MAX6321HPUK46CY-T资料

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元器件交易网www.cecb2b.com19-0496; Rev 7; 11/07

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

________________General Description

____________________________Features

The MAX6316–MAX6322 family of microprocessor (µP)♦Small 5-Pin SOT23 Package

supervisory circuits monitors power supplies andmicroprocessor activity in digital systems. It offers sev-♦Available in 26 Reset Threshold Voltages

2.5V to 5V, in 100mV Incrementseral combinations of push/pull, open-drain, and bidirec-tional (such as Motorola 68HC11) reset outputs, along♦Four Reset Timeout Periods

with watchdog and manual reset features. The Selector1ms, 20ms, 140ms, or 1.12s (min)Guidebelow lists the specific functions available from♦Four Watchdog Timeout Periods

each device. These devices are specifically designed6.3ms, 102ms, 1.6s, or 25.6s (typ) to ignore fast negative transients on VCC. Resets are♦Four Reset Output Stages

guaranteed valid for VCCdown to 1V.

Active-High, Push/PullActive-Low, Push/PullThese devices are available in 26 factory-trimmed resetActive-Low, Open-Drain threshold voltages (from 2.5V to 5V, in 100mV incre-Active-Low, Bidirectional

ments), featuring four minimum power-on reset timeout♦Guaranteed Reset Valid to VCC= 1V

periods (from 1ms to 1.12s), and four watchdog timeoutperiods (from 6.3ms to 25.6s). Thirteen standard ver-♦Immune to Short Negative VCCTransientssions are available with an order increment requirement♦Low Cost

of 2500 pieces (see Standard Versionstable); contact♦No External Components

the factory for availability of other versions, which have_______________Ordering Information

an order increment requirement of 10,000 pieces.

PARTTEMP RANGEPIN-PACKAGEThe MAX6316–MAX6322 are offered in a miniature 5-pin SOT23 package.

MAX6316LUK____-T-40°C to +125°C5 SOT23-5MAX6316MUK____-T-40°C to +125°C5 SOT23-5________________________Applications

MAX6317HUK____-T-40°C to +125°C5 SOT23-5Portable ComputersMAX6318HUK____-T-40°C to +125°C5 SOT23-5ComputersMAX6318MHUK____-T-40°C to +125°C5 SOT23-5Controllers

Devices are available in both leaded and lead-free packaging.Intelligent Instruments

Specify lead-free by replacing “-T” with “+T” when ordering.Portable/Battery-Powered EquipmentOrdering Information continued at end of data sheet.

Embedded Control Systems

Typical Operating Circuit and Pin Configurations appear atend of data sheet.

___________________________________________________________________Selector Guide

MANUALRESET OUTPUTS*PARTWATCHDOGINPUTRESETACTIVE-LOWACTIVE-HIGHACTIVE-LOWACTIVE-LOWINPUTPUSH/PULLPUSH/PULLBIDIRECTIONALOPEN-DRAINMAX6316L✔✔✔———MAX6316M✔✔——✔—MAX6317H✔✔—✔——MAX6318LH✔—✔✔——MAX6318MH✔——✔✔—MAX6319LH—✔✔✔——MAX6319MH—✔—✔✔—MAX6320P✔✔———✔MAX6321HP✔——✔—✔MAX6322HP—✔—✔—✔*The MAX6318/MAX6319/MAX6321/MAX6322 feature two types of reset output on each device.

________________________________________________________________Maxim Integrated Products1

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-42,or visit Maxim’s website at www.maxim-ic.com.

MAX6316–MAX6322元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with Watchdog and Manual ResetMAX6316–MAX6322ABSOLUTE MAXIMUM RATINGS

Voltage (with respect to GND)

VCC......................................................................-0.3V to +6VRESET(MAX6320/MAX6321/MAX6322 only)...... -0.3V to +6VAll Other Pins.........................................-0.3V to (VCC+ 0.3V)Input/Output Current, All Pins.............................................20mA

Continuous Power Dissipation (TA= +70°C)

SOT23-5 (derate 7.1mW/°C above +70°C)...............571mWOperating Temperature Range..........................-40°C to +125°CJunction Temperature......................................................+150°CStorage Temperature Range..............................-65°C to +160°CLead Temperature (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

(VCC= 2.5V to 5.5V, TA= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

PARAMETEROperating Voltage RangeSYMBOLVCCCONDITIONSTA = -40°C to +125°CMAX6316/MAX6317/MAX6318/MAX6320/MAX6321MAX6319/MAX6322:MR unconnectedVCC = 5.5VVCC = 3.6VVCC = 5.5VVCC = 3.6VMIN1.01053340TA = +25°CTA = -40°C to +125°CMAX63_ _ A_-TReset Active Timeout PeriodtRPMAX63_ _ B_-TMAX63_ _ C_-TMAX63_ _ D_-TVCC to RESET DelaytRDVCC falling at 1mV/µsVCC ≥ 1.0V, ISINK = 50µAVOLRESET Output VoltageVOHRE S ET Ri se Ti m e ( MA X 6316L,M AX 6318LH , M AX 6319LH ) tRVOLRESET Output VoltageVOHVCC ≥ 1.2V, ISINK = 100µAVCC ≥ 2.7V, ISINK = 1.2mAVCC ≥ 4.5V, ISINK = 3.2mAVCC ≥ 2.7V, ISOURCE = 500µAVCC ≥ 4.5V, ISOURCE = 800µARise time is measured from 10% to 90%of VCC; CL = 5pF, VCC = 3.3V (Note 3)VCC ≥ 2.7V, ISINK = 1.2mAVCC ≥ 4.5V, ISINK = 3.2mAVCC ≥ 1.8V, ISOURCE = 150µAVCC ≥ 2.7V, ISOURCE = 500µAVCC ≥ 4.5V, ISOURCE = 800µA0.8 x VCC0.8 x VCCVCC - 1.50.8 x VCCVCC - 1.55250.30.4VnsVTH - 1.5%VTH - 2.5%1201401120VTHVTH31.4282001600400.30.30.30.4V2402802240µsmsVTH + 1.5%VTH + 2.5%TYPMAX5.52012128ppm/°CVmVµAUNITSVSupply CurrentICCReset ThresholdTemperature CoefficientReset Threshold (Note 2)Reset Threshold HysteresisΔVTH/°CVRSTPUSH/PULL RESET OUTPUT (MAX6316L/MAX6317H/MAX6318_H/MAX6319_H/MAX6321HP/MAX6322HP)Note 1:Over-temperature limits are guaranteed by design, not production tested.Note 2:A factory-trimmed voltage divider programs the nominal reset threshold (VTH). Factory-trimmed reset thresholds are available in 100mV increments from 2.5V to 5V (see Table 1 at end of data sheet).

Note 3:Guaranteed by design.2

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元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

ELECTRICAL CHARACTERISTICS (continued)

(VCC= 2.5V to 5.5V, TA= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSBIDIRECTIONAL RESET OUTPUT (MAX6316M/MAX6318MH/MAX6319MH)Transitional Flip-Flop Setup TimetS(Note 4)400nsVCC = 3.0V, CL = 120pF333RESET Output Rise TimetRVCC = 5.0V, CL = 200pF333(Note 5)VCC = 3.0V, CL = 250pF666nsVCC = 5.0V, CL = 400pF666Active Pullup Enable ThresholdVPTHVCC = 5.0V0.40.65VRESET Active Pullup CurrentVCC = 5.0V20mARESET Pullup ResistanceTA = -40°C to +85°C4.24.75.2TA = -40°C to +125°C3..75.8kΩOPEN-DRAIN RESET OUTPUT (MAX6320P/MAX6321HP/MAX6322HP)VCC > 1.0V, ISINK = 50µA0.3RESET Output VoltageVVOLCC > 1.2V, ISINK = 100µA0.3VCC > 2.7V, ISINK = 1.2mA0.3VVCC > 4.5V, ISINK = 3.2mA0.4Open-Drain Reset OutputLeakage CurrentILKG1.0µAWATCHDOG INPUT (MAX6316/MAX6317H/MAX6318_H/MAX6320P/MAX6321HP)MAX63_ _ _W-T4.36.39.3msWatchdog Timeout PeriodtWDMAX63_ _ _X-T71102153MAX63_ _ _Y-T1.121.62.4MAX63_ _ _Z-T17.925.638.4sWDI Pulse WidthtWDIVIL = 0.3 x VCC, VIH = 0.7 x VCC50nsWDI Input ThresholdVILV(Note 6)0.3 x VCC0.7 x V VIHCC WDI Input CurrentWDI = VCC, time average120160(Note 7)IWDIVµAWDI = 0V, time average-20-15MANUAL RESET INPUT (MAX6316_/MAX6317H/MAX6319_H/MAX6320P/MAX6322HP)VILVTH > 4.0V0.8MR Input ThresholdVIH2.0VIL0.3 x VCCVVIHVTH < 4.0V0.7 x V CC MR Input Pulse WidthTA = -40°C to +85°C1TA = -40°C to +125°C1.5µsMR Glitch Rejection100nsMR Pullup Resistance355275kΩMR to Reset DelayVCC = 5V230nsNote 4:This is the minimum time RESETmust be held low by an external pulldown source to set the active pullup flip-flop. Note 5:Measured from RESETVOLto (0.8 x VCC), RLOAD= ∞.

Note 6:WDI is internally serviced within the watchdog period if WDI is left unconnected.

Note 7:

The WDI input current is specified as the average input current when the WDI input is driven high or low. The WDI input isdesigned for a three-stated-output device with a 10µA maximum leakage current and capable of driving a maximum capac-itive load of 200pF. The three-state device must be able to source and sink at least 200µA when active.

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MAX6316–MAX6322元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with Watchdog and Manual ResetMAX6316–MAX6322__________________________________________Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

MAX6316/MAX6317/MAX6318/MAX6320/MAX6321

SUPPLY CURRENT vs. TEMPERATURE

MAX6316toc01VCC FALLING TO RESET PROPAGATION

DELAY vs. TEMPERATURE

VCC FALLING AT 1mV/μsVRST - VCC = 100mVMAX6316toc02MAX6316/MAX6317/MAX6319/MAX6320/MAX6322

MANUAL RESET TO RESET

PROPAGATION DELAY vs. TEMPERATURE

300PROPAGATION DELAY (ns)280260240220200180160140

VCC = 5VMAX6316toc031098SUPPLY CURRENT (μA)763210-40

-20

VCC = 1VVCC = 3VVCC = 5V100RESET PROPAGATION DELAY (μs)320

80706050403020100

100-40-20020406080100-40-20020406080100

TEMPERATURE (°C)TEMPERATURE (°C)TEMPERATURE (°C)

NORMALIZED RESET TIMEOUTPERIOD vs. TEMPERATURE

MAX6316toc04MAX6316/MAX6317/MAX6318/MAX6320/MAX6321

NORMALIZED WATCHDOG TIMEOUT

PERIOD vs. TEMPERATURE

NORMALIZED WATCHDOG TIMEOUT PERIOD1.041.031.021.011.000.990.980.970.960.95

-40

-20

100

TEMPERATURE (°C)

MAX6316toc051.05NORMALIZED RESET TIMEOUT PERIOD1.041.031.021.011.000.990.980.970.960.95

-40

-20

1.05

100

TEMPERATURE (°C)

MAXIMUM VCC TRANSIENT DURATIONvs. RESET THRESHOLD OVERDRIVE

MAX6316toc06MAX6316M/6318MH/6319MH

BIDIRECTIONAL

PULLUP CHARACTERISTICS

MAX6316toc0780

RESET OCCURS ABOVE LINES70TRANSIENT DURATION (μs)605040302010010

100

VRST = 4.63VVRST = 3.3V+5V74HC05INPUT4.7kΩ100pFPASSIVE4.7kΩ PULLUP2V/divRESET, ACTIVEPULLUP2V/div+5VVRST = 2.63VINPUT74HC05100pFVCCRESETMRGNDRESETINPUT5V/div1000200ns/div

RESET THRESHOLD OVERDRIVE (mV) VRST - VCC

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元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

______________________________________________________________Pin Description

PINMAX6316LMAX6318LHMAX6319LHMAX6316MNAMEFUNCTIONMAX6317HMAX6318MHMAX6319MHMAX6320P MAX6321HPMAX6322HPMAX6316L/MAX6318LH/MAX6319LH:Active-Low, Reset Output. CMOS push/pulloutput (sources and sinks current).MAX6316M/MAX6318MH/MAX6319MH:Bidirectional, Active-Low, Reset Output.1—11RESETIntended to interface directly to microprocessorswith bidirectional resets such as the Motorola68HC11.MAX6320P/MAX6321HP/MAX6322HP:Open-Drain, Active-Low, Reset Output. NMOS out-put (sinks current only). Connect a pullup resistorfrom RESETto any supply voltage up to 6V.—133RESETActive-High, Reset Output. CMOS push/pull output(sources and sinks current). Inverse of RESET.2222GNDGroundActive-Low, Manual Reset Input. Pull low to force areset. Reset remains asserted for the duration of33—4MRthe Reset Timeout Period after MRtransitions fromlow to high. Leave unconnected or connected toVCCif not used.Watchdog Input. Triggers a reset if it remainseither high or low for the duration of the watchdogtimeout period. The internal watchdog timer clears444—WDIwhenever a reset asserts or whenever WDI sees arising or falling edge. To disable the watchdog fea-ture, leave WDI unconnected or three-state the dri-ver connected to WDI.Supply Voltage. Reset is asserted when VCCdrops below the Reset Threshold Voltage (VRST).5555VCCReset remains asserted until VCCrises aboveVRSTand for the duration of the Reset TimeoutPeriod (tRP) once VCCrises above VRST._______________________________________________________________________________________5

MAX6316–MAX6322元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with Watchdog and Manual ResetMAX6316–MAX6322VCCMAX6316–MAX6322RESET(ALL EXCEPT MAX6317)RESET(ALL EXCEPT MAX6316/MAX6320P)RESETGENERATORVCC1.23V52kΩMR(ALL EXCEPT MAX6318/MAX6321)WDI(ALL EXCEPT MAX6319/MAX6322)52kΩWATCHDOGTRANSITIONDETECTORWATCHDOGTIMERGNDFigure 1. Functional Diagram

_______________Detailed Description

A microprocessor’s (µP) reset input starts or restarts theµP in a known state. The reset output of the MAX6316–MAX6322 µP supervisory circuits interfaces with thereset input of the µP, preventing code-execution errorsduring power-up, power-down, and brownout condi-tions (see the Typical Operating Circuit). The MAX6316/MAX6317/MAX6318/MAX6320/MAX6321 are also capa-ble of asserting a reset should the µP become stuck inan infinite loop.

the watchdog timeout period (tWD). Reset remains assert-ed for the specified reset active timeout period (tRP) afterVCCrises above the reset threshold, after MRtransitionslow to high, or after the watchdog timer asserts the reset(MAX6316_/MAX6317H/MAX6318_H/MAX6320P/MAX6321HP). After the reset active timeout period (tRP)expires, the reset output deasserts, and the watchdogtimer restarts from zero (Figure 2).

VCC1VGNDRESETtRPtRDReset Output

The MAX6316L/MAX6318LH/MAX6319LH feature anactive-low reset output, while the MAX6317H/MAX6318_H/MAX6319_H/MAX6321HP/MAX6322HPfeature an active-high reset output. RESETis guaran-teed to be a logic low and RESET is guaranteed to be alogic high for VCCdown to 1V.

The MAX6316–MAX6322 assert reset when VCCis belowthe reset threshold (VRST), when MRis pulled low(MAX6316_/MAX6317H/MAX6319_H/MAX6320P/MAX6322HP only), or if the WDI pin is not serviced within

VRSTVRST1VRESETGNDtRPtRDFigure 2. Reset Timing Diagram

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元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

Bidirectional RESET Output

scratch. If, on the other hand, RESETis high after aThe MAX6316M/MAX6318MH/MAX6319MH are designeddelay of two external-clock cycles, the processorto interface with µPs that have bidirectional reset pins,knows that it caused the reset itself and can jump to asuch as the Motorola 68HC11. Like an open-drain output,different vector and use stored-state information tothese devices allow the µP or other devices to pull thedetermine what caused the reset.

bidirectional reset (RESET) low and assert a reset condi-tion. However, unlike a standard open-drain output, itA problem occurs with faster µPs; two external-clockincludes the commonly specified 4.7kΩpullup resistorcycles are only 500ns at 4MHz. When there are severalwith a P-channel active pullup in parallel.

devices on the reset line, and only a passive pullup resis-tor is used, the input capacitance and stray capacitanceThis configuration allows the MAX6316M/MAX6318MH/can prevent RESETfrom reaching the logic high state (0.8MAX6319MH to solve a problem associated with µPs✕VCC) in the time allowed. If this happens, all resets willthat have bidirectional reset pins in systems where sev-be interpreted as external. The µP output stage is guaran-eral devices connect to RESET(Figure 3). These µPsteed to sink 1.6mA, so the rise time can not be reducedcan often determine if a reset was asserted by an exter-considerably by decreasing the 4.7kΩinternal pullupnal device (i.e., the supervisor IC) or by the µP itselfresistance. See Bidirectional Pullup Characteristics in the(due to a watchdog fault, clock error, or other source),Typical Operating Characteristics.

and then jump to a vector appropriate for the source ofthe reset. However, if the µP does assert reset, it doesThe MAX6316M/MAX6318MH/MAX6319MH overcomenot retain the information, but must determine thethis problem with an active pullup FET in parallel with thecause after the reset has occurred.

4.7kΩresistor (Figures 4 and 5). The pullup transistorholds RESEThigh until the µP reset I/O or the supervisoryThe following procedure describes how this is done incircuit itself forces the line low. Once RESETgoes belowthe Motorola 68HC11. In all cases of reset, the µP pullsVPTH, a comparator sets the transition edge flip-flop, indi-RESETlow for about four external-clock cycles. It thencating that the next transition for RESETwill be low toreleases RESET, waits for two external-clock cycles,high. When RESETis released, the 4.7kΩresistor pullsthen checks RESET’s state. If RESETis still low, the µPRESETup toward VCC. Once RESETrises above VPTHconcludes that the source of the reset was externalbut is below (0.85 x VCC), the active P-channel pullupand, when RESETeventually reaches the high state, itturns on. Once RESETrises above (0.85 x VCC) or thejumps to the normal reset vector. In this case, stored-2µs one-shot times out, the active pullup turns off. Thestate information is erased and processing begins from

parallel combination of the 4.7kΩpullup and the

VCCVCCWDI*4.7kΩ68HC11MR**RESETCIRCUITRYRESETRESETRESETRESET***CIRCUITRYCCINCSTRAYINMAX6316MMAX6318MHMAX6319MHRESET*MAX6316M/MAX6318MHCINOTHER DEVICES**MAX6316M/MAX6319MH***ACTIVE-HIGH PUSH/PULL MAX6318MH/MAX6319MHFigure 3. MAX6316M/MAX6318MH/MAX6319MH Supports Additional Devices on the Reset Bus

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MAX6316–MAX6322元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with Watchdog and Manual ResetMAX6316–MAX6322VCCLASER-TRIMMEDRESISTORSMAX6316M MAX6318MHMAX6319MHVCCVREF52kΩRESETGENERATORWATCHDOG ON2μs ONE SHOTCIRCUITRYVCC2μs ONE SHOTTRANSITIONFLIP-FLOPRFFSQ4.7kΩMR(MAX6316M/MAX6319MH)(MAX6316M/MAX6318MH)WDIRESETACTIVE PULLUPENABLE COMPARATOR0.65V0.85VCCGNDFigure 4. MAX6316/MAX6318MH/MAX6319MH Bidirectional Reset Output Functional Diagram

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元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

P-channel transistor on-resistance quickly chargesregister a logic low (see Electrical Characteristics), andstray capacitance on the reset line, allowing RESETtosmall enough to register a logic high while supplying alltransition from low to high within the required two elec-input current and leakage paths connected to the RESETtronic-clock cycles, even with several devices on theline. A 10kΩpullup is sufficient in most applications.

reset line. This process occurs regardless of whetherthe reset was caused by VCCdipping below the resetManual-Reset Input

threshold, the watchdog timing out, MRbeing asserted,The MAX6316_/MAX6317H/MAX6319_H/MAX6320P/or the µP or other device asserting RESET. The parts doMAX6322HP feature a manual reset input. A logic low onnot require an external pullup. To minimize supply cur-MRasserts a reset. After MRtransitions low to high, resetrent consumption, the internal 4.7kΩpullup resistor dis-remains asserted for the duration of the reset timeout peri-connects from the supply whenever the MAX6316M/od (tRP). The MRinput is connected to VCCthrough anMAX6318MH/MAX6319MH assert reset.

internal 52kΩpullup resistor and therefore can be leftunconnected when not in use. MRcan be driven withOpen-Drain RESETOutput

TTL-logic levels in 5V systems, with CMOS-logic levels inThe MAX6320P/MAX6321HP/MAX6322HP have an3V systems, or with open-drain or open-collector outputactive-low, open-drain reset output. This output struc-devices. A normally-open momentary switch from MRtoture will sink current when RESETis asserted. Connectground can also be used; it requires no externala pullup resistor from RESETto any supply voltage updebouncing circuitry. MRis designed to reject fast, to 6V (Figure 6). Select a resistor value large enough to

negative-going transients (typically 100ns pulses). A0.1µF capacitor from MRto ground provides additionalnoise immunity.

VCCThe MRinput pin is equipped with internal ESD-protectionRESETtRP0.8 x VCCORcircuitry that may become forward biased. Should MRbe0.7VμC RESET DELAYdriven by voltages higher than VCC, excessive currentwould be drawn, which would damage the part. Forexample, assume that MRis driven by a +5V supply othertStRthan VCC. If VCCdrops lower than +4.7V, MR’s absolute maximum rating is violated [-0.3V to (VRESET PULLED LOWACTIVECC+ 0.3V)], andBY μC ORPULLUPundesirable current flows through the ESD structure fromRESET GENERATOR TURNS ONMRto VCC. To avoid this, use the same supply for MRasthe supply monitored by VCC. This guarantees that thevoltage at MRwill never exceed VCC.

Figure 5. Bidirectional RESETTiming Diagram

Watchdog Input

The MAX6316_/MAX6317H/MAX6318_H/MAX6320P/+3.3V+5.0VMAX6321HP feature a watchdog circuit that monitorsthe µP’s activity. If the µP does not toggle the watchdoginput (WDI) within the watchdog timeout period (tWD),VCCreset asserts. The internal watchdog timer is cleared byMR*10kΩreset or by a transition at WDI (which can detect pulsesWDI**RESETas short as 50ns). The watchdog timer remains clearedRESET***5V SYSTEMwhile reset is asserted. Once reset is released, thetimer begins counting again (Figure 7).

The WDI input is designed for a three-stated outputdevice with a 10µA maximum leakage current and theMAX6320capability of driving a maximum capacitive load of 200pF.MAX6321The three-state device must be able to source and sink atMAX6322GND*MAX6320/MAX6322**MAX6320/MAX6321least 200µA when active. Disable the watchdog function***MAX6321/MAX6322by leaving WDI unconnected or by three-stating the driverconnected to WDI. When the watchdog timer is left openFigure 6. MAX6320P/MAX6321HP/MAX6322HP Open-Draincircuited, the timer is cleared internally at intervals equalRESETOutput Allows Use with Multiple Supplies

to 7/8 of the watchdog period.

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MAX6316–MAX6322元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with Watchdog and Manual ResetMAX6316–MAX6322VCCtRSTRESETtRPtWDtRPMAX6316MAX6318MAX6319VCCVCCWDIGNDRESET100kΩMAX6316/MAX6317MAX6318/MAX6320MAX6321Figure 7. Watchdog Timing Relationship

Figure 8. Ensuring RESETValid to VCC= 0 on Active-LowPush/Pull and Bidirectional Outputs

Applications InformationWatchdog Input Current

The WDI input is internally driven through a buffer andseries resistor from the watchdog counter. For minimumwatchdog input current (minimum overall power con-sumption), leave WDI low for the majority of the watch-dog timeout period. When high, WDI can draw as muchas 160µA. Pulsing WDI high at a low duty cycle willreduce the effect of the large input current. When WDIis left unconnected, the watchdog timer is servicedwithin the watchdog timeout period by a low-high-lowpulse from the counter chain.

MAX6317MAX6318MAX6319MAX6321*MAX6322*VCCGNDRESETVCC100kΩNegative-Going VCCTransients

These supervisors are immune to short-duration, nega-tive-going VCCtransients (glitches), which usually donot require the entire system to shut down. Typically,200ns large-amplitude pulses (from ground to VCC) onthe supply will not cause a reset. Lower amplitude puls-es result in greater immunity. Typically, a VCCtransientthat goes 100mV under the reset threshold and lastsless than 4µs will not trigger a reset. An optional 0.1µFbypass capacitor mounted close to VCCprovides addi-tional transient immunity.

*THIS SCHEMATIC DOES NOT WORK ON THE OPEN-DRAIN OUTPUTS OF THE MAX6321/MAX6322.Figure 9. Ensuring RESET Valid to VCC= 0 on Active-HighPush/Pull Outputs

source current. This scheme does not work with theopen-drain outputs of the MAX6320/MAX6321/MAX6322.The resistor value used is not critical, but it must belarge enough not to load the reset output when VCCisabove the reset threshold. For most applications,100kΩis adequate.

Ensuring Valid Reset Outputs

Down to VCC= 0

The MAX6316_/MAX6317H/MAX6318_H/MAX6319_H/MAX6321HP/MAX6322HP are guaranteed to operateproperly down to VCC= 1V. In applications that requirevalid reset levels down to VCC= 0, a pulldown resistorto active-low outputs (push/pull and bidirectional only,Figure 8) and a pullup resistor to active-high outputs(push/pull only, Figure 9) will ensure that the reset lineis valid while the reset output can no longer sink or

Watchdog Software Considerations

(MAX6316/MAX6317/MAX6318/

MAX6320/MAX6321)

One way to help the watchdog timer monitor softwareexecution more closely is to set and reset the watchdoginput at different points in the program, rather thanpulsing the watchdog input high-low-high or low-high-low. This technique avoids a stuck loop, in which thewatchdog timer would continue to be reset inside theloop, keeping the watchdog from timing out.

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元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

Figure 10 shows an example of a flow diagram wherethe I/O driving the watchdog input is set high at thebeginning of the program, set low at the end of everySTARTsubroutine or loop, then set high again when the pro-gram returns to the beginning. If the program shouldhang in any subroutine, the problem would be quicklySET WDIHIGHcorrected, since the I/O is continually set low and thewatchdog timer is allowed to time out, causing a resetPROGRAMor interrupt to be issued. As described in the WatchdogCODEInput Currentsection, this scheme results in higher timeaverage WDI current than does leaving WDI low for thePOSSIBLE majority of the timeout period and periodically pulsing itSUBROUTINE ORINFINITE LOOP PATHlow-high-low.

PROGRAM LOOPSET WDI LOWRETURNFigure 10. Watchdog Flow Diagram

__________________Pin Configurations

Typical Operating Circuit

TOP VIEWRESET15VCCRESET15VCCVINVGND2MAX6316CCVCCMAX6320GND2MAX6317RESETRESETMR34WDIMR34WDIMAX6316μPMANUALMRWDII/OSOT23-5SOT23-5RESETGNDGNDRESET15VCCRESET15VCCGND2MAX6318MAX6321GND2MAX6319MAX6322RESET34WDIRESET34MRSOT23-5SOT23-5______________________________________________________________________________________11

MAX6316–MAX6322元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with Watchdog and Manual ResetMAX6316–MAX6322Table 1. Factory-Trimmed Reset Thresholds

PARTMAX63___50_ _-TMAX63___49_ _-TMAX63___48_ _-TMAX63___47_ _-TMAX63___46_ _-TMAX63___45_ _-TMAX63___44_ _-TMAX63___43_ _-TMAX63___42_ _-TMAX63___41_ _-TMAX63___40_ _-TMAX63___39_ _-TMAX63___38_ _-TMAX63___37_ _-TMAX63___36_ _-TMAX63___35_ _-TMAX63___34_ _-TMAX63___33_ _-TMAX63___32_ _-TMAX63___31_ _-TMAX63___30_ _-TMAX63___29_ _-TMAX63___28_ _-TMAX63___27_ _-TMAX63___26_ _-TMAX63___25_ _-TMIN4.9257.8274.7284.6304.5614.4334.3144.23.1374.0393.9403.8423.7433.53.63.4483.3493.2513.1523.0342.9552.8862.7582.6602.5912.463TA= +25°CTYP5.0004.9004.8004.7004.6304.5004.3904.3004.2004.1004.0003.9003.8003.7003.6003.5003.4003.3003.2003.0803.0002.9302.8002.7002.6302.500MAX5.07.9744.8724.7714.6994.5684.44.36.2634.1624.0603.9593.8573.7563.63.5533.4513.3503.2483.1263.0452.9742.8422.7412.6692.538TA= -40°C to +125°CMINMAX4.8755.12.7785.0234.6804.9204.5834.8184.5144.74.3884.6134.2704.4904.1934.4084.09.3053.9984.2033.9004.1003.8033.9983.7053.53.6083.7933.5103.6903.4133.5883.3153.4853.2183.3833.1203.2803.0033.1572.9253.0752.8573.0002.7302.8702.6332.7682.52.6962.4382.563Table 2. Standard Versions

PARTMAX6316LUK29CY-TMAX6316LUK46CY-TMAX6316MUK29CY-TMAX6316MUK46CY-TMAX6317HUK46CY-TMAX6318LHUK46CY-TMAX6318MHUK46CY-TMAX6319LHUK46C-TMAX6319MHUK46C-TMAX6320PUK29CY-TRESETTHRESHOLD (V)2.934.632.934.634.634.634.634.634.632.93MINIMUMRESETTIMEOUT (ms)140140140140140140140140140140TYPICALWATCHDOGTIMEOUTS (s)1.61.61.61.61.61.61.6——1.6SOTTOPMARKACDEACDDACDGACDFACDQACDHACDJACDKACDMACDO12______________________________________________________________________________________元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

Table 2. Standard Versions (continued)MINIMUMTYPICALSOTPARTRESETTHRESHOLD (V)RESETWATCHDOGTOPTIMEOUT (ms)TIMEOUTS (s)MARKMAX6320PUK46CY-T4.631401.6ACDNMAX6321HPUK46CY-T4.631401.6ACGLMAX6322HPUK46C-T4.631401.6ACGNNote:Thirteen standard versions are available, with a required order increment of 2500 pieces. Sample stock is generally held on stan-dard versions only. The required order increment for nonstandard versions is 10,000 pieces. Contact factory for availability.

Table 3. Reset/Watchdog Timeout Periods

__Ordering Information (continued)

RESET TIMEOUT PERIODSPARTTEMP RANGEPIN-PACKAGESUFFIXMINTYPMAXUNITSMAX6319LHUK____-T-40°C to +125°C5 SOT23-5A11.62MAX6319MHUK____-T-40°C to +125°C5 SOT23-5B203040msMAX6320PUK____-T-40°C to +125°C5 SOT23-5MAX6321HPUK____-T-40°C to +125°C5 SOT23-5C140200280MAX6322HPUK____-T-40°C to +125°C5 SOT23-5D1.121.602.24sDevices are available in both leaded and lead-free packaging.WATCHDOG TIMEOUTSpecify lead-free by replacing “-T” with “+T” when ordering.W4.36.39.3Note:These devices are available with factory-set VCCresetX71102153msthresholds from 2.5V to 5V, in 0.1V increments. Insert thedesired nominal reset threshold (25 to 50, from Table 1) into theY1.121.62.4blanks following the letters UK. All devices offer factory-pro-Z17.925.638.4sgrammed reset timeout periods. Insert the letter correspondingto the desired reset timeout period (A, B, C, or D from Table 3)into the blank following the reset threshold suffix. Parts that offera watchdog feature (see Selector Guide) are factory-trimmed toChip Information

one of four watchdog timeout periods. Insert the letter corre-sponding to the desired watchdog timeout period (W, X, Y, or Zfrom Table 3) into the blank following the reset timeout suffix.

TRANSISTOR COUNT: 191

SUBSTRATE IS INTERNALLY CONNECTED TO V+

______________________________________________________________________________________13

MAX6316–MAX6322元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with Watchdog and Manual Reset322Package 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.)

6XAM–6136XAM14SPE. L5 32-TOS______________________________________________________________________________________

元器件交易网www.cecb2b.com5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

Revision HistoryREVISIONREVISIONNUMBERDATEDESCRIPTIONPAGESCHANGED01/98Initial release—14/98Update to show MAX6319 as an existing part1, 2, 1227/98Update specifications, Selector Guide, and Table 21, 12, 1431/99Include extended temperature range in EC table globals, Table 1, Ordering1, 2, 3, 12, 13, 14411/99Update available products and versions in Table 2 and Ordering Information1, 12, 1459/02Addition of RESET rise time specification to EC table1, 2612/05Add lead-free option to Ordering Information1, 13, 14711/07Add automotive temperature to Ordering Information, EC table, Table 1, andupdate package outline1, 2, 3, 12, 13, 14Maxim cannot assume responsibility for use of any circuitry other than circuitry 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.

is a registered trademark of Maxim Integrated Products, Inc.

MAX6316–MAX6322

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