筆機(jī)本電源芯片

19-4323;Rev14;+5V供電、多通道RS-驅(qū)動(dòng)器概 新一MAX220MAX249系列線驅(qū)動(dòng)器 ，專為 器件特這些器件特別適合電池供電系統(tǒng)，這是由于其低功耗關(guān)斷模式可以將功耗減小到5μW以內(nèi)。MAX225、MAX233AX35以及MX245AX26A247不需要外部元件，用于印刷電路板面積有限的應(yīng)電池供RS232系統(tǒng)多點(diǎn)RS232網(wǎng)絡(luò)

RS-232收發(fā)器(MAX3246E提供UCSPTM封裝)MAX221E：±15kVESD保護(hù)、+5V、1μATEMPTEMPPIN-to16Plasticto16Narrowto16Wideto-to16Plastic-to16Narrow-to16Wide-to16-to16AutoShutdown和UCSP是IntegratedProducts,Inc.的商標(biāo)

定購(gòu)信息(續(xù))*片規(guī)格，請(qǐng)與工廠聯(lián)系

選擇No.ofNo.of40.047/0—Ultra-low-power,industry-standard4—4?MAX241andreceiversactivein0—?Availablein4—5driverswith+52—Standard+5/+12Vor +7.5tosamefunctionsas4—Industry4—Higherslewrate,small0——Noexternal0——Noexternalcaps,highslew4—Replaces0——Noexternal4—4—ComplementsIBMPCserial4—Replaces1488and+52—Standard+5/+12Vor +7.5tosingle-packagesolutionforIBMPCserial4—DIPorflatpack4—CompleteIBMPCserial4?Separateshutdownand4—Open-linedetectionsimplifies4—Highslew0—?Highslewrate,int.caps,twoshutdown0—?Highslewrate,int.caps,threeshutdown0—?Highslewrate,int.caps,nineoperating4?Highslewrate,selectivehalf-chip4?AvailableinquadflatpackIntegratedProducts1本文是 正式英文資料的譯文，不對(duì)翻譯中存在的差異或由此產(chǎn)生的錯(cuò)誤負(fù)責(zé)。請(qǐng)注意譯文中可能存在文字組織或翻譯錯(cuò)誤，如需確認(rèn)任何詞語(yǔ)的準(zhǔn)確性，請(qǐng)參考 提供的英文版資料。 ABSOLUTEUMRATINGS—SupplyVoltage VtoV+(Note (VCC-0.3V)toV-(Note +0.3VtoInput -0.3Vto(VCC-RIN(Except RIN TOUT(ExceptMAX220)(Note 0.3Vto(VCC+Driver/ReceiverOutputShortCircuitedto ContinuousPowerDissipation(TA=16-PinPlasticDIP(derate10.53mW/°Cabove+70°C)

18-PinPlasticDIP(derate11.11mW/°Cabove+70°C)..889mW20-PinPlasticDIP(derate8.00mW/°Cabove+70°C)..440mW16-PinNarrowSO(derate8.70mW/°Cabove+70°C)...696mW16-PinWideSO(derate9.52mW/°Cabove+70°C)762mW18-PinWideSO(derate9.52mW/°Cabove+70°C)20-PinWideSO(derate10.00mW/°Cabove 20-PinSSOP(derate8.00mW/°Cabove 16-PinCERDIP(derate10.00mW/°Cabove 18-PinCERDIP(derate10.53mW/°Cabove OperatingTemperatureMAX2__AC__,MAX2__C_ 0°CtoMAX2__AE__,MAX2__E_ ..-40°CtoMAX2__AM__,MAX2__M_ ..-55°CtoStorageTemperature ..-65°CtoLeadTemperature(soldering,10s)(Note Note1:FortheMAX220,V+andV-canhaveaummagnitudeof7V,buttheirabsolutedifferencecannotexceedNote2:InputvoltagemeasuredwithTOUTinhigh-impedancestate,SHDNorVCC=Note3:umreflowtemperaturefortheMAX225_WIandMAX233A_WPisStressesbeyondthoselistedunder“AbsoluteumRatings”maycausepermanentdamagetothedevice.Thesearestressratingsonly,andfunctionaloperationofthedeviceattheseoranyotherconditionsbeyondthoseindicatedintheoperationalsectionsofthespecificationsisnotimplied.Exposuretoabsoluteumratingconditionsforextendedperiodsmayaffectdevicereliability.ELECTRICALCHARACTERISTICS—(VCC=+5V±10%,C1–C4=0.1μF?MAX220,C1=0.047μF,C2–C4=0.33μF,TA=TMINtoTMAX?unlessotherwiseRS-232OutputVoltageAlltransmitteroutputsloadedwith3ktoVInputLogicThresholdVInputLogicThresholdAlldevicesexcept2VMAX220:VCC=LogicPullup/lnputAllexceptMAX220,normal5SHDN=0V,MAX222/MAX242,shutdown,OutputLeakageVCC=5.5V,SHDN=0V,VOUT=±15V,VCC=SHDN=VOUT=MAX220,VOUT=DataTransmitterOutputVCC=V+=V-=0V,VOUT=OutputShort-CircuitVOUT=VOUT=RS-232RS-232InputVoltageOperatingVRS-232InputThresholdVCC=AllexceptMAX243VMAX243R2IN(Note-RS-232InputThresholdVCC=AllexceptMAX243VMAX243R2IN(Note-- CHARACTERISTICS— (VCC=+5V±10%,C1–C4=0.1μF?MAX220,C1=0.047μF,C2–C4=0.33μF,TA=TMINtoTMAX?unlessotherwiseRS-232InputAllexceptMAX220/MAX243,VCC=5V,nohysteresisinSHDN1V1RS-232InputTA=+25°C357357TTL/CMOSOutputVoltageIOUT=VIOUT=1.6mATTL/CMOSOutputVoltageIOUT=- VCC-VTTL/CMOSOutputShort-CircuitSourcingVOUT=--ShrinkingVOUT=TTL/CMOSOutputLeakageSHDN=VCCorEN=VCC(SHDN=0VforMAX222),0VVOUTVCCENInputThresholdVENInputThresholdVOperatingSupplyVVCCSupplyCurrent(SHDN=VCC),figures5,6,11,19No 43kloadbothShutdownSupplyTA=TA=0°Cto2TA=-40°Cto2TA=-55°CtoSHDNInputLeakageSHDNThresholdVSHDNThresholdVTransitionSlewCL=50pFto2500pF,RL=to7k,VCC=5V,TA=+25°C,measured+3Vto-3Vor-63TransmitterPropagationDelayTLLtoRS-232(NormalOperation),Figure45Note4:MAX243R2OUTisguaranteedtobelowwhenR2INis0Voris CHARACTERISTICS— (VCC=+5V±10%,C1–C4=0.1μF?MAX220,C1=0.047μF,C2–C4=0.33μF,TA=TMINtoTMAX?unlessotherwiseReceiverPropagationDelayRS-232toTLL(NormalOperation),Figure2 ReceiverPropagationDelayRS-232toTLL(Shutdown),Figure2Receiver-OutputEnableTime,FigureReceiver-OutputDisableTime,FigureTransmitter-OutputEnableTime(SHDNGoesHigh),Figure4MAX222/MAX242,caps(includescharge-pumpTransmitter-OutputDisableTime(SHDNGoesLow),Figure40.1μFTransmitter+to-PropagationDelayDifference(NormalOperation)tPHLT-Receiver+to-PropagationDelayDifference(NormalOperation)tPHLR-

典型86OUTPUTOUTPUTVOLTAGE20-----

OUTPUTVOLTAGEvs.LOADEITHERV+ORV-VCC= NOLOADONTRANSMITTEROUTPUTS(EXCEPTMAX220,V-LOADED,NOLOADON 1F V+LOADED,NOLOADON

vs.DATARATEOUTPUTOUTPUTLOADCURRENTFLOWSFROMV+TOALLVCC=VCC=OUTPUTCURRENTOUTPUTCURRENT87654

V+,V-V+,V-VOLTAGE-

0.1F0.1F1F0.1F LOADCURRENT(mA) ABSOLUTEUMRATINGS— Vto (VCC-0.3V)to +0.3Vto-Input 0.3Vto(VCC+ Output (V++0.3V)to(V-- 0.3Vto(VCC+Short-CircuitDuration, ContinuousPowerDissipation(TA=14-PinPlasticDIP(derate10.00mW/°Cabove 16-PinPlasticDIP(derate10.53mW/°Cabove 20-PinPlasticDIP(derate11.11mW/°Cabove 24-PinNarrowPlastic(derate13.33mW/°Cabove 24-PinPlasticDIP(derate9.09mW/°Cabove 16-PinWideSO(derate9.52mW/°Cabove

20-PinWideSO(derate1000mW/°Cabove 24-PinWideSO(derate11.76mW/°Cabove 28-PinWideSO(derate12.50mW/°Cabove 44-PinPlasticFP(derate11.11mW/°Cabove 14-PinCERDIP(derate9.09mW/°Cabove 16-PinCERDIP(derate10.00mW/°Cabove 20-PinCERDIP(derate11.11mW/°Cabove 24-PinNarrow(derate12.50mW/°Cabove 24-PinSidebraze(derate20.0mW/°Cabove 28-PinSSOP(derate9.52mW/°Cabove OperatingTemperatureMAX2__C_ 0°CtoMAX2__E_ ..-40°CtoMAX2__M_ ..-55°CtoStorageTemperature ..-65°CtoLeadTemperature(soldering, Stressesbeyondthoselistedunder“AbsoluteumRatings”maycausepermanentdamagetothedevice.Thesearestressratingsonly,andfunctionaloperationofthedeviceattheseoranyotherconditionsbeyondthoseindicatedintheoperationalsectionsofthespecificationsisnotimplied.Exposuretoabsoluteumratingconditionsforextendedperiodsmayaffectdevicereliability.ELECTRICALCHARACTERISTICS—(MAX223/230/232/234/236/237/238/240/241,VCC=+5V±10;MAX233/MAX235,VCC=5V±5%?C1–C4=1.0μF;VCC=5V±10%;V+=7.5Vto13.2V;TA=TMINtoTMAX;unlessotherwiseOutputVoltageAlltransmitteroutputsloadedwith3ktoVVower-SupplyNoTA=57 V+Power-Supply 5ShutdownSupplyTA=1InputLogicThresholdTIN;EN,SHDN(MAX233);EN,SHDNVInputLogicThresholdVEN,SHDNEN,SHDNLogicPull-UpTIN=ReceiverInputVoltageOperatingRange-VELECTRICALCHARACTERISTICS—MAX223/MAX230–MAX241(MAX223/230/232/234/236/237/238/240/241,VCC=+5V±10;MAX233/MAX235,VCC=5V±5%?C1–C4=1.0μF;VCC=5V±10%;V+=7.5Vto13.2V;TA=TMINtoTMAX;unlessotherwiseRS-232InputThresholdTA=+25°C,VCC=5VNormalSHDN=5VSHDN=0VVShutdown(MAX223)SHDN=0V,EN=5V(R4IN,RS-232InputThresholdTA=+25°C,VCC=5VNormalSHDN=5VSHDN=0VVShutdown(MAX223)SHDN=0V,EN=5V(R4IN?RS-232InputVCC=5V,nohysteresisinVRS-232InputTA=+25°C,VCC=357TTL/CMOSOutputVoltageIOUT=1.6mA(MAX231/232/233,IOUT=VTTL/CMOSOutputVoltageIOUT=- VCC-VTTL/CMOSOutputLeakage0VROUTVCC;EN=0V(MAX223);EN=VCC(MAX235–241)ReceiverOutputEnableReceiverOutputDisablePropagationRS-232INtoCL=150pFNormalSHDN=0V46TransitionRegionSlewMAX223/MAX230/MAX234–241,TA=+25°C,VCC=RL=3kto7k?CL=50pFto2500pF,measured+3Vto-3Vor-3Vto3MAX231/MAX232/MAX233,TA=+25°C,VCC=RL=3kto7k,CL=50pFto2500pF,measured+3Vto-3Vor-3Vto4TransmitterOutputVCC=V+=V-=0V,VOUT=TransmitterOutputShort-CircuitVOHVOH4-6-VOLVOL----9

TRANSMITTEROUTPUTVOLTAGE(VOH)vs.5VCCTRANSMITTEROUTPUTVOLTAGE(VOL)vs.

TRANSMITTEROUTPUTVOLTAGE(VOH)vs.LOADCAPACITANCEATDIFFERENTDATARATESTA=+25°CC1–C4=1FTRANSMITTERSLOADS3k||VCC=3TRANSMITTERSRL=3kVOHVOH65 LOADCAPACITANCETRANSMITTEROUTPUTVOLTAGE(VOL)vs.LOADCAPACITANCEATDIFFERENTDATARATESVCC=3TRANSMITTERSRL=3k4TRANS-TA=+25°CMITTERSC1–C4=1F LOADS3k||-6-VOLVOL--7-7--7

12SLEWSLEWRATE4864V+,V+,V-0-----

典型TRANSMITTERLOADEDTATRANSMITTERLOADEDTA=VCC=+5VLOADED,RL=3kC1–C4=1F LOADCAPACITANCETA=+25°CVCC=+5VV-ONV+NOLOADONV-ALLTRANSMITTERS4 051015202530354045VCC LOADCAPACITANCEV+,V-WHENEXITINGSHUTDOWN(1FCAPACITORS)

*SHUTDOWNPOLARITYISFORNONMAX241 ABSOLUTEUMRATINGS—SupplyVoltage VtoInputTIN?ENA,ENB,ENR,ENT,ENRB,ENTA, 0.3Vto(VCC+ TOUT(Note 0.3Vto(VCC+ShortCircuit(oneoutputataTOUTto ROUTto

ContinuousPowerDissipation(TA=28-PinWideSO(derate12.50mW/°Cabove 40-PinPlasticDIP(derate11.11mW/°Cabove 44-PinPLCC(derate13.33mW/°Cabove OperatingTemperatureMAX225C__,MAX24_C_ 0°CtoMAX225E__,MAX24_E_ ..-40°CtoStorageTemperature ..-65°CtoLeadTemperature Note4:Inputvoltagemeasuredwithtransmitteroutputinahigh-impedancestate,shutdown,orVCC=Stressesbeyondthoselistedunder“AbsoluteumRatings”maycausepermanentdamagetothedevice.Thesearestressratingsonly,andfunctionaloperationofthedeviceattheseoranyotherconditionsbeyondthoseindicatedintheoperationalsectionsofthespecificationsisnotimplied.Exposuretoabsoluteumratingconditionsforextendedperiodsmayaffectdevicereliability.ELECTRICALCHARACTERISTICS—(MAX225,VCC=5.0V±5%;MAX244–MAX249,VCC=+5.0V±10%,externalcapacitorsC1–C4=1μF;TA=TMINtoTMAX;unlessoth-erwisenoted.)RS-232InputLogicThresholdVInputLogicThreshold2VLogicPull-Up/lnputTablesNormalDataTables1a–1d,normalOutputVoltageAlltransmitteroutputsloadedwith3ktoVOutputLeakageCurrentTablesENA,ENB,ENT,ENTA,ENTB=VCC,VOUT=±15VVCC=0V,VOUT=±15VTransmitterOutputVCC=V+=V-=0V,VOUT=±2V(NoteOutputShort-CircuitVOUT=RS-232RS-232InputVoltageOperatingVRS-232InputThresholdVCC=VRS-232InputThresholdVCC=VRS-232InputVCC=VRS-232Input357TTL/CMOSOutputVoltageIOUT=VTTL/CMOSOutputVoltageIOUT=- VCC-VTTL/CMOSOutputShort-CircuitSourcingVOUT=--ShrinkingVOUT=TTL/CMOSOutputLeakageNormaloperation,outputsTables1a–1d,0VVOUTVCC,ENR_=ELECTRICALCHARACTERISTICS—MAX225/MAX244–MAX249(MAX225,VCC=5.0V±5%;MAX244–MAX249,VCC=+5.0V±10%,externalcapacitorsC1–C4=1μF;TA=TMINtoTMAX;unlessoth-erwisenoted.)POWERSUPPLYANDCONTROLOperatingSupplyVVCCSupplyCurrent(NormalNo3kloadsonalloutputsShutdownSupplyTA=8TA=TMINtoControlLeakageThresholdVThresholdACTransitionSlewCL=50pFto2500pF,RL=3kto7k,VCC=TA=+25°C,measuredfrom+3Vto-3Vor-3Vto5TransmitterPropagationTLLtoRS-232(NormalOperation),Figure1ReceiverPropagationTLLtoRS-232(NormalOperation),Figure2ReceiverPropagationTLLtoRS-232(Low-PowerMode),Figure2Transmitter+to-DelayDifference(NormaltPHLT-Receiver+to-DelayDifference(NormaltPHLR-Receiver-OutputEnableTime,FigureReceiver-OutputDisableTime,FigureTransmitterEnable(excludescharge-pump5(includescharge-pumpTransmitterDisableTime,FigureNote5:The300minimumspecificationcomplieswithEIA/TIA-232E,buttheactual wheninshutdownmodeorVCC=0Vis10Masisimpliedbytheleakagespecification.

典型VCC=VCC=1FCAPACITORS40kb/sDATA8TRANSMITTERSLOADEDWITH642 LOADCAPACITANCE

86OUTPUTOUTPUTVOLTAGE20-----

OUTPUTvs.LOADCURRENTFORV+ANDV+V+ANDV-V=EXTERNALCHARGEPUMP1FCAPACITORS8TRANSMITTERSDRIVING5k2000pATV-V-V+ANDV-V+ LOADCURRENT

V+,VV+,V

TRANSMITTEROUTPUTVOLTAGE(V+,V-)vs.LOADCAPACITANCEATDIFFERENTDATARATESVCC=5VWITHALLTRANMITTERSVCC=5VWITHALLTRANMITTERSOADEDWTHLOADCAPACITANCETRANSMITTERSLEWRATE*EXCEPTFORR2ONTHEMAX243WHERE-3VISUSED.RXOUTc)DISABLEVOL+VOH-OUTPUTDISABLETIMEENEN OUTPUTENABLETIME+3-OUTPUTDISABLETIMESHDNRXVCC-RXVCC-a)TESTb)ENABLEa)TIMING1OR1ORVCC-b)TEST圖3.輸出使能與禁用時(shí) 圖4.發(fā)送器輸出禁用時(shí)表1a.MAX245控制引腳配置OPERATION00NormalAllAll01NormalAllAll3-10All3-AllLow-PowerReceive11All3-All3-表1b.MAX24500NormalAllAllAllAll01NormalAllAllRA1–RA43-RA5RB1–RB43-RB510All3-All3-AllLow-PowerReceiveAllLow-PowerReceive11All3-All3-RA1–RA43-ReceiveModeRB1–RB43-ReceiveMode表1c.MAX246控制引00NormalAllAllAllAll01NormalAllAll3-AllRB1–RB43-RB510All3-AllRA1–RA43-RA5All11All3-All3-RA1–RA43-ReceiveModeRB1–RB43-ReceiveMode表 MAX247/MAX248/MAX249控制引腳配0000NormalAllAllAllAll0001NormalAllAllAllAll3-State,exceptRB5staysactiveon0010NormalAllAllAll3-All0011NormalAllAllAll3-All3-State,exceptRB5staysactiveon0100NormalAllAll3-AllAll0101NormalAllAll3-AllAll3-State,exceptRB5staysactiveon0110NormalAllAll3-All3-All0111NormalAllAll3-All3-All3-State,exceptRB5staysactiveon1000NormalAll3-AllAllAll1001NormalAll3-AllAllAll3-State,exceptRB5staysactiveon1010NormalAll3-AllAll3-All1011NormalAll3-AllAll3-All3-State,exceptRB5staysactiveon1100All3-All3-ReceiveModeReceiveMode1101All3-All3-ReceiveModeAll3-State,exceptRB5staysactiveon1110All3-All3-All3-ReceiveMode1111All3-All3-All3-All3-State,exceptRB5staysactiveonMAX220MAX249包含4個(gè)部分：雙路電荷泵DCDC電壓轉(zhuǎn)換器、RS232驅(qū)動(dòng)器、RS232，以 MAX249有兩個(gè)電荷泵，將+5V轉(zhuǎn)換±10V空載)，為RS232驅(qū)動(dòng)器提供工作電壓。第一個(gè)轉(zhuǎn)換器利用電容C1將+5V輸入加倍，得到V+輸出端C3上的+10V；第二個(gè)轉(zhuǎn)換器利用電容C2將+10V轉(zhuǎn)換為V輸出端C4上的10V?？梢詮?10V(V+)和10V(V)輸出端獲取少量的電源功率，為外部電路供電(參見典型工作特性部分)；但MAX225與MAX245MAX247例外，因?yàn)樗鼈儾惶峁┻@些引腳。V+與V穩(wěn)壓，所以輸出電壓會(huì)隨負(fù)載電流的增大而下降。當(dāng)V+、V為外部電路提供電流時(shí)，注意不要因?yàn)樗迂?fù)載的原因使V+、V低于EIA/TIA232E驅(qū)動(dòng)器輸出電壓最小值±5V的限制。MAX240、MAX241以及MAX245MAX249上的關(guān)斷功能時(shí)，應(yīng)避免V+與V為外部電路供電。這些器件關(guān)斷時(shí)，V降至0V，V+降至+5V。對(duì)于那些能夠?qū)?10V外部電源提供到V+引腳(而不是使用電荷泵來產(chǎn)生+10V)的應(yīng)用，一定不要安裝電C1，并且必須SHDN引腳連接至VCC，這是因?yàn)樵陉P(guān)斷模式下V+被連接到VCC。如果負(fù)載是標(biāo)稱值為5k?的RS232，并且VCC+5V時(shí)，驅(qū)動(dòng)器輸出電壓擺幅的典型值為±8V。輸出擺幅確保符合EIA/TIA232E和V.28規(guī)范，該規(guī)范要求在最糟糕的情況下能夠滿足±5V驅(qū)動(dòng)器輸出電壓最小值的要求，其中包括3k?的負(fù)載電阻最小值，VCC=+4.5V，以及最高工作溫度?？蛰d時(shí)驅(qū)動(dòng)器輸出電壓范圍是(V+1.3V)至V+0.5V)。輸入門限兼容于TTL和CMOS邏輯。未使用的驅(qū)動(dòng)器輸入端可以不連接，有內(nèi)置的、與VCC相連的400k?輸入上拉電阻(MAX220除外)。上拉電阻將未使用的驅(qū)動(dòng)器輸出端強(qiáng)制為低電平，因?yàn)樗序?qū)動(dòng)器都是反相的。除了在上拉被禁用的關(guān)斷模式下，輸入上拉電阻通常消耗12A

斷開的情況下，驅(qū)動(dòng)器輸出關(guān)閉，并進(jìn)入高阻狀態(tài)，該狀態(tài)下的漏電流通常只有幾個(gè)微安最大值為25μA)出可以被驅(qū)動(dòng)到15V。在關(guān)斷模式下，電源電流通常降至8μA。MAX220不具備上拉電阻，所以不能將未使用的驅(qū)動(dòng)器輸出強(qiáng)制為低電平，請(qǐng)將未使用的輸入端連接至D或VCC。MAX235、MAX236、MAX240MAX241同時(shí)具備接器三態(tài)控制與低功耗關(guān)斷控制。表2說明了關(guān)斷控制與接只要三態(tài)使能線為高電平(對(duì)于MAX225/MAX235/ MAX241)，TTL/CMOS輸就處于高阻、三態(tài)模式；另外，當(dāng)關(guān)斷控制線為高電1μA，同時(shí)驅(qū)動(dòng)器輸出被拉至地。驅(qū)動(dòng)器輸出漏電流始終小于1AV至(VCC+6V0.V1串抗可箝約VCC+具有1?驅(qū)動(dòng)器輸出擺率限制在30V/μs以內(nèi)，與EIA/TIA232E和與2500pF負(fù)載下10V/μs。EIA/TIA232E與V.28規(guī)范將大于3V的電壓定義為邏輯和2.4V，驅(qū)動(dòng)器既響應(yīng)TTL電平輸入，也響應(yīng)EIA/TIA232E與V.28電平。輸入可以承受最高±25V的過壓輸入，并提供標(biāo)稱值為5k?的輸入端接電阻。符合V.28和EIA/TIAXHighImpedanceHighHighImpedanceHighImpedanceHigh輸入滯回的典型值為0.5V，并可確保0.2V最小值。這樣，對(duì)于慢變化輸入信號(hào)可以產(chǎn)生明確的輸出跳變，即使是在有一定噪聲和振蕩的情況下。傳輸延時(shí)典型值為60sMAX223、MAX242以及MAX245MAX249具有低功接收模式，可以使C進(jìn)入關(guān)斷狀態(tài)，但仍允許器件接收信息。這對(duì)周期性喚醒工作的應(yīng)用非常重要。在低功耗接收模式下，系統(tǒng)仍然可以接收喚醒器件的指令信號(hào)，使其準(zhǔn)備就緒、進(jìn)行高數(shù)據(jù)速率的通信。這種操作可以個(gè)輸入之一的RS232電纜故障保護(hù)。這意味著CTS與RTS等控制線可以被驅(qū)動(dòng)或懸空，而不會(huì)中斷通沒有電纜故障保護(hù)的輸入門限是0.8V，而不+1.4V。只有當(dāng)輸入與有源驅(qū)動(dòng)為負(fù)的控制線相連時(shí)，輸出才變?yōu)檎?。若沒有驅(qū)動(dòng)，則缺省狀態(tài)為0，或“允許發(fā)送”狀態(tài)。通常，MAX243的另一個(gè) (+1.4V門限)用于數(shù)據(jù)線TD或RD，而負(fù)門限 與控制線T、TTTS等)連。RS232系列的其他產(chǎn)品按照EATIA232E規(guī)范的規(guī)定，采用可選的電纜故障保護(hù)。這意味著只要輸入被驅(qū)動(dòng)為負(fù)、懸空或短路至地時(shí)，輸出就變?yōu)楦唠娖?。高電平的輸出通知串行通信IC停止發(fā)送數(shù)據(jù)。為避免這種情況，控制線必須被驅(qū)動(dòng)或與跳線連接，使其具有一定

與MAX241的所有都被禁用。當(dāng)處于關(guān)斷狀態(tài)時(shí)，MAX223與MAX242的兩個(gè) 在低功耗模式下保持工作狀態(tài)。在這樣的條件下，對(duì)于由高到低的輸入跳變，傳輸延時(shí)增加到大約2.5μs。關(guān)斷狀態(tài)下，接收器作為沒有滯回的CMOS反相器工作。MAX223與MAX242還具有使能輸入端(在MAX242中是EN、MAX223中是EN)，使的輸出控制與HDN無關(guān)(在MAX241中是SHDN。所有其他器件的SHDN在A21中是DN)也可輸。MAX225提供5個(gè)發(fā)送器和5個(gè)；MAX245提供個(gè)和8個(gè)發(fā)送器。這兩種器件都具有獨(dú)立與發(fā)送器使能控制。當(dāng)ENT輸入端作用有邏輯高電平時(shí)，電荷泵關(guān)閉并且器件關(guān)斷。在這種狀態(tài)下，電源電流降至25A以內(nèi)，而低功耗接模式下保三態(tài)模式A25有5個(gè)都由NR輸入控。AX245的8個(gè)輸出由NR輸入控制，而另外兩個(gè)RA5與RB5)NRRA1RA4RB1RB4MAX225以及MAX245MAX249具有發(fā)送器和使正常有效禁用)以及低功耗接收(以較低的數(shù)據(jù)速率使繼續(xù)保持有效)。使能輸入端控制全速接收和三態(tài)模式。發(fā)送器具有兩種工作模式：全速發(fā)送(正常有效)和三態(tài)禁用發(fā)送器被禁用時(shí)，器件進(jìn)入關(guān)斷模式。器件關(guān)斷時(shí)，有效的工作在低功耗接收模式下。1a1d定義了控制狀態(tài)。MAX244沒有控制引腳，因此分別控制器件的兩側(cè)。A側(cè)控制輸入(ENA)為邏輯高電平時(shí)，使4個(gè)A側(cè)的和驅(qū)動(dòng)器進(jìn)入三態(tài)模式；同理，B側(cè)控制輸入(ENB)可以使B側(cè)的驅(qū)動(dòng)器與 態(tài)模式。而在MAX245中，一個(gè)A側(cè)的 側(cè)的(RA5與RB5)將始終保持有效。當(dāng)A側(cè)、B側(cè)都被禁用(ENA=ENB=+5V)時(shí)，整個(gè)器件進(jìn)入關(guān)斷MAX247提供9個(gè) 和8個(gè)驅(qū)動(dòng)器，帶4個(gè)控制引腳。ENRA、ENRB是 使能輸入端，分別控制4輸出。ENTA、ENTB是發(fā)送器使能輸入端，分別控制4個(gè)驅(qū)動(dòng)器。第9個(gè)RB5始終有效。該器件在TA與B為輯電平進(jìn)關(guān)模式。MAX248提供8個(gè) 和8個(gè)驅(qū)動(dòng)器，帶4個(gè)控制引 使能輸入端，分別控制4

輸出。NTA、NTB是發(fā)送器使能輸入端，分別控制4驅(qū)器該器中有終有的該件在NTA、NTBMAX249提供10個(gè) 和6個(gè)驅(qū)動(dòng)器，帶4個(gè)控制引腳。NRA、ENRB是 使能輸入端，分別控制5輸出。NTA、NTB是發(fā)送器使能輸入端，分別控制3個(gè)驅(qū)器。該器中沒有終有效的。該件在NTA、NB均為邏輯高電平時(shí)進(jìn)入關(guān)斷模式，同時(shí)發(fā)送器進(jìn)入三態(tài)模式。在關(guān)斷模式下，保持有效的接收器作低功接模式最數(shù)速率為20bs。圖5至圖25給出了引腳配置與典型工作電路。在對(duì)電源噪聲敏感的應(yīng)用中，VCC可以用與C1、C2數(shù)值相同123456789CAPACITANCEC10.047001.0110.1+5VTOP+5VTOP13+5VTO+10VV+245C2-VOLTAGE+10VTO-V--11T1OUT10T2OUT12R1IN9 R2INTOP+5VINPUTC3ALLCAPACITORS=23(N.C.)(N.C.)EN1817VCCC1-VOLTAGE+5VTO76+10VTO-2C2-VOLTAGE-12T1IN11(EXCEPTT1OUT6(EXCEPTT2OUT13R1INR2IN101(N.C.) ()AREFORMAX222PINNUMBERSINTYPICALOPERATINGCIRCUITAREFORDIP/SOPACKAGES圖6.MAX222/MAX242引腳配置與典型126TOP

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MAX225FUNCTIONAL552CONTROL1RECEIVERENABLE1TRANSMITTERENABLE

71

PINS(ENR,GND,VCC,T5OUT)AREINTERNALLYCONNECTED.CONNECTEITHERORBOTHEXTERNALLY.T5OUTISASINGLEDRIVER.

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圖7.MAX225引腳配置與典型工作電TOP

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SHDN25圖8.MAX223/MAX241引腳配置與典型126+5VTOP1+5VTOP18107+5VTO+10V+10VTO-10VV+5T1OUT4T2OUTT3OUT15T4OUT19T5OUTN.C.x6+5VTOP1+75VTO12C+13+12VTO-12VV+143C-8V-4R2IN7109T2OUT4R1IN6R2INPINNUMBERSIN()AREFORSO圖10.MAX231引腳配置與典型工作電121234589RS-126+5V1TOP+5V1TOP7 2T1OUT1T2OUT3R1IN(V+)V+(C1-C1-20R2INV-C2+(C2-DONOT8(13)(V-)CONNECTIONSTO13(14)THESEPINS12INTERNAL- 175kC2+11C2+C2-10INTERNAL+10V14(8)69()AREFORSOPACKAGE+5VTOP176+5VTO+10V18191T1OUT161011+10VTO-10V14T1OUTT1INGNDVCCC1+V+1312111093T2OUT13T3OUT14T4OUT523圖12.MAX234引腳配置與典型工作電TOP 1

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圖13.MAX235引腳配置與典型工作電TOP

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圖15.MAX237引腳配置與典型工作電TOP

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圖16.MAX238引腳配置與典型工作電TOP

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