NJM2706
-1-
3D Surround Audio Processor with Dynamic Bass Boost
■
■■
■ GENERAL DESCRIPTION
The NJM2706 is the 3D surround audio processor with
dynamic bass boost, regenerates rich sound field with only
small two speakers.
The NJM2706 performs NJRC original surround technology
realizing natural surround sound field regarded center
orientation and NJRC original dynamic bass boost technology
provides graceful bass sound with low distortion.
It is suitable for mini-component, CD radio-cassette, TV,
speaker system and others.
■
■■
■ FEATURES
● Operating Voltage +4.7V to +13.0V
● Wide Dynamic Range 3.1Vrms typ.
● Low Output Noise 8.9µVrms typ.
● "eala" 3D Surround Function (Stereo only)
● Dynamic Bass Boost Function
● High Frequency Compensation (f=10kHz, GV=+3dB)
● Variable Surrou nd Ef f ect by externa l resistor
● Internal Mode Control Switch
● Bipolar Technology
● Package Outline SSOP24-E1
■
■■
■ BLOCK DIAGRAM
■
■■
■ PACKAGE OUTLINE
NJM2706VE1
H:eala_Bass
H:eala
L:BYPASS
H
L
L
H
H
L
1
50
K
50K
3D FILTE R
LPF
234511 12
1617
181920
21
22
Vref
50K 50
K
1415 1323
24
910
86 7
VC
HP
HP
H
LL:BYPASS
SW
SW
SW
SW
SW
SW
NJM2706
- 2 -
■
■■
■ PIN CONFIGURATION
1. LPF 13. V+
2. MIN 14. VREFOUT
3. MOUT 15. VREFIN
4. Ca 16. SW1
5. Cr 17. SW2
6. BASSFIL1 18. ealaFIL
7. BASSFIL2 19. HFFILL
8. BASSVRIN 20. HFFILR
9. BASSVROUT 21. ROUT
10. ealaVRIN 22. LOUT
11. ealaVROUT 23. RIN
12. GND 24. LIN
22
21 4
6
5
1
2
3
7
24
23
8
10
9
11
12
14
13
16
15
18
17
20
19
NJM2706
-3-
■
■■
■ABSOLUTE MAXIMUM RATING (Ta=25°C)
PARAMETER SYMBOL RATINGS UNIT
Supply Voltage V
+
15 V
Power Dissipation P
D
(SSOP24) 600 mW
Operating Temperature Range T
opr
-40 to +85 °C
Storage Temperature Range T
stg
-40 to +125 °C
■
■■
■OPER ATING VO L TAGE
PARAMETER
SYMBOL
TEST CONDIT ION MIN TYP MAX UNIT
Operating Voltage V
+
- 4.7 12.0 13.0 V
■
■■
■ELECTRICAL CHARACTERISTICS (Ta=25°C, V+=12V unless otherwise specified)
TEST CONDIT ION
INPUT
PARAMETER
SYMBOL
L R
OUT
PUT MODE eala
VR
Bass
VR
MIN TYP MAX UNIT
0 0 - Bypass - - - 15.4 23.0 Operating Current I
CC
No Signal 0 0 - Bass MAX - - 15.4 23.0 mA
Reference Volt age Vref No Signal 0 0 - - - - 5.8 6.0 6.2 V
●AC CHARAC TE RI ST ICS (Ta=25°C, V
+
=12V, V
IN
=-20dBV(100mVrms) unless otherwise specified)
TEST CONDIT ION
INPUT
PARAMETER
SYMBOL
L R
OUT
PUT MODE eala
VR
Bass
VR
MIN TYP MAX UNIT
f=1kHz
THD=3% V
IN
- -
V
IN
L
R Bypass - -
10.0
(3.2) 12.0
(4.0) -
f=100Hz
THD=3% V
IN
V
IN
*1 Bass MAX - - 6.0
(2.0) -
f=1kHz
THD=3% V
IN
- -
V
IN
L
R eala - MAX - 7.9
(2.5) -
f=10kHz
THD=3% V
IN
- -
V
IN
L
R eala
Bass MAX MAX 7.8
(2.5) 9.8
(3.1) -
Maximum
Input Voltage
V
IM
f=100Hz
THD=3% V
IN
- -
V
IN
L
R eala
Bass MAX MAX 3.4
(1.5) 5.4
(1.9) -
dBV
(Vrms)
Rg=0Ω
A-Weighted 0 0 L
R Bypass - - - -110
(3) -100
(10)
Rg=0Ω
A-Weighted 0 0 L
R Bass MAX - - -98
(13) -
Rg=0Ω
A-Weighted 0 0 L
R eala - MAX - -100
(10) -
Output Noise V
NO
Rg=0Ω
A-Weighted 0 0 L
R eala
Bass MAX MAX - -97
(14) -92
(25)
dBV
(µVrms)
f=1kHz V
IN
- -
V
IN
L
R Bypass - - - 0.005 0.01
f=100Hz V
IN
V
IN
V
IN
V
IN
L
R Bass MAX - - 0.05 -
f=1kHz V
IIN
- -
V
IN
L
R eala - MAX - 0.05 -
Total Harmonic
Distortion THD
f=1kHz V
IN
- -
V
IN
L
R eala
Bass MAX MAX - 0.05 0.5
%
*1:BASSVR2OUT
NJM2706
- 4 -
●AC CHARAC TE RI ST ICS (Ta=25°C, V
+
=12V, V
IN
=-20dBV(100mVrms) unless otherwise specified)
TEST CONDIT ION
INPUT
PARAMETER
SYMBOL
L R
OUT
PUT MODE
eala
VR
Bass
VR
MIN TYP MAX UNIT
Bypa ss Ga in G
VBYP
f=1kHz V
IN
- -
V
IN
L
R Bypass - - -1.0 0.0 1.0
dB
f=100Hz V
IN
V
IN
V
IN
V
IN
L
R Bass MAX - 4.4 6.4 8.4
f=100Hz V
IN
V
IN
V
IN
V
IN
L
R Bass MIN - -2.0 0.0 2.0
f=1kHz V
IN
- -
V
IN
L
R eala - MAX 2.1 4.1 6.1
f=1kHz V
IN
- -
V
IN
L
R eala - MIN -2.0 0.0 2.0
f=100Hz V
IN
- -
V
IN
L
R eala
Bass MAX MAX 5.9 7.9 9.9
eala Gain G
eala
f=10kHz V
IN
- -
V
IN
L
R eala
Bass MAX MAX 0.0 2.0 4.0
dB
●
●●
●CONTROL CHARACTERISTICS (Ta=25°C, V
+
=12V, unless otherwise specified)
PARAMETER
SYMBOL
TEST CONDIT ION MIN TYP MAX UNIT
V
IN
=High Level 2.0 - V
+
MODE Select
Control Voltage V
MODE
V
IN
=Low Level 0.0 - 0.7 V
■
■■
■SWITCH FUNCTION
MODE SW2 SW1 NOTES
Bypass L L
Input Through
eala L H
3D Surround mode
Bass H L
Bass Enhanced mode
eala Bass H H
3D Surround and Bass Enhanced mode
NJM2706
-5-
!
TERMINAL DESCRIPTION
No.
SYMBOL
FUNCTION EQUIVALENT CIRCUIT VOLTAGE
1 LPF Capacitor terminal for LPF
V+/2
2 MIN Monaural Amplifier Input
V+/2
3 MOUT Monaural Amplifier Output
V+/2
4
5 Ca
Cr
Capacitor Terminal for
Attack Time Constant
Capacitor Terminal for
Release Time Constant
0V
6 BASSFIL1 BASS Filter Terminal 1
0V
150
16k
V+ V+
150
V+ V+ V+
20k
V+
5050
V+
16k
10k
100
10k
V+ V+
150
V+ V+ V+
10k
82k
VCA
NJM2706
- 6 -
!
TERMINAL DESCRIPTION
No.
SYMBOL
FUNCTION EQUIVALENT CIRCUIT VOLTAGE
7
21
22
BASSFIL2
ROUT
LOUT
BASS Filter Terminal 2
Rch Output
Lch Output
V+/2
8 BASSVRIN
BASS Effect Adjust
Terminal
V+/2
9 BASSVROUT
BASS Effect Adjust
Terminal
V+/2
10 ealaVRIN
eala Effect Adjust
Terminal
V+/2
11 ealaVROUT
eala Effect Adjust
Terminal
V+/2
V+
5050
V+
150
V+ V+ V+
150
V+ V+ V+
20k
V+
5050
V+
20k
10k
V+
20k
150
V+
NJM2706
-7-
!
TERMINAL DESCRIPTION
No.
SYMBOL
FUNCTION EQUIVALENT CIRCUIT VOLTAGE
12 GND GND Terminal
0V
13 V+
Power Supply Terminal
V+
14 VREFOUT
Reference Voltage Output
V+/2
15 VREFIN
Reference Voltage Input
V+/2
16
17 SW1
SW2 Mode Switch 1
Mode Switch 2
0V
400
V+
5050
V+ V+
400
V+
50k50k
V+ V+
150
150k
V+ V+V+
NJM2706
- 8 -
!
TERMINAL DESCRIPTION
No.
SYMBOL
FUNCTION EQUIVALENT CIRCUIT VOLTAGE
18 ealaFIL eala Filter Terminal
V+/2
19
20 HFFILL
HFFILR
High Frequency Filter for
Lch
High Frequency Filter for
Rch
V+/2
23
24 RIN
LIN Rch Input
Lch Input
V+/2
V+
32k
10k
V+
V+
15k
V+
400
150
V+ V+
50k
VREF
V+
NJM2706
-9-
■
■■
■APPLICATION CIRCUIT
10
µ
F
100
µ
F
1
µ
F
10
µ
F
10
µ
F
0.0047µF
560pF
BassSW
R4
10K
C6
12
V
C15
C16
C12
C13
C8
10
µ
F
R3
10K
C7
C9
C5
C11
560pF
C10
R6
30K
R5
30K
ealaSW
0.1µF
C1
0.18µF
C4
MinMa
x
20KB
ealaVR
C2
1
µ
F
C3
10
µ
F
R1
20K
MinMa
x
20KB
BassVR
R2
20K
BASSFIL1
ealaVROUT
ealaVRIN
BASSVRIN
BASSVROUT
MIN
MOUT
BASSFIL2
LPF
3 421 7 8 9 10 11 12
15 14 13
6
5
24 23 22 21 20 19 18 17 16
Lch Input
Rch Input
Lch Output
Rch Output
VREFOU
T
VREFIN
V
+
GND
SW2
SW1
ealaFIL
HFFILL
ROUT
LOUT
RIN
LIN
Ca
Cr HFFILR
C17
10
µ
F
10
µ
F
10
µ
F
NJM2706
- 10 -
■
■■
■APPLICATION NO T E
1. Fine-Tuning the ealaBASS
The NJM2706 has quite sophisticated NJRC’s original dynamic bass-boost technology. Both of the level and the
frequenc y for bass -boost moves autom atically corr esponding to the inp ut signal level. T his dynam ic filterin g action
prevents the signals over boosted, and provides less distortion and wide dynamic range bass-boost processing.
In additi on, if you wa nt to f ine-tune t he bas s-boos t eff ect f or your s ystem , you ca n m odif y the bass- boost ef fect by
changing the external parts value as described below.
1-1. Modify the Boost Center Frequency
This plot shows the frequency response for NJM2706 ealaBASS.
The Boost Center Frequency can be adjusted by changing the value for the external capacitor, C4.
If your speaker system has more than 100Hz of f
0
(= Lower Frequency Response Range), or, if you would like to
get more powerful bass-boost effect than the typical settings shown on the page 9, increasing the Boost Center
Frequenc y higher c ould b e a good ide a. W e strongl y recom m end you to determ ine the ac tual cap acita nce va lue b y
testing and examinations on your actual application.
1-2. Modification for the LPF Cut-off Frequency f
CL
This picture shows the equivalent circuit for NJM2706’s LPF.
The LPF Cut-off Frequency f
CL
is given by the following equation:
Set the f
CL
as same as the Boost Center Frequency, which is det er mined as abo ve ( T he Boost Center Fr eq u ency =
the frequency of which the gain is +3dB). In the typical application circuit shown on the page 9, the LPF Cut-off
Frequency f
CL
is set to 100Hz.
-5
0
5
10
10 100 1000 10
4
10
5
Frequency Characteristics (eala Bass)
V+=12V Vin=-20dBV Lch Vout=L ch RL =4.7k Ω
ΩΩ
Ω
Rg=25Ω
ΩΩ
Ω
Gai n [d B ]
Frequency [Hz]
C4=0.1µF
C4=0.15µF
C4=0.18µF
20k
20k
R1 20k
16k
C1
0.1µ
MONO Amp.
Lch
Rch
LPF
2pin 3pin
1pin
f
CL
= 2πCR
12πC1×16k
1
=
NJM2706
-11-
REFERENCE VALUE
*) default
value
1-3. Adjusting the Summing Level for ealaBASS effect to L/R Output Signal
Changing the resistance value connected between the terminal 8 and 9 can modify the Summing Level for the
ealaBASS effect to the L/R Output Signal.
2. Adjusting the High Frequency Compensation Filter
The NJM2706 has Hig h Frequenc y Compens ation Filter, which c an produce we ll balance between b oosted–bass
frequency range and treble frequency range. This picture shows the equivalent circuit for the High Frequency
Compensation Filter.
The Cut-off Frequency f
CH
and the Voltage Gain G
VH
are defined as below:
In the typical application circuit shown on the page 9, the High Frequency Compensation Filter Cut-off Frequency
f
CH
is set to 10kHz and Voltage Gain G
VH
is set to 3.5dB.
Speaker Si ze Large(f=100Hz)
*)
Medium(f=150Hz) Small(f=200Hz)
C1[µ
µµ
µF] 0.1 0.068 0.047
C4[µ
µµ
µF] 0.18 0.15 0.1
G
VH
=R6
R6+15k
20log
f
CH
= 2πCR
1= 2π×C11×R6
1
15k
C11
560p
HFFIL
20pin
R6
30k
NJM2706
- 12 -
3. Fine-Tuning eala(surround)
Changing the external parts value modifies the eala surround effect as described below.
3-1.Adjust the Cut-off frequency
Plot below Shows Voltage gain vs. Frequency.
eala effect depends on C9 value. Changing C9 value controls eala filter cut-off frequency f
CL.
.
Initial is 1kHz. After trial listening, decide appropriate C9 value.
Surround frequency becomes higher by smaller value.
LPF circuit
3-2Adjust eala gain
Surroun d VR value (1 0pi n) c ontr ols e ala gain.
T ypical va lue is 20k Ω. Surround effect becomes stronger by larger value.
Gain vs Frequency
V+=12V, Vin=-10dBV, V out=Lch Output, Ta=25゜C
0
1
2
3
4
5
6
7
8
9
10
11
12
10 100 1000 10000 100000
Frequen cy [Hz]
Gain [dB]
電圧利得 対 周波数特性
V+=12V,Vin=-10dBV,Vout=Lch,Ta=25℃
0
2
4
6
8
10
12
14
10100 1000 10000 100000
周波数[Hz]
電圧利得[dB]
C9=0. 0027 µF
C9=0. 0047 µF
C9=0. 0082 µF
Surround VR =0
Ω
ΩΩ
Ω
Surround VR =5 k
Ω
ΩΩ
Ω
Surround VR =2 0 k
Ω
ΩΩ
Ω
Surround VR =5 0 k
Ω
ΩΩ
Ω
20k
20k
20k
32k
C9
0.0047µ
Lch
Rch
LPF
eala
FIL pin
20k
f
CL(Cut-off Freq u en cy)
= 2
π
ππ
πCR
1
2
π
ππ
πC1×
××
×32k
1
=
Gain vs. Frequency
V+=12V,Vin=-10dB,Vout=Lch,Ta=25
o
C
Gain [ d B]
Frequency [Hz]
Surround VR =1 0 k
Ω
ΩΩ
Ω
NJM2706
-13-
■
■■
■TYPICAL CHARACTERISTICS
10
11
12
13
14
15
16
-50 0 50 100 150
Supply Current vs. Temperature
V+=12V
Supply Current [mA]
Temperature [
o
C]
BASS
Bypass
0
5
10
15
20
0 5 10 15 20
Supply Cu rrent vs. Supply Voltage
V+ = 1-13V, Ta= 25
o
C
Suppl y Current [mA]
Supply Vo ltage [V]
Bypass
eala BASS
eala
BASS
-10
-5
0
5
10
15
20
0481216
Maximum Input Voltage vs. Supply Vo l tage (Bypass)
Vin=Lch, Vout=Lch, f=1kHz, RL=4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω, Ta=25
o
C
Maxm um Input Volt age [d BV]
Supply Voltage [V]
-10
-5
0
5
10
15
20
0481216
Maximum Input Vol tage vs . Supply Voltage (BASS)
Vin =Lch+Rch, Vout =BA S SVRO U T, f=100Hz, RL= 4. 7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω, Ta=25
o
C
Maximum Input Voltage [dBV ]
Su pply Voltagte [V]
-15
-10
-5
0
5
10
15
0481216
Maximum In put Vol t ag e v s . S upply Volta ge ( e a la )
Vin= Lch, Vout=Lc h, f=1kHz , R L=4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω, Ta=25
o
C
Maximum Input Volta ge [dBV]
Supply Voltage [V]
-15
-10
-5
0
5
10
15
0481216
Maximum Input Voltage (eala BAS S)
Vin= Lch, Vout=Lch, f= 10kHz, RL=4 .7 k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω, Ta=25
o
C
Maximum Input Voltage [dBV]
Supply Voltage [V]
NJM2706
- 14 -
■
■■
■ TYPICAL CHA RACTERISTICS
-15
-10
-5
0
5
10
15
0481216
Maximum Input Voltage vs. Supply Voltage (eala BASS)
Vin=Lch+Rch, Vout=Lch, f=100Hz , RL= 4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω Ta=25
o
C
Maximum Input Voltage [dBV]
Supply Volta ge [V]
-120
-115
-110
-105
-100
-95
-90
-50 0 50 100 150
Output Noise vs. Temperature
V+=12V, Vin=GND, Vout=Lch
Output Noise [dBV]
Temperature [
o
C]
eala BASS
BASS
eala
Bypass
0.0001
0.001
0.01
0.1
1
10
-50 -40 -30 -20 -10 0 10 20
THD+N vs. Input Voltage (Bypass)
V+=12V, Vin=Lch, Vout=Lch, f=100Hz, RL=4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω, BW=10-80kHz
THD+ N [%]
Input V oltage [dBV]
Ta=85
o
C
Ta=25
o
C
Ta=-40
o
C
0.0001
0.001
0.01
0.1
1
10
-50 -40 -30 -20 -10 0 10 20
THD+N vs. Input Voltage (Bypass)
V+=12V, Vin=Lch, Vout=Lch, f=1kHz, RL=4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω, BW=10-80KHz
THD+N [%]
Input Voltage [dBV ]
Ta=85
o
C
Ta=25
o
C
Ta=-40
o
C
0.001
0.01
0.1
1
10
-50 -40 -30 -20 -10 0 10 20
THD+N vs. Input Voltage (Bypass)
V+=12V, Vin=Lch, Vout=Lch, f=10kHz, RL=4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω, BW=10-80kHz
THD+N [%]
Input Voltag e [dBV]
Ta=85
o
C
Ta=25
o
C
Ta=-40
o
C
0.01
0.1
1
10
-50 -40 -30 -20 -10 0 10 20
THD+N vs. Input Voltage (eala)
V+=12V, Vi n=Lch, Vout=Lch, f=1kHz, RL=4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω, BW=10-80kHz
THD+N [%]
Input Voltage [ d BV]
Ta=85oC
Ta=25oC
Ta=-40oC
NJM2706
-15-
■
■■
■ TYPICAL CHA RACTERISTICS
0.01
0.1
1
10
-50 -40 -30 -20 -10 0 10 20
THD+N vs. Input Voltage (eala B A SS)
V+=12V, Vin=Lch, V out=Lch, f=1kHz, RL=4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω, BW=10-80kHz
THD+N [%]
Input Voltage [ d BV]
Ta=85
o
C
Ta=25
o
C
Ta=-40
o
C
0.01
0.1
1
10
-50-40-30-20-10 0 10 20
THD+N vs. Input Voltage (eala BASS)
V+=12V, Vin=Lch, Vout =Lch, f=20kHz, RL=4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω, B W = 10-80kHz
THD+N [%]
Input Voltage [dBV]
Ta=85
o
C
Ta=25
o
C
Ta=-40
o
C
-3
-2
-1
0
1
2
3
10 100 1000 10
4
10
5
Gain vs. Frequency (Bypass)
V+=1 2V, Vin=-20dBV Lch, Vout =Lch, RL=4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω
Gai n [dB ]
Frequency [Hz]
Ta=85
o
C
Ta=25
o
C
Ta=-40
o
C
-2
0
2
4
6
8
10
12
10 100 1000 10
4
10
5
G ain vs. Freque ncy (BAS S )
V+=12V, Vin=-20dBV Lch+Rch, Vout=Lch, RL=4.7k Ω,
Ω,Ω,
Ω,
Rg=25Ω
ΩΩ
Ω
Gain [d B]
Frequency [H z]
Ta=85
o
C
Ta=25
o
C
Ta=-40
o
C
-2
0
2
4
6
8
10
12
10 100 1000 10
4
10
5
Gain vs. Frequency (eala )
V+=12V, Vin=-2 0dBV Lc h, Vout=Lch, RL= 4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω
Gain [dB]
Frequency [Hz]
Ta=85
o
C
Ta=25
o
C
Ta=-40
o
C
0.01
0.1
1
10
-50 -40 -30 -20 -10 0 10 20
THD+N v s. Input Voltage (eala BASS)
V+=12V, Vin=Lch, Vout=Lch, f=100Hz, RL=4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω, BW=10-80kHz
THD+N [%]
Input Voltage [dBV]
Ta=85
o
C
Ta=25
o
C
Ta=-40
o
C
NJM2706
- 16 -
■
■■
■ TYPICAL CHA RACTERISTICS
[CAUTION]
The specifications on this databook are only
given for information , without any guarantee
as regards either mistakes or omissions. The
applicati on 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.
-2
0
2
4
6
8
10
12
10 100 1000 10
4
10
5
Ga in vs. Fre quency (eala BASS)
V+=12V, Vin=-20dBV Lch, Vout=Lch, RL=4.7k Ω
ΩΩ
Ω,
Rg=25Ω
ΩΩ
Ω
Gain [dB]
Frequency [Hz]
Ta=85
o
C
Ta=25
o
C
Ta=-40
o
C
-5
0
5
10
15
20
10 100 1000 10
4
Gain vs. Frequency (eala BA SS)
Gain [dB]
Frequency [Hz]
-40dBV INPUT
0dBV INPUT
-30d BV I NP UT
-20dBV INPUT
-10dBV INPU T
