MITSUMI
IC for Headphone Stereos MM1376
IC for Headphone Stereos
Monolithic IC MM1376
Outline
This IC was developed for use in 3V headphone stereos, and combines all the basic audio circuitry for
headphone stereos on a single chip.
Recently hearing impairment caused by the high volumes of headphone stereos has become a problem, and
there has been strong demand for functions for limiting loud volumes in the sets themselves. This IC
incorporates an ALC circuit and has functions to hold the output from the headphone to a fixed level; it also
eliminates the ordinary electronic governor circuit in order to accommodate trends toward thinner sets, as
seen in the adoption of BSL motors.
Package
1. Configuration: Pre-and power amps, ALC circuit
2. Internal tape selector: A selector switch allows the user to select between normal and metal tapes.
3. Internal OCL circuit: No need for large-capacitance output capacitor
4. Preamp off function: Preamp alone can be turned off for connection to radio etc.
5. MM1376CF amp gain takes Dolby noise reduction into account
Package
SOP-22
Pin Assignment
SOP-22
1
3
6
9
2
4 5
8
7
10 11
22
18
15
21
19
17 16
14
20
12
13
Item
Symbol
Ratings
Units
Operating temperature
T
OPR
-10~+65
C
Storage temperature
T
STG
-40~+125
C
Power supply current
V
CC
-0.3~+7.5
V
Power consumption
Pd
350
mW
Absolute Maximum Ratings
1
COM1
12
Power output
2
Preamp non-inverted input
13
V
CC
3
Preamp inverted input
14
Ripple filter
4
Metal switching output
15
Preamp off
5
Preamp output
16
Tape selector
6
Power input
17
Power input
7
Rectifier pin
18
Preamp output
8
ALC control
19
Metal switching output
9
Power output
20
Preamp inverted input
10
COM2
21
Preamp non-inverted input
11
GND1
22
GND2
MITSUMI
IC for Headphone Stereos MM1376
Recommended Operating Conditions
Item
Symbol
Ratings
Units
Operating temperature
T
OPR
-10~65
C
Operating voltage
V
OPR
2.0~5.0
V
Electrical Characteristics
(Except where noted otherwise, Ta=25
C, V
CC
=3V, f=1kHz, R
L
1=10k
, R
L
2=16
)
Item
Measurement conditions
Min. Typ. Max. Units
Consumption current
V
IN
=0V
6
14
22
mA
Preamp unit
Open-circuit gain
72
dB
Closed-circuit gain I
Normal
Vo=-10dBm, f=1kHz
31
33.5
36
dB
Metal
29.5
32
34.5
Closed-circuit gain II
Normal
Vo=-10dBm, f=5kHz
28
30.5
33
dB
Metal
23
25.5
28
Maximum output voltage
THD=10%
0.30
0.45
Vrms
Total harmonic distortion ratio
V
OUT
=-10dBm
0.05
0.5
%
Output noise voltage
Normal
Rg=2.2k, BPF (400~30kHz)
30
75
150
Vrms
Metal
20
45
100
Crosstalk between channels
Rg=2.2k
, V
OUT
=-10dBm
50
70
dB
Ripple rejection
V
CC
=3V, V
R
=-20dBm, f
R
=100Hz Rg=2.2k
45
55
dB
Output voltage with preamp off
V
IN
=100mVrms, Pre off
-80
-60
dBm
ALC (off) + power amp
Voltage gain
P
OUT
=5mW
CF
24
26
28
dB
DF
30
32
34
Voltage gain difference between channels
-2
0
2
dB
Maximum output current
THD=10%, R
L
=16
30
50
mW
Total harmonic distortion ratio
P
OUT
=5mW
0.5
1.5
%
Crosstalk between channels
P
OUT
=5mW
35
45
dB
Output noise voltage
Rg=0
, BPF (400~30kHz)
CF
85
200
Vrms
DF
135
250
Ripple rejection
V
CC
=3V, V
R
=-20dBm
CF
35
45
dB
f
R
=100Hz, Rg=0
DF
35
40
Input resistance
19
24
29
k
ALC (on) + power amp
Power amp output voltage
V
IN
=-40dBm
-34
-30
-26
dBm
ALC initiation input voltage
CF
-56
dBm
DF
-62
ALC width
Input width for output from start of up to +4dB
30
40
dB
ALC total harmonic distortion
V
IN
=-40dBm
0.5
1.5
%
Noise of preamp+power amp+ALC
Rg=2.2k
(Pre amp), Noise of preamp+power amp
CF
1.5
6
mVrms
DF
2.8
6
MITSUMI
IC for Headphone Stereos MM1376
Application Circuits
Normal
Metal
60.0
55.0
50.0
45.0
40.0
35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.
10.0
100.0 1.0k
10.0k 100.0k 1.0x
10.0x
1.0
volt
dB
lin
Frequency (log)
Characteristics
ALC OFF
ALC ON (ADJUST)
ALC ON (max.)
10
0
-10
-20
-30
-40
-50
-60
-80 -70 -60 -50 -40 -30 -20 -10
0
V
OUT
(dBV)
V
IN
(dBV)
Preamp Gain- Frequency
ALC + power amp (32 dB) V
IN
-V
OUT
R
L
=16ohm
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