NJM2768B
HEADPHONE AMPLIFIER for CD-ROM
GENERAL DESCRIPTION
The
NJM2768B
is a headphone amplifier designed for CD-
ROM.
It includes 0dB closed loop gain and mute circuit, requires
few external component.
The
NJM2768B
realizes very low turn-noise at mute mode.
It is suitable for CD-ROM, and other general audio
headphone amplifier application.
PACKAGE OUTLINE
NJM2768BM
NJM2768BRB1
FEATURES
Operating Voltage
Operating Current
Fixed Gain
Stereo Headphone Output
Internal Mute Circuit
Bipolar Technology
Package Outline
2.8 to 5.5V
+
2mA typ. at V =5V
0dB typ.
DMP8,TVSP8
PIN CONFIGURATION
PIN FUNCTION
1.OUT1
2.MUTE
3.IN1
4.GND
5.IN2
6.BIAS
7.OUT2
+
8.V
1
2
3
4
8
7
6
5
BLOCK DIAGRAM
8
7
6
BIAS
5
MUTE
1
2
3
4
-1-
NJM2768B
ABSOLUTE MAXIMUM RATINGS
(Ta=25°C)
PARAMETER
Supply Voltage
Power Dissipation
Operating Temperature Range
Storage Temperature Range
SYMBOL
V
+
RATINGS
+7
(DMP8) 375
(TVSP8)320
-40 to +85
-50 to +150
UNIT
V
mW
°C
°C
P
D
Topr
Tstg
ELECTRICAL CHARACTERISTICS
(V
+
=5.0V,Vin=0dBV,f=1kHz,R
L
=32Ω,Ta=25°C unless otherwise specified)
PARAMETER
Operating Voltage
Operating Current
Reference Voltage
Closed Loop Gain
Channel Balance
Output Power
SYMBOL
V
+
TEST CONDITIONS
MIN.
2.8
TYP.
5.0
2.0
2.1
0
0
50
100
0.02
-104
(6.3)
-80
110
70
-
-
MAX.
5.5
4.0
-
1
+0.5
-
-
0.1
UNIT
V
mA
V
dB
dB
mW
mW
%
I
CC
Vref
G
V
∆G
V
P
O
1
P
O
2
No Signal
No Signal
-
-
-1
-0.5
R
L
=32Ω, THD=0.1%
R
L
=16Ω, THD=0.1%
30
40
-
Total Harmonic Distortion
Output Noise Voltage
Mute Attenuation
Channel Separation
Ripple Rejection Ratio
Input Voltage H-level
Input Voltage L-level
THD
Vno
ATT
CS
RR
V
IH
V
IL
Vripple=-20dBV, Rg=0Ω
Rg=0Ω, A-Weighted
Vo/Vin
-
-
90
-
2.0
0.0
dBV
-94
(20) (µVrms)
-70
-
-
V
+
dB
dB
dB
V
V
0.3
CONTROL PIN INFORMATION
PARAMETER
MUTE ON
MUTE OFF
CONTROL SIGNAL
L
H
OPERATING CONDITION
NON-SIGNAL
OUTPUT SIGNAL
-2-
NJM2768B
TERMINAL DESCRIPTION
PIN
SYMBOL
NO.
FUNCTION
EQUIVALENT CIRCUIT
TERMINAL
VOLTAGE
1
7
OUT1
OUT2
OUTPUT1
OUTPUT2
(V -1V
BE
)/2
+
10uA
2
MUTE
MUTE CONTROL
350k
-
50k
3
5
IN1
IN2
INPUT1
INPUT2
(V -1V
BE
)/2
50k
+
BIAS
50k
6
BIAS
REFERENCE VOLTAGE
STABILIIZED CAPACITOR
CONNECT TERMINAL
50k
(V -1V
BE
)/2
+
-3-
NJM2768B
TYPICAL APPLICATION
100μF
V
16Ω/32Ω
SPEAKER
100μF
+
47μF
OUT2
8
7
BIAS
6
BIAS
IN2
5
V
+
2
1
16Ω/32Ω
SPEAKER
1
OUT1
MUTE
H: SPEAKER Active
L: SPEAKER Mute
100kΩ
1μF
mute
2
MUTE
3
IN1
4
GND
1 F
-4-
NJM2768B
TYPICAL CHARACTERISTICS
Oprating Current vs. Operating Voltage
(MUTE=V+)
4
4
3.5
3
2.5
2
1.5
1
0.5
0
0
1
2
3
4
5
6
3.5
3
2.5
2
1.5
1
0.5
0
-40 -20
0
20 40 60
80 100 120
V
+
=2.8V
V
+
=5V
Operating Current vs. Ambient Temperature
Operating Current (mA)
Operating Current (mA)
Operating Voltage (V)
o
Ambient Temperature ( C)
Reference Voltage vs. Operating Voltage
3
2.5
2
1.5
1
0.5
0
0
1
2
3
4
5
6
Reference Voltage vs. Ambient Temperature
3
2.5
2
1.5
V
+
=2.8V
1
0.5
0
-40 -20
0
20 40 60
80 100 120
o
Reference Voltage (V)
Reference Voltage (V)
V
+
=5V
Operating Voltage (V)
Ambient Temperature ( C)
Power Dissipation vs.Output Power
(V+=5V,f=1KHz)
400
120
350
300
250
200
150
100
50
0
0
20
40
60
80
100
120
THD=10%
RL=32Ω
Power Dissipation vs.Output Power
(V+=2.8V,f=1KHz)
RL=16Ω
Power Dissipation (mW)
Power Dissipation (mW)
RL=16Ω
100
80
60
40
20
0
0
5
10
RL=32Ω
THD=10%
15
20
25
Output Power (mW)
Output Power (mW)
-5-
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