NJW4155GM1. Current Mode Control. Internal 1.8A MOSFET Switching Regulator IC for Buck Converter

Transcription

1 Current Mode Control Internal 1.8A MOSFET Switching Regulator IC for Buck Converter GENERA DESCRIPTION The NJW4155 is a buck converter with 4/1.8A MOSFET. It corresponds to high oscillating frequency, and ow ESR Output Capacitor (MCC) within wide input range from 4.5 to 4. Therefore, the NJW4155 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. PACKAGE OUTINE NJW4155GM1 NJW4155D3 FEATURES Current Mode Control External Clock Synchronization Wide Operating oltage Range 4.5 to 4 Switching Current 2.7A min. PWM Control Built-in Compensation Circuit Correspond to Ceramic Capacitor (MCC) Oscillating Frequency 45kHz typ. (A, C ver.) 3kHz typ. (B ver.) Soft Start Function 4ms typ. UO (Under oltage ockout) Over Current Protection (Hiccup type) Thermal Shutdown Protection Power Good Function (NJW4155GM1 only) Standby Function Package Outline NJW4155GM1 : HSOP8 NJW4155D3 : TO er

2 PRODUCT CASSIFICATION Part Number ersion Oscillation Frequency Power Good Package NJW4155GM1-A A 45kHz typ. HSOP8 NJW4155GM1-B B 3kHz typ. HSOP8 NJW4155D3-B B 3kHz typ. TO NJW4155GM1-C C 45kHz typ. HSOP8 (7pin: N.C.) Operating Temperature Range General Spec. Ta=-4 C to +125 C General Spec. Ta=-4 C to +125 C General Spec. Ta=-4 C to +125 C General Spec. Ta=-4 C to +125 C PIN CONFIGURATION SW SW EN/SYNC SW SW 2 7 N.C. 4 IN- GND PG EN/SYNC IN- GND PG EN/SYNC IN- 3 3 GND 2 SW 1 + Exposed PAD on backside connect to GND Exposed PAD on backside connect to GND NJW4155GM1-A NJW4155GM1-B NJW4155GM1-C NJW4155D3-B PIN DESCRIPTIONS PIN NUMBER HSOP8 HSOP8 TO PIN NAME FUNCTION A ver. C ver. B ver. B ver. 1 1 SW 2 Switch Output pin of Power MOSFET 2 2 GND GND pin Power Good pin. An open drain output that goes high impedance PG 4 4 when the IN- pin voltage is stable around 1%.(Only HSOP8 PKG) Output oltage Detecting pin IN Connects output voltage through the resistor divider tap to this pin in order to voltage of the IN- pin become.8. Standby Control pin The EN/SYNC pin internally pulls down with 1k. Normal EN/SYNC Operation at the time of High evel. Standby Mode at the time of ow evel or OPEN. Moreover, it operates by inputting clock signal at the oscillatory frequency that synchronized with the input signal. N.C. 7 Non Connection Power Supply pin for Power ine 8 Exposed Connect to GND (Only HSOP8 PKG) PAD er

3 BOCK DIAGRAM + SOPE COMP. CURRENT SENSE UO EN/SYNC High: ON ow : OFF(Standby) 1k Enable (Standby) SYNC OSC S Q R OCP Buffer SW IN- PWM TSD Soft Start ref ER AMP PG.8 GND Pow er Good Control ogic NJW4155GM1 only er

4 ABSOUTE MAXIMUM RATINGS (Ta=25 C) PARAMETER SYMBO MAXIMUM RATINGS UNIT Supply oltage + -.3~ SW pin oltage -SW +45 EN/SYNC pin oltage EN/SYNC -.3~+45 IN- pin oltage IN- -.3~+6 Power Good pin oltage (*1) PG -.3~+6 HSOP8 79 (*2) 2,5 (*3) Power Dissipation P D mw TO ,19 (*4) 3,125 (*3) Junction Temperature Range Tj -4 to +15 C Operating Temperature Range T opr -4 to +125 C Storage Temperature Range T stg -5 to +15 C (*1): Apply only the NJW4155GM1. (*2): Mounted on glass epoxy board. ( mm:based on EIA/JDEC standard, 2ayers) (*3): Mounted on glass epoxy board. ( mm:based on EIA/JDEC standard, 4ayers) (For 4ayers: Applying mm inner Cu area and a thermal via hole to a board based on JEDEC standard JESD51-5) (*4): Mounted on glass epoxy board. ( mm:based on EIA/JDEC standard size, 2ayers, Cu area 1mm 2 ) RECOMMENDED OPERATING CONDITIONS PARAMETER SYMBO MIN. TYP. MAX. UNIT Supply oltage Power Good pin oltage (*5) PG 5.5 External Clock Input Range A, C version B version (*5): Apply only the NJW4155GM1. f SYNC khz er

5 EECTRICA CHARACTERISTICS (Unless otherwise noted, + = EN./SYNC =12, Ta=25 C) PARAMETER SYMBO TEST CONDITION MIN. TYP. MAX. UNIT Under oltage ockout Block ON Threshold oltage T_ON + = H OFF Threshold oltage T_OFF + = H Hysteresis oltage HYS 7 9 m Soft Start Block Soft Start Time T SS B = ms Oscillator Block Oscillation Frequency Oscillation Frequency deviation (Supply voltage) Oscillation Frequency deviation (Temperature) f OSC A, C version, IN- = khz B version, IN- = khz f D + =4.5 to 4 1 % f DT Ta=-4 C to +85 C 5 % Error Amplifier Block Reference oltage B -1.%.8 +1.% Input Bias Current I B A PWM Comparate Block Maximum Duty Cycle M AX D UTY IN- = % Minimum ON Time1 A, C version 15 2 ns t (Use Built-in Oscillator) ON-min1 B version ns Minimum ON Time2 A, C version, f SYNC =5kHz 1 14 ns t (Use Ext CK) ON-min2 B version, f SYNC =4kHz ns OCP Block COO DOWN Time t COO 75 ms Output Block Output ON Resistance R ON I SW =1.5A.2.4 Switching Current imit I IM A SW eak Current I EAK EN/SYNC =, + =45, SW = 3 A er

6 EECTRICA CHARACTERISTICS (Unless otherwise noted, + = EN/SYNC =12, Ta=25 C) PARAMETER SYMBO TEST CONDITION MIN. TYP. MAX. UNIT Standby Control / Sync Block EN/SYNC pin High Threshold oltage EN/SYNC pin ow Threshold oltage Input Bias Current (EN/SYNC pin) THH_EN/SYNC EN/SYNC = H TH_EN/SYNC EN/SYNC = H.5 I EN EN/SYNC = A Power Good Block (*6) High evel Detection oltage THH_PG Measured at IN- pin ow evel Detection oltage TH_PG Measured at IN- pin Hysterisis Region HYS_PG 2 Power Good ON Resistance R ON_PG I PG =1mA 37 5 eak Current at OFF State I EAK_PG PG =6.1 A General Characteristics Quiescent Current I DD A, C version, R =no load, IN- = ma B version, R =no load, IN- = ma Standby Current I DD_STB EN/SYNC = 3 A (*6): Apply only the NJW4155GM er

7 THERMA CHARACTERISTICS PARAMETER SYMBO AUE UNIT Junction-to-ambient thermal resistance Junction-to-Top of package characterization parameter ja jt HSOP8 TO HSOP8 TO (*7) 5 (*8) 15 (*9) 4 (*8) 28 (*7) 12 (*8) 17 (*9) 12 (*8) (*7): Mounted on glass epoxy board. ( mm:based on EIA/JDEC standard, 2ayers) (*8): Mounted on glass epoxy board. ( mm:based on EIA/JDEC standard, 4ayers) (For 4ayers: Applying mm inner Cu area and a thermal via hole to a board based on JEDEC standard JESD51-5) (*9): Mounted on glass epoxy board. ( mm:based on EIA/JDEC standard size, 2ayers, Cu area 1mm 2 ) C/W C/W POWER DISSIPATION vs. AMBIENT TEMPERATURE Power Dissipation P D (mw) NJW4155GM1 (HSOP8 Package) Power Dissipation vs. Ambient Temperature (Tj=~15 C) At on 4 layer PC Board (*8) At on 2 layer PC Board (*7) Power Dissipation P D (mw) NJW4155D3 (TO Package) Power Dissipation vs. Ambient Temperature (Tj=~15 C) At on 4 layer PC Board (*8) At on 2 layer PC Board (*9) Ambient Temperature Ta ( C) Ambient Temperature Ta ( C) er

8 TYPICA APPICATIONS IN C IN2 C IN1 OUT EN/SYNC High: ON ow: OFF (Standby) EN/SYNC + NJW4155 SW C FB R2 Pow er Good PG IN- GND R FB (NJW4155GM1 only) SBD C OUT R1-8 - er

9 TYPICA CHARACTERISTICS (A, B, C version).81 Reference oltage vs. Supply oltage (Ta=25ºC).81 Reference oltage vs. Temperature ( + =12) Reference oltage B () Reference oltage B () Supply oltage + ().79 5 Switching Current imit vs. Temperature.4 Output ON Resistance vs. Temperature (I SW =1.5A) Switching Current imit I IM (A) =4 + =5 + =12 Output ON Resistance R ON (W) =5 + =12 + =4 2 er

10 TYPICA CHARACTERISTICS (A, B, C version) Under oltage ockout oltage vs. Temperature Soft Start Time vs. Temperature ( + =12, B =.75) Threshold oltage () T_ON T_OFF Soft Start Time Tss (ms) Switching eak Current I EAK (μa) Switching eak Current vs. Temperature ( + =45, EN/SYNC =, SW =) Standby Current I DD_STB (μa) Standby Current vs. Temperature ( EN/SYNC =) + =4 + =12 + = er

11 TYPICA CHARACTERISTICS (A, C version) Oscillation Frequnecny f OSC (khz) Oscillation Frequency vs. Supply oltage (A, C ver., IN -=.7, Ta=25ºC) Supply oltage + () Quiescent Current I DD (ma) Quiescent Current vs. Supply oltage (A, C ver, R =no load, IN -=.7, Ta=25ºC) Supply oltage + () Oscillation Frequency fosc (khz) Oscillation Frequency vs Temperature (A, C ver., + =12, IN -=.7) 4 Maximum Duty Cycle M AX D UTY (%) Maximum Duty Cycle vs. Temperature (A, C ver., + =12, IN -=.7) 9 Minimum ON Time1 t ON-min1 (ns) Minimum ON Time1 vs. Temperature (A, C ver., + =12) 1 Quiescent Current I DD (ma) Quiescent Current vs. Temperature (A, C ver., R =no load, IN -=.7) + =12 + =4 + =4.5 er

12 TYPICA CHARACTERISTICS (B version) Oscillation Frequnecny f OSC (khz) Oscillation Frequency vs. Supply oltage (B ver., IN -=.7, Ta=25ºC) Supply oltage + () Quiescent Current I DD (ma) Quiescent Current vs. Supply oltage (B ver, R =no load, IN -=.7, Ta=25ºC) Supply oltage + () Oscillation Frequency fosc (khz) Oscillation Frequency vs Temperature (B ver., + =12, IN -=.7) 27 Maximum Duty Cycle M AX D UTY (%) Maximum Duty Cycle vs. Temperature (B ver., + =12, IN -=.7) 9 3 Minimum ON Time1 vs. Temperature (B ver., + =12) 4 Quiescent Current vs. Temperature (B ver., R =no load, IN -=.7) Minimum ON Time1 ton-min1 (ns) Quiescent Current I DD (ma) =4.5 + =4 + = er

13 Description of Block Features 1. Basic Functions / Features NJW4155 Application NJW4155 Manual Technical Information Error Amplifier Section (ER AMP).8±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.8, 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 NJW4155 uses a constant frequency, current mode step down architecture. The oscillation frequency is 45kHz (typ.) at A, C version and 3kHz (typ.) at B 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 95.5% (typ.). Table 1. Minimum ON time of NJW4155 A, C version (f OSC =45kHz) Use Built-in 15ns typ. Oscillator Use External Clock 1ns typ. (@ f SYNC =5kHz) B version (f OSC =3kHz) 215ns typ. 145ns typ. (@ f SYNC =4kHz) The buck converter of ON time is decided the following formula. ton IN OUT f OSC s IN shows input voltage and OUT shows output voltage. When the ON time becomes below in t ON-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 2.7A(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 + pin and the SW pin up to +45. However, you should use an Schottky diode that has low saturation voltage. Power Supply, GND pin ( + 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 + pin the GND pin connection in order to lower high frequency impedance. er

14 Application Manual Technical Information Description of Block Features (Continued) 2. Additional and Protection Functions / Features Under oltage ockout (UO) The UO circuit operating is released above + =4.4(typ.) and IC operation starts. When power supply voltage is low, IC does not operate because the UO circuit operates. There is 9m(typ.) width hysteresis voltage at rise and decay of power supply voltage. Hysteresis prevents the malfunction at the time of UO 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 to.75. The soft start circuit operates after the release UO and/or recovery from thermal shutdown..8 ref, IN- pin oltage OSC Waveform SW pin ON OFF UO(4.4 typ.) Release, Standby, Recover from Thermal Shutdow n Soft Start time: Tss=4ms(typ.) to B =.75 Soft Start effective period to B =.8 Fig. 1. Startup Timing Chart Steady Operaton er

15 Application NJW4155 Manual Technical Information Description of Block Features (Continued) Over Current Protection Circuit (OCP) NJW4155 contains overcurrent protection circuit of hiccup architecture. The overcurrent protection circuit of hiccup architecture is able to decrease heat generation at the overload. The NJW4155 output returns automatically along with release from the over current condition. At when the switching current becomes I IM 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 the IN- pin voltage is.5 or lower(less), the switching operation stops after the overcurrent detection continued 128 pulses. After NJW4155 switching operation was stopped, it restarts by soft start function after the cool down time of approx 75ms (typ.). IN- pin oltage.8.5 Oscillation Frequency A, C ver.=45khz typ. B ver.=3khz typ. SW pin ON OFF Switching Current I IM Pulse Count : 128 pulse Cool Down time :75ms typ. Pulse by Pulse Static Status Detect Overcurrent Soft Start Fig. 2. Timing Chart at Over Current Detection Thermal Shutdown Function (TSD) When Junction temperature of the NJW4155 exceeds the 16 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 (15 C). (* Design value) Standby Function The NJW4155 stops the operating and becomes standby status when the EN/SYNC pin becomes less than.5. The EN/SYNC pin internally pulls down with 1k, therefore the NJW4155 becomes standby mode when the EN/SYNC pin is OPEN. You should connect this pin to + when you do not use standby function. er

16 Application Manual 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, C version (f OSC =45kHz) B version (f OSC =3kHz) Input Frequency 44kHz to 28kHz to 6kHz 5kHz Duty Cycle 25% to 75% 2% to 8% oltage magnitude 1.6 or more at High level.5 or less at ow level Technical Information 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 2 s to 3 s in order to prevent malfunctions. (Fig. 3.) High EN/SYNC pin ow SW pin ON OFF Standby Delay Time External Clock Synchronization Fig. 3. Switching Operation by External Synchronized Clock Power Good Function 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 1%(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 2 s to 3 s against the IN- pin voltage changes er

17 Application NJW4155 Manual 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 Inductor setting example is shown in Table 3. Table 3. Inductor Setting Example Inductor Input oltage Output oltage A, C version B version IN OUT (f OSC =45kHz) (f OSC =3kHz) H 39 H H 47 H H 47 H H 47 H H 56 H H 56 H Technical Information When increasing inductor value, it is necessary to increasing capacity of an output capacitor and to secure the stability of application. The minimum of inductor value is restricted from the following formula, when ON duty exceeds 5%. A, C version IN 2 D ON 1 [ H] 1.11 B version IN 2 D ON 1 [ H].74 Reducing 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. I IN OUT IN f OSC OUT [A] Ipk I OUT I 2 [A] Output Current I OUT Current Peak Current I PK Indunctor Ripple Current I Peak Current I PK Indunctor Ripple Current I t ON t OFF t ON t OFF Reducing alue Increasing value Fig. 4. Inductor Current State Transition (Continuous Conduction Mode) er

18 Application Manual 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 the NJW4155 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. I RMS I OUT OUT IN IN OUT [A] In the above formula, the maximum current is obtained when IN = 2 OUT, and the result in this case is I RMS = I OUT (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 NJW4155 corresponds to the output capacitor of low ESR, the ceramic capacitor is the optimal for compensation. The output capacitor setting example is shown in Table 4. Table 4. Output Capacitor Setting Example Input oltage Output oltage IN OUT A, C version 12, 24 B version 12, 24 Capacitor C OUT Part Number F / 6.3 GRM31CB3J476KE18: Murata F / 6.3 GRM31CB3J226ME18: Murata F / 1 GRM31CR61A226ME19: Murata F / GRM31CB3J476KE18: Murata 22 F / 6.3 GRM31CB3J226ME18: Murata F / 6.3 GRM31CB3J476KE18: Murata F / 16 GRM32EB31C476KE15: Murata The output capacitor uses capacity bigger than Table 4. 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. Technical Information ripple (p p) ESR I [] The effective ripple current that flows in a capacitor (I rms ) is obtained by the following equation. I rms I 2 3 [Arms] er

19 Application NJW4155 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. Setting Output oltage, Compensation Capacitor The output voltage OUT 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 R1 OUT 1 B [] The zero points are formed with R2 and C FB, and it makes for the phase compensation of NJW4155. The zero point is shown the following formula. f Z1 2 1 R2 C FB [Hz] You should set the zero point as a guide from 5kHz to 7kHz. Output voltage setting resistor and compensation capacitor setting example is shown in Table 5. Table 5. Output oltage Setting Resistor and Compensation Capacitor Setting Example Input oltage Output oltage IN OUT R1 R2 C FB k 15k 18pF 12, k 16k 15pF k 2k 12pF (A version, B version and C version are common.) er

20 Application Manual Technical Information Application Information (Continued) Board ayout 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 C IN -SW-SBD that occurs rapid current change in the switching. It is effective in reducing noise spikes caused by parasitic inductance. NJW4155 Built-in SW NJW4155 Built-in SW IN C IN SBD C OUT IN C IN SBD C OUT (a) Buck Converter SW ON (b) Buck Converter SW OFF Fig. 5. Current oop 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. + SW OUT IN C IN SBD C OUT R (Bypass Capacitor) NJW4155 C FB IN- GND R2 R1 To avoid the influence of the voltage drop, the output voltage should be detected near the load. Separate Digital(Signal) GND from Power GND Because IN- pin is high impedance, the voltage detection resistance: R1/R2 is put as much as possible near IC(IN-). Fig. 6. Board ayout at Buck Converter er

21 Application Information (Continued) NJW4155 Application NJW4155 Manual Technical Information GND IN IN SBD C IN EN/SYNC Power Good R2 C OUT Power GND Area R1 R FB C FB C OUT Signal GND Area OUT GND OUT Feed back signal HSOP8 Package (A version and B version) Connect Signal GND line and Power GND line on backside pattern Fig. 7. ayout Example (upper view) er

22 Application Manual Calculation of Package Power A lot of the power consumption of buck converter occurs from the internal switching element (Power MOSFET). Power consumption of NJW4155 is roughly estimated as follows. Input Power: P IN = IN I IN [W] Output Power: P OUT = OUT I OUT [W] Diode oss: P DIODE = F I (avg) OFF duty [W] NJW4155 Power Consumption: P OSS = P IN P OUT P DIODE [W] Where: IN : Input oltage for Converter I IN : Input Current for Converter OUT : Output oltage of Converter I OUT : Output Current of Converter F : Diode's Forward Saturation oltage I (avg) : Inductor Average Current OFF duty : Switch OFF Duty Efficiency ( ) is calculated as follows. = (P OUT P IN ) 1 [%] Technical Information You should consider temperature derating to the calculated power consumption: P D. You should design power consumption in rated range referring to the power dissipation vs. ambient temperature characteristics er

23 Application Design Examples Buck Converter Application Circuit IC : NJW4155GM1 Input oltage : IN =12 Output oltage : OUT =5 Output Current : I OUT =1.8A Oscillation frequency : A, C version fosc=45khz : B version fosc=3khz NJW4155 Application NJW4155 Manual IN =12 Technical Information EN/SYNC High: ON ow: OFF (Standby) Power Good (NJW4155GM1 only) EN/SYNC + NJW4155 PG IN- C IN2 Open SW GND SBD C IN1 1mF/5 A ver. 15mH/3.2A B ver. 22mH/2.7A C OUT 47mF/16 C FB 15pF R FB W (Short) OUT =-5 R2 16kW R1 3kW Reference Qty. Part Number Description Manufacturer IC 1 NJW4155GM1 Internal 1.8A MOSFET SW.REG. IC New JRC 1 A, C ver.: CF14T-15M Inductor 15 H, 3.2A TDK B ver.: CF14T-22M Inductor 22 H, 2.7A TDK SBD 1 CMS16 Schottky Diode 4, 3A Toshiba C IN1 1 UMK325BJ16MM Ceramic Capacitor F, 5, X5R Taiyo Yuden C IN2 1 Open Optional C OUT 1 GRM32EB31C476KE15 Ceramic Capacitor F, 16, B Murata C FB 1 15pF Ceramic Capacitor pF, 5, CH Std. R FB 1 (Short) Optional R1 1 3k Resistor 168 3k, 1%,.1W Std. R2 1 16k Resistor k, 1%,.1W Std. er

24 Application Manual Application Characteristics A, C version Efficiency [%] f=45khz =15 H Efficiency vs. Output Current ( OUT =5, Ta=25ºC) IN =24 IN =7 IN = Output Current I OUT [ma] Output oltage OUT [] Technical Information Output oltage vs. Output Current (Ta=25ºC) f=45khz =15 H IN =7, 12, Output Current I OUT [ma] Efficiency [%] B version f=3khz =22 H Efficiency vs. Output Current ( OUT =5, Ta=25ºC) IN =24 IN =7 IN = Output Current I OUT [ma] Output oltage OUT [] Output oltage vs. Output Current (Ta=25ºC) f=3khz =22 H IN =7, 12, Output Current I OUT [ma] er

25 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. er