NJM2379
PWM SWITCHING REGULATOR CONTROL IC FOR SLAVE TYPE
■
GENERAL DESCRIPTION
The
NJM2379
is a high speed switching regulator control
IC, and directly drive an external power MOS-FET to use
internal totempole output circuit.
The
NJM2379
operates slave mode which synchronous
external oscillation frequency, and the slave mode reduce
the total noise.
The
NJM2379
is suitable for flyback type switching
regulation up to 10W and several output power supply for
LCD panel.
■
PACKAGE OUTLINE
NJM2379D
( DIP8 )
NJM2379M
( DMP8 )
■
FEATURES
●
Operating Voltage
(3.6 to 32V)
●
Reference Voltage
(2.5V±2%)
●
Input Outside
Oscillator Frequency
(5 to 350 kHz)
●
Output Switch Current
(±8mA min.)
●
Under Voltage Lockouts Circuit
●
Bipolar Technology
●
Package Outline
DIP8, DMP8, SOP8 JEDEC 150mil
SSOP8
■
BLOCK DIAGRAM
REF
8
CT
7
30uA
CS
6
V
+
NJM2379E
( SOP8 )
NJM2379V
( SSOP8 )
5
V
REF
L.O
U.V.LO
S.C.P
0.52V
ER⋅AMP
PWM
PIN FUNCTION
1. IN
-
2. F.B
3. GND
4. OUT
5. V
+
6. CS
7. CT
8. REF
1
IN
-
2
F.B
3
GND
4
OUT
Ver.2011-12-08
-1-
NJM2379
■
ABSOLUTE MAXIMUM RATINGS
PARAMETER
Supply Voltage
Reference Output Current
CT Pin Voltage
Power Dissipation
SYMBOL
V
+
I
OR
V
CT
P
D
RATINGS
36
10
1.5
(DIP8)
(DMP8)
(SOP8)
(SSOP8)
Operating Temperature Range
Storage Temperature Range
T
OPR
T
STG
700
300
300
250
°C
°C
(T
a
=25°C)
UNIT
V
mA
V
mW
-40 to +85
-50 to +125
■
RECOMMENDED OPERATING CONDITIONS
PARAMETER
Operating Voltage
Feed Back Resistor
Oscillate
SYMBOL
V
+
R
NF
f
OSC
MIN.
3.6
100
5
(V
+
=6V, T
a
=25°C)
MAX.
32
-
350
UNIT
V
kΩ
kHz
INPUT WAVEFORM
PARAMETER
Triangle Waveform
Offset Voltage
SYMBOL
V
P-P
V
OFFSET
RECOMMENDED
0.5
0.5
UNIT
V
V
-2-
Ver.2011-12-08
NJM2379
■
ELECTRICAL CHARACTERISTICS
(V
+
=6V, R
T
=33kΩ, C
T
=1000pF, T
a
=25°C OSC:Triangle Waveform, V
P-P
=0.5V, Offset=0.5V, f
OSC
=100kHz)
REFERENCE VOLTAGE BLOCK
PARAMETER
Output Voltage
Line Regulation
Load Regulation
SYMBOL
V
REF
L
INE
L
OAD
TEST CONDITION
I
OR
=1mA
V
+
=3.6 to 32V, I
OR
=1mA
I
OR
=0.1 to 5.0mA
MIN.
2.45
-
-
TYP.
2.50
6.8
5
MAX.
2.55
20.7
30
UNIT
v
mV
mV
OSCILLATOR BLOCK
PARAMETER
Reference Voltage
Input Bias Current
Open Loop Gain
Gain Band width Product
Maximum Output Voltage
(F.B Pin)
Output Source Current
SYMBOL
V
B
I
B
A
V
G
B
V
OM+
V
OM-
I
OM+
R
NF
=100kΩ
R
NF
=100kΩ
V
OM
=1V
TEST CONDITION
MIN.
0.51
-
-
-
V
REF
-0.2
-
40
TYP.
0.52
5
90
0.6
-
-
85
MAX.
0.53
100
-
-
-
200
200
UNIT
V
nA
dB
MHz
V
mV
µA
PWM COMPARATOR BLOCK
PARAMETER
Triangle Waveform Input
Minimum Voltage (CT Pin)
Triangle Waveform Input
Maximum Voltage (CT Pin)
Input Threshold Voltage (F.B Pin)
Input Threshold Voltage (F.B Pin)
Maximum Duty Cycle
SYMBOL
OSC
LO
OSC
HI
V
TH0
V
TH50
αM
TEST CONDITION
CT Pin Triangle Waveform Input
CT Pin Triangular Wave Input
duty⋅cycle=0%
duty⋅cycle=50%
F.B Pin=1.2V
MIN.
0
0.7
-
-
55
TYP.
-
-
0.55
0.87
64
MAX.
0.4
1.3
0.65
-
85
UNIT
V
V
V
V
%
SOFT START CIRCUIT BLOCK
PARAMETER
Input Bias Current (CS Pin)
Input Threshold Voltage (CS Pin)
Input Threshold Voltage (CS Pin)
SYMBOL
I
BCS
V
THCS0
V
THCS50
duty⋅cycle=0%
duty⋅cycle=50%
TEST CONDITION
MIN.
-
-
-
TYP.
250
0.25
0.52
MAX.
650
0.35
-
UNIT
nA
V
V
Ver.2011-12-08
-3-
NJM2379
■
ELECTRICAL CHARACTERISTICS
(V
+
=6V, R
T
=33kΩ, C
T
=1000pF, T
a
=25°C OSC:Triangle Waveform, V
P-P
=0.5V, Offset=0.5V, f
OSC
=100kHz)
SHORT CIRCUIT PROTECTION
PARAMETER
Input Threshold Voltage (F.B Pin)
Charge Current (CS Pin)
Latch mode
Threshold Voltage (CS Pin)
SYMBOL
V
THPC
I
CHG
V
THLA
CS Pin=0V,F.B Pin=2V
TEST CONDITION
MIN.
1.20
10
1.20
TYP.
1.50
30
1.50
MAX.
1.80
50
1.80
UNIT
V
µA
V
UNDER VOLTAGE LOCKOUT
PARAMETER
ON Threshold Voltage
OFF Threshold Voltage
Hysteresis Voltage
SYMBOL
V
THON
V
THOFF
V
HYS
TEST CONDITION
MIN.
-
-
60
TYP.
2.70
2.52
180
MAX.
-
-
-
UNIT
V
V
mV
OUTPUT
PARAMETER
H-Output Voltage (OUT Pin)
L-Output Voltage (OUT Pin)
Output Source Current (OUT Pin)
SYMBOL
V
OH
V
OL
I
SOURCE
TEST CONDITION
R
L
=10kΩ
Output Sink Current=20mA
OUT Pin=0V
MIN.
3.50
-
-
TYP.
4.00
0.25
35
MAX.
-
0.65
-
UNIT
V
V
mA
GENERAL CHARACTERISTICS
PARAMETER
Quiescent Current
Average Quiescent Current
SYMBOL
I
CCLA
I
CCAV
TEST CONDITION
Latch Mode
R
L
=∞, duty⋅cycle=50%
MIN.
-
-
TYP.
1.6
5.2
MAX.
2.2
10.0
UNIT
mA
mA
-4-
Ver.2011-12-08
NJM2379
■
TYPICAL APPLICATIONS
Synchronous mode with
NJM2369
8
7
6
5
8
7
6
5
V
OUT
1
V
OUT
2
1
2
3
4
1
2
3
4
NJM2369
NJM2379
External pulse mode
V
+
Rsf
Duty 50%
Rsr
Cs
Input Pulse
0.5V
0.5V
GND
8
7
30uA
6
5
D1
V
OUT
V
REF
L.O
U.V.LO
C
IN
0.52V
ER⋅AMP
PWM
S.C.P
N1
N2
R1
L
C
OUT
1
2
3
4
C
LP
Q1
Rf
GND
*100kΩ
R2
GND
When Short Circuit Protection (SCP) is activated, Output terminal (Pin 4) becomes high impedance and the external
switching transistor (Q1) is turned off.
However, small leak current from Output terminal at high ambient temperature may turn on the external switching transistor
causing malfunction of the SCP particularly when FET is used as a switching device.
To avoid this issue, insert a 100kΩ resistor between the Gate and the Source of the external transistor.
Ver.2011-12-08
-5-
