MAX6315US41D1-T中文资料

19-2000; Rev 3; 12/05

Open-Drain SOT µP Reset Circuit

________________General Description

____________________________Features

The MAX6315 low-power CMOS microprocessor (µP)supervisory circuit is designed to monitor power sup- Small SOT143 Package

plies in µP and digital systems. It provides excellent cir- Open-Drain RESETOutput Can Exceed VCCcuit reliability and low cost by eliminating external Precision, Factory-Set VCCReset Thresholds:components and adjustments. The MAX6315 also pro-100mV Increments from 2.5V to 5V

vides a debounced manual reset input.

Four Reset Timeout Periods Available: This device performs a single function: it asserts a reset1ms, 20ms, 140ms, or 1120ms (minimum) signal whenever the VCCsupply voltage falls below apreset threshold or whenever manual reset is asserted. Immune to Short VCCTransientsReset remains asserted for an internally programmed 5µA Supply Current

interval (reset timeout period) after V Pin-Compatible with MAX811the reset threshold or manual reset is deasserted. TheCC has risen above Guaranteed Over Temperature

MAX6315’s open-drain RESEToutput can be pulled upto a voltage higher than VCC.

______________Ordering Information

The MAX6315 comes with factory-trimmed reset thresh-old voltages in 100mV increments from 2.5V to 5V.Preset timeout periods of 1ms, 20ms, 140ms, and1120ms (min) are also available. The device comes in aSOT143 package.

The MAX6315 is available in a SOT143 package, -40°C to

For microcontrollers (µCs) and µPs with bidirectional+125°C temperature range.

reset pins, see the MAX6314 data sheet.

The first two letters in the package top mark identify the part,while the remaining two letters are the lot tracking code.

________________________Applications

Devices are available in both leaded and lead-free packaging.Specify lead-free by replacing “-T” with “+T” when putersNote:All devices available in tape-and-reel only. Contact fac-Controllers

tory for availability.

Intelligent Instruments

Critical µP and µC Power MonitoringPortable/Battery-Powered Equipment

Ordering Information continued at end of data sheet.

__________Typical Operating Circuit

________________________________________________________________Maxim Integrated Products1

For pricing delivery, and ordering informationplease contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at .

MAX6315

Open-Drain SOT µP Reset CircuitMAX6315

ABSOLUTE MAXIMUM RATINGS

VCC........................................................................-0.3V to +6.0VRESET....................................................................-0.3V to +6.0VAll Other Pins..............................................-0.3V to (VCC+ 0.3V)Input Current (VCC).............................................................20mAOutput Current (RESET)......................................................20mARate of Rise (VCC)...........................................................100V/µs

Continuous Power Dissipation (TA= +70°C)

SOT143 (derate 4mW/°C above +70°C)........................320mWOperating Temperature Range.........................-40°C to +125°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:The MAX6315 monitors VCCthrough an internal factory-trimmed voltage-divider that programs the nominal reset threshold.

Factory-trimmed reset thresholds are available in 100mV increments from 2.5V to 5V (see the Ordering Information).

2_______________________________________________________________________________________

Open-Drain SOT µP Reset Circuit

__________________________________________Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

SUPPLY CURRENTPOWER-DOWN RESET DELAY

SUPPLY CURRENT vs. TEMPERATURE

vs. SUPPLY VOLTAGE

vs. TEMPERATURE

6650

5

5

)

sµ(40

)

A)

YµAAL( T4µ( NT4ED ENTREE30

RRSUEC3RUR C3

Y NLYPLWOPD20

U2PPSU2-SRE1WO1P10

00

0-50

-30

-10

10

30

50

70

90

1

2

3

4

5

-50

-30

-10

10

30

50

70

90

TEMPERATURE (°C)SUPPLY VOLTAGE (V)

TEMPERATURE (°C)

NORMALIZED RESET TIMEOUT PERIODNORMALIZED RESET THRESHOLDMAXIMUM TRANSIENT DURATION vs. TEMPERATURE (VCC RISING)

vs. TEMPERATURE (VCC FALLING)

vs. RESET COMPARATOR OVERDRIVE

1.044

01.0065

0-100

-55113366D

XXAA)

O1.03MMsD

µIRL1.004(E PON HO80

T1.02SIUETORAEH1.002RTUM1.01 DITT ET60

TSNEEES1.00R1.000IE SRDN DEAZRE0.99IT40

ZL ILAM0.998MAUM0.98ROMRIONXN0.970.996A20

M0.96

0.994

-50

-30

-10

10

30

50

70

90-50-30-101030507090

010

100

1000

TEMPERATURE (°C)TEMPERATURE (°C)

RESET COMP. OVERDRIVE, VTH - VCC (mV)

______________________________________________________________Pin Description

_______________________________________________________________________________________3

MAX6315

Open-Drain SOT µP Reset CircuitMAX6315

_______________Detailed Description

Reset Output

A microprocessor’s (µP’s) reset input starts the µP in aknown state. The MAX6315 asserts reset to preventcode-execution errors during power-up, power-down, or brownout conditions. RESETis guaranteed tobe a logic-low for VCC> 1V (see the ElectricalCharacteristics table). Once VCCexceeds the resetthreshold, the internal timer keeps reset asserted for thereset timeout period (tRP); after this interval RESETgoes high. If a brownout condition occurs (monitoredvoltage dips below its programmed reset threshold),RESETgoes low. Any time VCCdips below the resetthreshold, the internal timer resets to zero and RESETgoes low. The internal timer starts when VCCreturnsabove the reset threshold, and RESETremains low forthe reset timeout period.

The MAX6315’s RESEToutput structure is a simpleopen-drain n-channel MOSFET switch. Connect a pull-up resistor to any supply in the 0V to +6V range. Selecta resistor value large enough to register a logic lowwhen RESETis asserted (see the ElectricalCharacteristics table), and small enough to register alogic high while supplying all input current and leakagepaths connected to the RESETline. A 10k pullup issufficient in most applications.

Often, the pull-up connected to the MAX6315’s RESEToutput will connect to the supply voltage monitored atthe IC’s VCCpin. However, some systems may use theopen-drain output to level-shift from the monitored sup-ply to reset circuitry powered by some other supply(Figure 1). This is one useful feature of an open-drainoutput. Keep in mind that as the MAX6315’s VCCdecreases below 1V, so does the IC’s ability to sinkcurrent at RESET. Finally, with any pullup, RESETwillbe pulled high as VCCdecays toward 0V. The voltagewhere this occurs depends on the pull-up resistor valueand the voltage to which it connects (see the ElectricalCharacteristics table).

Figure 1. MAX6315 Open-Drain RESETOutput Allows Usewith Multiple Supplies

MRhas an internal 63k pullup resistor, so it can beleft open if not used. Connect a normally open momen-tary switch from MRto GND to create a manual resetfunction; external debounce circuitry is not required. If MRis driven from long cables or if the device is usedin a noisy environment, connecting a 0.1µF capacitorfrom MRto ground provides additional noise immunity.

__________Applications Information

In addition to issuing a reset to the µP during power-up,power-down, and brownout conditions, these devicesare relatively immune to short-duration negative-goingtransients (glitches). The Typical Operating Character-isticsshow the Maximum Transient Duration vs. ResetThreshold Overdrive, for which reset pulses are notgenerated. The graph was produced using negative-going pulses, starting at VRSTmax and ending belowthe programmed reset threshold by the magnitude indi-cated (reset threshold overdrive). The graph shows themaximum pulse width that a negative-going VCCtran-sient may typically have without causing a reset pulseto be issued. As the transient amplitude increases (i.e.,goes farther below the reset threshold), the maximumallowable pulse width decreases. A 0.1µF bypasscapacitor mounted close to VCCprovides additionaltransient immunity.

Negative-Going VCCTransients

Manual-Reset Input

Many µP-based products require manual-reset capa-bility, allowing the operator, a test technician, or exter-nal logic circuitry to initiate a reset. A logic low on MRasserts reset. Reset remains asserted while MRis low,and for the reset active timeout period after MRreturns high.

4_______________________________________________________________________________________

Open-Drain SOT µP Reset Circuit

___________________________________________Ordering Information (continued)

The MAX6315 is available in a SOT143 package, -40°C to +125°C temperature range.

The first two letters in the package top mark identify the part, while the remaining two letters are the lot tracking code.

Sample stocks generally held on the bolded products; also, the bolded products have 2,500 piece minimum-order quantities.

Non-bolded products have 10,000 piece minimum-order quantities. Contact factory for details.

Devices are available in both leaded and lead-free packaging. Specify lead-free by replacing “-T” with “+T” when ordering.Note:All devices available in tape-and-reel only. Contact factory for availability.

_______________________________________________________________________________________5

MAX6315

Open-Drain SOT µP Reset CircuitMAX6315

___________________________________________Ordering Information (continued)

The MAX6315 is available in a SOT143 package, -40°C to +125°C temperature range.

The first two letters in the package top mark identify the part, while the remaining two letters are the lot tracking code.

Sample stocks generally held on the bolded products; also, the bolded products have 2,500 piece minimum-order quantities.

Non-bolded products have 10,000 piece minimum-order quantities. Contact factory for details.

Devices are available in both leaded and lead-free packaging. Specify lead-free by replacing “-T” with “+T” when ordering.Note:All devices available in tape-and-reel only. Contact factory for availability.

6_______________________________________________________________________________________

Open-Drain SOT µP Reset Circuit

___________________Chip Information

TRANSISTOR COUNT: 519

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 .)

S

PE.L4 341-TOSMaxim 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.

7_____________________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.

MAX6315

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