NJRC NJW4154

NJW4154
Switching Regulator IC for Buck Converter
Current Mode Control w/ 40V/3A MOSFET
GENERAL DESCRIPTION
■ PACKAGE OUTLINE
The NJW4154 is a buck converter with 40V/3A MOSFET. It
corresponds to high oscillating frequency, and Low ESR Output
Capacitor (MLCC) within wide input range from 4.5V to 40V.
Therefore, the NJW4154 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 supplying power to a Car Accessory, Office
Automation Equipment, Industrial Instrument and so on.
NJW4154GM1
NJW4154DL3
FEATURES
Current Mode Control
External Clock Synchronization
Wide Operating Voltage Range
4.5V to 40V
Switching Current
4.5A min.
PWM Control
Built-in Compensation Circuit
Correspond to Ceramic Capacitor (MLCC)
Oscillating Frequency
300kHz typ. (A ver.)
Soft Start Function
4ms typ.
UVLO (Under Voltage Lockout)
Over Current Protection (Hiccup type)
Thermal Shutdown Protection
Power Good Function (NJW4154GM1 only)
Standby Function
Package Outline
NJW4154GM1 : HSOP8
NJW4154DL3 : TO-252-5
PRODUCT CLASSIFICATION
Version
Oscillation
Frequency
Power Good
Package
NJW4154GM1-A
A
300kHz typ.
√
HSOP8
NJW4154DL3-A
A
300kHz typ.
Part Number
Ver.2013-03-29
TO-252-5
Operating
Temperature
Range
General Spec.
-40°C to +85°C
General Spec.
-40°C to +85°C
-1-
NJW4154
PIN CONFIGURATION
3
1
8
2
7
3
6
4
5
PIN FUNCTION
1. SW
2. SW
3. GND
4. PG
5. IN6. EN/SYNC
7. V+
8. V+
Exposed PAD on
backside connect to GND
PIN FUNCTION
1. V+
2. SW
3. GND
4. IN5. EN/SYNC
1 2 3 4 5
NJW4154DL3-A
NJW4154GM1-A
BLOCK DIAGRAM
V+
SLOPE
COMP.
CURRENT
SENSE
UVLO
OCP
EN/SYNC
High: ON
Low : OFF(Standby)
Enable
(Standby)
100kΩ
SYNC
S Q
OSC
Buffer
R
Low Frequency
Control
PWM
SW
TSD
INER⋅AMP
Soft Start
Vref
0.8V
PG
GND
Pow er Good
Control Logic
NJW4154GM1 only
-2-
Ver.2013-03-29
NJW4154
ABSOLUTE MAXIMUM RATINGS
PARAMETER
SYMBOL
Supply Voltage
V+
+
V - SW pin Voltage
VV-SW
EN/SYNC pin Voltage
VEN/SYNC
IN- pin Voltage
VINPower Good pin Voltage (*1)
VPG
Power Dissipation
PD
Junction Temperature Range
Operating Temperature Range
Storage Temperature Range
Tj
Topr
Tstg
MAXIMUM RATINGS
+45
+45
+45
-0.3 to +6
-0.3 to +6
790
HSOP8
2,500
1,190
TO-252-5
3,125
-40 to +150
-40 to +85
-40 to +150
(Ta=25°C)
UNIT
V
V
V
V
V
(*2)
(*3)
(*4)
(*3)
mW
°C
°C
°C
(*1): Apply only the NJW4154GM1.
(*2): Mounted on glass epoxy board. (76.2×114.3×1.6mm:based on EIA/JDEC standard, 2Layers)
(*3): Mounted on glass epoxy board. (76.2×114.3×1.6mm:based on EIA/JDEC standard, 4Layers)
(For 4Layers: Applying 74.2×74.2mm inner Cu area and a thermal via hall to a board based on JEDEC standard JESD51-5)
(*4): Mounted on glass epoxy board. (76.2×114.3×1.6mm:based on EIA/JDEC standard size, 2Layers, Cu area 100mm2)
RECOMMENDED OPERATING CONDITIONS
PARAMETER
SYMBOL
Supply Voltage
V+
Power Good pin Voltage (*5)
VPG
External Clock Input Range
fSYNC
(*5): Apply only the NJW4154GM1.
Ver.2013-03-29
MIN.
4.5
0
290
TYP.
–
–
–
MAX.
40
5.5
500
UNIT
V
V
kHz
-3-
NJW4154
(Unless otherwise noted, V+=VEN./SYNC=12V, Ta=25°C)
ELECTRICAL CHARACTERISTICS
PARAMETER
SYMBOL
Under Voltage Lockout Block
ON Threshold Voltage
OFF Threshold Voltage
Hysteresis Voltage
VT_ON
VT_OFF
VHYS
Soft Start Block
Soft Start Time
Oscillator Block
Oscillation Frequency
Oscillation Frequency
OCP operates
Oscillation Frequency
deviation (Supply voltage)
Oscillation Frequency
deviation (Temperature)
Error Amplifier Block
Reference Voltage
Input Bias Current
PWM Comparate Block
Maximum Duty Cycle
Minimum ON Time1
(Use Built-in Oscillator)
Minimum ON Time2
(Use Ext CLK)
MIN.
TYP.
MAX.
UNIT
V+= L → H
V+= H → L
4.2
4.1
70
4.4
4.3
90
4.5
4.4
–
V
V
mV
TSS
VB=0.75V
2
4
8
ms
fOSC
A version, VIN-=0.7V
270
300
330
kHz
fOSC_LIM
A version, VIN-=0.4V
–
100
–
kHz
fDV
V+=4.5V to 40V
–
1
–
%
fDT
Ta=-40°C to +85°C
–
5
–
%
-1.0%
-0.1
0.8
–
+1.0%
+0.1
V
µA
88
93
–
%
–
250
340
ns
–
170
250
ns
–
25
–
ms
–
4.5
–
0.15
6
–
0.3
7.5
4
Ω
A
µA
VB
IB
MAXDUTY
VIN-=0.7V
tON-min1
tON-min2
OCP Block
COOL DOWN Time
tCOOL
Output Block
Output ON Resistance
Switching Current Limit
SW Leak Current
RON
ILIM
ILEAK
-4-
TEST CONDITION
fSYNC=400kHz
ISW=3A
VEN/SYNC=0V, V+=45V, VSW=0V
Ver.2013-03-29
NJW4154
(Unless otherwise noted, V+=VEN/SYNC=12V, Ta=25°C)
ELECTRICAL CHARACTERISTICS
PARAMETER
Standby Control / Sync Block
EN/SYNC pin
High Threshold Voltage
EN/SYNC pin
Low Threshold Voltage
Input Bias Current
(EN/SYNC pin)
Power Good Block (*6)
High Level Detection Voltage
High Level Detection Voltage
Hysterisis Region
Power Good ON Resistance
Leak Current at OFF State
SYMBOL
VTHH_EN/SYNC
VEN/SYNC= L → H
VTHL_EN/SYNC VEN/SYNC= H → L
IEN
VTHH_PG
VTHL_PG
VHYS_PG
RON_PG
ILEAK_PG
General Characteristics
Quiescent Current
IDD
Standby Current
IDD_STB
(*6): Apply only the NJW4154GM1.
Ver.2013-03-29
TEST CONDITION
VEN/SYNC=12V
Measured at IN- pin
Measured at IN- pin
IPG=10mA
VPG=6V
RL=no load, VIN-=0.7V
VEN/SYNC=0V
MIN.
TYP.
MAX.
UNIT
1.6
–
V+
V
0
–
0.5
V
–
170
250
µA
105
85
–
–
–
110
90
2
37
–
115
95
–
50
0.1
%
%
%
Ω
µA
–
–
3.5
–
4.2
3
mA
µA
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NJW4154
TYPICAL APPLICATIONS
V IN
CIN2
CIN1
L
EN/SYNC
EN/SYNC
High: ON
Low: OFF
(Standby)
Pow er Good
(NJW4154GM1 only)
V
+
V OUT
SW
CFB
NJW4154
PG
IN-
R2
RFB
GND
SBD
COUT
R1
-6-
Ver.2013-03-29
NJW4154
TYPICAL CHARACTERISTICS
Oscillation Frequency vs. Supply Voltage
(A ver., VIN-=0.7V, Ta=25°C)
0.81
308
306
Reference Voltage VB (V)
Oscillation Frequnecny fOSC (kHz)
310
Reference Voltage vs. Supply Voltage
(Ta=25°C)
304
302
300
298
296
294
0.805
0.8
0.795
292
290
0.79
0
40
0
10
20
30
+
Supply Voltage V (V)
40
Quiescent Current vs. Supply Voltage
(RL=no load, VIN-=0.7V, Ta=25°C)
6
Quiescent Current IDD (mA)
10
20
30
+
Supply Voltage V (V)
5
4
3
2
1
0
0
Ver.2013-03-29
10
20
30
+
Supply Voltage V (V)
40
-7-
NJW4154
TYPICAL CHARACTERISTICS
Oscillation Frequency vs Temperature
+
(A ver., V =12V, VIN-=0.7V)
Reference Voltage VB (V)
320
310
300
290
280
270
0.805
0.800
0.795
0.790
-50
-25
0
25 50 75 100 125 150
Ambient Temperature Ta (°C)
-50
Switching Current Limit vs. Temperature
8
Switching Current Limit ILIM (A)
0.810
+
V =40V
+
V =12V
+
V =5V
7
6
5
4
0.25
+
V =40V
0.2
V =12V
0.1
+
V =5V
0.05
0
-50
-50
-25
0
25 50 75 100 125 150
Ambient Temperature Ta (°C)
Under Voltage Lockout Voltage vs. Temperature
4.5
VT_ON
4.35
4.3
4.25
4.2
VT_OFF
4.15
4.1
Soft Start Time Tss (ms)
4.4
-25
0
25 50 75 100 125 150
Ambient Temperature Ta (°C)
Soft Start Time vs. Temperature
+
(V =12V, VB=0.75V)
8
4.45
Threshold Voltage (V)
+
0.15
3
7
6
5
4
3
2
-50
-8-
-25
0
25 50 75 100 125 150
Ambient Temperature Ta (°C)
Output ON Resistance vs. Temperature
(ISW=3A)
0.3
Output ON Resistance RON (Ω)
Oscillation Frequency fosc (kHz)
330
Reference Voltage vs. Temperature
+
(V =12V)
-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.2013-03-29
NJW4154
TYPICAL CHARACTERISTICS
Minimum ON Time1 vs. Temperature
+
(V =12V)
100
Maximum Duty Cycle MAXDUTY (%)
Minimum ON Time1 tON-min1 (ns)
340
320
300
280
260
240
220
200
180
-50
98
97
96
95
94
93
92
91
90
89
-25
0
25 50 75 100 125 150
Ambient Temperature Ta (°C)
-50
Quiescent Current vs. Temperature
(RL=no load, VIN-=0.7V)
5
-25
0
25 50 75 100 125 150
Ambient Temperature Ta (°C)
Standby Current vs. Temperature
(VEN/SYNC=0V)
10
9
4
+
V =40V
3.5
3
+
V =12V
2.5
2
+
V =4.5V
1.5
1
0.5
0
Standby Current IDD_STB (µA)
4.5
Quiescent Current IDD (mA)
99
88
160
8
7
6
+
V =40V
5
4
3
+
V =12V
+
V =4.5V
2
1
0
-50
-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)
Switching Leak Current vs. Temperature
+
(V =45V , VEN/SYNC=0V , VSW=0V)
10
Switching Leak Current ILEAK (µA)
Maximum Duty Cycle vs. Temperature
+
(V =12V, VIN-=0.7V)
9
8
7
6
5
4
3
2
1
0
-50
Ver.2013-03-29
-25
0
25 50 75 100 125 150
Ambient Temperature Ta (°C)
-9-
NJW4154
NJW4154Application Manual
Technical Information
PIN DESCRIPTIONS
PIN NAME
SW
GND
PIN NUMBER
TO-252-5
HSOP8
1
2
2
3
3
FUNCTION
Switch Output pin of Power MOSFET
GND pin
Power Good pin. An open drain output that goes high impedance
when the IN- pin voltage is stable around ±10%.
(Only HSOP8 PKG)
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.
Standby Control pin
The EN/SYNC pin internally pulls down with 100kΩ. 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.
PG
4
–
IN-
5
4
EN/SYNC
6
5
V+
7
8
1
Power Supply pin for Power Line
Exposed
PAD
–
–
Connect to GND (Only HSOP8 PKG)
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Ver.2013-03-29
NJW4154 ApplicationNJW4154
Manual
Technical Information
Description of Block Features
1. Basic Functions / Features
Error Amplifier Section (ER⋅AMP)
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.
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 NJW4154 uses a constant frequency, current mode step down architecture. The oscillation frequency is
300kHz (typ.) at A 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 93% (typ.).
The minimum ON time is limited to 250nsec (typ.) at using internal oscillator or 170nsec (typ.) at external
synchronization.
The buck converter of ON time is decided the following formula.
ton =
VOUT
[s]
VIN × fOSC
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 4.5A(min.) the overcurrent protection function. In case of step-down converter, the forward direction bias voltage is
generated with inductance current that flows into the external regenerative diode when MOSFET is turned off.
The SW pin allows voltage between the PV+ pin and the SW pin up to +45V. However, you should use an
Schottky diode that has low saturation voltage.
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 insert a bypass capacitor close to the V+ pin – the GND pin connection in
order to lower high frequency impedance.
Ver.2013-03-29
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NJW4154
NJW4154Application Manual
Technical Information
Description of Block Features (Continued)
2. Additional and Protection Functions / Features
Under Voltage Lockout (UVLO)
The UVLO circuit operating is released above V+=4.4V(typ.) and IC operation starts. When power supply voltage
is low, IC does not operate because the UVLO circuit operates. There is 90mV(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
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 and/or recovery from thermal shutdown.
0.8V
Vref,
IN- pin Voltage
OSC Waveform
ON
SW pin
OFF
UVLO(4.4V typ.) Release,
Standby,
Recover from Thermal
Shutdow n
Soft Start time: Tss=4ms(typ.) to V B=0.75V
Steady
Operaton
Soft Start effective period to V B=0.8V
Fig. 1. Startup Timing Chart
- 12 -
Ver.2013-03-29
NJW4154 ApplicationNJW4154
Manual
Technical Information
Description of Block Features (Continued)
Over Current Protection Circuit (OCP)
NJW4154 contains overcurrent protection circuit of hiccup architecture. The overcurrent protection circuit of hiccup
architecture is able to decrease heat generation at the overload.
The NJW4154 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 0.5V or less, it operates with 100kHz (typ.).
At the same time starts pulse counting, and stops the switching operation when the overcurrent detection
continues approx 1ms.
After NJW4154 switching operation was stopped, it restarts by soft start function after the cool down time of approx
25ms (typ.).
IN- pin
Voltage
0.8V
0.5V
0V
Oscillation Frequency
fosc=300kHz typ.
OCP Operates
Oscillation Frequency
f OSC_LIM=100kHz typ.
ON
SW pin
OFF
Sw itching
Current
ILIM
0
Pulse by
Pulse
Static Status
Pulse Count :about 1ms
Cool Dow n time :25ms typ.
Detect
Overcurrent
Soft Start
Fig. 2. Timing Chart at Over Current Detection
Thermal Shutdown Function (TSD)
When Junction temperature of the NJW4154 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 NJW4154 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 100kΩ, therefore the NJW4154 becomes standby mode when the
EN/SYNC pin is OPEN. You should connect this pin to V+ when you do not use standby function.
Ver.2013-03-29
- 13 -
NJW4154
NJW4154Application Manual
Technical Information
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.
Input Frequency
: 290kHz to 500kHz
Duty Cycle
: 20% to 80%
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 20µs to 30µs in order to prevent malfunctions. (Fig. 3.)
High
EN/SYNC pin
Low
ON
SW pin
OFF
Standby
Delay Time
External Clock Synchronization
Fig. 3. Switching Operation by External Synchronized Clock
Power Good Function (NJW4154GM1 only)
It monitors the output status and outputs a signal from PG pin that internally connected to open drain MOSFET.
The Power Good pin goes high impedance when the IN- pin voltage is stable around ±10%(typ.) of error amplifier
reference voltage.
A low on the pin indicates that the IN- pin voltage is out of the setting voltage.
To prevent malfunction of the Power Good output, it has hysterisis 2%(typ.) and the delay time approx 20µs to
30µs against the IN- pin voltage changes.
- 14 -
Ver.2013-03-29
NJW4154 ApplicationNJW4154
Manual
Technical Information
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.)
ViIN=12V → VOUT=3.3V
: L <= 3.5µH
ViIN=12V → VOUT=5.0V
: L <= 4.7µH
ViIN=24V → VOUT=5.0V
: L <= 3.5µH
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.
∆IL =
(VIN − VOUT ) × VOUT
L × VIN × fOSC
Ipk = IOUT +
[A]
∆ IL
[A]
2
Current
Peak Current IPK
Indunctor
Ripple Current ∆IL
Peak Current IPK
Output Current
IOUT
Indunctor
Ripple Current ∆IL
0
tON
tOFF
Reducing L Value
tON
tOFF
Increasing L value
Fig. 4. Inductor Current State Transition (Continuous Conduction Mode)
Ver.2013-03-29
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NJW4154
NJW4154Application Manual
Technical Information
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.
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 NJW4154
performance due to input voltage fluctuation. Therefore insert an input capacitor as close to the MOSFET as
possible. A ceramic capacitor is the optimal for input capacitor.
The effective input current can be expressed by the following formula.
IRMS = IOUT ×
VOUT × (VIN − VOUT )
VIN
[A]
In the above formula, the maximum current is obtained when VIN = 2 × VOUT, and the result in this case is
IRMS = IOUT (MAX) ÷ 2.
When selecting the input capacitor, carry out an evaluation based on the application, and use a capacitor that has
adequate margin.
Output Capacitor
An output capacitor stores power from the inductor, and stabilizes voltage provided to the output.
Because NJW4154 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 =3.3V
: COUT >= 100µF
VOUT =5.0V
: COUT >= 47µF
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.
Vripple( p −p ) = ESR × ∆IL [ V ]
The effective ripple current that flows in a capacitor (Irms) is obtained by the following equation.
Irms =
- 16 -
∆I L
[ Arms ]
2 3
Ver.2013-03-29
NJW4154 ApplicationNJW4154
Manual
Technical Information
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.
⎛ R2
⎞
VOUT = ⎜
+ 1⎟ × VB [ V ]
R
1
⎝
⎠
The zero points are formed with R2 and CFB, and it makes for the phase compensation of NJW4154.
The zero point is shown the following formula.
f Z1 =
1
[Hz]
2 × π × R2 × C FB
You should set the zero point as a guide from 50kHz to 70kHz.
Ver.2013-03-29
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NJW4154
NJW4154Application 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.5. shows a current loop
at step-down converter. Especially, should lay out high priority the loop of CIN-SW-SBD that occurs rapid current
change in the switching. It is effective in reducing noise spikes caused by parasitic inductance.
NJW4154
Built-in SW
V IN
CIN
NJW4154
Built-in SW
L
SBD
COUT
V IN
CIN
(a) Buck Converter SW ON
L
SBD
COUT
(b) Buck Converter SW OFF
Fig. 5. Current Loop at Buck 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 buck converter. Fig. 7 shows the PCB layout example.
L
V
V IN
V OUT
SW
+
CIN
SBD
COUT
RL
(Bypass Capacitor)
NJW4154
CFB
INR2
GND
Separate Digital(Signal)
GND from Pow er 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. 6. Board Layout at Buck Converter
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Ver.2013-03-29
NJW4154 ApplicationNJW4154
Manual
Technical Information
Application Information (Continued)
VOUT
GNDOUT
GNDOUT
VOUT
COUT
Feed back
signal
COUT
Power GND Area
Power GND Area
L
Signal GND Area
GND IN
L
GND IN
CFB
RFB
SBD
R2
R1
SBD
CIN1
CIN
C IN2
VIN
EN/SYNC
VIN
1pin
Power Good
EN/SYNC
R1
R2
Signal GND Area
RFB
CFB
Feed back
signal
HSOP8 Package
TO-252-5 Package
Connect Signal GND line and Power GND line on backside pattern
Fig. 7. Layout Example (upper view)
Ver.2013-03-29
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NJW4154
NJW4154Application Manual
Technical Information
Calculation of Package Power
A lot of the power consumption of buck converter occurs from the internal switching element (Power MOSFET).
Power consumption of NJW4154 is roughly estimated as follows.
Input Power:
Output Power:
Diode Loss:
NJW4154 Power Consumption:
Where:
VIN
VOUT
VF
OFF duty
PIN = VIN × IIN [W]
POUT = VOUT × IOUT [W]
PDIODE = VF × IL(avg) × OFF duty [W]
PLOSS = PIN − POUT − PDIODE [W]
: Input Voltage for Converter
: Output Voltage of Converter
: Diode's Forward Saturation Voltage
: Switch OFF Duty
IIN
IOUT
IL(avg)
: Input Current for Converter
: Output Current of Converter
: Inductor Average Current
Efficiency (η) is calculated as follows.
η = (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).
NJW4154GM1 (HSOP8 Package)
Power Dissipation vs. Ambient Temperature
(Tj=~150°C)
3500
At on 4 layer PC Board (*8)
At on 2 layer PC Board (*7)
2500
2000
1500
1000
500
Power Dissipation P D (mW)
Power Dissipation PD (mW)
3000
NJW4154DL3 (TO-252-5 Package)
Power Dissipation vs. Ambient Temperature
(Tj=~150°C)
At on 4 layer PC Board (*8)
At on 2 layer PC Board (*9)
3000
2500
2000
1500
1000
500
0
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
150
(*7): Mounted on glass epoxy board. (76.2×114.3×1.6mm:based on EIA/JDEC standard, 2Layers)
(*8): Mounted on glass epoxy board. (76.2×114.3×1.6mm:based on EIA/JDEC standard, 4Layers)
(For 4Layers: Applying 74.2×74.2mm inner Cu area and a thermal via hall to a board based on JEDEC standard JESD51-5)
(*9): Mounted on glass epoxy board. (76.2×114.3×1.6mm:based on EIA/JDEC standard size, 2Layers, Cu area 100mm2)
Fig. 8. Power Dissipation vs. Ambient Temperature Characteristics
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Ver.2013-03-29
NJW4154 ApplicationNJW4154
Manual
Technical Information
Application Design Examples
Buck Converter Application Circuit
IC
: NJW4154GM1-A
Input Voltage
: VIN=12V
Output Voltage
: VOUT=5V
Output Current
: IOUT=3A
Oscillation frequency : fosc=300kHz
V IN=12V
CIN2
0.47µF/50V
CIN1
10µF/50V
L
4.7µH/5.6A
EN/SYNC
EN/SYNC
High: ON
Low: OFF
(Standby)
V+
SW
CFB
15pF
NJW4154
PG
Pow er Good
IN-
GND
(NJW4154GM1 only)
V OUT =5V
SBD
COUT
100µF/6.3V
RFB
0Ω
(Short)
R2
160kΩ
R1
30kΩ
Reference
IC
L
Qty.
1
1
Part Number
NJW4154
CDRH127NP-4R7N
Description
Internal 3A MOSFET SW.REG. IC
Inductor 4.7µH, 5.6A
SBD
1
MBRS540T3G
Schottky Diode 40V, 5A
CIN1
CIN2
COUT
CFB
RFB
R1
R2
1
1
1
1
1
1
1
UMK325BJ106MM
0.47µF
GRM32EB30J107ME16L
15pF
0Ω (Short)
30kΩ
160kΩ
Ceramic Capacitor 3225 10µF, 50V, X5R
Ceramic Capacitor 2012 0.47µF, 50V, B
Ceramic Capacitor 3225 100µF, 6.3V, B
Ceramic Capacitor 1608 15pF, 50V, CH
Optional
Resistor 1608 30kΩ, ±1%, 0.1W
Resistor 1608 160kΩ, ±1%, 0.1W
Ver.2013-03-29
Manufacturer
New JRC
Sumida
ON
Semiconductor
Taiyo Yuden
Std.
Murata
Std.
⎯
Std.
Std.
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NJW4154
NJW4154Application Manual
Technical Information
Application Characteristics :NJW4154GM1-A
At VOUT=5.0V setting
Efficiency vs. Output Current
(A ver., VIN=12V, VOUT=5V, Ta=25°C)
100
6
f=300kHz
L=4.7µH
90
f=300kHz
L=4.7µH
5.8
Output Voltage VOUT (V)
80
Efficiency η (%)
Output Voltage vs. Output Current
(A ver., VIN=12V, Ta=25°C)
70
60
50
40
30
20
5.6
5.4
5.2
5
4.8
4.6
4.4
4.2
10
4
0
1
10
100
1000
Output Current IOUT (mA)
10000
1
10
100
1000
Output Current IOUT (mA)
10000
[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.
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Ver.2013-03-29