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
1
2
3
4
22 21 20 19 18 17 16 15 14 13 12
5
6
1 2 3 4 5 6 7 8 9 10 11
SOP-22
7
8
9
10
11
COM1
Preamp non-inverted input
Preamp inverted input
Metal switching output
Preamp output
Power input
Rectifier pin
ALC control
Power output
COM2
GND1
12
13
14
15
16
17
18
19
20
21
22
Power output
V
CC
Ripple filter
Preamp off
Tape selector
Power input
Preamp output
Metal switching output
Preamp inverted input
Preamp non-inverted input
GND2
Absolute Maximum Ratings
Item
Operating temperature
Storage temperature
Power supply current
Power consumption
Symbol
T
OPR
T
STG
V
CC
Pd
Ratings
-10~+65
-40~+125
-0.3~+7.5
350
Units
°
C
°
C
V
mW
MITSUMI
IC for Headphone Stereos MM1376
Recommended Operating Conditions
Item
Operating temperature
Operating voltage
Symbol
T
OPR
V
OPR
Ratings
-10~65
2.0~5.0
Units
°
C
V
Electrical Characteristics
Item
Consumption current
Preamp unit
Open-circuit gain
Closed-circuit gain
I
Closed-circuit gain
II
(Except where noted otherwise, Ta=25
°
C, V
CC
=3V, f=1kHz, R
L
1=10kΩ, R
L
2=16Ω)
Measurement conditions
V
IN
=0V
Min. Typ. Max. Units
6
14
72
22
mA
dB
36
34.5
33
28
0.5
150
100
dB
dB
Vrms
%
µVrms
dB
dB
-60
28
34
2
1.5
200
250
dBm
Normal
Metal
Normal
Metal
Vo=-10dBm, f=1kHz
Vo=-10dBm, f=5kHz
THD=10%
V
OUT
=-10dBm
Rg=2.2k, BPF (400~30kHz)
Rg=2.2kΩ, V
OUT
=-10dBm
V
CC
=3V, V
R
=-20dBm, f
R
=100Hz Rg=2.2kΩ
V
IN
=100mVrms, Pre off
CF
DF
31
29.5
28
23
0.30
30
20
50
45
33.5
32
30.5
25.5
0.45
0.05
75
45
70
55
-80
Maximum output voltage
Total harmonic distortion ratio
Output noise voltage
Normal
Metal
Crosstalk between channels
Ripple rejection
Output voltage with preamp off
ALC (off) + power amp
Voltage gain
Voltage gain difference between channels
Maximum output current
Total harmonic distortion ratio
Crosstalk between channels
Output noise voltage
P
OUT
=5mW
24
30
-2
30
35
26
32
0
50
0.5
45
85
135
dB
dB
mW
%
dB
µVrms
dB
THD=10%, R
L
=16Ω
P
OUT
=5mW
P
OUT
=5mW
Rg=0Ω, BPF (400~30kHz)
V
CC
=3V, V
R
=-20dBm
f
R
=100Hz, Rg=0Ω
CF
DF
CF
DF
Ripple rejection
Input resistance
ALC (on) + power amp
Power amp output voltage
ALC initiation input voltage
ALC width
ALC total harmonic distortion
Noise of preamp+power amp+ALC
35
35
19
45
40
24
-30
-56
-62
29
-26
kΩ
dBm
dBm
dB
V
IN
=-40dBm
CF
DF
Input width for output from start of up to +4dB
V
IN
=-40dBm
Rg=2.2kΩ (Pre amp), Noise of preamp+power amp
CF
DF
-34
30
40
0.5
1.5
2.8
1.5
6
6
%
mVrms
MITSUMI
IC for Headphone Stereos MM1376
Application Circuits
Characteristics
Preamp Gain- Frequency
60.0
55.0
50.0
45.0
40.0
volt
35.0
dB
30.0
25.0
lin
20.0
15.0
10.0
5.0
0.
1.0
ALC + power amp (32 dB) V
IN
-V
OUT
R
L
=16ohm
10
0
-10
ALC OFF
Normal
Metal
V
OUT
(dBV)
-20
-30
-40
-50
ALC ON (ADJUST)
ALC ON (max.)
-60
-80 -70 -60 -50 -40 -30 -20 -10
10.0 100.0 1.0k
10.0k 100.0k 1.0x
10.0x
0
Frequency (log)
V
IN
(dBV)
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