NCP1351的原理和使用方法.ppt

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,*,Click to edit Master title style,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,如何采用固定导通时间控制器进行设计,How to Design with a Fixed On-Time Controller,您优化轻载能效的关键所在,Your Key to Optimizing Light Load Efficiency,议程,Agenda,当前水准：准谐振和固定频率,State of the art:quasi resonant and fixed frequency,用于反激的固定导通时间,(FON),控制介绍,Introduction to the fixed on time control for flybacks,固定频率、准谐振和固定导通时间比较,Fixed frequency,quasi resonant,and fixed on time comparison,设计方法学及示例,Design methodology and example,将您的固定频率适配器更新为固定导通时间模式,Update your fixed frequency adapter to fixed on time,增添额外功能性的技巧与决窍,Tips and tricks to add additional functionality,面向快速简单的固定导通时间设计的资源,Resources for quick and easy fixed on time designs,议程,Agenda,当前水准：准谐振和固定频率,State of the art:quasi resonant and fixed frequency,用于反激的固定导通时间,(FON),控制介绍,Introduction to the fixed on time control for flybacks,固定频率、准谐振和固定导通时间比较,Fixed frequency,quasi resonant,and fixed on time comparison,设计方法学及示例,Design methodology and example,将您的固定频率适配器更新为固定导通时间模式,Update your fixed frequency adapter to fixed on time,增添额外功能性的技巧与决窍,Tips and tricks to add additional functionality,面向快速简单的固定导通时间设计的资源,Resources for quick and easy fixed on time designs,准谐振和固定频率,Quasi Resonant and Fixed Frequency,固定开关频率,Fixed F,sw,准谐振,Quasi resonant,频率,Frequency,固定,Fixed,可变,Variable,(,开关频率最小时功率最高,(max power at min F,sw,),轻载能效,Light Load Efficiencies,正常,Normal,(,采用跳周期或频率反走,with skip mode or freq foldback,),谷底跳适问题,(,噪声,),Valley jumping problem(noise)Max F,sw,at min P,out,满载能效,Full Load Efficiencies,正常,Normal,最佳,Best,工作模式,Operating mode,连续导电模式,/,非连续导电模式,CCM/DCM,边界导电模式,BCM(Borderline),变压器尺寸,Transformer Size,正常,Normal,较大,Larger,电磁干扰,EMI,正常,Normal,较小,Smaller,必须提升宽输出负载范围下的能效,Must improve the efficiency for a wide output load range,必须改善待机能耗,Must improve the standby,议程,Agenda,当前水准：准谐振和固定频率,State of the art:quasi resonant and fixed frequency,用于反激的固定导通时间,(FON),控制介绍,Introduction to the fixed on time control for flybacks,固定频率、准谐振和固定导通时间比较,Fixed frequency,quasi resonant,and fixed on time comparison,设计方法学及示例,Design methodology and example,将您的固定频率适配器更新为固定导通时间模式,Update your fixed frequency adapter to fixed on time,增添额外功能性的技巧与决窍,Tips and tricks to add additional functionality,面向快速简单的固定导通时间设计的资源,Resources for quick and easy fixed on time designs,固定导通时间,(FOT),工作原理,Fixed On Time(FOT)Principle of Operation,峰值电流保持恒定，而开关频率则会变化,(,改变关闭时间,),，以提供必需的输出功率：,The peak current is constant,switching frequency changes(Off time gets longer)to deliver the necessary output power:,频率最高时提供的功率最大,Maximum Power is delivered at maximum frequency,峰值电流保持恒定，可用用户选择,Constant peak current,user selectable,F,sw1,P,out1,F,sw2,P,out2,P,out1,P,out2,固定导通时间,(FOT),工作原理,Fixed On Time(FOT)Principle of Operation,峰值电流通过控制器来保持,恒定,the peak current is kept,constant,by the controller,频率,发生变化以满足上述等式,the,frequency,varies to satisfy the above equations,缺少环路控制,(,短路，启动,),时，,Fsw,被,(Ct,针对,NCP1351,进行,),钳位,in lack of loop control(short-circuit,startup),Fsw is clamped(by Ct for the NCP1351),开关频率由反馈回路进行控制,The FB loop controls the switching frequency,固定导通时间,(FOT),可变开关频率,FOT Variable Switching Frequency,(,时序电容电压,Timing capacitor voltage,),Load,C,t,由回路控制,Controlled by the loop,F,sw,钳位,clamp,在正常操作模式，,回路,固定着频率，而非,Ct,！,In normal operation,the,loop,fixes the frequency,NOT,C,t,!,轻载条件下，峰值电流减小，开关频率下降。这就限制了可听噪声问题。,In light load conditions,Ipeak reduces and Fsw goes down.This limits audible noise problems,.,满载条件下，开关频率增加，直至其碰到,Ct,钳位：故障,In full load conditions,Fsw increases until it hits the Ct clamp:fault,固定导通时间,(FOT),开关损耗,FOT Switching Losses,由于频率可变，与开关频率相关的损耗减少,：,As the frequency is variable,F,sw,related losses decrease:,C,oss,和门电荷损耗,Coss and gate charge losses,泄漏感抗损耗,Leakage inductance losses,FOT,大幅提高轻载能效,FOT dramatically improves light load efficiency,议程,Agenda,当前水准：准谐振和固定频率,State of the art:quasi resonant and fixed frequency,用于反激的固定导通时间,(FON),控制介绍,Introduction to the fixed on time control for flybacks,固定频率、准谐振和固定导通时间比较,Fixed frequency,quasi resonant,and fixed on time comparison,设计方法学及示例,Design methodology and example,将您的固定频率适配器更新为固定导通时间模式,Update your fixed frequency adapter to fixed on time,增添额外功能性的技巧与决窍,Tips and tricks to add additional functionality,面向快速简单的固定导通时间设计的资源,Resources for quick and easy fixed on time designs,控制拓扑结构比较,Control Topology Comparison,固定开关频率,Fixed F,sw,准谐振,Quasi resonant,固定导通时间,Fixed on time,频率,Frequency,固定,Fixed,可变,Variable,(,开关频率最小时功率最高,(max power at min F,sw,),可变,Variable,(,开关频率最小时功率最高,max power at max F,sw,),轻载能效,Light Load Efficiencies,正常,Normal,(,采用跳周期或频率反走,with skip mode or freq foldback,),谷底跳适问题,(,噪声,),Valley jumping problem(noise)Max F,sw,at min P,out,最佳,Best,满载能效,Full Load Efficiencies,正常,Normal,最佳,Best,正常,Normal,工作模式,Operating mode,连续导电模式,/,非连续导电模式,CCM/DCM,边界导电模式,BCM(Borderline),连续导电模式,/,非连续导电模式,CCM/DCM,变压器尺寸,Transformer Size,正常,Normal,较大,Larger,正常,Normal,电磁干扰,EMI,正常,Normal,较小,Smaller,正常,Normal,固定导通时间,(FOT),：适合极宽输出功率范围，是您改善待机能耗和优化工作能效的关键！,FOT:your key to improve standby and optimize efficiency for a wide output power range!,议程,Agenda,当前水准：准谐振和固定频率,State of the art:quasi resonant and fixed frequency,用于反激的固定导通时间,(FON),控制介绍,Introduction to the fixed on time control for flybacks,固定频率、准谐振和固定导通时间比较,Fixed frequency,quasi resonant,and fixed on time comparison,设计方法学及示例,Design methodology and example,新的,NCP1351,固定导通时间控制器,The,new NCP1351 FOT controller,设计方法学,Design methodology,设计示例,Design example,将您的固定频率适配器更新为固定导通时间模式,Update your fixed frequency adapter to fixed on time,增添额外功能性的技巧与决窍,Tips and tricks to add additional functionality,面向快速简单的固定导通时间设计的资源,Resources for quick and easy fixed on time designs,NCP1351,是一款瞄准总成本极为重要的低功率离线反激开关电源,(SMPS),应用的电流模式控制器,The NCP1351 is a current-mode controller targeting low power off-line flyback Switched Mode Power Supplies(SMPS)where total cost is of utmost importance,准固定导通时间，可变关闭时间,Quasi fixed Ton,variable Toff,带峰值电流压缩的频率反走,Frequency foldback with Peak Current Compression,短路保护,(,闭锁,A&C,或自动恢复,B&D),Short circuit protection,适应大输出功率瞬态现象,(,打印机,),Accommodates large output power transients(printers),初级端或次级端稳压,Primary or secondary side regulation,闩锁输入,Latch input,低启动电流,Low start-up current,固有的频率抖动,Natural frequency jittering,带可编程电流感测电阻的负电流感测功能,Negative current sensing with programmable current sense resistor,扩展的,Vcc,范围,：,28,V,Extended Vcc range:28 V,NCP1351XDR2G:SOIC8,X=A,B,C,D,Others Features,Ordering&Package Information,Market&Applications,NCP1351,固定,导通时间、可变关闭时间控制器,Fixed On Time,Variable Off Time Controller,Pb,O,DW,适配器,Adapters,离线电池充电器,Offline battery chargers,辅助电源,Auxiliary power supplies,简单而紧凑的设计,Simple and compact design,固有的频率反走,Natural frequency foldback,无噪声，轻载能效提高,Noise free&improved efficiency in light load,独立于辅助绕组,Independent of the aux.winding,Value Proposition,Unique Features,Benefits,Application Data,NCP1351,输入输出功率和功能描述,NCP1351 Pinout and Function Description,FB:,在此引脚注入电流，降低频率,Injecting current in this pin reduces the frequency,Ct:,没有反馈电流时设定最大开关频率,sets the maximum switching frequency at no feedback current,CS:,感测初级端电流,Senses the primary current,Timer:,设定故障确认前的持续时间,Sets the time duration before fault validation,Latch:,高于,5,V,的正电压完全闩锁控制器,A positive voltage above 5 V fully latches off the controller,Vcc:,为控制器提供高达,28,伏电压,Supplies the controller up to 28 V,DRV,:,驱动脉冲至功率,MOSFET,Driving pulses to the power MOSFET,NCP1351,峰值电流压缩,NCP1351 Peak Current Compression,FB current,Vds,light load,60 A,80 A,270 A,70 A,40 A,FAULT,(A,B versions),I,offset,大负载时峰值电流恒定,Constant peak current at high load,轻载时峰值电流下降,Reduced peak current at light load,没有饱和,No saturation,没有可听噪声,No Audible noise,峰值电流从,100%,降至,26%,Peak current reduction from,100%to 26%,NCP1351,负电流感测,NCP1351 Negative Current Sensing,I,CS,x,R,offset,产生正偏置,(,如,1 V),I,CS,x,Roffset,generates a positive offset(e.g.1 V),电流流过时，,Vsense,为负值,Vsense is negative when current flows,两路信号的和接近零时，,MOSFET,关闭,When,the sum of both signal reaches,0,MOSFET is off,0 V,Vsense,0 V,V,CS,不用担心！,Do not be afraid!,NCP1351,负电流感测,NCP1351 Negative Current Sensing,想要降低感测电阻的功率耗散？,Want to reduce,R,sense,power dissipation?,选择,Select,V,sense,=0.5 V,R,offset,=0.5/270u=1.8 k,洁净的电压图像：没有开启尖峰，更好的噪声免疫性,Clean voltage image:no turn-on spikes,better noise immunity,一种微调最大感测电压的途径,A way to fine tune the maximum sense voltage,如何计算感测电阻和偏置电阻？,How to calculate R,sense,and R,offset,?,NCP1351,过载,/,短路保护,NCP1351 Overload/Short-Circuit Protection,过载检测仅依赖于反馈变化,Overload detection only dependent of FB variation,2,个选项：闩锁或自动恢复,2 options:latched or auto recovery,过载,OVERLOAD,输出电压减小,V,out,decreases,反馈电流减小,Less FB,current,故障比较器切换,FAULT comparator toggles,time,V(C,TIMER,),5V,500mV,FB,45k,GND,Vdd,NCP1351,+,-,100mV,+,-,Timer,10A,5V,保护模式,Protection mode,(,闩锁或自动恢复,latched,or autorecovery,),D2,Vcc,V,OUT,C,TIMER,NCP1351,过载定时器,Overload Timer,适应大输出功率瞬态现象,Accommodates large output power transients,适合于打印机应用,Suitable for printers,V,out,故障定时器启动,Fault timer starts,输出负载,Output load,最大输出功率,Max output power,V,out,故障定时器启动,Fault timer starts,输出负载,Output load,最大峰值功率,Max peak power,过载,Over load,过载,Over load,瞬态峰值功率,Transient peak power,输出仍在稳压,Output still in regulation,最大直流功率,Max DC power,A&B,版本,versions,C&D,版本,versions,对,MOSFET,的,BVdss,降额后定义变比,Define turn ratio after derating the BV,dss,of the MOSFET:,NCP1351,设计方法学,Design Methodology,(,仅对非连续导电模式有效,valid for DCM only,),计算最大占空比,Calculate maximum duty cycle:,在功率最大期间输入电压最低时选择最大开关频率,Choose the maximum switching frequency F,sw,at V,in,min,during power peaks.,然后通过下列公式计算初级端感抗值：,Then calculate the primary inductance value by:,k,c,:,钳位系数,clamp coefficient,V,clamp,/V,r,V,ds,max,=85%BV,dss,推导初级端最大峰值电流,Deduce the maximum primary peak current,:,最后通过下列公式估计时序电容值,Finally estimate the timing capacitor value by:,MOSFET,、整流器、电感和缓冲器根据平均输出功率,(,非峰值功率,),来计算,NCP1351,设计方法学,NCP1351 Design Methodology,(,仅对非连续导电模式有效,valid for DCM only),(,设计示例中将涉及连续导电模式,design example will cover CCM),时序电容的正常值为,Normalized values for C,T,are,:,-65 kHz:270 pF,-100 kHz:180 pF,MOSFET,rectifiers,inductors and snubbers are designed according to the average delivered power(not the peak),NCP1351,设计示例,NCP1351 Design Example,输出电压,Output voltage:,19 V 57 W,输入电压,Input voltage:,90 265 Vrms,待机能耗,(,空载,),Standby power(no-load),无辅助绕组,DSS-No auxiliary winding,通用主电源,Universal mains,将您的固定频率适配器更新为固定导通时间模式！,Update Your Fixed Frequency Adapter to FOT!,采用,NCP1200,的,12,V/24,W,适配器原理图,12 V/24 W adapter schematic with NCP1200,开关频率为,65 kHz,Switching frequency:65 kHz,内部固定短路保护,Internal fixed short circuit protection,开关频率,65 kHz,Switching frequency 65 kHz,选择,choose,C,t,=270 pF,NCP1200,的最大电流设定点为,1 V,Maximum current setpoint of NCP1200 is 1 V,选择,choose,V,CS,=1 V，,并计算,R,offset,:,无须修改感测电阻,No need to modify R,sense,光耦合器配置,Optocoupler configuration,NCP1200:,共发射极,common emitter,NCP1351:,共集电极,common collector,将您的固定频率适配器更新为固定导通时间模式！,Update Your Fixed Frequency Adapter to FOT!,2.4 k,采用,NCP1351,的,12 V/24 W,适配器原理图,12 V/24 W adapter schematic with NCP1351,将您的固定频率适配器更新为固定导通时间模式！,Update Your Fixed Frequency Adapter to FOT!,将您的固定频率适配器更新为固定导通时间模式！,Update Your Fixed Frequency Adapter to FOT!,输入电压为,230 Vrms,时的效率和空载能耗,Efficiency and no-load power consumption at V,in,=230 Vrms,NCP1200,NCP1351,24 W,85%,85%,17 W,84%,85%,10.7 W,83%,84%,1.5 W,66%,75%,0.7 W,57%,70%,0.5 W,52%,65%,空载,No load,234 mW,78 mW,动态自供电功率耗散！,DSS power dissipation!,输出纹波比较,Output ripple comparison,V,out,1 mV/div.,V,ds,200 V/div.,V,out,10 mV/div.,V,ds,100 V/div.,NCP1200,空载,No load,NCP1351,空载,No load,NCP1351,的输出纹波要小,10,倍,The output ripple is 10 times smaller with NCP1351,将您的固定频率适配器更新为固定导通时间模式！,Update Your Fixed Frequency Adapter to FOT!,议程,Agenda,当前水准：准谐振和固定频率,State of the art:quasi resonant and fixed frequency,用于反激的固定导通时间,(FON),控制介绍,Introduction to the fixed on time control for flybacks,固定频率、准谐振和固定导通时间比较,Fixed frequency,quasi resonant,and fixed on time comparison,设计方法学及示例,Design methodology and example,将您的固定频率适配器更新为固定导通时间模式,Update your fixed frequency adapter to fixed on time,增添额外功能性的技巧与决窍,Tips and tricks to add additional functionality,面向快速简单的固定导通时间设计的资源,Resources for quick and easy fixed on time designs,启动技巧与决窍,Start-Up Tip&Trick,传统配置,Classical configuration,改善的启动耗散,Improved startup dissipation,启动电阻可被任意连接,The startup resistor can either be connected,:,至带启动电阻的大电容,To the bulk capacitor with,R,startup,至半波,对于相似的充电电流，选择,Rstartup/pi,To the half-wave for a similar,charging current,take Rstartup/pi,半波提供最佳的闩锁恢复时间,Half-wave gives the best latch recovering time,启动技巧与决窍,Start-Up Tip&Trick,轻载条件下，,Vcc,崩溃,In light load conditions,V,cc,collapses,:,增加,Vcc,电容，减小启动电阻,Increase,V,cc,capacitor degrades startup,将,Vcc,分解为两个电容,Split,V,cc,with two capacitors,Cvcc,单独正常启动,(D1),CVcc starts-up normally alone(D1),C,reser,在待机时维持,Vcc,工作状态,C,reser,keeps,V,cc,alive in standby,4.7 F,47 F,启动电压调节,Startup Voltage Adjustment,极低的启动电流,/,大启动电阻值,Extremely low start-up current/High start-up resistors values,启动电阻,Start-up resistors,最小启动电压调节,Minimum voltage,start-up adjustment,工作时固定最小高电压,Fix the minimum bulk voltage for operation,门驱动技巧与决窍,Gate Drive Tip&Trick,采用小型,PNP,来提高驱动能力,Improve drive capability with a small PNP,更好的传播延迟,better propagation delay,改进故障电流控制,improves current control in fault,No PNP,with PNP,200 ns/div,200 ns/div,过载保护,Over Power Protection,只需数量很少的外部元件,Requires limited number of external components,兼容于现有辅助绕组,Compatible with existing Aux winding,二极管避免,C,3,被反激充电,The diode avoids,C,3,charged by flyback,在任意电压条件下控制最大输出功率,Control the maximum output power,under any voltage condition,非耗散型！,Non dissipative!,频率抖动技巧与决窍,Frequency Jittering Tip&Trick,注入一些全波或半波纹波来增加固有频率抖动,Inject some full-wave or half-wave ripple to increase the natural frequency jittering,注入全波纹波至,CS,引脚,Inject full wave ripple into CS pin,注入半波纹波至,CS,引脚,Inject half wave ripple into CS pin,闩锁输入技巧与决窍,Latch Input Tip&Trick,NTC,参考电压,Reference,voltage,与闩锁引脚一起提供简单的过压保护和过温度保护,Combined with the latch pin gives easy OVP and OTP protection.,在,FB,引脚插入齐纳二极管，造就更便宜的参考,Inserting zener with FB pin,creates cheap reference.,欠压,Brown Out,欠压关闭,BO off,欠压导通,BO on,斜波补偿,Ramp Compensation,斜坡补偿,1,：正向斜坡补偿至,FB,引脚，以降低峰值,Ramp compensation 1:a positive ramp into the FB pin reduces the peak,斜波补偿,Ramp Compensation,斜坡补偿,2,：负电流在导通时间将,Ct,维持在低位,Ramp compensation 2:a negative current keeps,C,t,low during,t,on,接近,C,t,引脚,Close to,the,C,t,pin,软启动,Soft Start,软启动,(,如果有必要,),Soft Start,(if necessary),在电源开启期间通过软启动序列来限制应力,Limit the stress at power-on via a soft-start sequence.,V,CS,t,将,NCP1351,与其他控制器相连接,Interfacing NCP1351 with Other Controllers,NCP1351,怎样能够与其它控制器共享接地信号？,(,将负电流和正电流感测混合在一起,),How NCP1351 can share ground signal with other controller?(mixing negative and positive current sensing),NCP1351,接地,NCP1351 ground,主接地,Main ground,主接地,Main ground,1,2,3,4,5,8,6,7,Laux,D2,D1,Caux,100u,Cstbvcc,4.7u,Rsense,Rcs,NCP1351,连接至其它控制器的,VCC,引脚,To,other,controller,VCC pin,or,Lp,连接至其它控制的接地,引脚和大电容,To other controller GND pin,and bulk cap,布线建议,Layout Suggestions,R,sense,R,offset,22 pF,为了改善噪声免疫性，需要将元件布置在临近控制器的位置,To improve the noise immunity,keep components,close,to the controller,低阻抗点,Low impedance point,V,cc,改变最大开关频率,Changing the Maximum Switching Freq