MITSUMI
IC for Headphone Stereos (bass boost) LAG668
IC for Headphone Stereos (bass boost)
Monolithic IC LAG 668
Outline
This IC was developed to provide bass boost functions without deviating from the basic design concept of
Mitsumi's LAG665, which is highly regarded for applications in headphone stereos for overseas markets in
particular.
Bass boost functions are widely adopted in models for overseas markets as well. However, because of
stringent cost constraints, there has been a need for an IC which is simple and inexpensive. This IC can
provide bass boost functions simply by adding three resistors and one capacitor (per channel).
Moreover, it has the same pinout as the LAG665, so that by making selective use of set features, a product
lineup can be developed without changes to the printed circuit board.
Features
Package
Absolute Maximum Ratings
1. Configuration: pre and power amps, motor control, E. VR, bass boost
2. Preamp off function convenient for use in models with radios
3. Independent motor control circuit
1. Motor noise is effectively suppressed
2. With motor on/off pin (motor can be stopped easily when radio is in use)
3. With fast forward pin
4. Bass boost frequency characteristic can be changed simply by changing the resistance multiplier.
5. Well-balanced E. VR circuit
1. L, R channels variable using a single VR
2. A-curve can be reproduced using B-curve VR
6. Few external components
SOP-28B (LAG668F)
SDIP-30A (LAG668D)
Item
Symbol
Ratings
Units
Operating temperature
T
OPR
-20~+65
C
Storage temperature
T
STG
-40~+125
C
Power supply current
V
CC
max.
-0.3~+7.5
V
Power consumption
Pd
DIP : 750, SOP : 450
mW
Operating voltage
Vop
+2.0~+5.0
V
MITSUMI
IC for Headphone Stereos (bass boost) LAG668
Electrical Characteristics
(Except where noted otherwise, Ta=25
C
)
Item
Symbol
Measurement conditions
Min.
Typ.
Max. Units
Consumption current
I
CC
V
IN
=0v, IM=0mA
18
25
mA
Preamp unit (Ta=25
C)
Open-circuit gain
Gvo
V
O
=-10dBm, R
L
=infinite
72
dB
Closed-circuit gain
Gvc
V
O
=-10dBm
40
42
44
dB
Maximum output voltage
Vom
THD=10%
0.45
0.6
Vrms
Total harmonic distortion ratio
THD
V
OUT
=400mVrms
0.05
0.5
%
Output noise voltage
Vno
V
IN
=0, Rg=2.2k, BPF (30~20kHz)
150
300
Vrms
Input impedance
Z
IN
V
OUT
=-10dBm
18
22
k
Crosstalk between channels
C.T
Rg=2.2k, V
OUT
=-10dBm
30
dB
Output voltage with pre off
Vooff
V
IN
=100mVrms
-50
dB
Output resistance with pre off
Rooff
10
k
Input resistance on pre off
Rioff
10
k
Attenuator unit (Ta=25
C)
Maximum input voltage
Vi max.
0.2
Vrms
Maximum attenuation
Va max.
Vcont=min.
66
dB
Attenuation error
Vaerr
Vcont=max.
0
dB
Input impedance
Z
IN
200
k
Control pin input resistance
Zicot
100
k
Power amp unit (Ta=25
C)
Voltage gain
Gv
P
OUT
=5mW
36
38
40
dB
Voltage gain difference
Gv
Vcont=max.
0
3
dB
between channels
Maximum output power I
Pom1
THD=10%, R
L
=32
20
28
mW
Maximum output power II
Pom2
THD=10%, R
L
=16
30
mW
Total harmonic distortion ratio
THD
P
OUT
=5mW
0.5
2.0
%
Crosstalk between channels
C.T
P
OUT
=5mW
20
30
dB
Output noise voltage
Vn
Rg=2.2k, Vcont=max.
1.0
2.0
mVrms
Ripple rejection
RR
V
CC
=3V, 100Hz, 100mVp-p
31
37
dB
Noise of preamp + power amp + B.B.
Vnto
V
IN
=0, Rg=2.2k, Vcont=max.
*
1
3.0
6.0
mVrms
Motor control unit (Ta=25
C)
Consumption current
IMC
3.0
5.0
mA
Startup current
IMS
500
mA
Reference voltage
Vref
Between RML-ADJ pins
0.72
0.80
0.87
V
Reference voltage fluctuation I
Vref1
V
CC
between 2.1 and 5.0 V
0.05
%/V
Reference voltage fluctuation II
Vref2
I
M
between 25 and 250 mA
0.01
%/mA
Reference voltage fluctuation III
Vref3
Ta between -10 and 50
C
0.01
%/
C
Current coefficient
K
32
38
43
Current coefficient fluctuation I
K1
V
CC
between 2.1 and 5.0 V
0.5
%/V
Current coefficient fluctuation II
K2
I
M
between 25 and 250 mA
0.05
%/mA
Current coefficient fluctuation III
K3
Ta between -10 and 50
C
0.02
%/
C
Output voltage on forced on
VCEsa
I
M
=200mA, 14PIN=V
CC
0.6
V
Input resistance on forced on
Rion
5.6
k
Leakage current on forced off
IML
200
A
Input resistance on forced off
Ricon
33
k
*
Conditions unless stated otherwise
Amp unit: V
CC
=3.0V, f=1kHz, R
L
=16
, Pre OFF=OPEN
Motor unit: V
CC
=3.0V, I
M
=100mA, Motor unit: (Mitsumi model)
Note 1: Bass boost circuit constants are based on application circuit diagrams.
Note 2: Motor pin voltage fluctuations
MITSUMI
IC for Headphone Stereos (bass boost) LAG668
Block Diagram
MITSUMI
IC for Headphone Stereos (bass boost) LAG668
G
V
G
VH
G
VL
B
B Off
B
B ON
40
35
30
25
15
10
1
10
2
10
3
10
4
10
5
10
6
Frequency (Hz)
f1
f2
3dB
3dB
G
V
: Power amp gain
G
VH
=G
V
+20Log (dB)
f1, f2: Cutoff frequencies
G
VH
: Bass boost power amp gain
(high level)
G
VL
: Bass boost power amp gain
(low level, or boost off)
(
(
R1+R3
R3
G
VL
=G
V
+20Log (dB)
(
(
R2//R3+ R1
R2//R3
R1
f1= (Hz)
2
((R
1
//R
3
) +R
2
)C
1
f2= (Hz)
2
R
2
C
1
Power amp gain
(dB)
Bass Boost Power Amp Gain
Application Circuits
MITSUMI
IC for Headphone Stereos (bass boost) LAG668
40
35
30
25
20
15
10
1
10
2
10
3
10
4
10
5
10
6
Frequency (Hz)
R1=33k
R2=6.8k
R3=180k
C=0.1
F
G
VH
=37dB
G
VL
=23dB
f1=50Hz
f2=230Hz
No R4 or C2
Power amp gain
(dB)
R1=33k
R2=4.7k
R4=20k
R3=180k
C=0.1
F
C2=390pF
G
VH
=37dB
G
VH
=27dB
G
VL
=20dB
f1=50Hz
f2=340Hz
40
35
30
25
20
15
10
1
10
2
10
3
10
4
10
5
10
6
Frequency (Hz)
Power amp gain
(dB)
Response for poor headphone and cassette head characteristics
Bass + treble boost
Characteristics
(Bass boost)
40
35
30
25
20
15
10
1
10
2
10
3
10
4
10
5
10
6
Frequency (Hz)
R1=33k
R2=4.7k
R3=180k
C=0.1
F
G
VH
=37dB
G
VL
=20dB
f1=50Hz
f2=340Hz
No R4 or C2
Power amp gain
(dB)
40
35
30
25
20
15
10
1
10
2
10
3
10
4
10
5
10
6
Frequency (Hz)
R1=12k
R2=2.2k
R3=180k
C=0.1
F
G
VH
=37dB
G
VL
=20dB
f1=130Hz
f2=720Hz
No R4 or C2
Power amp gain
(dB)
Recommended constants
Bass boost efficiency
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