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文库下载 免费文档下载 http://www.wenkuxiazai.com/ 本文档下载自文库下载网,内容可能不完整,您可以点击以下网址继续阅读或下载: http://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.html MAX6340UK16-T 中文资料 19-2440; Rev 4; 12/05 Low-Power, SC70/SOT ?P Reset Circuits withCapacitor-Adjustable Reset Timeout Delay General Description Features The MAX6340/MAX6421–MAX6426 low-power micro-processor supervisor circuits monitor system voltages?Monitor System Voltages from 1.6V to 5Vfrom 1.6V to 5V. These devices perform a single function:?Capacitor-Adjustable Reset Timeout Periodthey assert a reset signal whenever the VCCsupply volt-age falls below its reset threshold. The reset output?Low Quiescent Current (1.6?A typ)remains asserted for the reset timeout period after V?Three RESET Output Options rises above the reset threshold. The reset timeout is exter-CCPush-Pull RESETnally set by a capacitor to provide more flexibility.Push-Pull RESETThe MAX6421/MAX6424 have an active-low, push-Open-Drain RESETpull reset output. The MAX6422 has an active-high,push-pull reset output and the MAX6340/MAX6423/?Guaranteed Reset Valid to VCC= 1VMAX6425/MAX6426 have an ahttp://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.htmlctive-low, open-drain?Immune to Short VCCTransients reset output. The MAX6421/MAX6422/MAX6423 areoffered in 4-pin SC70 or SOT143 packages. 文库下载 免费文档下载 http://www.wenkuxiazai.com/ The?Small 4-Pin SC70, 4-Pin SOT143, and 5-Pin SOT23MAX6340/MAX6424/MAX6425/MAX6426 are availablePackagesin 5-pin SOT23-5 packages. ?MAX6340 Pin Compatible with LP3470?MAX6424/MAX6425 Pin Compatible withNCP300–NCP303, MC33464/MC33465,S807/S808/S809, and RN5VDPortable Equipment ?MAX6426 Pin Compatible with PST92XX Battery-Powered Computers/ControllersOrdering Information AutomotiveMedical EquipmentIntelligent InstrumentsEmbedded ControllersCritical ?P MonitoringSet-Top BoxesComputers Typical Operating Circuit appears at end of data sheet. Note: The MAX6340/MAX6421–MAX6426 are available with fac-tory-trimmed reset thresholds from 1.575V to 5.0V in approxi-mately 0.1V increments. Insert the desired nominal resetthreshold suffix (frohttp://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.htmlm Table 1) into the blanks. There are 50 stan-dard versions with a required order increment of 2500 pieces.Sample stock is generally held on standard versions only (seeStandard Versions Table). Required order increment is 10,000pieces for nonstandard versions. Contact factory for availability.All devices are available in tape-and-reel only. Devices are available in both leaded and lead-free packaging.Specify lead-free by replacing "-T" with " T" when ordering.Selector Guide appears at end of data sheet. ________________________________________________________________Maxim Integrated Products 文库下载 免费文档下载 http://www.wenkuxiazai.com/ 1 For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. MAX6340/MAX6421–MAX6426 Low-Power, SC70/SOT ?P Reset Circuits withCapacitor-Adjustable Reset Timeout Delay MAX6340/MAXhttp://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.html6421–MAX 6426 ABSOLUTE MAXIMUM RATINGS All Voltages Referenced to GND VCC........................................................................-0.3V to 6.0VSRT, 0.3V)RESET(open RESET, RESET (push-pull).................-0.3V to drain)...............................................-0.3V 6.0VInput Current pins)......................................................±20mAOutput (VCC to (all Current (RESET, RESET)......................................±20mA Continuous Power Dissipation (TA= 70°C) 4-Pin SC70 (derate 3.1mW/°C above 70°C)..............245mW4-Pin SOT143 (derate 4mW/°C above 70°C).............320mW5-Pin SOT23 (derate 7.1mW/°C above 70°C)............571mWOperating Temperature Range.........................-40°C to 125°CStorage Temperature Range.............................-65°C to 文库下载 免费文档下载 http://www.wenkuxiazai.com/ 150°CJunction Temperature...................................................... 150°CLead http://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.htmlTemperature (soldering, 10s)................................. 300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functionaloperation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure toabsolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS 2_______________________________________________________________________________ ________ Low-Power, SC70/SOT ?P Reset Circuits withCapacitor-Adjustable Reset Timeout Delay (VCC= 5V, CSRT= 1500pF, TA = 25°C, unless otherwise noted.) SUPPLY CURRENTRESET TIMEOUT PERIODvs. SUPPLY VOLTAGE RESET TIMEOUT PERIOD vs. CSRT vs. TEMPERATURE 4.010,0002 4.30 文库下载 免费文档下载 http://www.wenkuxiazai.com/ 0cot http://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.html63.52/1246) ) Xs 1000 sA) mMmA3.0(( 4.25 ? DD( OTINOIRRE2.5EERP100 P R2.0TTUUUCO4.20 YOEEL1.5MMPIIPT10 T UTTSEE1.0SSEERR4.15 1 0.500.14.10 1 2 文库下载 免费文档下载 http://www.wenkuxiazai.com/ 3 4 56 0.001 0.01 0.1 110 100 1000 -50 -25 25 50 75 文库下载 免费文档下载 http://www.wenkuxiazai.com/ 100 125 SUPPLY VOLTAGE (V) CSRT (nF) TEMPERATURE (°C) RESET TIMEOUT PERIOD MAXIMUM TRANSIENT DURATIONVvs. TEMPERATURE CC TO RESET DELAY vs. RESET THRESHOLD OVERDRIVE vs. TEMPERATURE (VCC FALLING) 600175160 550150 150)s) ?s?)(500s (D N125?140(OO IYRITAE450100L130PAE RTD UTO400UD EET75S120MNERI T 350EISOTNT 110EA50 SCECR300RTV10025025 文库下载 免费文档下载 http://www.wenkuxiazai.com/ http://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.html90 200 80-50 -25 25 50 75 100125 200 400 600 800 文库下载 免费文档下载 http://www.wenkuxiazai.com/ 1000 -50 -25 255075100 125 TEMPERATURE (°C)RESET THRESHOLD OVERDRIVE (mV) TEMPERATURE (°C) POWER-UP/POWER-DOWN NORMALIZED RESET THRESHOLD CHARACTERISTIC vs. TEMPERATURE 8 1.0060cot 62/1D 24L1.0046OXAHMSER1V/div 文库下载 免费文档下载 http://www.wenkuxiazai.com/ H1.002T TESER1.000 DEZILA0.998MRON1V/div 0.9960.994 400?s/div -50-250255075100125 TEMPERATURE (°C) ________________________________________________________________________________ _______3 MAX6340/MAX6421–MAX6426 Low-Power, SC70/SOT ?P Reset Circuits withCapacitor-Adjustable Reset Timeout Delay MAX6340/MAX6421–MAX6426 Dhttp://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.htmletailed Description Reset Output The reset output is typically connected to the reset inputof a ?P. A ?P’s reset input starts or restarts the ?P in aknown state. The MAX6340/MAX6421–MAX6426 ?Psupervisory circuits provide the reset logic to preventcode-execution errors during power-up, power-down,and brownout conditions (see Typical OperatingCharacteristics). RESETchanges from high to low whenever VCCdropsbelow the threshold voltage. Once 文库下载 免费文档下载 http://www.wenkuxiazai.com/ VCCexceeds thethreshold voltage, RESETremains low for the capacitor-adjustable reset timeout period. The MAX6422 active-high RESET output is the inverselogic of the active-low RESEToutput. All device outputsare guaranteed valid for VCC> 1V. The MAX6340/MAX6423/MAX6425/MAX6426 are open-drain RESEToutputs. Connect an external pullup resis-tor to any supply from 0 to 5.5V. Select a resistor valuelarge enough to register a logic low RESETisassertedhttp://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.html when and small enough to register a logic highwhile supplying all input current and leakage pathsconnected to the RESETline. A 10k?to 100k?pullupis sufficient in most applications. Figure 1. MAX6340/MAX6423/MAX6425/MAX6426 Open-DrainRESETOutput Allows Use with Multiple Supplies Selecting a Reset Capacitor The reset timeout period is adjustable to accommodatea variety of ?P applications. Adjust the reset timeoutperiod (tRP) by connecting a capacitor (CSRT) betweenSRT and ground. Calculate the reset timeout capacitoras follows: 4_______________________________________________________________________________ ________ Low-Power, SC70/SOT ?P Reset Circuits withCapacitor-Adjustable Reset Timeout Delay CSRT= (tRP- 275?s) / (2.73 ?106) 文库下载 免费文档下载 http://www.wenkuxiazai.com/ where tRPis in seconds and CSRTis in farads. The reset delay time is set by a current/capacitor-con-trolled ramp compared to an internahttp://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.htmll 0.65V reference.An internal 240nA ramp current source charges theexternal capacitor. The charge to the capacitor iscleared when a reset condition is detected. Once thereset condition is removed, the voltage on the capacitorramps according to the formula: dV/dt = I/C. The CSRTcapacitor must ramp to 0.65V to deassert the reset.CSRTmust be a low-leakage ( Interfacing to Other Voltages for Logic Compatibility The open-drain outputs of the MAX6340/MAX6423/MAX6425/MAX6426 can be used to interface to ?Ps withother logic levels. As shown in Figure 1, the open-drainoutput can be connected to voltages from 0 to 5.5V. Thisallows for easy logic compatibility to various ?Ps. MAX6340/MAX6421–MAX6426 Wired-OR Reset To allow auxiliary circuitry to hold the system in reset,an external open-drain logic signal can be connectedto the open-drain RESETof the MAX6340/MAX6423/MAX6425/MAX6426, ashttp://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.html shown in Figure 2. This config-uration can reset the ?P, but does not provide the resettimeout when the external logic signal is released.In addition to issuing a reset to the ?P during power-up,power-down, and brownout conditions, these supervisorsare relatively immune to short-duration negative-goingtransients (glitches). The graph Maximum 文库下载 免费文档下载 http://www.wenkuxiazai.com/ TransientDuration vs. Reset Threshold Overdrive in the TypicalOperating Characteristicsshows this relationship. The area below the curve of the graph is the region inwhich these devices typically do not generate a resetpulse. This graph was generated using a negative-going pulse applied to VCC, starting above the actualOperating as a Voltage Detector The MAX6340/MAX6421–MAX6426 can be operated in avoltage detector mode by floating the SRT pin. The resetdelay times for VCCrising above or falling below thethreshold are not significantly different. The reset output isdeassehttp://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.htmlrted smoothly without false pulses. Negative-Going VCCTransients reset threshold (VTH) and ending below it by the magni-tude indicated (reset-threshold overdrive). As the mag-nitude of the transient decreases (farther below thereset threshold), the maximum allowable pulse widthdecreases. Typically, a VCCtransient that goes 100mVbelow the reset threshold and lasts 50?s or less doesnot cause a reset pulse to be issued. Ensuring a Valid RESET or RESET Down to VCC= 0 When Ving (sourcing) capabilities decline drastically. In theCCfalls below 1V, RESET/RESET current-sink-case of the MAX6421/MAX6424, high-impedanceCMOS-logic inputs connected to RESETcan drift toundetermined voltages. This presents no problems inmost applications, since most ?Ps and other circuitrydo not operate with VCCbelow 1V. 文库下载 免费文档下载 http://www.wenkuxiazai.com/ In those applications where RESETmust be valid downto zero, adding a pulldown resistorhttp://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.html between RESETand ground sinks any stray leakage currents, holdingRESETlow (Figure 3). The value of the pulldown resis-tor is not critical; 100k?is large enough not to loadRESETand small enough to pull RESETto ground. Forapplications using the MAX6422, a 100k?pullup resis- ________________________________________________________________________________ _______ 5 Low-Power, SC70/SOT ?P Reset Circuits withCapacitor-Adjustable Reset Timeout Delay MAX6340/MAX6421–MAX6426 Figure 3. Ensuring RESETValid to VCC = 0 CC tor between RESET and VCCholds RESET high whenVCCfalls below 1V (Figure 4). Open-drain RESETver-sions are not recommended for applications requiringvalid logic for VCCdown to zero. Layout Consideration SRT is a precise current source. When developing thelayout for the application, be 文库下载 免费文档下载 http://www.wenkuxiazai.com/ careful to minimize boardcapacitance and leakage chttp://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.htmlurrents around this pin.Traces connected to SRT should be kept as short aspossible. Traces carrying high-speed digital signalsand traces with large voltage potentials should be rout-ed as far from SRT as possible. Leakage current andstray capacitance (e.g., a scope probe) at this pincould cause errors in the reset timeout period. Whenevaluating these parts, use clean prototype boards toensure accurate reset periods. 6 ________________________________________________________________________________ _______ Low-Power, SC70/SOT ?P Reset Circuits withCapacitor-Adjustable Reset Timeout Delay factory for availability of nonstandard versions. 7 MAX6340/MAX6421–MAX6426 Low-Power, SC70/SOT ?P Reset Circuits withCapacitor-Adjustable Reset Timeout Delay MAX6340/MAX6421–MAX6426 Chip Information TRANSISTOR COUNT: 295PROCESS: BiCMOS 8__________http://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.html_________ 文库下载 免费文档下载 http://www.wenkuxiazai.com/ ____________________________________________________________________ Low-Power, SC70/SOT ?P Reset Circuits withCapacitor-Adjustable Reset Timeout Delay Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,go to www.maxim-ic.com/packages.) ________________________________________________________________________________ _______9 MAX6340/MAX6421–MAX6426 Low-Power, SC70/SOT ?P Reset Circuits withCapacitor-Adjustable Reset Timeout Delay MAX6340/MAX6421–MAX6426 Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,go to www.maxim-ic.com/packages.) Maxim cannot assume responsibility for use of any circuitry circuitrhttp://www.wenkuxiazai.com/doc/4b32722a5901020207409cff.htmly other than entirely embodied in a Maxim product. No circuit patent licenses areimplied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 文库下载 免费文档下载 http://www.wenkuxiazai.com/ 10____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600?2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc. 文库下载网是专业的免费文档搜索与下载网站,提供行业资料,考试资料,教 学课件,学术论文,技术资料,研究报告,工作范文,资格考试,word 文档, 专业文献,应用文书,行业论文等文档搜索与文档下载,是您文档写作和查找 参考资料的必备网站。 文库下载 http://www.wenkuxiazai.com/ 上亿文档资料,等你来发现