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MAX6315US39D4-T中文资料

________________General Description

The MAX6315 low-power CMOS microprocessor (μP)supervisory circuit is designed to monitor power sup-plies in μP and digital systems. It provides excellent cir-cuit reliability and low cost by eliminating external components and adjustments. The MAX6315 also pro-vides a debounced manual reset input.

This device performs a single function: it asserts a reset signal whenever the V CC supply voltage falls below a preset threshold or whenever manual reset is asserted.Reset remains asserted for an internally programmed interval (reset timeout period) after V CC has risen above the reset threshold or manual reset is deasserted. The MAX6315’s open-drain RESET output can be pulled up to a voltage higher than V CC .

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, and 1120ms (minimum) are also available. The device comes in a SOT143 package.

For microcontrollers (μCs) and μPs with bidirectional reset pins, see the MAX6314 data sheet.

________________________Applications

Computers Controllers

Intelligent Instruments

Critical μP and μC Power Monitoring Portable/Battery-Powered Equipment

____________________________Features

o Small SOT143 Package

o Open-Drain RESET Output Can Exceed V CC o Precision, Factory-Set V CC Reset Thresholds:100mV Increments from 2.5V to 5V o ±1.8% Reset Threshold Accuracy at T A = +25°C o ±2.5% Reset Threshold Accuracy Over Temp.o Four Reset Timeout Periods Available: 1ms, 20ms, 140ms, or 1120ms (minimum) o Immune to Short V CC Transients o 5μA Supply Current

o Pin-Compatible with MAX811

MAX6315

Open-Drain SOT μP Reset Circuit

________________________________________________________________Maxim Integrated Products 1

MAX6315US39D4-T中文资料

MAX6315US39D4-T中文资料

__________________Pin Configuration

__________Typical Operating Circuit

19-2000; Rev 1; 1/99

Ordering and Marking Information appear at end of data sheet.

For free samples & the latest literature: http://www.wendangku.net/doc/e19b220ade80d4d8d15a4fd6.html, or phone 1-800-998-8800.For small orders, phone 1-800-835-8769.

M A X 6315

MAX6315US39D4-T中文资料

Open-Drain SOT μP Reset Circuit 2_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V CC = +2.5V to +5.5V, T A = -40°C to +85°C, unless otherwise noted. Typical values are at T A = +25°C.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

Note 1:The MAX6315 monitors V CC through 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 Ordering and Marking Information ).

V CC ........................................................................-0.3V to +6.0V RESET ....................................................................-0.3V to +6.0V All Other Pins..............................................-0.3V to (V CC + 0.3V)Input Current (V CC ).............................................................20mA Output Current (RESET )......................................................20mA Rate of Rise (V CC )...........................................................100V/μs

Continuous Power Dissipation (T A = +70°C)

SOT143 (derate 4mW/°C above +70°C)........................320mW Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range.............................-65°C to +160°C Lead Temperature (soldering, 10sec).............................+300°C

MAX6315

Open-Drain SOT μP Reset Circuit

_______________________________________________________________________________________3

60-50

-30

30

90

SUPPLY CURRENT vs. TEMPERATURE

215

MAX6315US39D4-T中文资料

TEMPERATURE (°C)S U P P L Y C U R R E N T (μA )

-10

10

50

3470

60

1

3

5

SUPPLY CURRENT vs. SUPPLY VOLTAGE

215

MAX6315US39D4-T中文资料

SUPPLY VOLTAGE (V)

S U P P L Y C U R R E N T (μA )

2

3

44

50

0-50

-30

10

90

POWER-DOWN RESET DELAY

vs. TEMPERATURE

10

40

MAX6315US39D4-T中文资料

TEMPERATURE (°C)

P O W E R -D O W N R E S E T D E L A Y (μs )

-10

20

30

30

50

70

1.040.96

-50

-30

10

90NORMALIZED RESET TIMEOUT PERIOD vs. TEMPERATURE (V CC RISING)

0.970.981.021.001.03M A X 6315-04

TEMPERATURE (°C)N O R M A L I Z E D R E S E T T I M E O U T P E R I O D

-10

0.991.0130

50

70

1.0060.994

-50-301090

NORMALIZED RESET THRESHOLD vs. TEMPERATURE (V CC FALLING)

0.9960.9981.0041.000M A X 6315-05

TEMPERATURE (°C)

N O R M A L I Z E D R E S E T T H R E S H O L D

-101.002305070100

010

100

1000

MAXIMUM TRANSIENT DURATION vs. RESET COMPARATOR OVERDRIVE

20

MAX6315US39D4-T中文资料

RESET COMP. OVERDRIVE, V TH - V CC (mV)

M A X I M U M T R A N S I E N T D U R A T I O N (μs )

40

60

80

__________________________________________Typical Operating Characteristics

(T A

MAX6315US39D4-T中文资料

= +25°C, unless otherwise noted.)

______________________________________________________________Pin Description

_______________Detailed Description

Reset Output

MAX6315US39D4-T中文资料

A microprocessor’s (μP’s) reset input starts the μP in a known state. The MAX6315 asserts reset to prevent code-execution errors during power-up, power-down,or brownout conditions. RESET is guaranteed to be a logic low for V CC > 1V (see Electrical Characteristics ).Once V CC exceeds the reset threshold, the internal timer keeps reset asserted for the reset timeout period (t RP ); after this interval RESET goes high. If a brownout condition occurs (monitored voltage dips below its pro-grammed reset threshold), RESET goes low. Any time V CC dips below the reset threshold, the internal timer resets to zero and RESET goes low. The internal timer starts when V CC returns above the reset threshold, and RESET remains low for the reset timeout period.

The MAX6315’s RESET output structure is a simple open-drain N-channel MOSFET switch. Connect a pull-up resistor to any supply in the 0V to +6V range. Select a resistor value large enough to register a logic low when RESET is asserted (see Electrical Characteristics ),and small enough to register a logic high while supply-ing all input current and leakage paths connected to the RESET line. A 10k ?pull-up is sufficient in most applica-tions.

Often, the pull-up connected to the MAX6315’s RESET output will connect to the supply voltage monitored at the IC’s V CC pin. However, some systems may use the open-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-drain output. Keep in mind that as the MAX6315’s V CC decreases below 1V, so does the IC’s ability to sink current at RESET . Finally, with any pull-up, RESET will be pulled high as V CC decays toward 0V. The voltage where this occurs depends on the pull-up resistor value and the voltage to which it connects (see Electrical Characteristics ).

Manual-Reset Input

Many μP-based products require manual-reset capabil-ity, allowing the operator, a test technician, or external logic circuitry to initiate a reset. A logic low on MR asserts reset. Reset remains asserted while MR is low,and for the reset active timeout period after MR returns high.

MR has an internal 63k ?pull-up resistor, so it can be left open if not used. Connect a normally open momen-tary switch from MR to GND to create a manual reset function; external debounce circuitry is not required.

If MR is driven from long cables or if the device is used in a noisy environment, connecting a 0.1μF capacitor from MR to ground provides additional noise immunity.

__________Applications Information

Negative-Going V CC Transients

In addition to issuing a reset to the μP during power-up,power-down, and brownout conditions, these devices are relatively immune to short-duration negative-going transients (glitches). The Typical Operating Character-istics show the Maximum Transient Duration vs. Reset Threshold Overdrive, for which reset pulses are not generated. The graph was produced using negative-going pulses, starting at V RST max and ending below the programmed reset threshold by the magnitude indi-cated (reset threshold overdrive). The graph shows the maximum pulse width that a negative-going V CC tran-sient may typically have without causing a reset pulse to be issued. As the transient amplitude increases (i.e.,goes farther below the reset threshold), the maximum allowable pulse width decreases. A 0.1μF bypass capacitor mounted close to V CC provides additional transient immunity.

M A X 6315

Open-Drain SOT μP Reset Circuit 4_______________________________________________________________________________________

Figure 1. MAX6315 Open-Drain RESET Output Allows Use with Multiple Supplies

MAX6315

Open-Drain SOT μP Reset Circuit

_______________________________________________________________________________________5

________________________________________________________Ordering Information

MAX6315US39D4-T中文资料

MAX6315US39D4-T中文资料

?The MAX6315 is available in a SOT143 package, -40°C to +85°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.Note:All devices available in tape-and-reel only. Contact factory for availability.

M A X 6315

MAX6315US39D4-T中文资料

Open-Drain SOT μP Reset Circuit 6_______________________________________________________________________________________

___________________________________________Ordering Information (continued)

?The MAX6315 is available in a SOT143 package, -40°C to +85°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.Note:All devices available in tape-and-reel only. Contact factory for availability.

MAX6315

Open-Drain SOT μP Reset Circuit

_______________________________________________________________________________________7

___________________Chip Information

TRANSISTOR COUNT: 519

MAX6315US39D4-T中文资料

________________________________________________________Package Information

M A X 6315

Open-Drain SOT μP Reset Circuit NOTES

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

8_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600?1999 Maxim Integrated Products

Printed USA

is a registered trademark of Maxim Integrated Products.