MAX6319MHUK44AW-T_技术文档

19-0496; Rev 4; 11/99

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

________________General Description

____________________________Features

o Small 5-Pin SOT23 Package

The MAX6316–MAX6322 family of microprocessor (µP)

supervisory circuits monitors power supplies and

microprocessor activity in digital systems. It offers sev-

eral combinations of push/pull, open-drain, and bidirec-

tional (such as Motorola 68HC11) reset outputs, along

with watchdog and manual reset features. The Selector

Guide below lists the specific functions available from

each device. These devices are specifically designed

o Available in 26 Reset Threshold Voltages

2.5V to 5V, in 100mV Increments

o Four Reset Timeout Periods

1ms, 20ms, 140ms, or 1.12s (min)

o Four Watchdog Timeout Periods

6.3ms, 102ms, 1.6s, or 25.6s (typ)

o Four Reset Output Stages

Active-High, Push/Pull

Active-Low, Push/Pull

to ignore fast negative transients on V . Resets are

CC

guaranteed valid for V

down to 1V.

CC

Active-Low, Open-Drain

Active-Low, Bidirectional

These devices are available in 26 factory-trimmed reset

threshold voltages (from 2.5V to 5V, in 100mV incre-

ments), featuring four minimum power-on reset timeout

periods (from 1ms to 1.12s), and four watchdog timeout

periods (from 6.3ms to 25.6s). Thirteen standard ver-

sions are available with an order increment requirement

of 2500 pieces (see Standard Versions table); contact

the factory for availability of other versions, which have

an order increment requirement of 10,000 pieces.

o Guaranteed Reset Valid to V

o Immune to Short Negative V

o Low Cost

= 1V

Transients

CC

o No External Components

_______________Ordering Information

The MAX6316–MAX6322 are offered in a miniature

5-pin SOT23 package.

PART

TEMP. RANGE

-40°C to +85°C

PIN-PACKAGE

5 SOT23-5

MAX6316LUK____-T

MAX6316MUK____-T

MAX6317HUK____-T

MAX6318HUK____-T

________________________Applications

Portable Computers

Computers

Controllers

MAX6318MHUK____-T -40°C to +85°C

Intelligent Instruments

Ordering Information continued at end of data sheet.

Portable/Battery-Powered Equipment

Embedded Control Systems

Typical Operating Circuit and Pin Configurations appear at

end of data sheet.

___________________________________________________________________Selector Guide

RESET OUTPUTS*

MANUAL

RESET

INPUT

WATCHDOG

PART

ACTIVE-LOW

PUSH/PULL

ACTIVE-HIGH

PUSH/PULL

ACTIVE-LOW

BIDIRECTIONAL

ACTIVE-LOW

OPEN-DRAIN

INPUT

✔

MAX6316L

—

✔

—

✔

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 Products

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.

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

ABSOLUTE MAXIMUM RATINGS

Voltage (with respect to GND)

Continuous Power Dissipation (T = +70°C)

A

V

......................................................................-0.3V to +6V

SOT23-5 (derate 7.1mW/°C above +70°C)...............571mW

Operating Temperature Range............................-40°C to +85°C

Junction Temperature ......................................................+150°C

Storage Temperature Range..............................-65°C to +160°C

Lead Temperature (soldering, 10s) .................................+300°C

CC

RESET (MAX6320/MAX6321/MAX6322 only)...... -0.3V to +6V

All Other Pins.........................................-0.3V to (V + 0.3V)

CC

Input/Output Current, All Pins .............................................20mA

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.

ELECTRICAL CHARACTERISTICS

(V

= 2.5V to 5.5V, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)

CC

A

PARAMETER

SYMBOL

CONDITIONS

= -40°C to +85°C

A

MIN

TYP

MAX UNITS

Operating Voltage Range

Supply Current

V

CC

T

1

5.5

20

V

MAX6316/MAX6317/MAX6318/

MAX6320/MAX6321:

MR and WDI unconnected

V

= 5.5V

= 3.6V

10

5

CC

12

CC

I

µA

CC

V

= 5.5V

= 3.6V

5

3

12

8

MAX6319/MAX6322:

MR unconnected

CC

Reset Threshold Temperature

Coefficient

V

TH

/°C

40

ppm/°C

T

= +25°C

V

-1.5% V

V

+1.5%

+2.5%

A

TH

Reset Threshold (Note 2)

Reset Threshold Hysteresis

V

RST

V

= -40°C to +85°C

-2.5% V

A

TH

3

mV

MAX63_ _A_-T

MAX63_ _B_-T

MAX63_ _C_-T

MAX63_ _D_-T

1

1.4

28

2

20

40

Reset Active Timeout Period

t

ms

µs

RP

140

200

1600

40

280

2240

1120

t

V

CC

falling at 1mV/µs

V

CC

to RESET Delay

RD

PUSH/PULL RESET OUTPUT (MAX6316L/MAX6317H/MAX6318_H/MAX6319_H/MAX6321HP/MAX6322HP)

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

1.0V, I

1.2V, I

2.7V, I

4.5V, I

2.7V, I

4.5V, I

2.7V, I

4.5V, I

1.8V, I

2.7V, I

4.5V, I

= 50µA

0.3

0.4

SINK

= 100µA

= 1.2mA

= 3.2mA

V

OL

V

RESET Output Voltage

= 500µA

= 800µA

0.8 x V

CC

SOURCE

V

OH

V

CC

- 1.5

= 1.2mA

0.3

0.4

SINK

V

OL

= 3.2mA

SINK

RESET Output Voltage

= 150µA

= 500µA

= 800µA

0.8 x V

SOURCE

CC

V

OH

CC

V

CC

- 1.5

Note 1: Over-temperature limits are guaranteed by design, not production tested.

Note 2: A factory-trimmed voltage divider programs the nominal reset threshold (V ). Factory-trimmed reset thresholds are

TH

available in 100mV increments from 2.5V to 5V (see Table 1 at end of data sheet).

2

_______________________________________________________________________________________

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

ELECTRICAL CHARACTERISTICS (continued)

(V

= 2.5V to 5.5V, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)

CC

A

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX UNITS

BIDIRECTIONAL RESET OUTPUT (MAX6316M/MAX6318MH/MAX6319MH)

Transition Flip-Flop Setup Time

t

S

(Note 3)

400

ns

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

= 3.0V, C = 120pF

333

L

= 5.0V, C = 200pF

333

ns

L

RESET Output Rise Time

(Note 4)

t

R

= 3.0V, C = 250pF

666

L

= 5.0V, C = 400pF

L

666

Active Pullup Enable Threshold

RESET Active Pullup Current

RESET Pullup Resistance

V

= 5.0V

0.4

4.2

0.65

20

V

PTH

mA

4.7

5.2

k

OPEN-DRAIN RESET OUTPUT (MAX6320P/MAX6321HP/MAX6322HP)

V

CC

V

CC

V

CC

V

CC

1.0V, I

1.2V, I

2.7V, I

4.5V, I

= 50µA

0.3

0.4

SINK

= 100µA

= 1.2mA

= 3.2mA

V

OL

V

RESET Output Voltage

Open-Drain Reset Output

Leakage Current

I

1.0

µA

ms

LKG

WATCHDOG INPUT (MAX6316/MAX6317H/MAX6318_H/MAX6320P/MAX6321HP)

MAX63_ _ _ W-T

MAX63_ _ _ X-T

4.3

71

6.3

102

1.6

9.3

153

2.4

Watchdog Timeout Period

t

WD

MAX63_ _ _ Y-T

MAX63_ _ _ Z-T

1.12

17.9

50

s

ns

V

25.6

38.4

WDI Pulse Width

t

V = 0.3 x V , V = 0.7 x V

IL CC IH CC

WDI

V

IL

0.3 x V

CC

WDI Input Threshold

(Note 5)

WDI = V , time average

V

0.7 x V

CC

IH

120

-15

160

CC

WDI Input Current

(Note 6)

I

µA

WDI

V

WDI

= 0, time average

-20

0.8

MANUAL RESET INPUT (MAX6316_/MAX6317H/MAX6319_H/MAX6320P/MAX6322HP)

V

IL

V

> 4.0V

< 4.0V

TH

V

2.0

IH

V

MR Input Threshold

V

IL

0.3 x V

1

CC

V

0.7 x V

CC

IH

µs

ns

k

MR Input Pulse Width

MR Glitch Rejection

MR Pullup Resistance

MR to Reset Delay

100

52

35

75

V

CC

= 5V

230

ns

Note 3: This is the minimum time RESET must be held low by an external pulldown source to set the active pullup flip-flop.

Note 4: Measured from RESET V to (0.8 x V ), R

=

LOAD

.

OL

CC

Note 5: WDI is internally serviced within the watchdog period if WDI is left unconnected.

Note 6: The WDI input current is specified as the average input current when the WDI input is driven high or low. The WDI input is

designed for a three-stated-output device with a 10µA maximum leakage current and capable of driving a maximum capaci-

tive load of 200pF. The three-state device must be able to source and sink at least 200µA when active.

_______________________________________________________________________________________

3

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

__________________________________________Typical Operating Characteristics

(T = +25°C, unless otherwise noted.)

A

MAX6316/MAX6317/MAX6319/MAX6320/MAX6322

MANUAL RESET TO RESET

MAX6316/MAX6317/MAX6318/MAX6320/MAX6321

V

FALLING TO RESET PROPAGATION

DELAY vs. TEMPERATURE

CC

SUPPLY CURRENT vs. TEMPERATURE

PROPAGATION DELAY vs. TEMPERATURE

10

320

100

90

80

70

60

50

40

30

20

10

0

V

FALLING AT 1mV/ s

V

CC

= 5V

CC

9

300

280

260

240

220

200

180

160

140

- V = 100mV

RST

CC

V

= 5V

CC

8

7

6

5

4

V

= 3V

= 1V

CC

3

2

1

0

-40 -20

0

20

40

60

80 100

-40 -20

0

20

40

60

80 100

-40 -20

0

20

40

60

80 100

TEMPERATURE ( C)

MAX6316/MAX6317/MAX6318/MAX6320/MAX6321

NORMALIZED WATCHDOG TIMEOUT

PERIOD vs. TEMPERATURE

1.05

NORMALIZED RESET TIMEOUT

PERIOD vs. TEMPERATURE

1.05

1.04

1.03

1.02

1.01

1.00

0.99

0.98

0.97

0.96

0.95

1.04

1.03

1.02

1.01

1.00

0.99

0.98

0.97

0.96

0.95

-40 -20

0

20

40

60

80 100

-40 -20

0

20

40

60

80 100

TEMPERATURE ( C)

MAX6316M/6318MH/6319MH

BIDIRECTIONAL

MAXIMUM V TRANSIENT DURATION

CC

vs. RESET THRESHOLD OVERDRIVE

PULLUP CHARACTERISTICS

MAX6316toc07

80

70

60

+5V

4.7k

PASSIVE

4.7k

PULLUP

2V/div

RESET OCCURS ABOVE LINES

74HC05

V

= 3.3V

RST

100pF

INPUT

V

= 4.63V

RST

V

50

40

30

20

10

0

RESET, ACTIVE

PULLUP

+5V

V_CC

RESET

2V/div

= 2.63V

74HC05

100pF

RST

INPUT

RESET

INPUT

5V/div

GND

MR

200ns/div

10

100

1000

CC

RESET THRESHOLD OVERDRIVE (mV) V - V

RST

4

_______________________________________________________________________________________

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

______________________________________________________________Pin Description

MAX6316L

MAX6316M

MAX6320P

MAX6318LH

MAX6318MH

MAX6321HP

MAX6319LH

MAX6319MH

MAX6322HP

NAME

FUNCTION

MAX6317H

MAX6316L/MAX6318LH/MAX6319LH:

Active-Low, Reset Output. CMOS push/pull

output (sources and sinks current).

MAX6316M/MAX6318MH/MAX6319MH:

Bidirectional, Active-Low, Reset Output.

Intended to interface directly to microprocessors

with bidirectional resets such as the Motorola

68HC11.

1

—

1

RESET

MAX6320P/MAX6321HP/MAX6322HP:

Open-Drain, Active-Low, Reset Output. NMOS out-

put (sinks current only). Connect a pullup resistor

from RESET to any supply voltage up to 6V.

Active-High, Reset Output. CMOS push/pull output

(sources and sinks current). Inverse of RESET.

—

2

1

2

3

2

3

2

RESET

GND

Ground

Active-Low, Manual Reset Input. Pull low to force a

reset. Reset remains asserted for the duration of

the Reset Timeout Period after MR transitions from

low to high. Leave unconnected or connected to

3

4

5

3

4

5

—

4

—

5

MR

V

CC

if not used.

Watchdog Input. Triggers a reset if it remains

either high or low for the duration of the watchdog

timeout period. The internal watchdog timer clears

whenever a reset asserts or whenever WDI sees a

rising or falling edge. To disable the watchdog fea-

ture, leave WDI unconnected or three-state the dri-

ver connected to WDI.

4

WDI

Supply Voltage. Reset is asserted when V

CC

drops below the Reset Threshold Voltage (V

).

RST

5

V

CC

Reset remains asserted until V

rises above

CC

V

RST

and for the duration of the Reset Timeout

Period (t ) once V

rises above V

.

RP

CC

RST

_______________________________________________________________________________________

5

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

V

CC

MAX6316–MAX6322

RESET

(ALL EXCEPT MAX6317)

RESET

GENERATOR

RESET

(ALL EXCEPT

MAX6316/MAX6320P)

V

CC

1.23V

52k

MR

(ALL EXCEPT

MAX6318/MAX6321)

WATCHDOG

TRANSITION

DETECTOR

WATCHDOG

TIMER

WDI

(ALL EXCEPT

MAX6319/MAX6322)

52k

GND

Figure 1. Functional Diagram

the watchdog timeout period (t ). Reset remains assert-

WD

_______________Detailed Description

ed for the specified reset active timeout period (t ) after

RP

A microprocessor’s (µP) reset input starts or restarts the

µP in a known state. The reset output of the MAX6316–

MAX6322 µP supervisory circuits interfaces with the

reset input of the µP, preventing code-execution errors

during 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 in

an infinite loop.

V

CC

rises above the reset threshold, after MR transitions

low to high, or after the watchdog timer asserts the reset

(MAX6316_/MAX6317H/MAX6318_H/MAX6320P/

MAX6321HP). After the reset active timeout period (t

)

RP

expires, the reset output deasserts, and the watchdog

timer restarts from zero (Figure 2).

V

CC

V

RST

1V

Reset Output

The MAX6316L/MAX6318LH/MAX6319LH feature an

active-low reset output, while the MAX6317H/

MAX6318_H/MAX6319_H/MAX6321HP/MAX6322HP

feature an active-high reset output. RESET is guaran-

teed to be a logic low and RESET is guaranteed to be a

GND

t

RP

t

RD

RESET

t

logic high for V

down to 1V.

t

RD

CC

RESET

GND

The MAX6316–MAX6322 assert reset when V

is below

CC

the reset threshold (V

), when MR is pulled low

RST

(MAX6316_/MAX6317H/MAX6319_H/MAX6320P/

MAX6322HP only), or if the WDI pin is not serviced within

Figure 2. Reset Timing Diagram

6

_______________________________________________________________________________________

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

scratch. If, on the other hand, RESET is high after a

delay of two external-clock cycles, the processor

knows that it caused the reset itself and can jump to a

different vector and use stored-state information to

determine what caused the reset.

RESET

Bidirectional

Output

The MAX6316M/MAX6318MH/MAX6319MH are designed

to interface with µPs that have bidirectional reset pins,

such as the Motorola 68HC11. Like an open-drain output,

these devices allow the µP or other devices to pull the

bidirectional reset (RESET) low and assert a reset condi-

tion. However, unlike a standard open-drain output, it

includes the commonly specified 4.7k pullup resistor

with a P-channel active pullup in parallel.

A problem occurs with faster µPs; two external-clock

cycles are only 500ns at 4MHz. When there are several

devices on the reset line, and only a passive pullup resis-

tor is used, the input capacitance and stray capacitance

can prevent RESET from reaching the logic high state (0.8

✕

This configuration allows the MAX6316M/MAX6318MH/

MAX6319MH to solve a problem associated with µPs

that have bidirectional reset pins in systems where sev-

eral devices connect to RESET (Figure 3). These µPs

can often determine if a reset was asserted by an exter-

nal device (i.e., the supervisor IC) or by the µP itself

(due to a watchdog fault, clock error, or other source),

and then jump to a vector appropriate for the source of

the reset. However, if the µP does assert reset, it does

not retain the information, but must determine the

cause after the reset has occurred.

V ) in the time allowed. If this happens, all resets will

CC

be interpreted as external. The µP output stage is guaran-

teed to sink 1.6mA, so the rise time can not be reduced

considerably by decreasing the 4.7k internal pullup

resistance. See Bidirectional Pullup Characteristics in the

Typical Operating Characteristics.

The MAX6316M/MAX6318MH/MAX6319MH overcome

this problem with an active pullup FET in parallel with the

4.7k resistor (Figures 4 and 5). The pullup transistor

holds RESET high until the µP reset I/O or the supervisory

circuit itself forces the line low. Once RESET goes below

The following procedure describes how this is done in

the Motorola 68HC11. In all cases of reset, the µP pulls

RESET low for about four external-clock cycles. It then

releases RESET, waits for two external-clock cycles,

then checks RESET’s state. If RESET is still low, the µP

concludes that the source of the reset was external

and, when RESET eventually reaches the high state, it

jumps to the normal reset vector. In this case, stored-

state information is erased and processing begins from

V

, a comparator sets the transition edge flip-flop, indi-

PTH

cating that the next transition for RESET will be low to

high. When RESET is released, the 4.7k resistor pulls

RESET up toward V . Once RESET rises above V

CC

PTH

but is below (0.85 x V ), the active P-channel pullup

CC

turns on. Once RESET rises above (0.85 x V ) or the

CC

2µs one-shot times out, the active pullup turns off. The

parallel combination of the 4.7k pullup and the

V

CC

V

CC

WDI*

MR**

4.7k

68HC11

RESET

CIRCUITRY

RESET

CIRCUITRY

RESET***

C

IN

C

STRAY

IN

MAX6316M

MAX6318MH

MAX6319MH

C

OTHER DEVICES

IN

*

**

***

MAX6316M/MAX6318MH

MAX6316M/MAX6319MH

ACTIVE-HIGH PUSH/PULL MAX6318MH/MAX6319MH

Figure 3. MAX6316M/MAX6318MH/MAX6319MH Supports Additional Devices on the Reset Bus

_______________________________________________________________________________________

7

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

V

CC

MAX6316M

MAX6318MH

MAX6319MH

LASER-

TRIMMED

RESISTORS

V

CC

VREF

52k

MR

(MAX6316M/

MAX6319MH)

RESET

GENERATOR

(MAX6316M/

MAX6318MH)

WATCHDOG ON

2 s ONE SHOT

CIRCUITRY

WDI

V

CC

2 s ONE SHOT

TRANSITION

FLIP-FLOP

R

Q

4.7k

FF

S

RESET

ACTIVE PULLUP

ENABLE COMPARATOR

0.65V

0.85V

CC

GND

Figure 4. MAX6316/MAX6318MH/MAX6319MH Bidirectional Reset Output Functional Diagram

8

_______________________________________________________________________________________

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

P-channel transistor on-resistance quickly charges

register a logic low (see Electrical Characteristics), and

small enough to register a logic high while supplying all

input current and leakage paths connected to the RESET

line. A 10k pullup is sufficient in most applications.

stray capacitance on the reset line, allowing RESET to

transition from low to high within the required two elec-

tronic-clock cycles, even with several devices on the

reset line. This process occurs regardless of whether

Manual-Reset Input

The MAX6316_/MAX6317H/MAX6319_H/MAX6320P/

MAX6322HP feature a manual reset input. A logic low on

MR asserts a reset. After MR transitions low to high, reset

remains asserted for the duration of the reset timeout peri-

the reset was caused by V

dipping below the reset

CC

threshold, the watchdog timing out, MR being asserted,

or the µP or other device asserting RESET. The parts do

not require an external pullup. To minimize supply cur-

rent consumption, the internal 4.7k pullup resistor dis-

connects from the supply whenever the MAX6316M/

MAX6318MH/MAX6319MH assert reset.

od (t ). The MR input is connected to V

through an

RP

CC

internal 52k pullup resistor and therefore can be left

unconnected when not in use. MR can be driven with

TTL-logic levels in 5V systems, with CMOS-logic levels in

3V systems, or with open-drain or open-collector output

devices. A normally-open momentary switch from MR to

ground can also be used; it requires no external

debouncing circuitry. MR is designed to reject fast,

negative-going transients (typically 100ns pulses). A

0.1µF capacitor from MR to ground provides additional

noise immunity.

RESET

Open-Drain

Output

The MAX6320P/MAX6321HP/MAX6322HP have an

active-low, open-drain reset output. This output struc-

ture will sink current when RESET is asserted. Connect

a pullup resistor from RESET to any supply voltage up

to 6V (Figure 6). Select a resistor value large enough to

V

CC

The MR input pin is equipped with internal ESD-protection

circuitry that may become forward biased. Should MR be

t

0.8 x V

RP

CC

RESET

OR

driven by voltages higher than V , excessive current

CC

C RESET DELAY

0.7V

would be drawn, which would damage the part. For

example, assume that MR is driven by a +5V supply other

t

R

t

S

than V . If V

drops lower than +4.7V, MR’s absolute

CC

maximum rating is violated [-0.3V to (V

+ 0.3V)], and

CC

ACTIVE

PULLUP

TURNS ON

RESET PULLED LOW

BY C OR

RESET GENERATOR

undesirable current flows through the ESD structure from

MR to V . To avoid this, use the same supply for MR as

CC

the supply monitored by V . This guarantees that the

CC

voltage at MR will never exceed V

.

CC

Figure 5. Bidirectional RESET Timing Diagram

Watchdog Input

The MAX6316_/MAX6317H/MAX6318_H/MAX6320P/

MAX6321HP feature a watchdog circuit that monitors

the µP’s activity. If the µP does not toggle the watchdog

+3.3V

+5.0V

input (WDI) within the watchdog timeout period (t ),

WD

V

reset asserts. The internal watchdog timer is cleared by

reset or by a transition at WDI (which can detect pulses

as short as 50ns). The watchdog timer remains cleared

while reset is asserted. Once reset is released, the

timer begins counting again (Figure 7).

CC

MR*

10k

WDI**

RESET

5V SYSTEM

RESET***

The WDI input is designed for a three-stated output

device with a 10µA maximum leakage current and the

capability of driving a maximum capacitive load of 200pF.

The three-state device must be able to source and sink at

least 200µA when active. Disable the watchdog function

by leaving WDI unconnected or by three-stating the driver

connected to WDI. When the watchdog timer is left open

circuited, the timer is cleared internally at intervals equal

to 7/8 of the watchdog period.

MAX6320

MAX6321

MAX6322

* MAX6320/MAX6322

** MAX6320/MAX6321

*** MAX6321/MAX6322

GND

Figure 6. MAX6320P/MAX6321HP/MAX6322HP Open-Drain

RESET Output Allows Use with Multiple Supplies

_______________________________________________________________________________________

9

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

V

CC

t

RST

V

CC

MAX6316

MAX6318

MAX6319

RESET

WDI

t

RP

t

RP

WD

V

CC

GND

RESET

100k

MAX6316/MAX6317

MAX6318/MAX6320

MAX6321

Figure 7. Watchdog Timing Relationship

Figure 8. Ensuring RESET Valid to V

= 0 on Active-Low

CC

Push/Pull and Bidirectional Outputs

Applications Information

Watchdog Input Current

The WDI input is internally driven through a buffer and

series resistor from the watchdog counter. For minimum

watchdog 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 much

as 160µA. Pulsing WDI high at a low duty cycle will

reduce the effect of the large input current. When WDI

is left unconnected, the watchdog timer is serviced

within the watchdog timeout period by a low-high-low

pulse from the counter chain.

MAX6317

MAX6318

MAX6319

MAX6321*

V

CC

100k

MAX6322*

V

CC

GND

RESET

*THIS SCHEMATIC DOES NOT WORK ON THE OPEN-DRAIN

OUTPUTS OF THE MAX6321/MAX6322.

Negative-Going V

Transients

CC

Figure 9. Ensuring RESET Valid to V

Push/Pull Outputs

= 0 on Active-High

These supervisors are immune to short-duration, nega-

tive-going V transients (glitches), which usually do

CC

not require the entire system to shut down. Typically,

source current. This scheme does not work with the

open-drain outputs of the MAX6320/MAX6321/MAX6322.

The resistor value used is not critical, but it must be

large enough not to load the reset output when V

above the reset threshold. For most applications,

100k is adequate.

200ns large-amplitude pulses (from ground to V ) on

CC

the supply will not cause a reset. Lower amplitude puls-

es result in greater immunity. Typically, a V

transient

CC

is

CC

that goes 100mV under the reset threshold and lasts

less than 4µs will not trigger a reset. An optional 0.1µF

bypass capacitor mounted close to V

tional transient immunity.

provides addi-

CC

Watchdog Software Considerations

(MAX6316/MAX6317/MAX6318/

Ensuring Valid Reset Outputs

MAX6320/MAX6321)

Down to V

= 0

CC

One way to help the watchdog timer monitor software

execution more closely is to set and reset the watchdog

input at different points in the program, rather than

pulsing the watchdog input high-low-high or low-high-

low. This technique avoids a stuck loop, in which the

watchdog timer would continue to be reset inside the

loop, keeping the watchdog from timing out.

The MAX6316_/MAX6317H/MAX6318_H/MAX6319_H/

MAX6321HP/MAX6322HP are guaranteed to operate

properly down to V

= 1V. In applications that require

CC

valid reset levels down to V

= 0, a pulldown resistor

CC

to 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 line

is valid while the reset output can no longer sink or

10 ______________________________________________________________________________________

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

Figure 10 shows an example of a flow diagram where

the I/O driving the watchdog input is set high at the

beginning of the program, set low at the end of every

subroutine or loop, then set high again when the pro-

gram returns to the beginning. If the program should

hang in any subroutine, the problem would be quickly

corrected, since the I/O is continually set low and the

watchdog timer is allowed to time out, causing a reset

or interrupt to be issued. As described in the Watchdog

Input Current section, this scheme results in higher time

average WDI current than does leaving WDI low for the

majority of the timeout period and periodically pulsing it

low-high-low.

START

SET WDI

HIGH

PROGRAM

CODE

POSSIBLE

INFINITE LOOP PATH

SUBROUTINE OR

PROGRAM LOOP

SET WDI LOW

RETURN

Figure 10. Watchdog Flow Diagram

__________________Pin Configurations

Typical Operating Circuit

TOP VIEW

RESET

GND

MR

1

2

3

5

V

RESET

GND

MR

1

2

3

5

V

CC

V

IN

V

MAX6316

MAX6320

MAX6317

CC

P

RESET

I/O

MAX6316

4

WDI

4

WDI

MR

WDI

MANUAL

RESET

GND

SOT23-5

RESET

GND

1

2

3

5

4

V

RESET

GND

1

2

3

5

4

V

CC

MAX6318

MAX6321

MAX6319

MAX6322

RESET

WDI

RESET

MR

SOT23-5

______________________________________________________________________________________ 11

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

Table 1. Factory-Trimmed Reset Thresholds

T

A

= +25°C

TYP

T = -40°C to +85°C

A

PART

MIN

MAX

5.075

4.974

4.872

4.771

4.699

4.568

4.446

4.365

4.263

4.162

4.060

3.959

3.857

3.756

3.654

3.553

3.451

3.350

3.248

3.126

3.045

2.974

2.842

2.741

2.669

2.538

MIN

MAX

MAX63___50_ _-T

MAX63___49_ _-T

MAX63___48_ _-T

MAX63___47_ _-T

MAX63___46_ _-T

MAX63___45_ _-T

MAX63___44_ _-T

MAX63___43_ _-T

MAX63___42_ _-T

MAX63___41_ _-T

MAX63___40_ _-T

MAX63___39_ _-T

MAX63___38_ _-T

MAX63___37_ _-T

MAX63___36_ _-T

MAX63___35_ _-T

MAX63___34_ _-T

MAX63___33_ _-T

MAX63___32_ _-T

MAX63___31_ _-T

MAX63___30_ _-T

MAX63___29_ _-T

MAX63___28_ _-T

MAX63___27_ _-T

MAX63___26_ _-T

MAX63___25_ _-T

4.925

7.827

4.728

4.630

4.561

4.433

4.314

4.236

4.137

4.039

3.940

3.842

3.743

3.645

3.546

3.448

3.349

3.251

3.152

3.034

2.955

2.886

2.758

2.660

2.591

2.463

5.000

4.900

4.800

4.700

4.630

4.500

4.390

4.300

4.200

4.100

4.000

3.900

3.800

3.700

3.600

3.500

3.400

3.300

3.200

3.080

3.000

2.930

2.800

2.700

2.630

2.500

4.875

4.778

4.680

4.583

4.514

4.388

4.270

4.193

4.095

3.998

3.900

3.803

3.705

3.608

3.510

3.413

3.315

3.218

3.120

3.003

2.925

2.857

2.730

2.633

2.564

2.438

5.125

5.023

4.920

4.818

4.746

4.613

4.490

4.408

4.305

4.203

4.100

3.998

3.895

3.793

3.690

3.588

3.485

3.383

3.280

3.157

3.075

3.000

2.870

2.768

2.696

2.563

Table 2. Standard Versions

MINIMUM

RESET

TIMEOUT (ms)

TYPICAL

WATCHDOG

TIMEOUTS (s)

SOT

TOP

MARK

RESET

THRESHOLD (V)

PART

MAX6316LUK29CY-T

MAX6316LUK46CY-T

MAX6316MUK29CY-T

MAX6316MUK46CY-T

MAX6317HUK46CY-T

MAX6318LHUK46CY-T

MAX6318MHUK46CY-T

MAX6319LHUK46C-T

MAX6319MHUK46C-T

MAX6320PUK29CY-T

2.93

4.63

2.93

4.63

2.93

140

1.6

—

ACDE

ACDD

ACDG

ACDF

ACDQ

ACDH

ACDJ

ACDK

ACDM

ACDO

—

1.6

12 ______________________________________________________________________________________

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

Table 2. Standard Versions (continued)

MINIMUM

RESET

TIMEOUT (ms)

TYPICAL

WATCHDOG

TIMEOUTS (s)

SOT

TOP

MARK

RESET

PART

THRESHOLD (V)

MAX6320PUK46CY-T

MAX6321HPUK46CY-T

MAX6322HPUK46C-T

4.63

140

1.6

ACDN

ACGL

ACGN

Note: 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.

__Ordering Information (continued)

Table 3. Reset/Watchdog Timeout Periods

PART

TEMP. RANGE

-40°C to +85°C

PIN-PACKAGE

5 SOT23-5

RESET TIMEOUT PERIODS

MAX6319LHUK____-T

MAX6319MHUK____-T

MAX6320PUK____-T

MAX6321HPUK____-T

MAX6322HPUK____-T

SUFFIX

MIN

1

TYP

1.6

MAX

2

UNITS

ms

A

B

C

D

20

30

40

140

1.12

200

1.60

280

2.24

s

Note: These devices are available with factory-set V

reset

CC

thresholds from 2.5V to 5V, in 0.1V increments. Insert the

desired nominal reset threshold (25 to 50, from Table 1) into the

blanks following the letters UK. All devices offer factory-pro-

grammed reset timeout periods. Insert the letter corresponding

to the desired reset timeout period (A, B, C, or D from Table 3)

into the blank following the reset threshold suffix. Parts that offer

a watchdog feature (see Selector Guide) are factory-trimmed to

one of four watchdog timeout periods. Insert the letter corre-

sponding to the desired watchdog timeout period (W, X, Y, or Z

from Table 3) into the blank following the reset timeout suffix.

WATCHDOG TIMEOUT

W

X

4.3

6.3

102

1.6

9.3

ms

s

71

153

2.4

Y

1.12

17.9

Z

25.6

38.4

Chip Information

TRANSISTOR COUNT: 191

SUBSTRATE IS INTERNALLY CONNECTED TO V+

______________________________________________________________________________________ 13

5-Pin µP Supervisory Circuits with

Watchdog and Manual Reset

Package Information

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.

14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

Printed USA

is a registered trademark of Maxim Integrated Products.


型号：	MAX6319MHUK44AW-T
厂家：	MAXIM INTEGRATED PRODUCTS
描述：	Analog IC 模拟IC\n 模拟IC 电源电路电源管理电路光电二极管输入元件
文件：	总14页 (文件大小：205K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

MAX6319MHUK44AW-T [MAXIM]

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