NJW4140
MOSFET Drive Switching Regulator IC for Boost / Fly-back Converter
■ PACKAGE OUTLINE
GENERAL DESCRIPTION
The NJW4140 is a MOSFET Drive switching regulator IC for
Boost / Fly-back Converter that operates wide input range from
3V to 40V. It can provide large current application because of
built-in highly effective Nch MOSFET drive circuit.
Built-in pulse-by-pulse current detecting type over current
protection limits the output current at over load.
It is suitable for boost/fly-back application such as Car
Accessory, Office Automation Equipment, Industrial Instrument
and so on.
FEATURES
Nch MOSFET Driving
Wide Operating Voltage Range
PWM Control
Wide Oscillating Frequency
Over Current Protection
UVLO (Under Voltage Lockout)
Standby Function
Package Outline
NJW4140R
NJW4140M
Driving Voltage 5.3V (typ.)
3V to 40V
40kHz to 1MHz
NJW4140R : MSOP8(VSP8)*
NJW4140M : DMP8
*MEET JEDEC MO-187-DA
Ver.2020-03-11
-1-
NJW4140
PIN CONFIGURATION
1
8
2
7
3
6
4
5
PIN FUNCTION
1. V+
2. EN
3. IN4. FB
5. CT
6. GND
7. SI
8. OUT
NJW4140R
NJW4140M
BLOCK DIAGRAM
V
Enable
Control
EN
High: ON
Low : OFF
(Standby)
ON/OFF
5V
Reg.
500k
Soft
Start
Vref
Low Frequency
Control
Driver
0.8V
Pulse by
Pulse
IN-
PWM
Comparator
FB
OUT
OSC
Error AMP
-2-
+
CT
SI
VIPK
GND
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NJW4140
ABSOLUTE MAXIMUM RATINGS
PARAMETER
SYMBOL
Supply Voltage
V+
OUT pin Voltage
VOUT
SI pin Voltage
VSI
EN pin Voltage
VEN
IN- pin Voltage
VINCT pin Voltage
VCT
IO_PEAK+
OUT pin Peak Current
IO_PEAKPower Dissipation
PD
(Ta=25°C)
UNIT
V
V
V
V
V
V
MAXIMUM RATINGS
+45
-0.3 to +6 (*1)
-0.3 to +6
+45
+6
+6 (*1)
200 (Source)
700 (Sink)
mA
MSOP8(VSP8)
595 (*2)
DMP8
530 (*2)
+150
-40 to +150
mW
C
C
(*1): When Supply voltage is less than +6V, the absolute maximum EN pin voltage is equal to the Supply voltage.
(*2): Mounted on glass epoxy board. (76.2×114.3×1.6mm:based on EIA/JDEC standard, 2Layers)
Junction Temperature
Storage Temperature
Tjmax
Tstg
RECOMMENDED OPERATING CONDITIONS
PARAMETER
SYMBOL
MIN.
Supply Voltage
V+
3
Timing Capacitor
CT
120
Oscillating Frequency
fOSC
40
Operating Temperature
Topr
-40
Ver.2020-03-11
TYP.
–
–
–
–
MAX.
40
3,900
1,000
+85
UNIT
V
pF
kHz
C
-3-
NJW4140
ELECTRICAL CHARACTERISTICS
(Unless otherwise noted, V+=VEN=12V, CT=470pF, Ta=25C)
PARAMETER
SYMBOL
TEST CONDITION
MIN.
TYP.
MAX.
UNIT
Oscillator Block
Oscillation Frequency 1
fOSC1
CT=470pF
270
300
330
kHz
Oscillation Frequency 2
Charge Current
fOSC2
Ichg
CT=680pF
180
150
210
200
240
250
kHz
A
Discharge Current
Idis
150
200
250
A
Voltage amplitude
VOSC
–
0.7
–
V
Oscillation Frequency
deviation (Supply voltage)
Oscillation Frequency
deviation (Temperature)
Oscillation Frequency
(Low Frequency Control)
fDV
V+=3 to 40V
–
1
–
%
fDT
Ta= -40 to +85C
–
6
–
%
VIN-=0.3V, VFB=0.7V,
CT=470pF
90
105
120
kHz
VB=0.75V
2
4
8
ms
-1.0%
-0.1
–
–
0.8
–
80
3
+1.0%
0.1
–
–
V
A
dB
MHz
fOSC_LOW
Soft Start Block
Soft Start Time
TSS
Error Amplifier Block
Reference Voltage
Input Bias Current
Open Loop Gain
Gain Bandwidth
VB
IB
AV
GB
Output Source Current
IOM+
VFB=1V, VIN-=0.7V
50
100
150
A
Output Sink Current
IOM-
VFB=1V, VIN-=0.9V
2
4
6
mA
0.32
0.63
85
0.4
0.7
90
0.54
0.77
95
V
V
%
115
140
165
mV
ΔVSI=300mV
–
90
–
ns
ROH
IO= -50mA
–
3
4.5
ROL
IO= +50mA
–
2.5
3.5
OUT pin= 4.5V
45
5
65
5.3
85
5.55
mA
V
PWM Comparate Block
Input Threshold Voltage
(FB pin)
Maximum Duty Cycle
Current Limit Detection Block
Current Limit Detection
Voltage
Delay Time
VT_0
VT_50
MAXDUTY
Duty=0%, VIN-=0.6V
Duty=50%, VIN-=0.6V
VFB=1.2V
VIPK
TDELAY
Output Block
Output High Level
ON Resistance
Output Low Level
ON Resistance
Output Source Current
Output pin Limiting Voltage
-4-
IOH
VOLIM
Ver.2020-03-11
NJW4140
ELECTRICAL CHARACTERISTICS
(Unless otherwise noted, V+=VEN=12V, CT=470pF, Ta=25C)
PARAMETER
SYMBOL
Under Voltage Lockout Block
ON Threshold Voltage
OFF Threshold Voltage
VT_ON
VT_OFF
VON
VOFF
RPD
Enable Control Block
ON Control Voltage
OFF Control Voltage
Pull-down Resistance
General Characteristics
Quiescent Current
Standby Current
Ver.2020-03-11
IDD
IDD_STB
TEST CONDITION
MIN.
TYP.
MAX.
UNIT
V+= L → H
V+= H → L
2.65
2.4
2.8
2.55
2.95
2.7
V
V
VEN= L → H
VEN= H → L
1.7
0
–
–
–
500
V+
0.9
–
V
V
k
–
–
1.4
2.5
1.7
6
mA
A
RL=no load, VIN-= VFB= 0.7V
VEN=0V
-5-
NJW4140
APPLICATION EXAMPLE
Non-isolated Boost Converter
CNF
RNF
EN
High: ON
Low: OFF(Standby)
V IN
CIN1
CIN2
L
SBD
4
3
2
1
FB
IN-
EN
V+
COUT
CFB
R2
Pow er
MOSFET
NJW4140
CT
GND
SI
OUT
5
6
7
8
V OUT
RFB
RSENSE
R1
CT
Filter
Non-isolated Fly-back Converter
CNF
RNF
EN
High: ON
Low: OFF(Standby)
SBD
T
COUT
V OUT
V IN
CIN1
CFB
CIN2
R2
RFB
4
3
2
1
FB
IN-
EN
V+
R1
Pow er
MOSFET
NJW4140
CT
GND
SI
OUT
5
6
7
8
RSENSE
CT
Filter
-6-
Ver.2020-03-11
NJW4140
TYPICAL CHARACTERISTICS
Oscillation frequency vs. Timing Capacitor
+
(V =12V, Ta=25°C)
100
Maximum Duty Cycle MAXDUTY (%)
Oscillation frequency fOSC (kHz)
1000
100
10
100
Maximum Duty Cycle vs. Oscillator Frequency
+
(V =12V, VFB=1.2V, Ta=25°C)
90
80
70
60
50
40
30
20
10
0
1000
Timing Capacitor CT (pF)
10
10000
Oscillation Frequency vs. Supply Voltage
(CT=470pF, Ta=25°C)
1000
Reference Voltage vs. Supply Voltage
(Ta=25°C)
0.810
320
315
Reference Voltage VB (V)
310
305
300
295
290
0.805
0.800
0.795
285
280
0.790
0
10
20
30
Supply Voltage V+ (V)
40
0
40
Error Amplifier Block
Voltage Gain, Phase vs. Frequency
+
(V =12V, Gain=40dB, Ta=25°C)
Quiescent Current vs. Supply Voltage
(RL=no load, VIN-=VFB=0.7V, Ta=25°C)
2
60
1.8
180
Phase
1.6
Voltage Gain Av (dB)
Quiescent Current IDD (mA)
10
20
30
Supply Voltage V+ (V)
1.4
1.2
1
0.8
0.6
0.4
45
135
Gain
30
90
15
45
0.2
0
0
Ver.2020-03-11
10
20
30
Supply Voltage V+ (V)
40
0
100
1k
10k
100k
Frequency f (kHz)
1M
0
10M
-7-
Phase Φ (deg)
Oscillation Frequnecny fOSC (kHz)
100
Oscillator Frequency fOSC (kHz)
NJW4140
TYPICAL CHARACTERISTICS
Oscillation Frequency vs Temperature
+
(V =12V, CT=470pF)
320
0.810
Reference Voltage VB (V)
Oscillator Frequency fOSC (kHz)
330
Reference Voltage vs. Temperature
+
(V =12V)
310
300
290
280
270
-50
0.805
0.800
0.795
0.790
-25
0
25
50
75 100 125 150
Ambient Temperature Ta (°C)
-50
Current Limit Detection Votage vs.Temperature
+
(V =12V)
OUT pin Limiting Voltage vs.Temperature
+
(V =12V)
170
Current Limit Detection Voltage
VIPK (mV)
OUT pin Limiting Voltage VOLIM (V)
12
160
150
140
130
120
10
110
6
4
2
-25
0
25
50
75 100 125 150
Ambient Temperature Ta (°C)
-50
Output High Level ON Resistance vs.Temperature
(IO=-50mA)
7
6
5
+
V =3V
4
3
+
V =12V
V+=40V
2
1
0
-25
0
25
50
75 100 125 150
Ambient Temperature Ta (°C)
Output Low Level ON Resistance vs.Temperature
(IO=+50mA)
5
Output Low Level ON Resistance
ROL ()
Output High Level ON Resistance
ROH ()
8
0
-50
4
+
V =3V
3
2
V+=12V
+
V =40V
1
0
-50
-8-
-25
0
25
50
75 100 125 150
Ambient Temperature Ta (°C)
-25
0
25
50
75 100 125 150
Ambient Temperature Ta (°C)
-50
-25
0
25
50
75 100 125 150
Ambient Temperature Ta (°C)
Ver.2020-03-11
NJW4140
TYPICAL CHARACTERISTICS
Enable Control ON/OFF Voltage vs.Temperature
+
(V =12V)
2
Under Voltage Lockout Voltage vs. Temperature
3.00
Threshold Voltage (V)
VT_ON
2.80
2.70
2.60
VT_OFF
2.50
ON/OFF Voltage VON/OFF (V)
1.8
2.90
VON
1.6
1.4
1.2
VOFF
1
0.8
0.6
0.4
0.2
2.40
0
-50
-25
0
25
50
75 100 125 150
Ambient Temperature Ta (°C)
-50
Quiescent Current vs. Temperature
(RL=no load, VIN-=VFB=0.7V)
Standby Current vs. Temperature
(VEN=0V)
2
+
V =40V
1.6
1.4
V+=12V
1.2
1
+
V =3V
0.8
0.6
0.4
Standby Current IDD_STB (μA)
6
1.8
Quiescent Current IDD (mA)
-25
0
25
50
75 100 125 150
Ambient Temperature Ta (°C)
5
4
3
+
V =40V
2
V+=3V
1
V+=12V
0.2
0
0
-50
Ver.2020-03-11
-25
0
25
50
75 100 125 150
Ambient Temperature Ta (°C)
-50
-25
0
25
50
75 100 125 150
Ambient Temperature Ta (°C)
-9-
NJW4140
NJW4140Application Manual
Technical Information
PIN DESCRIPTIONS
PIN
PIN NAME
NUMBER
1
V+
- 10 -
2
EN
3
IN-
4
FB
5
CT
6
GND
7
SI
8
OUT
FUNCTION
Power Supply pin
Enable Control pin
The ON/OFF pin internally pulls down with 500k. Normal Operation at the time
of High Level. Standby Mode at the time of Low Level or OPEN.
Output Voltage Detecting pin
Connects output voltage through the resistor divider tap to this pin in order to
voltage of the IN- pin become 0.8V.
Feedback Setting pin
The feedback resistor and capacitor are connected between the FB pin and the
IN- pin.
Oscillating Frequency Setting pin by Timing Capacitor
Oscillating Frequency should set between 40kHz and 1MHz.
GND pin
Current Sensing pin
When difference voltage between the SI pin and the GND pin exceeds
140mV(typ.), over current protection operates.
Output pin for Power MOSFET Driving
The OUT pin Voltage is clamped with 5.3V(typ.) at the time of High level, in order
to protect a gate of Nch MOSFET.
Ver.2020-03-11
NJW4140 ApplicationNJW4140
Manual
Technical Information
Description of Block Features
Error Amplifier Section (ERAMP)
0.8V±1% precise reference voltage is connected to the non-inverted input of this section.
To set the output voltage, connects converter's output to inverted input of this section (IN- pin). If requires output
voltage over 0.8V, inserts resistor divider.
This AMP section has high gain and external feedback pin (FB pin). It is easy to insert a feedback resistor and a
capacitor between the FB pin and the IN- pin, making possible to set optimum loop compensation for each type of
application.
Oscillation frequency vs. Timing Capacitor
+
(V =12V, Ta=25°C)
1000
Oscillation frequency fOSC (kHz)
Oscillation Circuit Section (OSC)
Oscillation frequency can be set by inserting capacitor
between the CT pin and GND. Referring to the sample
characteristics in "Timing Capacitor and Oscillation
Frequency", set oscillation frequency between 40kHz and
1MHz.
The triangular wave of the oscillating circuit is generated
in the IC, having amplitude between 0.4V and 1.0V at
CT=470pF(ref.).
If voltage of the IN- pin becomes less than 0.4V, the
oscillation frequency decreases to one third (33%) and the
energy consumption is suppressed.
100
10
100
1000
Timing Capacitor CT (pF)
10000
PWM Comparator Section (PWM)
This section controls the switching duty ratio.
PWM comparator receives the signal of the error amplifier and the triangular wave, and controls the duty ratio
between 0% and 90%. The timing chart is shown in Fig.1.
Max Duty setting
FB pin Voltage
OSC
Waveform
(IC internal)
Maximum duty: 90%
V+
High
OUT pin
Low
Fig. 1. Timing Chart PWM Comparator and OUT pin
Ver.2020-03-11
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NJW4140
NJW4140Application Manual
Technical Information
Description of Block Features (Continued)
Driver Section (Driver)
The output driver circuit is configured a totem pole type, it can efficiently drive a Nch MOSFET switching device.
When the output is high level, the OUT pin voltage is clamped with 5.3V (typ.) by the internal regulator to protect gate
of Nch MOSFET. (Ref. Fig.2. OUT pin)
V+
V+
5.3V
5V
Regulator
GND
OUT
From PWM
Comparator
To turn on Nch MOSFET
High Level Output
OFF
Driver
ON
OFF
ON
To turn off Nch MOSFET
Low Level Output
V GS
Fig. 2. Driver Circuit and the OUT pin Voltage
When supply voltage is decreasing, gate drive voltage output from the OUT pin is also decreasing. Although the
OUT pin voltage is kept gate drive voltage by bypassing the internal regulator around supply voltage 5V. Fig.3.
shows the example of the OUT pin voltage vs. supply voltage characteristic
The optimum drive ability of MOSFET depends on the oscillation frequency and the gate capacitance of MOSFET.
OUT pin Voltage vs. Supply Voltage
(IO_SINK=0mA, Ta=25°C)
OUT pin Voltage VOUT (V)
6
5
4
3
2
1
0
3
4
5
6
7
Supply Voltage V+ (V)
8
Fig. 3. OUT pin Voltage vs. Supply Voltage Characteristic
- 12 -
Ver.2020-03-11
NJW4140 ApplicationNJW4140
Manual
Technical Information
Description of Block Features (Continued)
Power Supply, GND pin (V+, GND)
In line with MOSFET drive, current flows into the IC according to frequency. If the power supply impedance
provided to the power supply circuit is high, it will not be possible to take advantage of IC performance due to input
voltage fluctuation. Therefore insert a bypass capacitor close to the V+ pin – the GND pin connection in order to
lower high frequency impedance.
Under Voltage Lockout Function (UVLO)
The UVLO circuit operating is released above V+=2.8V(typ.) and IC operation starts. When power supply voltage
is low, IC does not operate because the UVLO circuit operates. There is 250mV width hysteresis voltage at rise and
decay of power supply voltage. Hysteresis prevents the malfunction at the time of UVLO operating and releasing.
Enable Function (Enable Control)
The NJW4140 stops the operating and becomes standby status when the EN pin becomes less than 0.9V.
The EN pin internally pulls down with 500k, therefore the NJW4140 becomes standby mode when the EN pin is
OPEN. You should connect this pin to V+ when you do not use Enable function.
Soft Start Function (Soft Start)
The output voltage of the converter gradually rises to a set value by the soft start function. The soft start time is
4ms (typ). It is defined with the time of the error amplifier reference voltage becoming from 0V to 0.75V. The soft start
circuit operates after the release UVLO. The operating frequency is controlled with a low frequency, approximately
33% of the set value by the timing resistor, until voltage of the IN- pin becomes approximately 0.4V.
0.8V
Vref,
IN- pin Voltage
Max Duty setting
FB pin Voltage
OSC Waveform
V+
High
OUT pin
Low
UVLO(2.8V typ.) Release,
Standby
Low Frequency Control
VIN-=approx 0.4V
Soft Start time: Tss=4ms(typ.) to VB=0.75V
Steady
Operaton
Soft Start effective period to VB=0.8V
Fig. 4. Startup Timing Chart
Ver.2020-03-11
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NJW4140
NJW4140Application Manual
Technical Information
Description of Block Features (Continued)
Over Current Protection Circuit
At when the potential difference between the V+ pin and the SI pin becomes 140mV or more, the over current
protection circuit is stopped the switch output. The switching current is detected by inserted current sensing resistor
(RSENSE) between the SI pin and the GND pin. Fig.5. shows the timing chart of the over current protection detection.
The switching output holds low level until next pulse output at OCP operating. The NJW4140 output returns
automatically along with release from the over current condition because the OCP is pulse-by-pulse type.
If voltage of the IN- pin becomes less than 0.4V, the oscillation frequency decreases to one third (33%) and the
energy consumption is suppressed.
Max Duty setting
FB pin Voltage
OSC
Waveform
V+
High
OUT pin
Low
Sw itching
Current
ILIM
0
Static State
Static State
Detect
Overcurrent
Fig. 5. Timing Chart at Over Current Detection
The current waveform contains high frequency superimposed noises due to the parasitic elements of MOSFET,
the inductor and the others. Depending on the application, inserting RC low-pass filter between current sensing
resistor (RSENSE) and the SI pin to prevent the malfunction due to such noise. The time constant of RC low-pass filter
should be equivalent to the spike width (T R C) as a rough guide (Fig. 6).
OUT
Spike Noise
Current Limit Detection
SI
To Pulse
by Pulse
R
C
V IPK
T
Current Waveform example
RSENSE
Low Pass Filter
Fig. 6. Current Waveform and Filter Circuit
- 14 -
Ver.2020-03-11
NJW4140 ApplicationNJW4140
Manual
Technical Information
Application Information
Inductors
Current
Peak Current Ipk
Large currents flow into inductor, therefore you must
provide current capacity that does not saturate.
Inductor
(1) Continuous
Reducing L, the size of the inductor can be smaller. Current IL
Conduction Mode
However, peak current increases and adversely affecting
(2) Critical Mode
efficiency.
(3) Continuous
On the other hand, increasing L, peak current can be
0
Conduction Mode
reduced at switching time. Therefore conversion
Frequency
tON
tOFF
efficiency improves, and output ripple voltage reduces.
fOSC
Above a certain level, increasing inductance windings
increases loss (copper loss) due to the resistor element.
Fig. 7. Inductor Current State Transition
Ideally, the value of L is set so that inductance current is in
continuous conduction mode. However, as the load current decreases, the current waveform changes from (1)
CCM: Continuous Conduction Mode (2) Critical Mode (3) DCM: Discontinuous Conduction Mode (Fig. 7.).
In discontinuous mode, peak current increases with respect to output current, and conversion efficiency tend to
decrease. Depending on the situation, increase L to widen the load current area to maintain continuous mode.
Catch Diode
When the switch element is in OFF cycle, power stored in the inductor flows via the catch diode to the output
capacitor. Therefore during each cycle current flows to the diode in response to load current. Because diode's
forward saturation voltage and current accumulation cause power loss, a Schottky Barrier Diode (SBD), which has a
low forward saturation voltage, is ideal.
An SBD also has a short reverse recovery time. If the reverse recovery time is long, through current flows when
the switching transistor transitions from OFF cycle to ON cycle. This current may lower efficiency and affect such
factors as noise generation.
When the switch element is in ON cycle, a reverse voltage flows to SBD. Therefore you should select a SBD that
has reverse voltage rating greater than maximum output voltage. The power loss, which stored in output capacitor,
will be increase due to increasing reverse current through SBD at high temperature. Therefore, there is cases
preferring reverse current characteristics to forward current characteristic in order to improve efficiency.
Switching Element
You should use a switching element (Nch MOSFET) that is specified for use as a switch. And select sufficiently
low RON MOSFET at less than VGS=5V because the NJW4140 OUT pin voltage is clamped 5.3 (typ.).
However, when the supply voltage of the NJW4140 is low, the OUT pin voltage becomes low. You should select a
suitable MOSFET according to the supply voltage specification. (Ref. Driver section)
Large gate capacitance is a source of decreased efficiency. That is charge and discharge from gate capacitance
delays switching rise and fall time, generating switching loss.
The spike noise might occur at the time of charge/discharge of gate by the parasitic inductance element. You
should insert resistance between the OUT pin and the gate and limit the current for gate protection when gate
capacitance is small. However, it should be noted that the efficiency might decrease because the shape of waves
may become duller when resistance is too large. The last fine-tuning should be done on the actual device and
equipment.
Ver.2020-03-11
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NJW4140
NJW4140Application Manual
Technical Information
Application Information (Continued)
Input Capacitor
Transient current flows into the input section of a switching regulator responsive to frequency. If the power supply
impedance provided to the power supply circuit is large, it will not be possible to take advantage of NJW4140
performance due to input voltage fluctuation. Therefore insert an input capacitor as close to the MOSFET as
possible.
Output Capacitor
An output capacitor stores power from the inductor, and stabilizes voltage provided to the output.
When selecting an output capacitor, you must consider Equivalent Series Resistance (ESR) characteristics, ripple
current, and breakdown voltage.
Also, the ambient temperature affects capacitors, decreasing capacitance and increasing ESR (at low
temperature), and decreasing lifetime (at high temperature). Concerning capacitor rating, it is advisable to allow
sufficient margin.
Output capacitor ESR characteristics have a major influence on output ripple noise. A capacitor with low ESR can
further reduce ripple voltage. Be sure to note the following points; when ceramic capacitor is used, the capacitance
value decreases with DC voltage applied to the capacitor.
- 16 -
Ver.2020-03-11
NJW4140 ApplicationNJW4140
Manual
Technical Information
Application Information (Continued)
Board Layout
In the switching regulator application, because the current flow corresponds to the oscillation frequency, the
substrate (PCB) layout becomes an important.
You should attempt the transition voltage decrease by making a current loop area minimize as much as possible.
Therefore, you should make a current flowing line thick and short as much as possible. Fig.8. shows a current loop
at step-down converter.
L
V IN
SBD
L
COUT
CIN
V IN
SW
SBD
COUT
CIN
SW
NJW4140
NJW4140
(a) Boost Converter SW ON
(b) Boost Converter SW OFF
Fig. 8. Current Loop at Boost Converter
Concerning the GND line, it is preferred to separate the power system and the signal system, and use single
ground point.
The voltage sensing feedback line should be as far away as possible from the inductance. Because this line has
high impedance, it is laid out to avoid the influence noise caused by flux leaked from the inductance.
Fig. 9. shows example of wiring at boost converter. Fig. 10 shows the PCB layout example.
L
V IN
SBD
CIN
V OUT
COUT
RL
SW
OUT
(Bypass Capacitor)
V+
RFB
CFB
NJW4140
INCT
CT
Separate Digital(Signal)
GND from Pow er GND
R2
GND
R1
To avoid the influence of the voltage
drop, the output voltage should be
detected near the load.
Because IN- pin is high impedance, the
voltage detection resistance: R1/R2 is
put as much as possible near IC(IN-).
Fig. 9. Board Layout at Boost Converter
Ver.2020-03-11
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NJW4140
NJW4140Application Manual
Technical Information
Application Information (Continued)
VIN
VOUT
L
SBD
CIN1
COUT1
COUT2
FET
RSENSE
GND IN
GNDOUT
Power GND Area
CS1 RS1
RG
EN
CIN2
IC
Feed back signal
CT
REN
Signal GND Area
CNF RNF R1 R2 RFB CFB
Fig. 10 Layout Example (upper view)
- 18 -
Ver.2020-03-11
NJW4140 ApplicationNJW4140
Manual
Technical Information
Calculation of Package Power
You should consider derating power consumption under using high ambient temperature.
Moreover, you should consider the power consumption that occurs in order to drive the switching element.
Supply Voltage:
Quiescent Current:
Oscillation Frequency:
ON time:
Gate charge amount:
V+
IDD
fOSC
ton
Qg
The gate of MOSFET has the character of high impedance. The power consumption increases by quickening the
switching frequency due to charge and discharge the gate capacitance. Power consumption: PD is calculated as
follows.
PD = (V+ IDD) + (V+ Qg fOSC) [W]
You should consider temperature derating to the calculated power consumption: PD.
You should design power consumption in rated range referring to the power dissipation vs. ambient temperature
characteristics (Fig. 11).
NJW4140M (DMP8 Package)
Power Dissipation vs. Ambient Temperature
(Tj=~150°C)
1000
At on 4 layer PC Board
At on 2 layer PC Board
800
Power Dissipation P D (mW)
Power Dissipation P D (mW)
1000
NJW4140R (MSOP8(VSP8) Package)
Power Dissipation vs. Ambient Temperature
(Tj=~150°C)
600
400
200
0
At on 4 layer PC Board
At on 2 layer PC Board
800
600
Operating Temp.
Extend Spec.
400
General Spec.
200
0
-50
-25
0
25
50
75
100
Ambient Temperature Ta (°C)
125
150
-50
-25
0
25
50
75
100
Ambient Temperature Ta (°C)
125
Mounted on glass epoxy board. (76.2114.31.6mm:EIA/JDEC standard size, 2Layers)
Mounted on glass epoxy board. (76.2114.31.6mm:EIA/JDEC standard size, 4Layers),
internal Cu area: 74.274.2mm
Fig. 11. Power Dissipation vs. Ambient Temperature Characteristics
Ver.2020-03-11
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150
NJW4140
NJW4140Application Manual
Technical Information
Application Design Examples
Step-Up Application Circuit
IC
: NJW4140R
Input Voltage
: VIN=9V to 15V
Output Voltage
: VOUT=20V
Output Current
: IOUT=1.5A (@VIN=12V)
Oscillation frequency : fosc=300kHz
CNF
RNF
10,000pF 13k
EN
High: ON
Low: OFF(Standby)
VIN=12V
CIN1
220F/35V
CIN2
0.1F/50V
4
3
2
1
FB
IN-
EN
V+
NJW4140
L1
22H/4.7A
SBD
GND
SI
OUT
5
6
7
8
VOUT=20V
CFB
820pF
RG
0
Q1
CT
COUT1
COUT2
100F/35V, 0.1F/50V
x2pcs.
RFB
20k
RSENSE
39m
R2
82k
R1
3.3k
CT
470pF
CS1
390pF
Reference
Qty.
RS1
330
Part Number
IC
1
NJW4140R
Q1
L1
SBD
CIN1
CIN2
COUT1
COUT2
CT
CNF
CFB
CS1
R1
R2
RNF
RFB
RSENSE
RG
RS1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
TPCA8052-H
CDRH127LDNP-220
DE5SC4M
EEEFP1V221AP
0.1F
EEEFP1V101AP
0.1F
470pF
10,000pF
820pF
390pF
3.3k
82k
13k
20k
UR73D3ATTE39L0F
0 (Short)
330
- 20 -
Description
MOSFET Drive Switching Regulator IC
for Boost / Fly-back Converter IC
Nch MOSFET 40V, 20A
Inductor 22H, 4.7A
Schottky Diode 40V, 5A
Aluminum Electrolytic Capacitor 220F, 35V
Ceramic Capacitor 1608 0.1F, 50V, B
Aluminum Electrolytic Capacitor 100F, 35V
Ceramic Capacitor 1608 0.1F, 50V, B
Ceramic Capacitor 1608 470pF, 50V, CH
Ceramic Capacitor 1608 10,000pF, 50V, B
Ceramic Capacitor 1608 820pF, 50V, B
Ceramic Capacitor 1608 390pF, 50V, CH
Resistor 1608 3.3k, 1%, 0.1W
Resistor 1608 82k, 1%, 0.1W
Resistor 1608 13k, 1%, 0.1W
Resistor 1608 20k, 1%, 0.1W
Resistor 2512 39m, ±1%, 1W
Resistor 1608 0, 0.1W
Resistor 1608 330, 1%, 0.1W
Manufacturer
New JRC
Toshiba
Sumida
Shindengen
Panasonic
Std.
Panasonic
Std.
Std.
Std.
Std.
Std.
Std.
Std.
Std.
Std.
KOA
Std.
Std.
Ver.2020-03-11
NJW4140 ApplicationNJW4140
Manual
Technical Information
Application Design Examples (Continued)
Setting Oscillation Frequency
From the Oscillation frequency vs. Timing Capacitor Characteristic, reads CT=470 [pF], t=3.33[s] at fosc=300kHz.
Step-Up converter duty ratio is shown with the following equation.
V
Duty 1 IN
VOUT
12
100 1
100 40 %
20
Therefore, tON=1.33 [s], tOFF=2.0 [s]
Selecting Inductance
The inductor's average current equals input current (IIN). Estimated efficiency () is 93% and calculates input
current as follows.
IIN
VOUT IOUT
20 1.5
2.69 A
VIN
0.93 12
IL is Inductance ripple current. When IL is 27% of input current:
IL = 0.27 IIN = 0.27 2.69 = 0.73 [A]
This obtains inductance L.
L
12
VIN
1.33 22 [H]
t ON
0
.73
IL
Inductance L is a theoretical value. The optimum value
varies according such factors as application specifications
and components. Fine-tuning should be done on the actual
device.
Peak Current: Ipk
Inductance
Current: IL
Output Current: IOUT
0
This obtains the peak current Ipk at switching time.
Ipk IIN
IL
0.73
2.69
3.06[ A ]
2
2
tON
tOFF
Period: t
Frequency: fOSC=1/t
Fig. 12. Inductor Current Waveform
The current that flows into the inductance provides sufficient margin for peak current at switching time.
In the application circuit, use L=22H, 4.5A.
Setting Over Current Detection
In this application, current limitation value: ILIMIT is set to Ipk=3.5A.
ILIMIT = VIPK / RSC = 140mV / 39m =3.59 [A]
The limit value increases slightly according to response time from the overcurrent detection with the SI pin to the
OUT pin stop.
ILIMIT _ DELAY ILIMIT
Ver.2020-03-11
VIN
12
TDELAY 3.59
90n 3.64 [ A ]
L
22
- 21 -
NJW4140
NJW4140Application Manual
Technical Information
Application Design Examples (Continued)
Selecting the Input Capacitor
The input capacitor corresponds to the input of the power supply. It is required to adequately reduce the
impedance of the power supply. The input capacitor selection should be determined by the input ripple current and
the maximum input voltage of the capacitor rather than its capacitance value.
The effective input current can be expressed by the following formula.
IRMS _ CIN
I L
2 3
0.73
2 3
0.21 [ Arms]
When selecting the input capacitor, carry out an evaluation based on the application, and use a capacitor that has
adequate margin.
Selecting the Output Capacitor
The output capacitor is an important component that determines output ripple noise. Equivalent Series Resistance
(ESR), ripple current, and capacitor breakdown voltage are important in determining the output capacitor.
The output ripple noise can be expressed by the following formula.
I
0.73
Vripple ESR IL L 40m 2.69
122 [mV ]
2
2
When selecting output capacitance, select a capacitor that allows for sufficient ripple current.
The effective ripple current that flows in a capacitor (IRMS_COUT) is obtained by the following equation.
IRMS _ COUT I OUT
VOUT VIN
20 12
1 .5
1.22 [ Arms ]
VIN
12
Consider sufficient margin, and use a capacitor that fulfills the above spec.
In the application circuit, Aluminum Electrolytic Capacitor COUT=100F/35V are used by 2 parallel.
Setting Output Voltage
The output voltage VOUT is determined by the relative resistances of R1, R2. The current that flows in R1, R2 must
be a value that can ignore the bias current that flows in Error AMP.
R2
82k
VOUT
1 VB
1 0.8 20.7 [ V ]
R
1
3
.
3
k
It is easy to make a feedback loop, because the error amplifier output connects to FB pin. DC gain affects voltage
sensing of the error amplifier. If AC gain increases, it affects stability of regulator due to AC gain which contains
switching noise, ripple noise and the others.
Recommended way of feedback is high DC gain and low AC gain.
In this application, a feedback resistor RNF=13k and capacitor CNF=10,000pF are connected in serial.
However, if the AC gain is lowered too much, it happens slower transient response against fast load changes. The
optimum value varies according such factors as application specifications and components. Fine-tuning should be
done on the actual device.
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Ver.2020-03-11
NJW4140 ApplicationNJW4140
Manual
Technical Information
■ Application Characteristics
Efficiency vs. Output Current
(VOUT=20V, Ta=25ºC)
100
f=300kHz
L=22H
90
Efficiency η (%)
80
V+=9V, 12V, 15V
70
60
50
40
30
20
10
0
1
10
100
1000
Output Current IOUT (mA)
10000
Output Voltage vs Output Current
(Ta=25ºC)
Output Voltage VOUT (V)
21.0
f=300kHz
L=22H
20.9
V+=9V, 12V, 15V
20.8
20.7
20.6
20.5
20.4
1
Ver.2020-03-11
10
100
1000
Output Current IOUT (mA)
10000
- 23 -
NJW4140
MEMO
[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.
- 24 -
Ver.2020-03-11
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