Page 1
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
136924587
10 11
22 18 1521 19 17 16 1420 1213
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
Page 2
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, VCC=3V, f=1kHz, R
L
1=10kΩ, RL2=16Ω)
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
µVrms
Metal 20 45 100
Crosstalk between channels Rg=2.2kΩ, V
OUT=
-
10dBm 50 70 dB
Ripple rejection
VCC=3V, VR=-20dBm, f
R
=100Hz Rg=2.2kΩ
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
-
20 2dB
Maximum output current THD=10%, R
L=16Ω 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=0Ω, BPF (400~30kHz)
CF 85 200
µVrms
DF 135 250
Ripple rejection
V
CC=3V, VR=
-
20dBm CF 35 45
dB
f
R=100Hz, Rg=0Ω DF 35 40
Input resistance 19 24 29 kΩ
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=2.2kΩ (Pre amp), Noise of preamp+power amp
CF 1.5 6
mVrms
DF 2.8 6
Page 3
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
VOUT
(dBV)
V
IN (dBV)
Preamp Gain- Frequency
ALC + power amp (32 dB) VIN-
V
OUT
RL=16ohm
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