-30kHz)
0.001
0.01
0.1
1
10
0.01 0.1 1 10
Input Voltage [Vrms]
THD+N [%]
85℃
25℃
-40℃
Mic AMP THD+N vs Input Voltage
(V+=3.3V,MUT=0.3V, RL=5.1kΩ , Gain=40dB , Rf=300kΩ, Ri=3kΩ, BW:400Hz-30kHz)
0.1
1
10
0.0001 0.001 0.01 0.1
Input Voltage [Vrms]
THD+N [%]
85℃
(MUT=0V)
25℃
-40℃
85℃
(MUT=0.3V)
Mic AMP THD+N vs Input Voltage
(V+=4.0V,MUT=0.3V, RL=5.1kΩ , Gain=40dB , Rf=300kΩ, Ri=3kΩ, BW:400Hz-30kHz)
0.1
1
10
0.0001 0.001 0.01 0.1
Input Voltage [Vrms]
THD+N [%]
85℃
(MUT=0V)
25℃
-40℃
85℃
(MUT=0.3V)
Mic AMP THD+N vs Input Voltage
(V+=3.3V,MUT=0.3V, RL=5.1kΩ , Gain=40dB , Rf=300kΩ, Ri=3kΩ, BW:400Hz-30kHz)
0.01
0.1
1
10
0.01 0.1 1 10
Input Voltage [Vrms]
THD+N [%]
85℃
(MUT=0V)
25℃
-40℃
85℃
(MUT=0.3V)
Mic AMP THD+N vs Input Voltage
(V+=4.0V,MUT=0.3V, RL=5.1kΩ , Gain=40dB , Rf=300kΩ, Ri=3kΩ, BW:400Hz-30kHz)
0.001
0.01
0.1
1
10
0.01 0.1 1 10
Input Voltage [Vrms]
THD+N [%]
85℃
(MUT=0V)
25℃
-40℃
85℃
(MUT=0.3V)
NJW1124
– 12 –
!
!!
!
TYPICAL CHARACTERISTICS
LINE AMP THD+N vs Input Voltage
(V+=3.3V, RL=1.2kΩ , Gain=26dB , Rf=51kΩ, Ri=5.1kΩ, BW:400Hz-30kHz)
0.1
1
10
0.001 0.01 0.1 1
Input Voltage [Vrms]
THD+N [%]
25℃
-40℃
85℃
LINE AMP THD+N vs Input Voltage
(V+=4.0V, RL=1.2kΩ , Gain=26dB , Rf=51kΩ, Ri=5.1kΩ, BW:4 00Hz- 30kHz)
0.1
1
10
0.001 0.01 0.1 1
Input Voltage [Vrms]
THD+N [%]
25℃
-40℃
85℃
RTSW PIN Voltage vs Rx&Tx ATT. Gain
(V+=3.3V)
-50
-40
-30
-20
-10
0
10
0 0.5 1 1.5 2 2.5 3 3.5
RTSW PIN Voltage [V]
Rx & Tx ATT. Gai
n
Tx 85℃
Tx 25℃
Tx -40℃
Rx 85℃
Rx 25℃
Rx -40℃
Rx 85℃
Rx 25℃
Rx -40℃
Tx 85℃
Tx 25 ℃
Tx -40℃
RTSW PIN Voltage vs Rx&Tx ATT. Gain
(V+=4.0V)
-50
-40
-30
-20
-10
0
10
0 0.5 1 1.5 2 2.5 3 3.5 4
RTSW PIN Voltage [V]
Rx & Tx ATT. Gai
n
Tx 85℃
Tx 25℃
Tx -40℃
Rx 85℃
Rx 25℃
Rx -40℃
Rx 85℃
Rx 25℃
Rx -40℃
Tx 85℃
Tx 25 ℃
Tx -40℃
NJW1124
– 13 –
■APPLICATION NOTES
■GENERAL DESCRIPTION
The NJW1124 is a Voice Switched Speakerphone Circuit. The NJW1124 includes all of functions
processing a high quality hands–free speakerphone system, such as the necessary amplifiers
( Microphone amplifier , Receive amplifier, Line amplifier), attenuators, level detectors .
All external capacitors are sufficient small so that ceramic capacitors are applied.
The NJW1124 detects a signal to judges which path is talking. After that, the one side path is
active, another path is attenuated. This is half-duplex system. Appropriate operating keeps closed loop
gain less than 0dB, and that prevents acoustic coupling.
The resister and capacitor values in Fig.1 below are references. For correct operating, check in
actual condition as possible as you can. And adjust the levels input each detectors.
On this application notes, Base unit is defined as the unit included the NJW1124.
Fig.1 NJW1124 Block Diagram
The resistance and capacitor value above is just one example.
Certain Half-duplex operation are not guaranteed.
Best value depends on your microphone, speaker, and chassis.
Especially, select capacitor value connected to V+(17pin) to be powe
r
supply ripple enough small (less than 5mVp-p).
when 1µF is not enough, select larger value capacitor.
BIAS
Tx Attenuator
At t en ua to r
Control
Level
Detector
Background
NoiseMon it or
Monitor
Speaker
Microphone
-1
Rx Attenuator
Level
Detector
Background
NoiseMonitor
V
+
IC2
NJU7084
Power Amplifier
Line Amplifier
V
+
Line Out
VLC
V
+
MCI MCO TLI2 TLI1 TXO LII LiO- LiO+
V
+
RT SW
CPR
TLO1
RL O1
GND
FIRLI1
RL I2RXO
VREF2
V
RE
F
CP
T
RL O2
TLO2
MUT
CT
Recive In
VREF
C3
470n
C4
470n
C2
1u
C23
1µ
µµ
µ
R9
22k
R8
11k
C17
100n
R11
10k
C6
100n
R2
5.1k
R3
51k
C7
100n
R4
51k
R5
10k
C8
100n
R6
5.1k
R7
51k
R12
51k C18
100n
R13
5.1k
C12
100n
R14
5.1k
C21
470n
C20
470n
C22
1µ
µµ
µ
C5
1µ
µµ
µ
C11
1µ
µµ
µ
C19
100n
C9
100n
C1
1µ
µµ
µ
R1
300k
Mic
Am
p
lifier
Receiv e
A
m
p
lifie
r
1.2µ
µµ
µA
C10
V
+
:Recive
GND :Trensmit
Open :idle
MUT
V+ :MUTE
GND :ACTIVE
VREF
VREF
R
VLC
5.0V
+
10µ
µµ
µ
C14 1 µ
1 µ 1µ
1 µ
1µ
1µ1µ
1µ
FO
C16
C13
IC1
NJW1124
V
+
C15
1µ
µµ
µ
R10
15k
MU T
V+ : Active
GND : Disable
NJW1124
– 14 –
1.Receive Attenuator
Receive Attenuator has 3 modes depending on base and satellite unit condition.
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Receive Attenuator Gain 1 G
R1
RX-mode (Receive) 3.0 6.0 9.0 dB
Receive Attenuator Gain 2 G
R2
TX-mode (Transmit) -43 -46 -50 dB
Receive Attenuator Gain 3 G
R3
Idle-mode
(Standby),CPT=CPR=V
+
-17 -20 -23 dB
1.Receive Attenuator Gain 1 , (Receive mode :Gain=+6dB)
Condition: Receive signal from satellite unit, and no transmit signal to base unit.
2. Receive Attenuator Gain 2 , (Transmit mode :Gain=-46dB)
Condition: Transmit signal to base unit, and no receive signal from satellite unit.
3. Receive Attenuator Gain 3 , (Idle mode :Gain=-20dB)
Condition: Transmit signal to base unit, and no receive signal from satellite unit.
Volume Control
Receive Attenuator includes Volume Control.
Volume is controlled by resister value connected
to VCL pin.
Fig.2 shows Volume attenuate vs. Resister value.
Volume max.(0dB) : 0Ω,
Volume min. (-40dB): 100kΩ .
Transmit Attenuator doesn’t equip Volume Control.
Fig.2 Volume vs. VCR Resister
-40
-30
-20
-10
0
0 20406080100
VLC Resistor [kΩ]
Volume [dB]
NJW1124
– 15 –
2.
Transmit Attenuator
Transmit Attenuator has 3 modes depending on base and satellite unit condition.
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Transmit Attenuator Gain 1 G
T1
RX-mode (Receive) 3.0 6.0 9.0 dB
Transmit Attenuator Gain 2 G
T2
TX-mode (Transmit) -43 -46 -50 dB
Transmit Attenuator Gain 3 G
T3
Idle-mode
(Standby),CPT=CPR=V
+
-17 -20 -23 dB
1.Transmit Attenuator Gain 1 , (Transmit mode :Gain=+6dB)
Condition: Receive signal from satellite unit, and no transmit signal to base unit.
2. Transmit Attenuator Gain 2 , (Transmit mode :Gain=-46dB)
Condition: Transmit signal to base unit, and no receive signal from satellite unit.
3. Transmit Attenuator Gain 3 , (Idle mode :Gain=-20dB)
Condition: Transmit signal to base unit, and no receive signal from satellite unit.
3.
Microphone Amplifier
Microphone Amplifier is an operational Amplifier amplifying the signal from microphone to line level.
Fig.3 shows Block Diagram of Mic.Amp..
Non-inverting input keeps reference voltage inside. Mic.Amp is used as inverting amplifier. The Gain should be
40dB or less.
Mic.amp equips Mute function.
Fig.3 Mic.Amp Block.(20dB Application)
Microphone
V
+
MCI MCO
VREF
C6
100n
R2
5.1k
R3
51k
C1
1µ
µµ
µ
R1
300k
Mic
A
m
p
lifie
r
MUT
V+ :MUTE
GND :ACTIVE
Tx Attenuator
Outside parts Function recommend value Detail Memo
C6 DC decoupling 100nF～10
µ
F-Sha
p
e HPF : fc=1/
(
2π×C6×R2
)
R2
R3
R1 100Ω～300kΩ
C1 100n～10
µ
F
Gain Setting
Pop noise
reduction
3kΩ～300kΩGv=R3/R2
Input impedance＝R2
The control voltage is made
gradual with RC filter.
Recommend gain less than :40dB
Large resistance value may cause oscillating.
-
VIH >1.5V
VIL <0.3V
MICAMP MUTE
MICAMP ACTIVE
MUT(2pin) Input Voltage Operation
NJW1124
– 16 –
4.Receive Amplifier
Receive Amplifier is an operational Amplifier receiving the signal from satellite unit.
Fig.4 shows Block Diagram of Mic.Amp Block Non-inverting input keeps reference voltage inside.
Receive Amp is used as inverting amplifier. The Gain should be 40dB or less.
Receive Amplifier doesn’t equip Mute function.
Fig.4 Receive.Amp Block.(0dB Application)
Rx Attenuator
FI
Recive In
R13
5.1k
R14
5.1k
C19
100n
Receiv e
A
m
p
lifie
r
VREF
FO
Outside parts Function recommend value Detail Memo
C19 DC decoupling 100nF～10
µ
F-Sha
p
e HPF : fc=1/
(
2π×C19×R14
)
R１4
R１3Gain Setting 3kΩ～300kΩGv=R13/R14
Input impedance＝R14
Recommend gain less than :40dB
Large resistance value may cause oscillating.
NJW1124
– 17 –
5.Line Amplifier
Line Amplifier transmits the signal from Tx attenuator to satellite unit. Line Amplifier consists of two operational
Amplifiers.
First Amplifier non-inverting input keeps reference voltage inside. First Amplifier is used as inverting amplifier.
Second Amplifier includes –1 fixed Gain.
These two amplifiers enable to differential output from single-ended signal.
Line Amplifier may oscillates, long transmission path becoming large capacitive load. In this case, add ceramic
capacitor (47p to 100p) between LII and LIO-.
Add it as close as possible to the terminal. The frequency should be cut more than you need.
LIO+,LIO- should not be short to GND. LIO+,LIO- terminal are biased to V+/2).
Fig.5 Line Amplifier Block(26dB Application)
Fig.6 Forbidden Circuit.
-1
Line Amplifier
Line Out
TXO LII LiO- LiO+
R6
5.1k
R7
51k
C9
100n
C10
VREF
-1
Line Amplifier
TXO LII LiO- LiO+
R8
5.1k
R9
51k
C11
100n
CfL
VREF
LINE Cable
Outside parts Function recommend value Detail Memo
C9 DC decoupling 100nF～10
µ
F-Sha
p
e HPF : fc=1/
(
2π×C9×R6
)
R6
R7
C10 oscillation prevention 10p～100pF Sha
p
e LPF : fc=1/
(
2π×C10×R7
)
Gain Setting 3kΩ～300kΩGv=R7/R6
Input impedance＝R6
Recommend gain less than :26dB
Large resistance value may cause oscillating.
NJW1124
– 18 –
6.Monitor Terminal
Monitor Terminal switches Voltage mode depending NJW1124 condition.
NJW1124 condition : Monitor Terminal Voltage
Receive mode V+
Transmit mode GND
Idle mode Hi-Z or (V+/2)
7.Level Detector Block
The NJW1124 includes Level Detector Block and Background Noise Monitor on transmit block and receive block.
Level Detector Block consists of two same detectors.
Fig.7 shows Level Detector block.
The signal(S1 to S4) output each detector transmits to attenuator controller to change the mode.
Next 7.1 and 7.2 explain about each detector and Background Noise Monitor operation details.
About S1 to S4 signals, refer to 8 part.,
Fig.7 Level Detector Block
Tx:RLO2
Rx :TLO1
Tx : TLI2
Rx : RLI1
Level
Detec tor
Circ uit
Level
Detec tor
Circ uit
Background
Nois e
Monitor
Tx : RLI2
Rx : TLI1
Tx : TLO2
Rx : RLO1
Tx : S3
Rx : S4
Tx : S1
Rx : S2
NJW1124
– 19 –
7.1 Level Detector Circuit
Fig.8 shows level detector circuit.
Level detector circuit includes logarithmic amplifier using diodes (D1,D2) to keep dynamic range.
The signals input to each level detector through external coupling capacitor Ci , are converted to current by input
resistance Rin and input logarithmic amplifier through TLI2,1 and RLI1,2.
The current input changes diode(D1) current .
When the current more than 0.54µA(Current Source circuit ) inputs ,diode D1 is off, and A point voltage drops.
In case of sinking current, the current increase D1 current, that increase A point voltage rises.
The point voltage is defined as follows. .
∆V
A
=0.026 x Ln [ { Iin
+ (0.54x10
-6
) } / (0.54x10
-6
) ]
Iin=Vin/Rin.( Actually, Ci effects)
The voltage A point goes through buffer Amplifier AMP2, charge the capacitor connected to TLO1.2,RLO1.2.
The charging completes immediately.
Response Example1 shows TLO2(Co=C5=0.1µF) signal waveform outputting 200mVrms/1kHz from
MICOUT(MCO pin).
without input signal from TL1,TL2,RL1,and RL2,Co releases current.
The Voltage Gradient is defined as follows:
δVc=-0.3µA/Co
Response Example 2 shows the signal response finishing input the signal.
Actual application being influenced on leak current and equivalent resistance in series,
δVc does not accords with the formula completely. Check on the operation using actual capacitor
(Use high input impedance probe like FET Measuring instrument)
Small capacitor shortens the time to detect, and deteriorate the low frequency rectification characteristics.
That influences on Noise Detector on next page.
Large capacitor improves rectification characteristics, and noise detector function.
However, extends the time to detect, it may judges the signal on noise.
Appropriate capacitor value depends on a application.
The input current TLI1,TLI2,RLI1,and RLI2 should be less than 100µΑ
µΑµΑ
µΑ for normal operating .
Especially, gain mode has 9dB gain max, care of excessive input.
Voice switch circuit may malfunctions with Excessive input current
Fig.9 shows Rin(input impedance) vs. minimum input sensitivity of noise detector and maximum permissible
voltage.
Fig.8 Level Detector Circuit Diagram
Iin
C
o
(C3,C20
C21,C4)
I1
0.54uA
I3
0.3uA
TLI2,1
RLI1,2
TLO2, 1
RLO1,2
C
i
(C7,C8
C18,C17)
R
in
(R4,R5
R12,R11)
Ref
A
A
MP1
D1
D2
I2
0.54uA
A
MP2
V
in
I
O
Outside parts Function recommend value Detail Memo
Cin DC decoupling 100nF～1
µ
F-Sha
p
e HPF : fc=1/
(
2π×Cin×Rin
)
Rin V/I Convert 5kΩ～100kΩIin＝Vin/Rin Use " Iin " by 100mA or less.
Co
D
etection level keepin
g
0.05µF～1.0mF δVC ＝ -0.3uA / CO
Use the capacitor leaking a little. Small capacitor
deteriorate the low frequency rectification
characteristics .
NJW1124
– 20 –
Response example.1
MCO vs. TLO2signal (starting input)
MCO = 200mVrms/1kHz C5 = 0.1µF
-400
-300
-200
-100
0
100
200
300
400
0123456
time [m sec]
MCO [mV]
880
900
920
940
960
980
1000
1020
1040
TLO2 [mV]
MCO
TLO2
⊿VA
-400
-300
-200
-100
0
100
200
300
400
0 5 10 15 20 25 30 35 40
time [m sec]
MCO [mV]
880
900
920
940
960
980
1000
1020
1040
TLO2 [mV]
MCO
TLO2
δVc
Fig.9 Minimum Input Voltage vs. Input Resistance
(R4 or R12 Theoretical Value resistance
R4=R5
,
R12=R11 condition
)
10
100
1000
10000
1 10 100
Input Resistance[kΩ]
MCO or FO Pin AC Voltage[mVrms]
Minumum Sensitivity Voltage
Maximum Input Voltage
Maximum Input Voltage(Vin(Fig.8)),which equal
to MCO or FO Maximum Output Voltage
Note: Maximum Voltage is defined by the smaller resister,
35% value of R5, R11 or R4, R11 value.
Response example.2
MCO vs. TLO2signal (finishing input)
MCO = 200mVrms/1kHz C5 = 0.1µF
Minimum Input Voltage(sensitivity),which is the Voltage
shifting mode(idle to receive, idle to transmit).
NJW1124
– 21 –
7.2 Background Noise Monitor
Background Noise Monitor judges whether the input signal is noise or sound or voice by TLO2 and RLO2 voltage,
and change the mode.
The NJW1124 includes the Background noise monitor on transmit side and receive side.
Fig.10 shows Block diagram of Background noise monitor.
The voltage difference between TLO2 or RLO1 and Ref is amplified 8.6dB on AMP1.
The signal from AMP1 inputs 2
nd
stage AMP2 and comparator (COMP).
The COMP non-inverting input voltage becoming 36mV higher than inverting, COMP output 1,which shows the
NJW1124 is transmit or receive mode.
At the same time, external capacitor charged from 0.8µA internal current source, until the C
CP
voltage becomes
46mV higher than AMP2 input voltage.
The equivalent below shows C
CP
voltage charging.
∆V
CCP
= 0.8µA/C
CP
For example, C
CP
=1µF, δV
CP
=0.8V/sec.
Without the input signal, C
CP
discharged and finally reset the Background noise monitor.
Response example is ex.3.
The signal like continued sign wave inputting, COMP output ‘0’ which is noise-monitoring mode (idle-mode).
The signal like conversation sound inputting, C
CP
continues to charge and discharge. COMP output continued
to ‘1’, which is transmit or receive mode.
Small C
cp
shortens the time shifting to ‘0’ condition. Too small C
CP
attenuates even the conversation signal.
Large C
CP
keeps ‘1’ condition long, which lengthen attenuating time.
Capacitor should be adjusted appropriately on actual application.
(Use high input impedance like FET probe measuring voltage of CPT, CPR pin.)
Fig.8 Background Noise Monitor Block Diagram
800
850
900
950
1000
1050
1100
1150
1200
1250
1300
0 100 200 300 400 500
time [m sec]
TLO2 , CPT [mV]
TLO2
CPT
800
850
900
950
1000
1050
1100
1150
1200
1250
1300
0 1020304050
time [m sec]
TLO2 , CPT [mV]
TLO2
CPT
Ref
Level
Detec tor
Tx : S3
Rx : S4
Tx : TLO2
Rx : RLO1
A
MP1
A
MP2 COMP
36mV
Tx : CPT
Rx : CPR
C
CP
(C2,C22)
19kΩ32kΩ
0.8µ
µµ
µA
46mV
Response example.3
TLO2 vs. CPT signal (input start)
MCO = 200mVrms/1kHz
C5 = 0.1µF, C4 =1µF
Response example.4
TLO2 vs. CPT signal (input finish)
MCO = 200mVrms/1kHz
C5 = 0.1µF, C4 =1µF
Function recommendation value Detail Memo
Noise Detection 100nF～1
µ
F- The time for noise detection depends on this.
NJW1124
– 22 –
8.Attenuator Controller
Attenuator Controller controls each mode(Transmit or Receive or idle) by the signal(S1 to S4) from level detector
according as table.1 below
Table.1 shows truth table (On RTSW=Open).
Internal 12µA current source circuit charges and discharges C7, connected with CT pin
On the mode changing condition, δV
C5
shows voltage change according as the formula below. .
δV
C7
= ±12uA/C
5
(11.1) (C7 is C5 capacitance connected to CT pin.)
on initial state, CT pin voltage equals to Vref voltage. Shifting to transmit mode, C7 discharges and become lower
voltage than Vref voltage. Example 5 and 6 shows behaviors. V
CT
voltage is CT voltage minus Vref voltage.
On receive mode, internal current source charging C
5
raises CT voltage.
CT pin voltage shows operating condition(Transmit or Receive or idle).
( more than 100MΩ impedance probe should be monitoring the voltage.
‘FAST idle mode’ enables to shift promptly charging C7 rapidly.
On ‘SLOW idle mode’, mode shifts gently.
Both time constants τ are below:
τ=R
AX
C
5
(R
AX
is R
A1
R
A2
resistance. After τ sec, The voltage is attenuated to 1/e default value)
For example, C7=1µF, τ =600m sec.
attenuator gain G
AT
estimate as below:
G
AT(TX)
= 0.1 x exp { -V
CT
/ 0.026 } on transmit mode (11.3)
G
AT(RX)
=0.1 x exp { V
CT
/ 0.026 } on receive mode (11.4)
C
5
= 1µF, attenuator time constant on SLOW idle mode is about 225m sec.
Table.6 as below shows response of transmit signal wave:
Fig.11 shows V
CT
vs. G
AT
.
Adjust this order for appropriate operating:
1.Resistance connecting to TLI1.2 and RLI1.2
2.Capacitor connecting to TLO1.2 and RLO1.2
3.Capacitor connecting CPT, CPR.
When adjusting above doesn’t enable to appropriate operating(attenuating too fast or shifting too slow etc.),
adjust C
5
value connecting to CT pin . Typical value is 1µF.
Table.1 Truth Table
S1 ：Result comparing RLO2 and TLO2
(RLI2 and TLI2 •••Detecting Base Unit side)
RLO2>TLO2 [Rx]
TLO2>RLO2 [Tx]
S2 ：Result comparing RLO1and TLO1
(RLI1 and TLI1•••Detecting Satellite Unit side)
RLO1>TLO1 [Rx]
TLO1>RLO1 [Tx]
S3＆S4 ：Output Background Noise Monitor
[1]:Detecting signal
[0]:Judging noise
[x]：Don’t Care
[y]：Both C3 and C4 is not 0.
S1 S2 S3 S4 Mode
Tx Tx 1 X Tx Mode
Tx Rx y y FAST Idle Mode
Rx Tx y y FAST Idle Mode
Rx Rx X 1 Rx Mode
Tx Tx 0 X SLOW Idle Mode
Tx Rx 0 0 SLOW Idle Mode
Rx Tx 0 0 SLOW Idle Mode
RX Rx X 0 SLOW Idle Mode
NJW1124
– 23 –
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
02468101214
time [m sec]
V
CT
[mV]
-400
-300
-200
-100
0
100
200
300
400
MCO[mV]
VCT
MCO
-800
-600
-400
-200
0
200
400
600
800
02468101214
time [m sec]
MCO , TCO [mV]
TXO
MCO
-800
-600
-400
-200
0
200
400
600
800
0 250 500 750 1000 1250 1500 1750 2000
time [m sec]
TXO [mV]
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
G
AT(Tx)
TXO
GATTx
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
0 250 500 750 1000 1250 1500 1750 2000
time [m sec]
VCT [mV]
360m sec
Fig.11 G
AT
vs. V
CT
Calculated Spectrum
-50
-40
-30
-20
-10
0
10
-100 -75 -50 -25 0 25 50 75 100
V
CT
[mV]
G
AT
[dB]
GAT(TX)
GAT(RX)
Response example.5
MCO vs. CT-VREF signal (input start)
MCO = 200mVrms/1kHz
C7=1µF
Response example.6
MCO vs. TXO(AC) signal (input start)
MCO = 200mVrms/1kHz C7=1µF
Response example.7
CT-VREF signal (input continue)
MCO = 200mVrms/1kHz C7=1µF
SLOW idle mode
Response example.8
G
AT
vs. TCO signal (input start)
MCO = 200mVrms/1kHz C7=1µF
SLOW idle mode
NJW1124
– 24 –
RTSW shifts the mode forcibly. RTSW changes the CTpin voltage forcibly to shift the mode.
Ex.9 shows the response to RTSW.
-100
-80
-60
-40
-20
0
20
40
60
80
100
0 2 4 6 8 10 12 14 16 18 20
time [m sec]
VCT [mV]
RTSW State :
Rx -> Tx
Rx Mode Level
Tx Mode Level
Response example.9
RTSW shifting (Receive mode to Transmit mode)
C7=1µF
NJW1124
– 25 –
10.Acoustic Coupling Reduction
To reduce Acoustic Coupling, isolating speaker and microphone is effective.
Adjusting resistance value connected to TLI1, TLI2, (R4, R5, R11) and RLI1 is also effective,
For example, configure R12,R4 value is 2 to 6 times than R5,R11.
Reducing sensitivity to echo enables to operate normally.
Reducing the sensitivity of R4,R12 reduces the time shifting to noise mode.
In case of too fast shifting, enlarge capacitor connected to CPT,CPR.
BIAS
Tx Attenuator
At t en uat o r
Control
Level
Detector
Background
NoiseMonitor
Monitor
Speaker
Microphone
-1
Rx Attenuator
Level
Detector
Background
NoiseMonitor
V
+
IC2
NJU7084
Power Amplifier
Line Amplifier
V
+
Line Out
VLC
V
+
MCI MCO TLI2 TLI1 TXO LII LiO- LiO+
V
+
RT SW
CPR
TLO1
RL O1
GND
FIRL I 1
RLI2RXO
V
REF2
V
RE
F
CPT
RL O2
TLO2
MUT
CT
Recive In
VREF
C3
470n
C4
470n
C2
1u
C23
1µ
µµ
µ
R9
22k
R8
11k
C17
100n
R11
10k
C6
100n
R2
5.1k
R3
51k
C7
100n
R4
51k
R5
10k
C8
100n
R6
5.1k
R7
51k
R12
51k C18
100n
R13
5.1k
C12
100n
R14
5.1k
C21
470n
C20
470n
C22
1µ
µµ
µ
C5
1µ
µµ
µ
C11
1µ
µµ
µ
C19
100n
C9
100n
C1
1µ
µµ
µ
R1
300k
Mic
A
m
p
lifier
Receive
Am
p
lifier
1.2µ
µµ
µA
C10
VREF
VREF
R
VLC
5.0V
+
10µ
µµ
µ
C14 1 µ
1 µ 1 µ
1 µ
1µ
1µ1µ
1µ
FO
C16
C13
IC1
NJW1124
V
+
C15
1µ
µµ
µ
R10
15k
Receive Sound
Receive Voice
Acoustic coupling
Setting TLI2 resistance (R4) twice to
6times than RLI2 resistance (R11),
reduces the level detector sensitivity
to reduce acoustic coupling.
Fig.12 Acoustic Coupling Reduction
Sensitivity:High
Sensitivity:Low
NJW1124
– 26 –
Notes:1
To reduce Pop-Noise of power-on and off.
Appropriate power supply sequence reduces pop-noise.
Initial condition: No power supply.
CD switch of Speaker Amplifier should be standby condition.
The circuit connected to Line out and Receive In is off.
Power-on sequence
1.Power-on NJW1124. Concurrently The circuit connected to Receive In power on.
2.After 1 sec later, the circuit connected to Line OUT and Speaker Amplifier IC power on.
3.After 1 sec later, Speaker Amplifier IC shifts active mode.
Power-off sequence
1.Speaker Amplifier shift standby mode.
2.After 1 sec later, the circuit connected to Line OUT and Speaker Amplifier power off.
3.After 1 sec later, NJW1124 power off. Concurrently, the circuit connected to Receive In power off.
NJW1124
– 27 –
Notes:2:
Filter circuit using Receive amplifier, Mic. Amplifier, Line amplifier.
Receive amplifier, Mic. Amplifier, Line amplifier enable to form active filter circuit which is 1
st
order or 2
nd
order,
HPF or LPF or BPF.
1.1
st
order HPF,LPF circuit example
Fig.13 shows 1
st
order (-6dB/oct) HPF, LPF circuit.
Combining HPF formed by Co and R1, and LPF formed by C1 and R2, forms BPF.
(Co should be also used typical application as DC decoupling.)
10
)(
21RC
f
HPFC
π
=
21
)(
21RC
f
LPFC
π
=
2.2
nd
order LPF circuit example
Fig.14 shows 1
st
order (-12dB/oct) LPF circuit.
Same as 1st order filter, Co should be used as DC decoupling. C2 selecting arbitrarily, Butterworth filter forming
coefficient is as below.
2)(
1
22 1CfG
R
LPFC
π
=
2)(
2
22 1Cf
R
LPFC
π
=
2)(
3
)1(22 1CfG
R
LPFC
π
+
=
23
)1(2 CGC +=
GainG =
f
C(HPF)
is same as 1
st
order type above.
+6dB/oc -6dB/oct
Response
Frequency
fc
(HPF)
fc
(LPF)
Fig.13 1
s
t
order HPF,LPF circuit example
Fig.14 2
n
d
order LPF circuit example
+6dB/oc
-12dB/oct
Response
Frequency
fc
(HPF)
fc
(LPF)
Ref
Receive In
C
0
R
1
C
1
R
2
FO
FI
Ref
Receive In
C
0
R
1
C
2
R
3
C
1
R
2
FI
FO
Ref
Receive In
C
0
R
1
C
2
R
3
C
1
R
2
FI
FO
NJW1124
– 28 –
Fig.15 shows 2
nd
order LPF(Gain=20dB, fc
(LPF)
= 4kHz) circuit example.
Fig.15 2
nd
order LPF(Gain=20dB, fc
(LPF)
= 4kHz, Butterworth filter) circuit example.
3.2
nd
order HPF circuit example
Fig.16 shows 2
st
order (-12dB/oct) HPF circuit.
Co=C2, Butterworth filter forming coefficient is as below.
)/12(2 2
0)(
1
GCf
R
HPFC
+
=
π
0)(
2
212 Cf G
R
HPFC
π
+
=
G
C
C
0
1
=
20
*
CC =
Fig.17 shows HPF(Gain=20dB,Fc
(HPF)
=200Hz) circuit example.
Fig.16 2
n
d
order HPF circuit example.
Ref
Receive In
C
0
510p
5.1k
12n
56k
FI
FO
5.6k
Ref
Receive In
C
0
R
2
C
2
FO
R
1
C
1
FI
Ref
Receive In
100n
160k
100n
FO
5.6k
FI
10n
Fig.17 2
n
d
order HPF circuit example.
Gain=20dB,Fc
(HPF)
=200Hz, Butterworth filter
NJW1124
– 29 –
Notes:3 list of Parts of Attenuator controller
[CAUTION]
The specifications on this databook are only
given for information , without any guarantee
as regards either mistakes or omissions. The
application circuits in this databook are
described only to show representative usages
of the product and not intended for the
guarantee or permission of any right including
the industrial rights.
Terminal Parts Recommend Value Notes
Cin C7,C8,C17,C1 100nF～1µFThe input capacitor forms HPF with Rin.
Rin R4,R5,R11,R1
2
5.1k～51kΩ
V-I converter,which depends on sensitivity of each level detectors and noise
detector. Smaller value lower detection level. Larger value raise detection level.
In
p
ut volta
g
e should be less than 100mA
(
200
µ
Α
@
25
o
C
)
.
Co C4,C5,C20,C2 0.05µF～1µF
The capacitor keeps voltage level.Larger value extends swicthing time.Smaller
value shortens swicthing time, and deteriorate rectification property that adverse
affects back ground noise monitor on low frequency signal.
Cct C5 1µF
The capacitor generates the voltage controlling attenuater. Larger value extends
attenuating time on switching and idle mode.Smaller value shortens the
attenuating time.Please be careful of conduction caused by condensation due to
this terminal is high impedance.Attenuater gain may be fluctuant .
The capacitor judges whether the signal is noise.Larger value extends the judging
time.Smaller value shortens the judging time.
Cc
p
C2,C22 100nF～1µF
