NJM2381
Ver
3
.
3
-1-
SWITCHING REGULATOR CONTROL IC FOR FLYBACK
WITH CURRENT SENSE AMPLIFIER
■GENERAL DESCRIPTION ■PACKAGE OUTLINE
■FEATURES
● PWM switching control
● Operating Voltage (3.6 to 32V)
● Wide Oscillator Range (5 to 350 kHz)
● Current Sensing Amplifier
● Soft-Start Function
● UVLO(Under Voltage Lockouts)
● Bipolar Technology
● Package Outline DIP14, DMP14, SSOP10
■PIN CONFIGURATION
The NJM2381 is a low voltage operation DC/DC converter
control IC.
It features totem pole output directly driving external
bipolar transistor and operates at high switching frequenc
y
which improves transient response.
It is suitable for LCD back light, and other portable
applications.
NJM2381D
NJM2381V
NJM2381M
1.IN
-
1
2.IN
-
2
3.F.B
4.GND
5.OUT
6. V
+
7.CS
8.CT
9.REF
10.IN
+
PIN FUNCTION
1
4
3
2
5 6
7
8
9
10
NJM2381D
NJM2381M
1.NC
2.IN
-
1
3.IN
-
2
4.F.B
5.GND
6.OUT
7.NC
8.NC
9. V
+
10.CS
11.CT
12.REF
13.IN
+
14.NC
PIN FUNCTION
1
4
3
2
14
11
12
13
5
6
7 8
9
10
NJM2381V
NJM2381
- 2 -
■BLOCK DIAGRAM
1
V
REF
CURRENT
SENSE AMP
V
+
ER·AMP
L.O
500Ω
U.V.LO
OSC
PWM
9 8
76 543 2
10
CSCTIN
+
REF
IN
-
1 IN
-
2 OUT GNDF.B
0.52V
1112 13 14
NC
NC
NC
NC
(Package: DIP14, DMP14)
1
V
REF
CURRENT
SENSE AMP
V
+
ER·AMP
L.O
500Ω
U.V.LO
OSC
PWM
9 8 7 6
5 432
10
CSCTIN
+
REF
IN
-
1 IN
-
2 OUT GNDF. B
0.52V
(Package: SSOP10)
NJM2381
-
3
-
■ABSOLUTE MAXIMUM RATINGS (Ta=25°C )
PARAMETER SYMBOL MAXIMUM RATINGS UNIT
Input Voltage V
+
36 V
Reference Output Current I
OR
10 mA
Output Current I
O
±50 mA
Differential Input Voltage V
ID
2.5 V
Common Mode Input Voltage V
IC
-0.3 ∼ 2.5 V
Power Dissipation
P
D
(DIP 14) 700
(DMP 14) 300
(SSOP 10) 250
mW
Operating Temperature Range T
OPR
-40 ∼ +85 °C
Storage Temperature Range T
STG
-50 ∼ +125 °C
■ELECTRICAL CHARACTERISTICS (V
+
=6V,R
T
=33kΩ,C
T
=1000pF,Ta=25°C)
REFERENCE VOLTAGE BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Output Voltage V
REF
I
OR
=1mA 2.45 2.50 2.55 V
Line Regulation L
INE
V
+
=3.6 ∼ 32V, I
OR
=1mA – 6.8 20.7 mV
Load Regulation L
OAD
I
OR
=0.1 ∼ 5.0mA – 5 30 mV
OSCILLATOR BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Oscillation Frequency f
OSC
R
T
=33kΩ, C
T
=1000pF 85 105 125 kHz
Oscillate Fluctuations1
(Line Fluctuations)
f
dV
V
+
=3.6 ∼ 32V – 1 – %
Oscillate Fluctuations2
(Temp Fluctuations)
f
dT
Ta=-40 ∼ 85°C – 5 – %
CURRENT SENSE AMPLIFIER BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Input Offset Voltage1 V
IO
1 – 2 7 mV
Input Offset Current1 I
IO
1 – 5 50 nA
Input Bias Current1 I
B
1 – 5 100 nA
Open Loop Gain1 A
V
1 – 90 – dB
Gain Bandwidth Product1 G
B
1 – 0.6 – MHz
Input Common Mode
Voltage Ratio1
V
ICM
1 – 0 ∼
V
REF
-0.8
– V
Maximum Output Voltage1
(F.B Pin)
V
OM-
1 R
NF
=100kΩ – – 1 V
Maximum Source Current1
(F.B Pin)
I
OM+
1 V
OM
=0.5V 40 85 200 µA
NJM2381
- 4 -
■ELECTRICAL CHARACTERISTICS (V
+
=6V,R
T
=33kΩ,C
T
=1000pF,Ta=25°C)
ERROR AMPLIFIER BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Reference Voltage2 V
B
2 0.51 0.52 0.53 V
Input Bias Current2 I
B
2 – 5 100 nA
Open Loop Gain2 A
V
2 – 90 – dB
Gain Bandwidth Product2 G
B
2 – 0.6 – MHz
Maximum Output Voltage2
(F.B Pin)
V
OM-
2 R
NF
=100kΩ – – 1 V
Maximum Source Current2
(F.B Pin)
I
OM+
2 V
OM
=0.5V 40 85 200 µA
PWM COMPARATE BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Input Threshold Voltage
(F.B Pin)
V
TH0
duty·cycle=0% – 1.65 1.75 V
Input Threshold Voltage
(F.B Pin)
V
TH50
duty·cycle=50% – 1.88 – V
Maximum Duty Cycle αM Current Sense Amp.=HIGH
Error Amp.=HIGH ,CS Pin=1.2V
55 64 85 %
SOFT START CIRCUIT BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Input Bias Current (CS Pin) I
BCS
CS Pin=1.8V – 250 650 nA
Input Threshold Voltage
(CS Pin
)
V
THCS0
duty·cycle=0% – 0.25 0.35 V
Input Threshold Voltage
(CS Pin
)
V
THCS50
duty·cycle=50% – 0.52 – V
UNDER VOLTAGE LOCKOUT BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
ON Threshold Voltage V
THON
– 2.70 – V
OFF Threshold Voltage V
THOFF
– 2.52 – V
Hysteresis Voltage V
HYS
60 180 – mV
OUTPUT BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
H-Output Voltage (OUT Pin) V
OH
R
L
=10kΩ 3.50 4.00 – V
L-Output Voltage (OUT Pin) V
OL
Output Sink Current=20mA – 0.25 0.65 V
Output Source Current
(OUT Pin)
I
SOURCE
OUT Pin=0V 8 11 – mA
GENERAL CHARACTERISTICS
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Latch Mode
Threshold Voltage (CS Pin)
V
THLA
1.2 1.5 1.8 V
Quiescent Current I
CCLA
Latch Mode – 1.6 2.2 mA
Average Quiescent Current I
CCAV
RL= , duty·cycle=50% – 3.5 4.8 mA
NJM2381
-
5
-
■ TYPICAL APPLICATIONS
1
V
REF
CURRENT
SENSE AMP
ER·AMP
L.O
500Ω
U.V.LO
OSC
PWM
9 8 7 6
54 3 2
10
0.52V
36kΩ
GND
2.50V
V
+
V
OUT
330kΩ 330kΩ4.7µF
1000pF
(Package:SSOP10)
NJM2381
-
6
-
■TIPICAL CHARACTERISTICS
H Output Voltage vs. Source Current
(V
+
=6V,R
T
=33kΩ,C
T
=1000pF,
OUT Pin=0V,Ta=25°C)
0
1
2
3
4
5
6
7
8
024681012
Source Current I
SOURCE
(mA)
H Output Voltage V
OH
(V)
Oscillator Frequency vs. Timing Resistor
(V
+
=6V,Ta=25°C)
1
10
100
1000
1 10 100 1000 10000
Timing Resistor R
T
(kΩ)
Oscilltor Frequency f
OSC
(kHz)
C
T
=470pF
C
T
=1000pF
Oscillator Frequency vs. Timing Capacitor
(V+=6V,Ta=25°C)
1
10
100
1000
10 100 1000 10000 100000
Timing Capacitor CT (pF)
Oscillator Frequencey fOSC
(kHz)
RT=10kΩ
RT=100kΩ
RT=33kΩ
Reference Voltage vs. Operating Voltage
(V
+
=6V,Ta=25°C)
2.48
2.49
2.5
2.51
2.52
0 10203040
Operating Voltage V
+
(V)
Reference Voltage V
REF
(V)
Operating Current vs. Operating Voltage
(Ta=25°C)
0
1
2
3
4
5
6
0 10203040
Operating Voltage V
+
(V)
Operating Voltage I
CC
(mA)
I
CCAV
I
CCLA
L Output Voltage vs. Sink Current
(V
+
=6V,R
T
=33kΩ,C
T
=1000pF,Ta=25°C)
0
0.2
0.4
0.6
0.8
1
0 102030405060
Sink Current I
SINK
(mA)
L Output Voltage V
OL
(V)
NJM2381
-7-
■TIPICAL CHARACTERISTICS
Maximum Duty Cycle vs. Oscillator Frequency
(V
+
=6V,Ta=25°C)
0
10
20
30
40
50
60
70
80
10 100 1000
Oscillator Frequency f
OSC
(kHz)
Maximum Duty Cycle αM (%)
Duty Cycle vs. CS Pin Voltage
(V
+
=6V,Ta=25°C)
0
10
20
30
40
50
60
70
80
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
CS Pin Voltage V
THCS
(V)
Duty Cycle α (%)
NJM2381
-
8
-
■TIPICAL CHARACTERISTICS
Oscillator Frequency vs. Temperature
(V
+
=6V,R
T
=33kΩ,C
T
=1000pF)
60
80
100
120
140
160
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Oscillator Frequency
f
OSC
(kHz)
Reference Voltage vs. Temperature
(V
+
=6V,I
OR
=1mA)
2
2.2
2.4
2.6
2.8
3
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Reference Voltage
V
REF
(V)
H Output Voltage vs. Temperature
(V
+
=6V,R
L
=10kΩ,R
T
=33kΩ,C
T
=1000pF)
0
2
4
6
8
10
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
H Output Voltage V
OH
(V)
L Output Voltage vs. Trmperature
(V
+
=6V,I
SINK
=20mA,R
T
=33kΩ,C
T
=1000pF)
0
0.1
0.2
0.3
0.4
0.5
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
L Output Voltage V
OL
(V)
Operating Current vs. Temperature
(V
+
=6V,R
T
=33kΩ,C
T
=1000pF)
0
1
2
3
4
5
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Operating Current I
CC
(mA)
I
CCAV
I
CCLA
[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.
