MAXIM MAX6701A Technical data

General Description

The MAX6701–MAX6708 microprocessor (µP) supervisory
circuits reduce the complexity and components required
to monitor power-supply functions in µP systems. These
devices significantly improve system reliability and accu­racy compared to separate ICs or discrete components.

The MAX6701–MAX6708 family provides four functions:
a reset output during power-up, power-down, and
brownout conditions; an independent watchdog output
that goes low if the watchdog input has not been toggled
within 1.6s; a 0.62V threshold detector for power-fail
warning; and an active-low manual reset input.

The MAX6701–MAX6708 family offers several pinout
options to accommodate a variety of multivoltage micro­processor supervision applications.

The MAX6701(A)/MAX6702(A)/MAX6703(A) monitor
three supply voltages (one fixed threshold and two
adjustable) to drive a single reset output and include a
manual reset input and a watchdog timer with an inde­pendent output. The MAX6704 monitors a single-supply
voltage to drive complementary reset outputs and
includes an independent adjustable power-fail-in/power­fail-out comparator, a manual reset input, and a reset­based watchdog timer. The MAX6705(A)/MAX6706(A)/
MAX6707(A) monitor a single-supply voltage to drive a
single reset output and include an independent
adjustable power-fail-in/power-fail-out comparator, a
manual reset input, and a watchdog timer with an inde­pendent output. The MAX6708 is the same as the
MAX6704 but without the watchdog timer function.

See the Detailed Description for differences between
non-A and A versions.

Applications

Computers

Controllers

Intelligent Instruments

Automotive Systems

Critical µP Power Monitoring

White Goods

Networking

Telecommunications

Features

♦ Small 8-Pin SOT23 Package
♦ Precision Monitoring of +5.0V, +3.3V, +3.0V, +2.5V

Supply Voltages

♦ 140ms Reset Timeout Delay
♦ Power-Fail Input with Independent Output;

Monitor Inputs Down to 0.62V (MAX6704–MAX6708)

♦ Dual Adjustable Reset Input for Triple-Voltage

Monitoring (MAX6701(A)/MAX6702(A)/MAX6703(A))

♦ 1.6s Watchdog Timeout Period

(MAX6701(A)–MAX6707(A))

♦ Independent Watchdog Output

(MAX6701(A)/MAX6702(A)/MAX6703(A)/
MAX6705(A)/MAX6706(A)/MAX6707(A))

♦ Manual Reset Input
♦ Four Reset Output Stage Options

Active Low Push-Pull (MAX6701(A), MAX6705(A))
Active Low Open Drain (MAX6703(A), MAX6707(A))
Active High Push-Pull (MAX6702(A), MAX6706(A))
Dual Active Low/High Push-Pull (MAX6704,
MAX6708)

♦ Guaranteed Reset Valid to V

CC

= 1V

♦ Immune to Short Falling V

CC

Transients

♦ Low Cost, Few External Components

MAX6701–08/MAX6701A–03A/05A–07A

Low-Voltage, SOT23 µP Supervisors with Power-

Fail In/Out, Manual Reset, and Watchdog Timer

________________________________________________________________ Maxim Integrated Products 1

Pin Configurations

Ordering Information

19-1952; Rev 2; 8/03

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.

Insert the desired suffix letter (from the Threshold Suffix Guide
table) into the blank to complete the part number. All devices
must be ordered in increments of 2500 pieces. Sample stock is
typically held on standard versions only. Contact factory for
availability.

Ordering Information continued at end of data sheet.

Typical Operating Circuit and Selector Guide appear at end
of data sheet.

Pin Configurations continued at end of data sheet.

查询MAX6701供应商

PART TEMP RANGE PIN-PACKAGE

MAX6701_KA-T -40°C to +125°C 8 SOT23-8

MAX6701A_KA-T -40°C to +125°C 8 SOT23-8

TOP VIEW

MR

GND

1

2

CC

3

4

MAX6701(A)
MAX6702(A)
MAX6703(A)

87WDO

RESET (RESET)V

WDI

6

RST_IN2RST_IN1

5

( ) ARE FOR MAX6702(A) ONLY.

SOT23

MAX6701–08/MAX6701A–03A/05A–07A

Low-Voltage, SOT23 µP Supervisors with Power­Fail In/Out, Manual Reset, and Watchdog Timer

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +4.25V to +5.5V for L/M versions, VCC= +2.55V to +3.6V for the T/S/R versions, VCC= +2.1V to +2.75V for the Z/Y versions.
T

A

= -40°C to +125°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 1)

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.

VCC........................................................................-0.3V to +6.0V

Open-Drain RESET, WDO, PFO ...........................-0.3V to +6.0V

Push-Pull RESET, RESET, WDO, PFO ........-0.3V to (V

CC

+ 0.3V)

MR, WDI, PFI, RST_IN1, RST_IN2 ..............-0.3V to (V

CC

+ 0.3V)

Input Current (V

CC

).............................................................20mA

Output Current (RESET, RESET, PFO, WDO) .....................20mA

Continuous Power Dissipation (T

A

= +70°C)

8-Pin SOT23 (derate 8.9mW/°C above +70°C)............714mW

Operating Temperature Range .........................-40°C to +125°C

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

Storage Temperature Range .............................-65°C to +150°C

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

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Operating Voltage Range V

Supply Current
MR Unconnected

VCC Reset Threshold

falling)

(V

CC

I

CC

V

Reset Threshold
Temperature Coefficient

VCC to Reset Output Delay VCC falling at 10mV/µs 12 µs

Reset Timeout Period t

VCC Falling to WDO Delay

PFI, RST_IN1, RST_IN2
Threshold

PFI Hysteresis 6mV

∆V

RP

TA = 0°C to +125°C 1.0 5.5

CC

TA = -40°C to +125°C 1.2 5.5

VCC < 5.5V, no load 12 25

VCC < 3.6V, no load 9 20

VCC < 3.6V, no load (MAX6708 only) 6 20

MAX670_L/MAX670_AL

M AX 670_M /M AX 670_AM

MAX670_T/MAX670_AT

MAX670_S/MAX670_AS

TH

MAX670_R/MAX670_AR

MAX670_Z/MAX670_AZ

MAX670_Y/MAX670_AY

TH

M AX 6701( A) /M AX 6702( A) /M AX 6703( A) /M AX 6705( A) /
M AX 6706( A) /M AX 6707( A)

= 1.8V to 5.5V

V

C C

TA = -40°C to +85°C 4.50 4.63 4.75

= -40°C to +125°C 4.47 4.78

T

A

TA = -40°C to +85°C 4.25 4.38 4.50

= -40°C to +125°C 4.22 4.53

T

A

TA = -40°C to +85°C 3.00 3.08 3.15

= -40°C to +125°C 2.97 3.17

T

A

TA = -40°C to +85°C 2.85 2.93 3.00

= -40°C to +125°C 2.83 3.02

T

A

TA = -40°C to +85°C 2.55 2.63 2.70

= -40°C to +125°C 2.53 2.72

T

A

TA = -40°C to +85°C 2.25 2.32 2.38

= -40°C to +125°C 2.24 2.40

T

A

TA = -40°C to +85°C 2.12 2.19 2.25

= -40°C to +125°C 2.11 2.27

T

A

TA = -40°C to +85°C 140 200 280

TA = -40°C to +125°C 120 300

TA = -40°C to +85°C 602 618 634

= -40°C to +125°C 593 642

T

A

V

µA

V

60 ppm/°C

ms

5µs

mV

MAX6701–08/MAX6701A–03A/05A–07A

Low-Voltage, SOT23 µP Supervisors with Power-

Fail In/Out, Manual Reset, and Watchdog Timer

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +4.25V to +5.5V for L/M versions, VCC= +2.55V to +3.6V for the T/S/R versions, VCC= +2.1V to +2.75V for the Z/Y versions.
T

A

= -40°C to +125°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 1)

Note 1: Over-temperature limits are guaranteed by design and not production tested. Devices are tested at T

A

= +25°C.

Note 2: Guaranteed by design. Not production tested.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

PFI, RST_IN1, RST_IN2
Leakage Current

PFI to PFO Delay t

MR Input Voltage

(Note 2)

PF

V

IL

V

IH

TA = -40°C to +85°C

T

= -40°C to +125°C

A

-50

-200

0.7 x V

+50

+200

nA

1µs

0.3 x V

CC

CC

V

MR Minimum Input Pulse 1µs
MR Glitch Rejection 100 ns
MR to Reset Delay t

VCC Rising to WDO Delay

MD

MAX6701(A)/MAX6702(A)/MAX6703(A)/
MAX6705(A)/MAX6706(A)/MAX6707(A)

200 ns

100 ns

MR Pullup Resistance 25 50 75 kΩ

Watchdog Timeout Period t

WDI Pulse Width t

WDI Input Voltage

WDI Input Current I

RESET, WDO Output Low
(Push-Pull or Open Drain)

PFO Output Low
(Push-Pull or Open Drain)

RESET, WDO, PFO Output
High (Push-Pull Only)

WDI

V

V

WDI

V

V

V

WD

OH

TA = -40°C to +85°C 1.12 1.6 2.4

TA = -40°C to +125°C 0.96 2.52

(Note 2) 50 ns

IL

IH

OL

OL

WDI = 0V or V

VCC ≥ 1.0V, I
(T

= 0°C to +125°C)

A

VCC ≥ 1.2V, I

V

≥ 2.55V , I

C C

V

≥ 4.25V , I

C C

V

≥ 1.80V , I

C C

V

≥ 2.55V , I

C C

V

≥ 4.25V , I

C C

V

≥ 2.7V , I

C C

V

≥ 4.75V , I

C C

CC

= 50µA, output asserted

SINK

= 100µA, output asserted 0.3

SINK

= 1.2m A, outp ut asser ted 0.3

S IN K

= 3.2m A, outp ut asser ted 0.4

S IN K

= 200µA, outp ut asser ted 0.3

S IN K

= 1.2m A, outp ut asser ted 0.3

S IN K

= 3.2m A, outp ut asser ted 0.4

S IN K

= 500µA, outp ut not asser ted 0.8 x V

S OU RC E

= 800µA, outp ut not asser ted 0.8 x V

S OU RC E

0.7 x V

CC

-1 +1 µA

CC

CC

0.3 x V

0.3

CC

s

V

V

V

V

RESET, WDO, PFO Output
Open-Drain Leakage

I

LKG

VCC > VTH, output not asserted 1.0 µA

Current

RESET Output High
(Push-Pull Only)

RESET Output Low
(Push-Pull Only)

VCC ≥ 1.0V, I
(T

= 0°C to +125°C)

A

V

OH

VCC ≥ 1.2V, I

VCC ≥ 2.55V, I

VCC ≥ 4.25V, I

OL

VCC ≥ 2.7V, I

VCC ≥ 4.75V, I

V

= 1µA, reset asserted

SOURCE

= 50µA, reset asserted 0.8 x V

SOURCE

= 500µA, reset asserted 0.8 x V

SOURCE

= 800µA, reset asserted 0.8 x V

SOURCE

= 1.2mA, reset not asserted 0.3

SINK

= 3.2mA, reset not asserted 0.4

SINK

0.8 x V

CC

CC

CC

CC

V

V

MAX6701–08/MAX6701A–03A/05A–07A

Low-Voltage, SOT23 µP Supervisors with Power­Fail In/Out, Manual Reset, and Watchdog Timer

4 _______________________________________________________________________________________

Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

0

4

12

8

16

20

-40 10-15 35 60 85

SUPPLY CURRENT vs. TEMPERATURE

MAX6701 toc01

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

VCC = 5V

VCC = 3.3V

MAX6705(A)

MAX6708

210

205

200

195

190

-40 10-15 35 60 85

RESET TIMEOUT PERIOD

vs. TEMPERATURE

MAX6701 toc02

TEMPERATURE (°C)

RESET TIMEOUT PERIOD (ms)

20

15

10

5

0

-40 10-15 356085

VCC TO RESET OUTPUT DELAY

vs. TEMPERATURE

MAX6701 toc03

TEMPERATURE (°C)

V

CC

TO RESET OUTPUT DELAY (µs)

1.70

1.65

1.60

1.55

1.50

-40 10-15 35 60 85

WATCHDOG TIMEOUT PERIOD

vs. TEMPERATURE

MAX6701 toc04

TEMPERATURE (°C)

WATCHDOG TIMEOUT PERIOD (s)

0.95

0.98

0.97

0.96

0.99

1.00

1.01

1.02

1.03

1.04

1.05

-40 10-15 35 60 85

NORMALIZED RESET THRESHOLD

vs. TEMPERATURE

MAX6701 toc05

TEMPERATURE (°C)

NORMALIZED RESET THRESOLD

0 40 80 120 160

MAXIMUM VCC TRANSIENT DURATION

vs. RESET THRESHOLD OVERDRIVE

MAX6701 toc06

RESET THRESHOLD OVERDRIVE (mV)

MAXIMUM TRANSIENT DURATION (µs)

0

10

20

30

40

50

60

MAX670_Y

RESET OCCURS
ABOVE LINE

0

25

50

75

100

0 800 1600 2400400 1200 2000 2800 3200

OUTPUT VOLTAGE LOW

vs. SINK CURRENT

MAX6701 toc07

SINK CURRENT (µA)

V

OL

(mV)

VCC ≥ 4.25V

0

50

150

100

250

300

200

350

0 800 1200400 1600 2000 2400 2800 3200

VCC - VOH vs. SOURCE CURRENT

MAX6701 toc08

SOURCE CURRENT (µA)

V

CC

- V

OH

(mV)

VCC ≥ 4.25V

MAX6701–08/MAX6701A–03A/05A–07A

Low-Voltage, SOT23 µP Supervisors with Power-

Fail In/Out, Manual Reset, and Watchdog Timer

_______________________________________________________________________________________ 5

Pin Description

PIN

MAX6701(A)
MAX6702(A)
MAX6703(A)

11 11MR

22 22V

3 3 3 3 GND Ground

— 4 4 4 PFI

— 555PFO

66 6— WDI

MAX6704

MAX6705(A)
MAX6706(A)
MAX6707(A)

MAX6708

NAME FUNCTION

CC

Active-Low, Manual Reset Input, Internal 50kΩ Pullup to V
Pull low to force a reset. Reset remains active as long as MR is
low and the reset timeout period after MR goes high. Leave
unconnected or connect to V
when MR is low ( M AX 6701( A) /M AX 6702( A) /M AX 6703( A) /
M AX 6705( A) / M AX 6706( A) /M AX 6707( A) onl y) .

S up p l y V ol tag e for M AX 6701–M AX 6708 and Inp ut for P r i m ar y
Reset Thr eshol d M oni tor . P ush- p ul l outp uts ar e p ow er ed b y V

Power-Fail Voltage Monitor Input. High-impedance input for
internal power-fail comparator. Connect this pin to an external
resistive-divider network to set the reset threshold voltage;

0.62V (typ) threshold. Connect to GND or V

Power-Fail Monitor Output. Open drain or push-pull active low.
PFO goes low when PFI is less than 0.62V.

Watchd og Inp ut. If WD I r em ai ns hi g h or l ow for l ong er than the
w atchd og ti m eout p er i od , the i nter nal w atchd og ti m er r uns out and
WDO i s asser ted . WDO i s asser ted l ow after each w atchd og
over fl ow and r em ai ns l ow unti l the w atchd og ti m er i s cl ear ed ( the
r eset outp ut i s not affected ) . The i nter nal w atchd og ti m er cl ear s
w henever a V
r eset i s asser ted , or WD I sees a r i si ng or fal l i ng ed g e. The
w atchd og ti m er r em ai ns cl ear ed unti l the r eset outp ut i s
d easser ted . On the M AX 6704, RES ET p ul se asser ts for the r eset
ti m eout p er i od after each w atchd og ti m eout over fl ow . The
w atchd og ti m er cannot b e d i sab l ed .

/RS T_IN 1/RS T_IN 2 r eset i s a sser ted , the m anual

C C

if unused. WDO deasserts

CC

when not used.

CC

CC

.

C C

.

—— — 6 N.C. No Connection. Not internally connected.

Acti ve- Low Reset Outp ut ( Op en D r ai n or P ush- P ul l ) . RES ET

77 77RESET

chang es fr om hi g h to l ow w hen the V
sel ected r eset thr eshol d ( or RS T_IN 1/ RS T_IN 2 for the
M AX 6701( A) /M AX 6702( A) /M AX 6703( A) , MR i s p ul l ed l ow , or the
w atchd og tr i g g er s a r eset ( M AX 6704 onl y) . RES ET r em ai ns l ow for
the r eset ti m eout p er i od after the r eset cond i ti ons ar e ter m i nated .

i np ut d r op s b el ow the

C C

Detailed Description

Figures 1, 2, and 3 are functional diagrams for the
MAX6705(A)/MAX6706(A)/MAX6707(A), MAX6704/
MAX6708, and MAX6701(A)/ MAX6702(A)/MAX6703(A),
respectively.

Reset Output

A microprocessor’s (µP’s) reset input starts the µP in a
known state. The MAX6701–MAX6708 assert reset dur­ing power-up and prevent code execution errors during
power-down or brownout conditions.

On power-up, once VCCreaches 1V, RESET is a guar­anteed logic low of 0.4V or less. As VCCrises, RESET

stays low. After VCC, RST_IN1, or RST_IN2 rise above
the reset threshold, an internal timer holds RESET low
for about 200ms. RESET pulses low whenever VCCdips
below the reset threshold, including brownout condi­tions. If a brownout occurs in the middle of a previously
initiated reset pulse, the pulse continues for at least
another 140ms. On power-down, once VCCfalls below
the reset threshold, RESET stays low and is guaranteed
to be 0.4V or less, until VCCdrops below 1V.

The MAX6702(A)/MAX6704/MAX6706(A)/MAX6708
active-high RESET output is the complement of the
RESET output, and is guaranteed to be valid with V

CC

down to 1V.

MAX6701–08/MAX6701A–03A/05A–07A

Low-Voltage, SOT23 µP Supervisors with Power­Fail In/Out, Manual Reset, and Watchdog Timer

6 _______________________________________________________________________________________

Pin Description (continued)

*RESET active-high for the MAX6702(A)/MAX6706(A).

PIN

MAX6701(A)
MAX6702(A)
MAX6703(A)

8 — 8 — WDO

7* 8 7* 8 RESET

4 ———RST_IN1

MAX6704

MAX6705(A)
MAX6706(A)
MAX6707(A)

MAX6708

NAME FUNCTION

Active-Low Watchdog Output (Open Drain or Push-Pull). WDO
is asserted whenever the watchdog times out and V
reset inputs are below their respective thresholds. WDO
deasserts after a valid WDI transition without a reset timeout
period. In the A versions, WDO deasserts without a timeout
delay when V
threshold. Pull MR low to assert WDO (MAX6701/MAX6702/
MAX6703/MAX6705/MAX6706/MAX6707 only). Pull MR low to
deassert WDO (MAX6701(A)/MAX6702(A)/MAX6703(A)/
MAX6705(A)/MAX6706(A)MAX6707(A) only).

Active-High Reset Output (Push-Pull). RESET changes from low
to high when the V
threshold (or RST_IN1/RST_IN2 for MAX6701(A)/MAX6702(A)/
MAX6703(A), MR is pulled low, or the watchdog triggers a
reset (MAX6704 only). RESET remains high for the reset
timeout period after the reset conditions are terminated.

Input for User-Adjustable V
for second internal reset comparator. Connect this pin to an
external resistive-divider network to set the reset threshold
voltage; 0.62V (typ) threshold. Connect to V
Reset is asserted when either V
below threshold.

, RST_IN1, and RST_IN2 rises above its

CC

input drops below the selected reset

CC

Monitor. High-impedance input

CC2

, RST_IN1, or RST_IN2 are

CC

or the

CC

when not used.

CC

5 ———RST_IN2

Input for User-Adjustable V
for third internal reset comparator. Connect this pin to an
external resistive-divider network to set the reset threshold
voltage; 0.62V (typ) threshold. Connect to V
Reset is asserted when either V
below threshold.

Monitor. High-impedance input

CC3

CC

when not used.

, RST_IN1, or RST_IN2 are

CC

MAX6701–08/MAX6701A–03A/05A–07A

Low-Voltage, SOT23 µP Supervisors with Power-

Fail In/Out, Manual Reset, and Watchdog Timer

_______________________________________________________________________________________ 7

Figure 2. MAX6704/MAX6708 Functional Diagram

Figure 3. MAX6701(A)/MAX6702(A)/MAX6703(A) Functional
Diagram

WATCHDOG

TIMER

RESET

GENERATOR

V

CC

50kΩ

8

WDO

7

RESET
(RESET)

5

PFO

GND

3

0.62V

( ) ARE FOR MAX6706(A) ONLY.

6

WDI

1

MR

2

V

V

REF

CC

4

PFI

MAX6705(A)
MAX6706(A)
MAX6707(A)

Figure 1. MAX6705(A)/MAX6706(A)/MAX6707(A) Functional
Diagram

t

RP

t

RP

V

CC

0V

RESET

WDO

V

CC

0V

WDI

V

CC

0V

MR

MR EXTERNALLY DRIVEN LOW

V

CC

0V

V

CC

V

TH

V

TH

t

MD

NOTE: THE MAX6706 RESET OUTPUT IS THE INVERSE OF THE RESET SHOWN.

Figure 4. MAX6705/MAX6706/MAX6707

RESET, MR, WDO

,

and WDI Timing

V

CC

V

CC

MAX6704

50kΩ

1

MR

2

V

CC

MAX6708

RESET

GENERATOR

8

7

RESET

RESET

50kΩ

MR

V

CC

V

REF

RST_IN1 RST_IN2

0.62V

( ) ARE FOR MAX6702(A) ONLY.

MAX6703(A)

RESET

GENERATOR

MAX6701(A)
MAX6702(A)

WATCHDOG

TIMER

0.62V

RESET (RESET)

WDO

WDI

WATCHDOG

TIMER

4

PFI

V

REF

0.62V

GND

3

6

WDI
(MAX6704 ONLY)

5

PFO

MAX6701–08/MAX6701A–03A/05A–07A

Low-Voltage, SOT23 µP Supervisors with Power­Fail In/Out, Manual Reset, and Watchdog Timer

8 _______________________________________________________________________________________

Standard- vs. A-Version Comparison

The MAX6701/MAX6702/MAX6703/MAX6705/MAX6706/
MAX6707s’ WDO latches low when one of the following
events occurs:

• The watchdog timer times out (1.6s, typ).

• VCC, RST_IN1, or RST_IN2 is below its reset threshold.

• MR is pulled low.

• WDO only deasserts with a valid WDI transition.

TheMAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/MAX6707(A)s’ WDO asserts when either
VCC, RST_IN1, or RST_IN2 is below its reset threshold.
WDO deasserts without a timeout delay when the
undervoltage situation has expired. WDO is latched low
when the watchdog timer elapses without seeing a WDI
transition. WDO deasserts with a valid WDI transition
OR by pulling MR low.

See Figures 4 and 5 for standard-version timing. See
Figures 6 and 7 for A-version timing.

Watchdog Timer

The MAX6701–MAX6707 watchdog circuit monitors the
µP’s activity. If the µP does not toggle the WDI within 1.6s,
WDO goes low. When RESET is asserted, the watchdog
timer stays cleared and does not count. As soon as reset
is released, the timer starts counting. WDO deasserts
after a valid transition is detected at WDI. Pulses as short
as 50ns can be detected.

Typically, WDO is connected to the NMI input of a µP.
When VCC, RST_IN1, or RST_IN2 drop below the reset

threshold, WDO goes low whether or not the watchdog
timer has timed out. Normally this would trigger an NMI,
but RESET goes low simultaneously, and thus overrides
the NMI.

The MAX6704 watchdog circuit does not have an inde­pendent watchdog output (WDO). If the µP does not
toggle the watchdog input within 1.6s, the MAX6704
asserts a reset output pulse for the reset timeout period.

Manual Reset

The manual reset input (MR) allows reset to be trig­gered by a pushbutton switch. The switch is effectively
debounced by the reset pulse width. MR is CMOS logic
compatible, so it can be driven by an external logic
line. MR can be used to force a watchdog timeout to
generate a reset pulse in the MAX6701(A)/MAX6702(A)/
MAX6703(A)/MAX6705(A)/MAX6706(A)/MAX6707(A) by
connecting WDO to MR.

Power-Fail Comparator

The uncommitted power-fail comparator can be used
for various purposes because its noninverting input and
output are externally available. The inverting input is
internally connected to a 0.62V reference. To build an
early warning circuit for power failure, connect the PFI
pin to a voltage-divider (see Typical Operating Circuit).
Choose the voltage-divider ratio so that the voltage at
PFI falls below 0.62V just before the regulator drops
out. Use PFO to interrupt the µP so it can prepare for an
orderly power-down. The low-input current at this pin
allows for large resistor values in the divider.

t

WD

t

WD

+5V

0V

WDI

+5V

0V

WDO

+5V

0V

RESET

+5V

0V

(RESET)

t

RP

RESET EXTERNALLY

TRIGGERED BY MR

+5V

0V

MR

( ) ARE FOR MAX6702/MAX6706 ONLY.

t

WDI

t

RP

t

RP

+5V

0V

RESET

WDO

+5V

0V

MR

t

MR

+5V

0V

V

CC

V

TH

V

TH

t

MD

Figure 5. MAX6701/MAX6702/MAX6703/MAX6705/MAX6706/
MAX6707 Watchdog

Figure 6. MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/MAX6707(A) RESET, MR, and WDO Timing with
WDI Three-Stated

Reset Input

The MAX6701(A)/MAX6702(A)/MAX6703(A) include two
adjustable reset inputs for monitoring up to a total of
three system voltages (including V

CC

). The thresholds
for the monitored RST_IN supplies are externally set
with resistor-divider networks (Figure 8). The reset out­put is asserted if any of the monitored supplies (VCC,
RST_IN1, or RST_IN2) go below its specified threshold
and remains asserted for the reset timeout period after
all supplies are above their thresholds.

Applications Information

Ensuring a Valid

RESET

Output Down to VCC= 0

When VCCfalls below 1V, the MAX6701–MAX6708
RESET output no longer sinks current—it becomes an
open circuit. High-impedance CMOS logic inputs can
drift to undetermined voltages if left undriven. If a pull­down resistor is added to the RESET pin as shown in
Figure 9, any stray charge or leakage currents are
drained to ground, holding RESET low. A resistor value
(R1) is not critical; 100kΩ is large enough not to load
RESET and small enough to pull RESET to ground. This
application works for push-pull output only (not for
open-drain resets).

Monitoring Other System Voltages

Other systems can be monitored by connecting a volt­age-divider to PFI and adjusting the ratio appropriately.
In noisy systems, a capacitor between PFI and GND
reduces the power-fail circuit’s sensitivity to high-fre­quency noise on the line being monitored. Reset can
be asserted on other voltages in addition to the V

CC

supply line. Connect PFO to MR to initiate a reset out­put pulse when PFI drops below 0.62V. Figure 10
shows the MAX6704–MAX6708 configured to assert a
reset output when the secondary supply falls below the
reset threshold.

Generating a Reset

from Watchdog Overflow

Connect WDO to MR to force a watchdog timeout to gen­erate a reset pulse for only the reset timeout period on the
MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/MAX6707(A). When the MAX6704 watch­dog times out, reset outputs are automatically asserted
(no external connections required). For the MAX6701/
MAX6702/MAX6703/MAX6705/MAX6706/MAX6707 non-A
versions, do not connect WDO to MR; this creates a
locked condition.

MAX6701–08/MAX6701A–03A/05A–07A

Low-Voltage, SOT23 µP Supervisors with Power-

Fail In/Out, Manual Reset, and Watchdog Timer

_______________________________________________________________________________________ 9

Figure 7. MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/MAX6707(A) Watchdog Timing

R1

R2

0.62V

PFI, RST_IN1, OR RST_IN2

V

EXTERNAL

0.62

R1 = R2 x

(

V

EXT-TH

- 1

)

R2

V

EXT-TH

= (1 +

R1

)

x 0.62V

WHERE V

EXT-TH

IS THE EXTERNAL VOLTAGE TRIP LEVEL.

MAX6701(A)–
MAX6708

Figure 8. Calculating Adjustable Voltage Thresholds

t

WDI

+5V

WDI

0V

+5V

WDO

0V

+5V

RESET

0V

+5V

(RESET)

0V

+5V

MR

0V

( ) ARE FOR MAX6702(A)/MAX6706(A) ONLY.

t

WD

t

WD

t

WD

t

RP

MAX6701–08/MAX6701A–03A/05A–07A

Low-Voltage, SOT23 µP Supervisors with Power­Fail In/Out, Manual Reset, and Watchdog Timer

10 ______________________________________________________________________________________

Threshold Suffix Guide

Bold indicates standard version.

R1 (100kΩ)

RESET

MAX6701(A)
MAX6704
MAX6705(A)
MAX6708

Figure 9.

RESET

Valid to Ground Circuit

V

CC

PFI

MR

PFO

RESET

0.9V

3.3V

MAX6704–
MAX6708

I/O

SUPPLY

CORE
SUPPLY

µP

RESET

(RESET)

() ARE FOR MAX6704/MAX6706(A)/MAX6708 ONLY.

Figure 10. Monitoring Other System Voltages

Selector Guide

PP = push-pull, OD = open drain.

*

WDO

deasserts when MRis pulled low. See the Standard- vs. A-Version Comparison section for the differences on

WDO

.

PART

MAX6701 ✔ ——✔✔ PP — ✔

MAX6701A* ✔ ——✔✔ PP — ✔

MAX6702 — ✔ — ✔✔ PP — ✔

MAX6702A* — ✔ — ✔✔ PP — ✔

MAX6703 —— ✔✔✔ OD — ✔

MAX6703A* ——✔✔✔ OD — ✔

MAX6704 ✔✔— ✔ — ✔ PP —

MAX6705 ✔ ——✔✔ PP ✔ PP —

MAX6705A* ✔ ——✔✔ PP ✔ PP —

MAX6706 — ✔ — ✔✔ PP ✔ PP —

MAX6706A* — ✔ — ✔✔ PP ✔ PP —

MAX6707 —— ✔✔✔ OD ✔ OD —

MAX6707A* ——✔✔✔ OD ✔ OD —

MAX6708 ✔✔———✔ PP —

RESET

PP LOW

SUFFIX

RESET

PP HIGH

RESET

THRESHOLD (V)

RESET

OD-LOW

WDI WDO

L 4.63

M 4.38

T 3.08
S 2.93
R 2.63
Z 2.32
Y 2.19

PFI,

PFO

RST_IN1,

RST_IN2

MAX6701–08/MAX6701A–03A/05A–07A

Low-Voltage, SOT23 µP Supervisors with Power-

Fail In/Out, Manual Reset, and Watchdog Timer

______________________________________________________________________________________ 11

Typical Operating Circuit

Pin Configurations (continued)

Chip Information

TRANSISTOR COUNT: 716

PROCESS: BiCMOS

Ordering Information (continued)

Insert the desired suffix letter (from the Threshold Suffix Guide
table) into the blank to complete the part number. All devices
must be ordered in increments of 2500 pieces. Sample stock is
typically held on standard versions only. Contact factory for
availability.

TOP VIEW

MR

GND

UNREGULATED DC

PUSHBUTTON

1

2

CC

MAX6704

3

4

87RESET

RESETV

WDI

6

PFOPFI

5

MR

CC

GND

SOT23

DC/DC

SWITCH

REGULATOR

V
PFI

MR

CC

MAX6705(A)
MAX6706(A)
MAX6707(A)

RESET

WDI

WDO

PFO

µP

V

CC

RESET
I/O

NMI
INTERRUPT

1

2

87WDO

MAX6705(A)
MAX6706(A)

3

4

MAX6707(A)

6

5

SOT23

( ) ARE FOR MAX6706(A) ONLY.

MAX6702_ KA-T -40°C to +125°C 8 SOT23-8

MAX6702A_ KA-T -40°C to +125°C 8 SOT23-8

MAX6703_ KA-T -40°C to +125°C 8 SOT23-8

MAX6703A_ KA-T -40°C to +125°C 8 SOT23-8

MAX6704_KA-T -40°C to +125°C 8 SOT23-8

MAX6705_KA-T -40°C to +125°C 8 SOT23-8

MAX6705A_KA-T -40°C to +125°C 8 SOT23-8

MAX6706_KA-T -40°C to +125°C 8 SOT23-8

MAX6706A_KA-T -40°C to +125°C 8 SOT23-8

MAX6707_KA-T -40°C to +125°C 8 SOT23-8

MAX6707A_KA-T -40°C to +125°C 8 SOT23-8

MAX6708_KA-T -40°C to +125°C 8 SOT23-8

MR

1

RESET (RESET)V

WDI

PFOPFI

GND

2

CC

MAX6708

3

4

SOT23

PART TEMP RANGE PIN-PACKAGE

87RESET

RESETV

N.C.

6

PFOPFI

5

MAX6701–08/MAX6701A–03A/05A–07A

Low-Voltage, SOT23 µP Supervisors with Power­Fail In/Out, Manual Reset, and Watchdog Timer

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.

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

© 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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

.)

PIN 1

I.D. DOT

(SEE NOTE 6)

A

SEE DETAIL "A"

b

C

L

C

L

e1

D

C

L

A2

e

C

E

A1

L

C

SEATING PLANE C

E1

SYMBOL

A

C

L

L2
e

e1

0

L

NOTE:

1. ALL DIMENSIONS ARE IN MILLIMETERS.

2. FOOT LENGTH MEASURED FROM LEAD TIP TO UPPER RADIUS OF
HEEL OF THE LEAD PARALLEL TO SEATING PLANE C.

3. PACKAGE OUTLINE EXCLUSIVE OF MOLD FLASH & METAL BURR.

4. PACKAGE OUTLINE INCLUSIVE OF SOLDER PLATING.

5. COPLANARITY 4 MILS. MAX.

6. PIN 1 I.D. DOT IS 0.3 MM MIN. LOCATED ABOVE PIN 1.

7. SOLDER THICKNESS MEASURED AT FLAT SECTION OF LEAD

BETWEEN 0.08mm AND 0.15mm FROM LEAD TIP.

8. MEETS JEDEC MO178.

PROPRIETARY INFORMATION

TITLE:

PACKAGE OUTLINE, SOT-23, 8L BODY

DETAIL "A"

MIN

0.90

0.00A1

0.90A2

0.28b

0.09

2.80D

1.50E1

0.30

0.25 BSC.

0.65 BSC.

1.95 REF.

0

L2

0

21-0078

MAX

1.45

0.15

1.30

0.45

0.20

3.00

3.002.60E

1.75

0.60

8

GAUGE PLANE

SOT23, 8L .EPS

REV.DOCUMENT CONTROL NO.APPROVAL

1

D

1