NJW4132
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Switching Regulator IC for Boost Converter
Current Mode Control w/ 45V/1.75A MOSFET
GENERAL DESCRIPTION ■ PACKAGE OUTLINE
FEATURES
Current Mode Control
External Clock Synchronization
Wide Operating Voltage Range 4.5V to 40V
Switching Current 1.75A min.
PWM Control
Built-in Compensation Circuit
Correspond to Ceramic Capacitor (MLCC)
Oscillating Frequency 300kHz typ. (A ver.)
700kHz typ. (B ver.)
2.0MHz typ. (C ver.)
Soft Start Function 10ms typ.
UVLO (Under Voltage Lockout)
Over Current Protection (Hiccup type)
Thermal Shutdown Protection
Standby Function
Package Outline NJW4132U2 : SOT-89-5-2
PRODUCT CLASSIFICATION
Part Number Version Oscillation
Frequency Package
Operating
Temperature
Range
NJW4132U2-A A 300kHz typ. SOT-89-5-2 General Spec.
-40 C to +85 C
NJW4132U2-B B 700kHz typ. SOT-89-5-2 General Spec.
-40 C to +85 C
NJW4132U2-C C 2.0MHz typ. SOT-89-5-2 General Spec.
-40 C to +85 C
The NJW4132 is a boost converter with 45V/1.75A MOSFET. It
corresponds to high oscillating frequency, and Low ESR Output
Capacitor (MLCC) within wide input range from 4.5V to 40V.
Therefore, the NJW4132 can realize downsizing of applications
with a few external parts so that adopts current mode control.
Also, it has a soft start function, external clock synchronization,
over current protection and thermal shutdown circuit.
It is suitable for boost application to a Car Accessory, Office
Automation Equipment, Industrial Instrument and so on.
NJW4132U2
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PIN CONFIGURATION
BLOCK DIAGRAM
V+
IN-
ER AMP
Buffer
OCP
CURRENT
SENSE
TSD
VrefSoft Start
UVLO
SLOPE
COMP.
1V
S Q
R
OSC
Enable
(Standby)
GND
High: ON
Low : OFF(Standby)
EN/SYNC
SW
PWM
SYNC
Low Frequency
Control
100k
PIN FUNCTION
1. SW
2. GND
3. IN-
4. EN/SYNC
5. V+
NJW4132U2
1 2 3
4 5 (2)
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ABSOLUTE MAXIMUM RATINGS (Ta=25°C)
PARAMETER SYMBOL
MAXIMUM RATINGS UNIT
Supply Voltage V
+
+45 V
SW pin Voltage VSW +45 V
IN- pin Voltage VIN- -0.3 to +6 V
EN/SYNC pin Voltage VEN/SYNC +45 V
Power Dissipation PD SOT-89-5-2
625 (*1)
2,400 (*2)
mW
Junction Temperature Range Tj -40 to +150 C
Operating Temperature Range T
opr
-40 to +85 C
Storage Temperature Range T
stg
-40 to +150 C
(*1): Mounted on glass epoxy board. (76.2×114.3×1.6mm:based on EIA/JEDEC standard, 2Layers)
(*2): Mounted on glass epoxy board. (76.2×114.3×1.6mm:based on EIA/JEDEC standard, 4Layers)
(For 4Layers: Applying 74.2×74.2mm inner Cu area and a thermal via hole to a board based on JEDEC standard JESD51-5)
RECOMMENDED OPERATING CONDITIONS
PARAMETER SYMBOL MIN. TYP. MAX. UNIT
Supply Voltage V
+
4.5 – 40 V
External Clock Input Range
A version
B version
C version
fSYNC
290
690
1,800
–
–
–
500
1,000
2,400
kHz
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ELECTRICAL CHARACTERISTICS (Unless otherwise noted, V+=VEN./SYNC=12V, Ta=25 C)
PARAMETER SYMBOL
TEST CONDITION MIN. TYP. MAX.
UNIT
Under Voltage Lockout Block
ON Threshold Voltage VT_ON V
+
= L → H 4.2 4.35 4.5 V
OFF Threshold Voltage VT_OFF V
+
= H → L 4.1 4.25 4.4 V
Hysteresis Voltage VHYS 70 100 – mV
Soft Start Block
Soft Start Time TSS VB=0.95V 5 10 15 ms
Oscillator Block
Oscillation Frequency fOSC
A version, V
IN
-
=0.9V 270 300 330 kHz
B version, V
IN
-
=0.9V 630 700 770 kHz
C version, V
IN
-
=0.9V 1.82 2.0 2.2 MHz
Oscillation Frequency
OCP operates fOSC_LIM
A version, V
IN
-
=0.4V – 50 – kHz
B version, V
IN
-
=0.4V – 117 – kHz
C version, V
IN
-
=0.4V – 410 – kHz
Oscillation Frequency
deviation (Supply voltage) fDV V+=4.5V to 40V – 1 – %
Oscillation Frequency
deviation (Temperature) fDT Ta=-40 C to +85 C – 5 – %
Error Amplifier Block
Reference Voltage VB -1.0%
1.0 +1.0%
V
Input Bias Current I
B
-0.1 – 0.1 A
PWM Comparate Block
Maximum Duty Cycle MAXDUTY A version, B version, V
IN
-
=0.9V 85 90 – %
C version, V
IN
-
=0.9V 80 85 – %
Minimum ON Time1
(Use Built-in Oscillator) tON-min1
A version – 300 425 ns
B version – 110 155 ns
C version – 80 120 ns
Minimum ON Time2
(Use Ext CLK) tON-min2
A version, fSYNC=400kHz – 220 355 ns
B version, fSYNC=800kHz – 90 125 ns
C version, fSYNC=2.2MHz – 80 120 ns
OCP Block
COOL DOWN Time tCOOL – 42 – ms
Output Block
Output ON Resistance R
ON
I
SW
=1A – 0.4 0.65
Switching Current Limit I
LIM
1.75 2.1 2.25 A
SW Leak Current I
LEAK
V
EN/SYNC
=0V, V
SW
=45V – – 1 A
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ELECTRICAL CHARACTERISTICS (Unless otherwise noted, V+=VEN/SYNC=12V, Ta=25 C)
PARAMETER SYMBOL
TEST CONDITION MIN. TYP. MAX.
UNIT
Standby Control Block
ON Control Voltage VON VEN/SYNC= L → H 1.6 – V
+
V
OFF Control Voltage VOFF VEN/SYNC= H → L 0 – 0.5 V
Input Bias Current
(EN/SYNC pin) IEN
A version, B version,
V
EN/SYNC
=12V – 165 300 A
C version, VEN/SYNC=12V – 250 400 A
General Characteristics
Quiescent Current IDD
A version,
R
L
=no load, V
IN
-
=0.9V – 2.1 2.65 mA
B version,
R
L
=no load, V
IN
-
=0.9V – 2.5 3.0 mA
C version,
R
L
=no load, V
IN
-
=0.9V – 3.5 4.0 mA
Standby Current IDD_STB VEN/SYNC=0V – – 1 A
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TYPICAL APPLICATIONS
Boost Converter
GND IN-
V+
CFB
R2
COUT
L SBD
NJW4132
V
IN CIN
R1
V
OUT
RFB
SW
EN/
SYNC
EN/SYNC
High: ON
Low: OFF
(Standby)
Buck-Boost (SEPIC) Converter
GND IN-
V+
CFB
R2
COUT
L1 SBD
NJW4132
V
IN CIN
R1
V
OUT
RFB
SW
EN/
SYNC
EN/SYNC
High: ON
Low: OFF
(Standby)
C1
L2
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TYPICAL CHARACTERISTICS (A, B, C version)
Reference Voltage vs. Supply Voltage
(Ta=25°C)
0.99
0.995
1
1.005
1.01
0 10 20 30 40
Supply Voltage V+ (V)
Reference Voltage VB (V)
Switching Current Limit vs. Temperature
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Switching Current Limit ILIM (A)
V+=4.5V, 12V, 40V
Reference Voltage vs. Temperature
(V+=12V)
0.99
0.995
1
1.005
1.01
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Reference Voltage VB (V)
Output ON Resistance vs. Temperature
(ISW=1A)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Output ON Resistance RON (W)
V+=4.5V, 12V, 40V
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TYPICAL CHARACTERISTICS (A, B, C version)
Under Voltage Lockout Voltage vs. Temperature
4.1
4.15
4.2
4.25
4.3
4.35
4.4
4.45
4.5
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Threshold Voltage (V)
VT_ON
VT_OFF
Standby Current vs. Temperature
(VEN/SYNC=0V)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Standby Current IDD_STB (μA)
V+=40V
V+=12V
V+=4.5V
Switching Leak Current vs. Temperature
(V+=12V, VEN/SYNC=0V, VSW=45V)
0
0.5
1
1.5
2
2.5
3
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Switching Leak Current ILEAK (μA)
Soft Start Time vs. Temperature
(V+=12V, VB=0.95V)
5
6
7
8
9
10
11
12
13
14
15
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Soft Start Time Tss (ms)
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TYPICAL CHARACTERISTICS (A version)
Oscillation Frequency vs. Supply Voltage
(A ver., VIN-=0.9V, Ta=25°C)
280
285
290
295
300
305
310
315
320
0 10 20 30 40
Supply Voltage V+ (V)
Oscillation Frequnecny fOSC (kHz)
Quiescent Current vs. Supply Voltage
(A ver., RL=no load, VIN-=0.9V, Ta=25°C)
0
0.5
1
1.5
2
2.5
3
0 10 20 30 40
Supply Voltage V+ (V)
Quiescent Current IDD (mA)
Maximum Duty Cycle vs. Temperature
(A ver., V+=12V, VIN-=0.9V)
84
86
88
90
92
94
96
98
100
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Maximum Duty Cycle MAXDUTY (%)
Minimum ON Time1 vs. Temperature
(A ver., V+=12V)
150
200
250
300
350
400
450
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Minimum ON Time1 tON-min1 (ns)
Oscillation Frequency vs Temperature
(A ver., V+=12V, VIN-=0.9V)
270
280
290
300
310
320
330
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Oscillation Frequency fosc (kHz)
Quiescent Current vs. Temperature
(A ver., RL=no load, VIN-=0.9V)
0
0.5
1
1.5
2
2.5
3
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Quiescent Current IDD (mA)
V+=12V, 40V
V+=4.5V
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TYPICAL CHARACTERISTICS (B version)
Oscillation Frequency vs Temperature
(B ver., V+=12V, VIN-=0.9V)
620
640
660
680
700
720
740
760
780
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Oscillation Frequency fosc (kHz)
Quiescent Current vs. Supply Voltage
(B ver., RL=no load, VIN-=0.9V, Ta=25°C)
0
0.5
1
1.5
2
2.5
3
0 10 20 30 40
Supply Voltage V+ (V)
Quiescent Current IDD (mA)
Oscillation Frequency vs. Supply Voltage
(B ver., VIN-=0.9V, Ta=25°C)
680
685
690
695
700
705
710
715
720
0 10 20 30 40
Supply Voltage V+ (V)
Oscillation Frequnecny fOSC (kHz)
Maximum Duty Cycle vs. Temperature
(B ver., V+=12V, VIN-=0.9V)
84
86
88
90
92
94
96
98
100
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Maximum Duty Cycle MAXDUTY (%)
Minimum ON Time1 vs. Temperature
(B ver., V+=12V)
60
80
100
120
140
160
180
-50 -25 0 25 50 75 100 125 150
Ambient Temperature Ta (°C)
Minimum ON Time1 tON-min1 (ns)
0
0.5
1
1.5
2
2.5
3
-50 -25 0 25 50 75 100 125 150
Quiescent Current IDD (mA)
Ambient Temperature Ta (°C)
Quiescent Current vs. Temperature
(B ver., RL=no load, VIN-=0.9V)
V+=4.5V, 12V, 40V
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TYPICAL CHARACTERISTICS (C version)
0
20
40
60
80
100
120
-50 -25 0 25 50 75 100 125 150
Minimum ON Time1 tON-min1 (ns)
Ambient Temperature Ta (ºC)
Minimum ON Time1 vs. Temperature
(C ver., V+=12V)
1.9
1.92
1.94
1.96
1.98
2
2.02
2.04
2.06
2.08
2.1
0 10 20 30 40
Oscillation Frequency fOSC (MHz)
Supply Voltage V+(V)
Oscillation Frequency vs. Supply Voltage
(C ver., VIN-=0.9V, Ta=25ºC)
80
82
84
86
88
90
92
94
96
98
100
-50 -25 0 25 50 75 100 125 150
Maximum Duty Cycle MAXDUTY (%)
Ambient Temperature Ta (ºC)
Maximum Duty Cycle vs. Temperature
(C ver., V+=12V, VIN-=0.9V)
0
0.5
1
1.5
2
2.5
3
3.5
4
0 10 20 30 40
Quiescent Current IDD (mA)
Supply Voltage V+(V)
Quiescent Current vs. Supply Voltage
(C ver., RL=no load, VIN-=0.9V, Ta=25ºC)
0
0.5
1
1.5
2
2.5
3
3.5
4
-50 -25 0 25 50 75 100 125 150
Quiescent Current IDD (mA)
Ambient Temperature Ta (ºC)
Quiescent Current vs. Temperature
(C ver., RL=no load, VIN-=0.9V)
V+=4.5V, 12V, 40V
1.7
1.8
1.9
2
2.1
2.2
-50 -25 0 25 50 75 100 125 150
Oscillation Frequency fOSC (MHz)
Ambient Temperature Ta (ºC)
Oscillation Frequency vs. Temperature
(C ver., V+=12V, VIN-=0.9V)
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PIN DESCRIPTIONS
PIN NAME PIN
NUMBER FUNCTION
SW 1 Switch Output pin of Power MOSFET
GND 2 GND pin
IN- 3
Output Voltage Detecting pin
Connects output voltage through the resistor divider tap to this pin in order to voltage
of the IN- pin become 1.0V.
EN/SYNC 4
Standby Control pin
The EN/SYNC pin internally pulls down with 100k . Normal Operation at the time of
High Level. Standby Mode at the time of Low Level or OPEN.
Moreover, it operates by inputting clock signal at the oscillatory frequency that
synchronized with the input signal.
V
+
5 Power Supply pin for Power Line
Technical Information
NJW4132 Application Manual
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Description of Block Features
1. Basic Functions / Features
Error Amplifier Section (ER AMP)
1.0V±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, inserts resistor divider.
Because the optimized compensation circuit is built-in, the application circuit can be composed of minimum
external parts.
PWM Comparator Section (PWM), Oscillation Circuit Section (OSC)
The NJW4132 uses a constant frequency, current mode step up architecture. The oscillation frequency are
300kHz (typ.) at A version, 700kHz (typ.) at B version and 2.0MHz (typ.) at C version. The PWM signal is output by
feedback of output voltage and slope compensation switching current at the PWM comparator block.
The maximum duty ratio is 90% (typ.) in A version and B version.
Minimum ON time is limited in the inside of the IC. (Table 1.)
Table 1. Minimum ON time of NJW4132
A version
(f
OSC
=300kHz)
B version
(f
OSC
=700kHz)
C version
(f
OSC
=2.0MHz)
Use Built-in
Oscillator 300ns typ. 110ns typ. 80ns typ.
Use External
Clock
220ns typ.
(@ f
SYNC
=400kHz)
90ns typ.
(@ f
SYNC
=800kHz)
80ns typ.
(@ f
SYNC
=2.2MHz)
The boost converter of ON time is decided the following formula.
s
fV
V
ton
OSCOUT
IN 1
1
VIN shows input voltage and VOUT shows output voltage.
When the ON time becomes below in tON-min, in order to maintain output voltage at a stable state, change of duty or
pulse skip operation may be performed.
Power MOSFET (SW Output Section)
The power is stored in the inductor by the switch operation of built-in power MOSFET. The output current is limited
to 1.75A(min.) the overcurrent protection function.
Power Supply, GND pin (V+ and GND)
In line with switching element 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 connect the input capacitor near V+ pin – the GND pin. When an IC and
an input capacitor are far, insert bypass capacitor generally 0.1 F, and lower the high frequency impedance.
Technical Information
NJW4132 Application Manual
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Description of Block Features (Continued)
2. Additional and Protection Functions / Features
Under Voltage Lockout (UVLO)
The UVLO circuit operating is released above V+=4.35V(typ.) and IC operation starts. When power supply voltage
is low, IC does not operate because the UVLO circuit operates. There is 100mV(typ.) width hysteresis voltage at rise
and decay of power supply voltage. Hysteresis prevents the malfunction at the time of UVLO operating and
releasing.
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
10ms (typ.). It is defined with the time of the error amplifier reference voltage becoming from 0V to 0.95V. The soft
start circuit operates after the release UVLO and/or recovery from thermal shutdown.
SW pin
1.0V
ON
OFF
Vref,
IN- pin Voltage
OSC Waveform
Steady
Operaton
UVLO(4.35V typ.) Release,
Standby,
Recover from Thermal
Shutdow n
Soft Start effective period to VB=1.0V
Soft Start time: Tss=10ms(typ.) to VB=0.95V
Fig. 1. Startup Timing Chart
Technical Information
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Description of Block Features (Continued)
Over Current Protection Circuit (OCP)
NJW4132 contains overcurrent protection circuit of hiccup architecture. The overcurrent protection circuit of hiccup
architecture is able to decrease heat generation at the overload.
The NJW4132 output returns automatically along with release from the over current condition.
At when the switching current becomes ILIM or more, the overcurrent protection circuit is stopped the MOSFET
output. The switching output holds low level down to next pulse output at OCP operating.
When IN- pin voltage becomes 0.75V or less, it oscillation frequency decreases to approximately 17%
At the same time starts pulse counting, and stops the switching operation when the overcurrent detection
continues approx 7ms (@ A ver.), 5ms (@ B ver.) and 2ms (@C ver.).
After NJW4132 switching operation was stopped, it restarts by soft start function after the cool down time of approx
42ms (typ.).
SW pin
ON
OFF
Switching
Current
ILIM
0
1.0V
0.75V
0V
IN- pin
Voltage
OCP Operates Oscillation Frequency
A ver.=50kHz typ.
B ver.=117kHz typ.
C ver.=410kHz typ.
Cool Down time :42ms typ.
Oscillation Frequency
A ver.=300kHz typ.
B ver.=700kHz typ.
C ver.=2.0MHz typ.
Static Status Detect
Overcurrent
Soft Start
Pulse by
Pulse
Pulse Count
A ver.=about 7ms
B ver.=about 5ms
C ver.=about 2ms
Fig. 2. Timing Chart at Over Current Detection
Thermal Shutdown Function (TSD)
When Junction temperature of the NJW4132 exceeds the 160°C*, internal thermal shutdown circuit function stops
SW function. When junction temperature decreases to 145°C* or less, SW operation returns with soft start operation.
The purpose of this function is to prevent malfunctioning of IC at the high junction temperature. Therefore it is not
something that urges positive use. You should make sure to operate within the junction temperature range rated
(150 C). (* Design value)
Standby Function
The NJW4132 stops the operating and becomes standby status when the EN/SYNC pin becomes less than 0.5V.
The EN/SYNC pin internally pulls down with 100k , therefore the NJW4132 becomes standby mode when the
EN/SYNC pin is OPEN. You should connect this pin to V+ when you do not use standby function.
Technical Information
NJW4132 Application Manual
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Description of Block Features (Continued)
External Clock Synchronization
By inputting a square wave to EN/SYNC pin, can be synchronized to an external frequency.
You should fulfill the following specification about a square wave. (Table 2.)
Table 2. The input square wave to an EN/SYNC pin.
A version
(f
OSC
=300kHz)
B version
(f
OSC
=700kHz)
C version
(f
OSC
=2.0MHz)
Input Frequency
290kHz to
500kHz
690kHz to
1,000kHz
1.8MHz to
2.4MHz
Duty Cycle 20% to 80% 35% to 65% 40% to 60%
Voltage
magnitude
1.6V or more at High level
0.5V or less at Low level
The trigger of the switching operating at the external synchronized mode is detected to the rising edge of the input
signal. At the time of switching operation from standby or asynchronous to synchronous operation, it has set a delay
time approx 20 s to 30 s (@ A ver.) , 10 s to 20 s (@ B ver.) and 3 s to 8 s (@ C ver.) in order to prevent
malfunctions. (Fig. 3.)
Standby Delay Time
SW pin
ON
OFF
External Clock Synchronization
EN/SYNC pin
High
Low
Fig. 3. Switching Operation by External Synchronized Clock
Technical Information
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Application Information
Inductors
Because a large current flows to the inductor, you should select the inductor with the large current capacity not to
saturate. Optimized inductor value is determined by the input voltage and output voltage.
The Optimized inductor value: (It is a reference value.)
VIN=5V VOUT=12V : L < = 10 H
You should set the inductor as a guide from above mentioned value to half value.
Reducing L decreases the size of the inductor. However a peak current increases and adversely affects the
efficiency. (Fig. 4.)
Moreover, you should be aware that the output current is limited because it becomes easy to operating to the
overcurrent limit.
The peak current is decided the following formula.
A
V
IV
I
IN
OUTOUT
IN
]A[
fVL
VVV
I
OSCOUT
ININOUT
L
]A[
I
IIpk L
IN
2
Input Current
IIN
Inductor
Ripple Current DIL
0
Current
tON tOFF
Peak Current IPK
Inductor
Ripple Current DIL
Peak Current IPK
tON tOFF
Reducing L Value Increasing L value
Fig. 4. Inductor Current State Transition (Continuous Conduction Mode)
Technical Information
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Application Information (Continued)
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.
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 the NJW4132
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.
Because NJW4132 corresponds to the output capacitor of low ESR, the ceramic capacitor is the optimal for
compensation.
The Optimized capacitor value: (It is a reference value.)
VOUT =12V : COUT > = 22 F
In addition, you should consider varied characteristics of capacitor (a frequency characteristic, a temperature
characteristic, a DC bias characteristic and so on) and unevenness peculiar to a capacitor supplier enough.
Therefore when selecting a capacitors, you should confirm the characteristics with supplier datasheets.
When selecting an output capacitor, you must consider Equivalent Series Resistance (ESR) characteristics, ripple
current, and breakdown voltage.
The output ripple noise can be expressed by the following formula.
]V[IESRV L)pp(ripple
The effective ripple current that flows in a capacitor (Irms) is obtained by the following equation.
]Arms[III OUTPKrms
22
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Application Information (Continued)
Setting Output Voltage, Compensation Capacitor
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 ER AMP.
]V[V
R
R
VBOUT 1
1
2
The zero points are formed with R2 and CFB, and it makes for the phase compensation of NJW4132.
The zero point is shown the following formula.
]Hz[
CR
f
FB
Z22
1
1
You should set the zero point as a guide from 20kHz to 60kHz. Please optimize CFB by application.
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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.5. shows a current loop
at Boost converter.
COUT
L SBD
CIN
V
IN COUT
L SBD
CIN
V
IN NJW4132
Built-in SW
NJW4132
Built-in SW
(a) Boost Converter SW ON (b) Boost Converter SW OFF
Fig. 5. 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. 6. shows example of wiring at boost converter. Fig. 7. shows the PCB layout example.
SW
IN-
V+
CFB
R2
COUT
L SBD
NJW4132
CIN
R1
V
OUT
RFB
V
IN
RL
GND
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-).
Separate Digital(Signal)
GND from Pow er GND
The capacitor is
connected near an IC.
Fig. 6. Board Layout at Boost Converter
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Application Information (Continued)
CIN
CFB
RFB
R1
VOUT
Feed back
signal
GNDOUT GND IN
VIN
Signal
GND
Area
EN/SYNC
L
COUT
R2
SBD
Power GND Area
1pin
Connect Signal GND line and Power GND line on backside pattern
Fig. 7. Layout Example (upper view)
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Calculation of Package Power
A lot of the power consumption of boost converter occurs from the internal switching element (Power MOSFET).
Power consumption of NJW4132 is roughly estimated as follows.
Input Power: PIN = VIN IIN [W]
Output Power: POUT = VOUT IOUT [W]
Diode Loss: PDIODE = VF IL(avg) OFF duty [W]
NJW4132 Power Consumption: PLOSS = PIN POUT PDIODE [W]
Where:
V
IN
: Input Voltage for Converter I
IN
: Input Current for Converter
V
OUT
: Output Voltage of Converter I
OUT
: Output Current of Converter
V
F
: Diode's Forward Saturation Voltage I
L(avg)
: Inductor Average Current
OFF duty
: Switch OFF Duty Cycle
Efficiency ( ) is calculated as follows.
= (POUT PIN) 100 [%]
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. 8).
0
500
1000
1500
2000
2500
3000
-50 -25 0 25 50 75 100 125 150
Power Dissipation PD(mW)
Ambient Temperature Ta (°C)
NJW4132U2 (SOT-89-5-2 Package)
Power Dissipation vs. Ambient Temperature
(Tj=~150°C)
At on 4 layer PC Board (*4)
At on 2 layer PC Board (*3)
(*3): Mounted on glass epoxy board. (76.2×114.3×1.6mm:based on EIA/JEDEC standard, 2Layers)
(*4): Mounted on glass epoxy board. (76.2×114.3×1.6mm:based on EIA/JEDEC standard, 4Layers)
(For 4Layers: Applying 74.2×74.2mm inner Cu area and a thermal via hole to a board based on JEDEC standard JESD51-5)
Fig. 8. Power Dissipation vs. Ambient Temperature Characteristics
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Application Design Examples
Boost Converter Application Circuit
IC
Input Voltage
: NJW4132U2-B
: V
IN
=5V
Output Voltage : V
OUT
=12V
Output Current : I
OUT
=400mA
Oscillation frequency : fosc=700kHz
GND IN-
V+
SBD
NJW4132
SW
EN/
SYNC
EN/SYNC
High: ON
Low: OFF
(Standby)
CFB
15pF R2
220k
COUT
22 F/16V
L
10 H/3.4A
V
IN=5V
R1
20k
V
OUT =12V
RFB
0
CIN
10 F/50V
Reference Qty. Part Number Description Manufacturer
IC 1 NJW4132U2-B Internal 45V MOSFET SW.REG. IC New JRC
L 1 CDRH8D28HPNP-100N Inductor 10 H, 3.4A Sumida
SBD 1 CMS16 Schottky Diode 40V, 3A Toshiba
C
IN
1 10 F Ceramic Capacitor 3225 10 F, 50V, X5R Murata
C
OUT
1 22 F Ceramic Capacitor 3225 22 F, 16V, B Murata
C
FB
1 15pF Ceramic Capacitor 1608 15pF, 50V, CH Std.
R
FB
1 0 (Short) Optional
R1 1 20k Resistor 1608 20k , 1%, 0.1W Std.
R2 1 220k Resistor 1608 220k , 1%, 0.1W Std.
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Application Characteristics
Technical Information
Efficiency vs. Output Current
(VIN=5V, VOUT=12V)
0
10
20
30
40
50
60
70
80
90
100
1 10 100 1000
Output Current IOUT (mA)
Efficiency (%)
f=700kHz
L=10 H
Output Voltage vs. Output Current
(VIN=5V)
11.0
11.2
11.4
11.6
11.8
12.0
12.2
12.4
12.6
12.8
13.0
1 10 100 1000
Output Current IOUT (mA)
Output Voltage VOUT (V)
f=700kHz
L=10 H
[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.
NJW4132 Application Manual
