NJM2768B
-1-
HEADPHONE AMPLIFIER for CD-ROM
GENERAL DESCRIPTION PACKAGE OUTLINE
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.
FEATURES
Operating Voltage 2.8 to 5.5V
Operating Current 2mA typ. at V+=5V
Fixed Gain 0dB typ.
Stereo Headphone Output
Internal Mute Circuit
Bipolar Technology
Package Outline DMP8,TVSP8
PIN CONFIGURATION
1
2
3
4
8
7
6
5
BLOCK DIAGRAM
1 2 3 4
8 7 6 5
BIAS
MUTE
PIN FUNCTION
1.OUT1
2.MUTE
3.IN1
4.GND
5.IN2
6.BIAS
7.OUT2
8.V+
NJM2768BM NJM2768BRB1
NJM2768B
-2-
ABSOLUTE MAXIMUM RATINGS (Ta=25°C)
PARAMETER SYMBOL RATINGS UNIT
Supply Voltage V+ +7 V
Power Dissipation PD (DMP8) 375
750 (note)
(TVSP8)320 mW
Operating Temperature Range Topr -40 to +85 °C
Storage Temperature Range Tstg -50 to +150 °C
(note) At on PC board
ELECTRICAL CHARACTERISTICS (V+=5.0V,Vin=0dBV,f=1kHz,RL=32Ω,Ta=25°C unless otherwise specified)
PARAMETER SYMBOL TEST CONDITIONS MIN. TYP. MAX. UNIT
Operating Voltage V+ 2.8 5.0 5.5 V
Operating Current ICC No Signal - 2.0 4.0 mA
Reference Voltage Vref No Signal - 2.1 - V
Closed Loop Gain GV -1 0 1 dB
Channel Balance ∆GV -0.5 0 +0.5 dB
Output Power PO1 RL=32Ω, THD=0.1% 30 50 - mW
P
O2 RL=16Ω, THD=0.1% 40 100 - mW
Total Harmonic Distortion THD - 0.02 0.1 %
Output Noise Voltage Vno Rg=0Ω, A-Weighted - -104
(6.3) -94
(20) dBV
(µVrms)
Mute Attenuation ATT Vo/Vin - -80 -70 dB
Channel Separation CS 90 110 - dB
Ripple Rejection Ratio RR Vripple=-20dBV, Rg=0Ω - 70 - dB
Input Voltage H-level VIH 2.0 - V+ V
Input Voltage L-level VIL 0.0 - 0.3 V
CONTROL PIN INFORMATION
PARAMETER CONTROL SIGNAL OPERATING CONDITION
MUTE ON L NON-SIGNAL
MUTE OFF H OUTPUT SIGNAL
NJM2768B
-3-
TERMINAL DESCRIPTION
PIN
NO. SYMBOL FUNCTION EQUIVALENT CIRCUIT
TERMINAL
VOLTAGE
1
7 OUT1
OUT2 OUTPUT1
OUTPUT2
(V+-1VBE)/2
2 MUTE MUTE CONTROL
-
3
5 IN1
IN2 INPUT1
INPUT2
(V+-1VBE)/2
6 BIAS REFERENCE VOLTAGE
STABILIIZED CAPACITOR
CONNECT TERMINAL
(V+-1VBE)/2
350k
10uA
50k
50k
BIAS
50k
50k
FB
NJM2768B
-4-
TYPICAL APPLICATION
16Ω/32Ω
GND
IN1
MUTEOUT1
OUT2
mute
BIAS
1
2
8765
1 2 34
BIAS IN2
V
+
1 F
16Ω/32Ω
SPEAKER
H: SPEAKER Active
L: SPEAKER Mute
MUTE
100µF
+
V
47µF
1µF
100k
Ω
100µF
SPEAKER
NJM2768B
-5-
TYPICAL CHARACTERISTICS
0
0.5
1
1.5
2
2.5
3
3.5
4
0123456
Oprating Current vs. Operating Voltage
Oper atin g Current (m A)
Operating Voltage (V)
(MUTE=V+)
0
0.5
1
1.5
2
2.5
3
3.5
4
-40 -20 0 20 40 60 80 100 120
O per atin g Cur rent vs. A m bi ent T emper at ure
Oper atin g Current (m A)
Ambient Temperature (oC)
V+=5V
V+=2.8V
0
0.5
1
1.5
2
2.5
3
0123456
Reference Voltage vs. Operating Voltage
Reference Voltage (V)
Operating Voltage (V)
0
0.5
1
1.5
2
2.5
3
-40-200 20406080100120
Reference Voltage vs. Ambient Temperature
Reference Voltage (V)
Ambient Temperature (oC)
V+=5V
V+=2.8V
0
50
100
150
200
250
300
350
400
0 20 40 60 80 100 120
Power Dissipation vs.Output Power
Power Dissipation ( mW )
Output Power (mW)
THD=10%
(V+=5V,f=1KHz)
RL=32Ω
RL=16Ω
0
20
40
60
80
100
120
0 5 10 15 20 25
Power Dissipation vs.Output Pow er
Power Dissipatio n ( mW )
Output Power (mW)
THD=10%
(V+=2.8V,f=1KHz)
RL=32Ω
RL=16Ω
0
50
100
150
200
250
300
350
400
0 20 40 60 80 100 120
Power Dissipation vs. Output Power
Power Dissipation (mW)
Output Power (mW)
THD=10%
(V+=5V,f=1KHz)
RL=16
RL=32
0
20
40
60
80
100
120
0 5 10 15 20 25
Power Dissipation vs. Output Power
Power Dissipation (mW)
Output Power (mW)
THD=10%
(V+=2.8V,f=1KHz)
RL=16
RL=32
NJM2768B
-6-
-100
-90
-80
-70
-60
-50
10 100 1K 10K
Mute Level vs. Frequency
Mute Level (dB)
Frequency (Hz)
(V+=5V,Vin=-6dBV,RL=32Ω)
Ta=-40oC
Ta=25oC
Ta=85oC
0.01
0.1
1
10
0.001 0.01 0.1
THD+N v s. Output Power
THD+N (%)
Output Power (mW)
(V+=5V,f=1KHz,RL=32Ω)
Ta=-40oC
Ta=25oC
Ta=85oC
0.01
0.1
1
10
0.001 0.01 0.1
THD+N vs. Output Power
THD+N (%)
Output Power (mW)
(V+=5V,f=1KHz,RL=16Ω)
Ta=85oC
Ta=-40oC
Ta=25oC
0.01
0.1
1
10
1 10 100
THD+N v s. Output Power
THD+N (%)
Output Power (mW)
(V+=2.8V,f=1KHz,RL=32Ω)
Ta=-40oC
Ta=25oC
Ta=85oC
0.01
0.1
1
10
1 10 100
THD+N vs. Output Power
THD+N (%)
Output Power (mW)
(V+=2.8V,f=1KHz,RL=16Ω)
Ta=85oC
Ta=-40oC
Ta=25oC
-110
-105
-100
-95
-90
-40-200 20406080100120
O utput Noise Vol tage vs. Ambient Tem perat ure
Output Noise Voltage ( dBV)
Ambient Temperature (oC)
(RL=32Ω,A-Weigthed)
V+=5V
V+=2.8V
NJM2768B
-7-
[CAUTION]
The specifications on this databook are only
given for information , without any guarantee
as regards either mistakes or omissions. The
application circuits in this databook are
described only to show representative usages
of the product and not intended for the
guarantee or permission of any right including
the industrial rights.
40
50
60
70
80
90
100
110
120
10 100 1000 104
Channel Separation vs. Frequency
Channel Separa tion (dB)
Frequency (Hz)
(V+=5V,f=1KHz,RL=32Ω)
0
20
40
60
80
100
0.01 0.1 1 10
Ripple Rejection Ratio vs. Frequency
Ripple Rejection Ratio (dB)
Frequency (Hz)
(Vripple=-20dBV,RL=32Ω)
V+=5V
V+=2.8V
-100
-80
-60
-40
-20
0
20
00.511.5
Voltage G ain vs M ute Contr ol Vol tage
Volt age Gain (dB)
MUTE Covtrol Vol tage ( V)
(V+=5V,f=1KHz,Vin=-6dBV)
Ta=-40oC
Ta=25oC
Ta=85oC
