NJM2381
Ver
3
.1 - 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
VREF
CURRENT
SENSE AMP
V+
ER·AMP
L.O
500Ω
U.V.LO
OSC
PWM
9 8
7 6 5 4 3 2
10
CS CT IN+ REF
IN-1 IN-2 OUT GND F.B
0.52V
11 12 13 14
NC
NC
NC
NC
(Package: DIP14, DMP14)
1
VREF
CURRENT
SENSE AMP
V+
ER·AMP
L.O
500Ω
U.V.LO
OSC
PWM
9 8 7 6
5 4 3 2
10
CS CT IN+ REF
IN-1 IN-2 OUT GND F. 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 IOR 10 mA
Output Current IO ±50 mA
Differential Input Voltage VID 2.5 V
Common Mode Input Voltage VIC -0.3 ∼ 2.5 V
Power Dissipation
PD
(DIP 14) 700
(DMP 14) 300
(SSOP 14) 250
mW
Operating Temperature Range TOPR -40 ∼ +85 °C
Storage Temperature Range TSTG -50 ∼ +125 °C
■ELECTRICAL CHARACTERISTICS (V+=6V,RT=33kΩ,CT=1000pF,Ta=25°C)
REFERENCE VOLTAGE BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Output Voltage VREF I
OR=1mA 2.45 2.50 2.55 V
Line Regulation LINE V+=3.6 ∼ 32V, IOR=1mA – 6.8 20.7 mV
Load Regulation LOAD IOR=0.1 ∼ 5.0mA – 5 30 mV
OSCILLATOR BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Oscillation Frequency fOSC R
T=33kΩ, CT=1000pF 85 105 125 kHz
Oscillate Fluctuations1
(Line Fluctuations)
fdV V+=3.6 ∼ 32V – 1 – %
Oscillate Fluctuations2
(Temp Fluctuations)
fdT Ta=-40 ∼ 85°C – 5 – %
CURRENT SENSE AMPLIFIER BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Input Offset Voltage1 VIO1 – 2 7 mV
Input Offset Current1 IIO1 – 5 50 nA
Input Bias Current1 IB1 – 5 100 nA
Open Loop Gain1 AV1 – 90 – dB
Gain Bandwidth Product1 GB1 – 0.6 – MHz
Input Common Mode
Voltage Ratio1
VICM1 – 0 ∼
VREF-0.8
– V
Maximum Output Voltage1
(F.B Pin)
VOM-1 RNF=100kΩ – – 1 V
Maximum Source Current1
(F.B Pin)
IOM+1 VOM=0.5V 40 85 200 µA
NJM2381
- 4 -
■ELECTRICAL CHARACTERISTICS (V+=6V,RT=33kΩ,CT=1000pF,Ta=25°C)
ERROR AMPLIFIER BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Reference Voltage2 VB2 0.51 0.52 0.53 V
Input Bias Voltage2 IB2 – 5 100 nA
Open Loop Gain2 AV2 – 90 – dB
Gain Bandwidth Product2 GB2 – 0.6 – MHz
Maximum Output Voltage2
(F.B Pin)
VOM-2 RNF=100kΩ – – 1 V
Maximum Source Current2
(F.B Pin)
IOM+2 VOM=0.5V 40 85 200 µA
PWM COMPARATE BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Input Bias Voltage
(F.B Pin)
VTH0 duty·cycle=0% – 1.65 1.75 V
Input Threshold Voltage
(F.B Pin)
VTH50 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) IBCS CS Pin=1.8V – 250 650 nA
Input Threshold Voltage
(CS Pin
)
VTHCS0 duty·cycle=0% – 0.25 0.35 V
Input Threshold Voltage
(CS Pin
)
VTHCS50 duty·cycle=50% – 0.52 – V
UNDER VOLTAGE LOCKOUT BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
ON Threshold Voltage VTHON – 2.70 – V
OFF Threshold Voltage VTHOFF – 2.52 – V
Hysteresis Voltage VHYS 60 180 – mV
OUTPUT BLOCK
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
H-Output Voltage (OUT Pin) VOH R
L=10kΩ 3.50 4.00 – V
L-Output Voltage (OUT Pin) VOL Output Sink Current=20mA – 0.25 0.65 V
Output Source Current
(OUT Pin)
ISOURCE OUT Pin=0V 8 11 – mA
GENERAL CHARACTERISTICS
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Latch Mode
Threshold Voltage (CS Pin)
VTHLA 1.2 1.5 1.8 V
Quiescent Current ICCLA Latch Mode – 1.6 2.2 mA
Average Quiescent Current ICCAV RL= , duty·cycle=50% – 3.5 4.8 mA
NJM2381
-
5
-
■ TYPICAL APPLICATIONS
1
VREF
CURRENT
SENSE AMP
ER·AMP
L.O
500Ω
U.V.LO
OSC
PWM
9 8 7 6
5 4 3 2
10
0.52V
36kΩ
GND
2.50V
V+
VOUT
330kΩ 330kΩ 4.7µF
1000pF
(Package:SSOP10)
NJM2381
-
6
-
■TIPICAL CHARACTERISTICS
H Output Voltage vs. Source Current
(V+=6V,RT=33kΩ,CT=1000pF,
OUT Pin=0V,Ta=25°C)
0
1
2
3
4
5
6
7
8
024681012
Source Current ISOURCE (mA)
H Output Voltage VOH (V)
Oscillator Frequency vs. Timing Resistor
(V+=6V,Ta=25°C)
1
10
100
1000
1 10 100 1000 10000
Timing Resistor RT (kΩ)
Oscilltor Frequency fOSC
(kHz)
CT=470pF
CT=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 VREF (V)
Operating Current vs. Operating Voltage
(Ta=25°C)
0
1
2
3
4
5
6
0 10203040
Operating Voltage V+ (V)
Operating Voltage ICC (mA)
ICCAV
ICCLA
L Output Voltage vs. Sink Current
(V+=6V,RT=33kΩ,CT=1000pF,Ta=25°C)
0
0.2
0.4
0.6
0.8
1
0 102030405060
Sink Current ISINK (mA)
L Output Voltage VOL (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 fOSC (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 VTHCS (V)
Duty Cycle α (%)
NJM2381
-
8
-
■TIPICAL CHARACTERISTICS
Oscillator Frequency vs. Temperature
(V+=6V,RT=33kΩ,CT=1000pF)
60
80
100
120
140
160
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Oscillator Frequency
fOSC (kHz)
Reference Voltage vs. Temperature
(V+=6V,IOR=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
VREF (V)
H Output Voltage vs. Temperature
(V+=6V,RL=10kΩ,RT=33kΩ,CT=1000pF)
0
2
4
6
8
10
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
H Output Voltage VOH (V)
L Output Voltage vs. Trmperature
(V+=6V,ISINK=20mA,RT=33kΩ,CT=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 VOL (V)
Operating Current vs. Temperature
(V+=6V,RT=33kΩ,CT=1000pF)
0
1
2
3
4
5
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Operating Current ICC (mA)
ICCAV
ICCLA
[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.
