MAX6702ARKA+ [MAXIM]
Power Supply Management Circuit, Adjustable, 3 Channel, BICMOS, PDSO8, MO176BA, ROHS COMPLIANT, SOT-23, 8 PIN;
| 型号： | MAX6702ARKA+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Power Supply Management Circuit, Adjustable, 3 Channel, BICMOS, PDSO8, MO176BA, ROHS COMPLIANT, SOT-23, 8 PIN 信息通信管理 光电二极管 |
| 文件： | 总12页 (文件大小：1075K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MAX6701-08/
MAX6701A-03A/
MAX6705A-07A
Low-Voltage, SOT23 µP Supervisors with Power-Fail
In/Out, Manual Reset, and Watchdog Timer
General Description
Features
● Small 8-Pin SOT23 Package
TheMAX6701–MAX6708microprocessor(µP)supervisory
circuits reduce the complexity and components required
to monitor power-supply functions in µP systems. These
devices significantly improve system reliability and accu-
racy compared to separate ICs or discrete components.
● 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)
The MAX6701−MAX6708 family provides four func-
tions: 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.
● 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))
The MAX6701–MAX6708 family offers several pinout
options to accommodate a variety of multivoltage micro-
processor supervision applications.
● Manual Reset Input
● Four Reset Output Stage Options
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 inde-
pendent output. The MAX6704 monitors a single-supply
voltage to drive complementary reset outputs and
includes an independent adjustable power-fail-in/power-
fail-out comparator, a manual reset input, and a reset-
based 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 inde-
pendent output. The MAX6708 is the same as the
MAX6704 but without the watchdog timer function.
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
= 1V
CC
● Immune to Short Falling V
Transients
CC
● Low Cost, Few External Components
Ordering Information
PART
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
8 SOT23
MAX6701_KA-T
MAX6701A_KA-T
8 SOT23
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.
See the Detailed Description for differences between
non-A and A versions.
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
Applications
Ordering Information continued at end of data sheet.
Pin Configurations
TOP VIEW
● Computers
● Controllers
● Intelligent Instruments
● Critical µP Power
Monitoring
● Networking
● Telecommunications
MR
1
2
3
4
8
7
6
5
WDO
V
RESET (RESET)
WDI
CC
MAX6701(A)
MAX6702(A)
MAX6703(A)
● White Goods
GND
RST_IN1
RST_IN2
Typical Operating Circuit and Selector Guide appear at
end of data sheet.
SOT23
( ) ARE FOR MAX6702(A) ONLY.
Pin Configurations continued at end of data sheet.
19-1952; Rev 4; 5/14
MAX6701-08/
MAX6701A-03A/
MAX6705A-07A
Low-Voltage, SOT23 µP Supervisors with Power-Fail
In/Out, Manual Reset, and Watchdog Timer
Absolute Maximum Ratings
CC
V
.......................................................................-0.3V to +6.0V
Continuous Power Dissipation (T = +70°C)
A
Open-Drain RESET, WDO, PFO ........................-0.3V to +6.0V
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
Push-Pull RESET, RESET, WDO, PFO... -0.3V to (V
MR, WDI, PFI, RST_IN1, RST_IN2 ......... -0.3V to (V
+ 0.3V)
+ 0.3V)
CC
CC
Input Current (V )............................................................20mA
CC
Output Current (O, WDO) ..................................................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
CC
(V
= +4.25V to +5.5V for L/M versions, V
= +2.55V to +3.6V for the T/S/R versions, V
= +2.1V to +2.75V for the Z/Y versions.
CC
CC
T
= -40°C to +125°C, unless otherwise specified. Typical values are at T = +25°C.) (Note 1)
A
A
PARAMETER
SYMBOL
CONDITIONS
= 0°C to +125°C
MIN
1.0
TYP
MAX
5.5
UNITS
T
T
A
A
Operating Voltage Range
V
V
CC
= -40°C to +125°C
1.2
5.5
V
V
V
< 5.5V, no load
12
9
25
CC
CC
CC
Supply Current
MR Unconnected
I
< 3.6V, no load
20
µA
CC
< 3.6V, no load (MAX6708 only)
6
20
T
T
T
T
T
T
T
T
T
T
T
T
T
T
= -40°C to +85°C
= -40°C to +125°C
= -40°C to +85°C
= -40°C to +125°C
= -40°C to +85°C
= -40°C to +125°C
= -40°C to +85°C
= -40°C to +125°C
= -40°C to +85°C
= -40°C to +125°C
= -40°C to +85°C
= -40°C to +125°C
= -40°C to +85°C
= -40°C to +125°C
4.50
4.47
4.25
4.22
3.00
2.97
2.85
2.83
2.55
2.53
2.25
2.24
2.12
2.11
4.63
4.75
4.78
4.50
4.53
3.15
3.17
3.00
3.02
2.70
2.72
2.38
2.40
2.25
2.27
A
A
A
A
A
A
A
A
A
A
A
A
A
A
MAX670_L/MAX670_AL
MAX670_M/MAX670_AM
MAX670_T/MAX670_AT
MAX670_S/MAX670_AS
MAX670_R/MAX670_AR
MAX670_Z/MAX670_AZ
MAX670_Y/MAX670_AY
4.38
3.08
2.93
2.63
2.32
2.19
V
Reset Threshold
falling)
CC
CC
V
V
TH
(V
Reset Threshold
∆V
60
ppm/°C
µs
TH
Temperature Coefficient
V
to Reset Output Delay
V
falling at 10mV/µs
CC
12
CC
T
T
= -40°C to +85°C
= -40°C to +125°C
140
120
200
280
300
A
A
Reset Timeout Period
t
ms
µs
RP
MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/MAX6707(A)
V
Falling to WDO Delay
5
CC
T
T
= -40°C to +85°C
= -40°C to +125°C
602
593
618
634
642
A
A
PFI, RST_IN1, RST_IN2
Threshold
V
= 1.8V to 5.5V
mV
mV
CC
PFI Hysteresis
6
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MAX6701-08/
MAX6701A-03A/
MAX6705A-07A
Low-Voltage, SOT23 µP Supervisors with Power-Fail
In/Out, Manual Reset, and Watchdog Timer
Electrical Characteristics (continued)
(V
= +4.25V to +5.5V for L/M versions, V
= +2.55V to +3.6V for the T/S/R versions, V
= +2.1V to +2.75V for the Z/Y versions.
CC
CC
CC
T
= -40°C to +125°C, unless otherwise specified. Typical values are at T = +25°C.) (Note 1)
A
A
PARAMETER
SYMBOL
CONDITIONS
MIN
-50
TYP
MAX
+50
UNITS
nA
T
T
= -40°C to +85°C
= -40°C to +125°C
A
PFI, RST_IN1, RST_IN2
Leakage Current
(Note 2)
-200
+200
A
PFI to PFO Delay
MR Input Voltage
t
1
µs
PF
V
0.3 x V
CC
IL
V
V
0.7 x V
1
IH
CC
MR Minimum Input Pulse
MR Glitch Rejection
MR to Reset Delay
µs
ns
ns
100
200
t
MD
MAX6701(A)/MAX6702(A)/MAX6703(A)/
MAX6705(A)/MAX6706(A)/MAX6707(A)
V
Rising to WDO Delay
100
ns
CC
MR Pullup Resistance
Watchdog Timeout Period
WDI Pulse Width
25
1.12
0.96
50
50
75
kΩ
T
T
= -40°C to +85°C
= -40°C to +125°C
1.6
2.4
A
t
s
WD
2.52
A
t
(Note 2)
ns
V
WDI
V
0.3 x V
CC
IL
WDI Input Voltage
V
0.7 x V
-1
IH
CC
WDI Input Current
I
V
V
= 0V or V
+1
µA
WDI
WDI
CC
≥ 1.0V, I
= 50µA, output asserted
CC
SINK
0.3
(T = 0°C to +125°C)
A
RESET, WDO Output Low
(Push-Pull or Open Drain)
V
V
V
V
V
V
V
V
V
≥ 1.2V, I
SINK
= 100µA, output asserted
= 1.2mA, output asserted
= 3.2mA, output asserted
= 200µA, output asserted
= 1.2mA, output asserted
= 3.2mA, output asserted
0.3
0.3
0.4
0.3
0.3
0.4
V
OL
CC
CC
CC
CC
CC
CC
CC
CC
≥ 2.55V, I
≥ 4.25V, I
≥ 1.80V, I
≥ 2.55V, I
≥ 4.25V, I
≥ 2.7V, I
SINK
SINK
SINK
SINK
SINK
PFO Output Low
V
V
V
OL
(Push-Pull or Open Drain)
= 500µA, output not asserted 0.8 x V
= 800µA, output not asserted 0.8 x V
RESET, WDO, PFO Output
High (Push-Pull Only)
SOURCE
CC
V
OH
≥ 4.75V, I
SOURCE
CC
RESET, WDO, PFO
Output Open-Drain
Leakage Current
I
V
> V , output not asserted
TH
1.0
µA
LKG
CC
CC
V
≥ 1.0V, I
= 1µA, reset asserted
SOURCE
0.8 x V
CC
(T = 0°C to +125°C)
A
RESET Output High
(Push-Pull Only)
V
V
V
V
V
V
≥ 1.2V, I
= 50µA, reset asserted
0.8 x V
0.8 x V
0.8 x V
V
V
OH
CC
CC
CC
CC
CC
SOURCE
CC
CC
CC
≥ 2.55V, I
≥ 4.25V, I
≥ 2.7V, I
= 500µA, reset asserted
= 800µA, reset asserted
SOURCE
SOURCE
= 1.2mA, reset not asserted
0.3
0.4
RESET Output Low
(Push-Pull Only)
SINK
V
OL
≥ 4.75V, I
= 3.2mA, reset not asserted
SINK
Note 1: Over-temperature limits are guaranteed by design and not production tested. Devices are tested at T = +25°C.
A
Note 2: Guaranteed by design. Not production tested.
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MAX6701-08/
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MAX6705A-07A
Low-Voltage, SOT23 µP Supervisors with Power-Fail
In/Out, Manual Reset, and Watchdog Timer
Typical Operating Characteristics
(T = +25°C, unless otherwise noted.)
A
RESET TIMEOUT PERIOD
vs. TEMPERATURE
SUPPLY CURRENT
vs. TEMPERATURE
V
TO RESET OUTPUT DELAY
vs. TEMPERATURE
CC
20
15
10
5
20
210
205
200
195
190
16
MAX6705(A)
V
V
= 5V
CC
12
8
MAX6708
= 3.3V
CC
4
0
0
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
WATCHDOG TIMEOUT PERIOD
vs. TEMPERATURE
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
MAXIMUM V TRANSIENT DURATION
CC
vs. RESET THRESHOLD OVERDRIVE
1.05
1.04
1.03
1.02
1.01
1.00
0.99
0.98
0.97
0.96
0.95
60
50
1.70
1.65
1.60
1.55
1.50
MAX670_Y
40
30
20
10
0
RESET OCCURS
ABOVE LINE
-40
-15
10
35
60
85
0
40
80
120
160
-40
-15
10
35
60
85
TEMPERATURE (°C)
RESET THRESHOLD OVERDRIVE (mV)
TEMPERATURE (°C)
OUTPUT-VOLTAGE LOW
vs. SINK CURRENT
V
- V
CC OH
vs. SOURCE CURRENT
100
75
350
300
250
200
150
100
50
V
CC
4.25V
V
CC
4.25V
50
25
0
0
0
400 800 1200 1600 2000 2400 2800 3200
0
400 800 1200 1600 2000 2400 2800 3200
SINK CURRENT (µA)
SOURCE CURRENT (µA)
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MAX6701-08/
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Low-Voltage, SOT23 µP Supervisors with Power-Fail
In/Out, Manual Reset, and Watchdog Timer
Pin Description
PIN
MAX6705(A)
MAX6701(A)
NAME
FUNCTION
MAX6702(A)
MAX6703(A)
MAX6704
MAX6706(A)
MAX6707(A)
MAX6708
Active-Low, Manual Reset Input, Internal 50kΩ Pullup
to V . Pull low to force a reset. Reset remains active
CC
as long as MR is low and the reset timeout period after
1
1
1
1
MR
MR goes high. Leave unconnected or connect to V
if
CC
unused. WDO deasserts when MR is low (MAX6701(A)/
MAX6702(A)/MAX6703(A)/ MAX6705(A)/ MAX6706(A)/
MAX6707(A) only)
Supply Voltage for MAX6701–MAX6708 and Input for
Primary Reset Threshold Monitor. Push-pull outputs are
2
3
2
3
2
3
2
3
V
CC
powered by V
CC.
GND
PFI
Ground
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
—
—
4
5
4
5
4
5
to GND or V
when not used.
CC
Power-Fail Monitor Output. Open drain or push-pull
active low. PFO goes low when PFI is less than 0.62V.
PFO
Watchdog Input. If WDI remains high or low for longer
than the watchdog timeout period, the internal watchdog
timer runs out and WDO is asserted. WDO is asserted
low after each watchdog overflow and remains low until
the watchdog timer is cleared (the reset output is not
affected). The internal watchdog timer clears whenever
6
6
6
—
WDI
a V /RST_IN1/RST_IN2 reset is asserted, the manual
CC
reset is asserted, or WDI sees a rising or falling edge.
The watchdog timer remains cleared until the reset output
is deasserted. On the MAX6704, RESET pulse asserts
for the reset timeout period after each watchdog timeout
overflow. The watchdog timer cannot be disabled.
—
7
—
7
—
7
6
7
N.C.
No Connection. Not internally connected.
Active-Low Reset Output (Open Drain or Push-Pull).
RESET changes from high to low when the V
input
CC
drops below the selected reset threshold (or RST_IN1/
RST_IN2 for the MAX6701(A)/MAX6702(A)/MAX6703(A),
MR is pulled low, or the watchdog triggers a reset
(MAX6704 only). RESET remains low for the reset timeout
period after the reset conditions are terminated.
RESET
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MAX6705A-07A
Low-Voltage, SOT23 µP Supervisors with Power-Fail
In/Out, Manual Reset, and Watchdog Timer
Pin Description (continued)
PIN
MAX6701(A)
MAX6702(A)
MAX6703(A)
MAX6705(A)
MAX6706(A)
MAX6707(A)
NAME
FUNCTION
MAX6704
MAX6708
Active-Low Watchdog Output (Open Drain or Push-
Pull). WDO is asserted whenever the watchdog
times out and V
or the reset inputs are below their
CC
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
8
—
8
—
WDO
V
, RST_IN1, and RST_IN2 rises above its threshold.
CC
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
input drops below the
CC
selected reset 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.
7*
8
7*
—
—
8
RESET
Input for User-Adjustable V
impedance input for second internal reset comparator.
Connect this pin to an external resistive-divider network
Monitor. High-
CC2
4
—
—
—
—
RST_IN1 to set the reset threshold voltage; 0.62V (typ) threshold.
Connect to V when not used. Reset is asserted
CC
when either V , RST_IN1, or RST_IN2 are below
CC
threshold.
Input for User-Adjustable V
impedance input for third internal reset comparator.
Connect this pin to an external resistive-divider network
Monitor. High-
CC3
5
RST_IN2 to set the reset threshold voltage; 0.62V (typ) threshold.
Connect to V
when not used. Reset is asserted
CC
CC
when either V , RST_IN1, or RST_IN2 are below
threshold.
*RESET active-high for the MAX6702(A)/MAX6706(A).
RESET stays low. After V , RST_IN1, or RST_IN2 rise
CC
Detailed Description
above the reset threshold, an internal timer holds RESET
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.
low for about 200ms. RESET pulses low whenever
V
dips below the reset threshold, including brownout
CC
conditions. If a brownout occurs in the middle of a
previously initiated reset pulse, the pulse continues for
Reset Output
at least another 140ms. On power-down, once V
CC
falls below the reset threshold, RESET stays low and is
guaranteed to be 0.4V or less, until V drops below 1V.
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.
CC
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
down to 1V.
On power-up, once V
guaranteed logic-low of 0.4V or less. As V
reaches 1V, RESET is a
CC
CC
rises,
CC
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Low-Voltage, SOT23 µP Supervisors with Power-Fail
In/Out, Manual Reset, and Watchdog Timer
V
CC
6
8
WATCHDOG
TIMER
WDI
WDO
MAX6701(A)
MAX6702(A)
MAX6703(A)
50kΩ
V
CC
MR
50kΩ
V
CC
1
2
MR
V
CC
RESET
GENERATOR
RESET (RESET)
7
5
RESET
GENERATOR
RESET
WDO
(RESET)
WATCHDOG
TIMER
WDI
V
REF
MAX6705(A)
MAX6706(A)
MAX6707(A)
V
REF
4
RST_IN1
RST_IN2
PFI
PFO
0.62V
0.62V
0.62V
3
GND
( ) ARE FOR MAX6706(A) ONLY.
( ) ARE FOR MAX6702(A) ONLY.
Figure 1. MAX6705(A)/MAX6706(A)/MAX6707(A) Functional
Diagram
Figure 3. MAX6701(A)/MAX6702(A)/MAX6703(A) Functional
Diagram
V
TH
V
TH
V
CC
V
CC
MAX6704
MAX6708
t
t
RP
RP
50kΩ
8
7
RESET
1
2
V
CC
MR
RESET
GENERATOR
RESET
RESET
V
CC
0V
WATCHDOG
TIMER
6
V
CC
WDI
MR
(MAX6704 ONLY)
0V
t
MD
V
REF
V
CC
WDO
4
PFI
5
0V
PFO
MR EXTERNALLY DRIVEN LOW
V
CC
0.62V
WDI
0V
3
NOTE: THE MAX6706 RESET OUTPUT IS THE INVERSE OF THE RESET SHOWN.
GND
Figure 2. MAX6704/MAX6708 Functional Diagram
Figure 4. MAX6705/MAX6706/MAX6707 RESET, MR, WDO,
and WDI Timing
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MAX6701-08/
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Low-Voltage, SOT23 µP Supervisors with Power-Fail
In/Out, Manual Reset, and Watchdog Timer
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.
Standard- vs. A-Version Comparison
The MAX6701/MAX6702/MAX6703/MAX6705/MAX6706/
MAX6707s’ WDO latches low when one of the following
events occurs:
The MAX6704 watchdog circuit does not have an inde-
pendent 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.
● The watchdog timer times out (1.6s, typ).
● V , RST_IN1, or RST_IN2 is below its reset
CC
threshold.
●
●
MR is pulled low.
Manual Reset
WDO only deasserts with a valid WDI transition.
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.
TheMAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/ MAX6707(A)s’ WDO asserts when either
V , RST_IN1, or RST_IN2 is below its reset thresh-
CC
old. 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.
Power-Fail Comparator
See Figures 4 and 5 for standard-version timing. See
Figures 6 and 7 for A-version timing.
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 the 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.
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 V , RST_IN1, or RST_IN2 drop below the reset
CC
t
WD
t
t
WDI
WD
V
TH
V
TH
+5V
0V
V
CC
WDI
t
t
RP
RP
+5V
RESET
+5V
0V
WDO
0V
+5V
RESET
+5V
0V
0V
MR
RESET EXTERNALLY
TRIGGERED BY MR
t
RP
+5V
t
MD
(RESET)
0V
+5V
0V
t
MR
+5V
0V
MR
WDO
( ) ARE FOR MAX6702/MAX6706 ONLY.
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
Maxim Integrated
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MAX6701-08/
MAX6701A-03A/
MAX6705A-07A
Low-Voltage, SOT23 µP Supervisors with Power-Fail
In/Out, Manual Reset, and Watchdog Timer
t
t
WD
WDI
t
WD
+5V
0V
WDI
t
WD
MAX6701(A)–
MAX6708
V
EXTERNAL
+5V
0V
R1
R2
PFI, RST_IN1, OR RST_IN2
WDO
+5V
RESET
0V
0.62V
t
RP
+5V
(RESET)
0V
+5V
0V
V
R1
R2
EXT-TH
0.62
V
=
1 +
x 0.62V
R1 = R2 x
- 1
EXT-TH
(
)
(
)
MR
WHERE V
IS THE EXTERNAL VOLTAGE TRIP LEVEL.
EXT-TH
( ) ARE FOR MAX6702(A)/MAX6706(A) ONLY.
Figure 7. MAX6701(A)/MAX6702(A)/MAX6703(A)/
Figure 8. Calculating Adjustable Voltage Thresholds
MAX6705(A)/ MAX6706(A)/MAX6707(A) Watchdog Timing
Reset Input
Monitoring Other System Voltages
The MAX6701(A)/MAX6702(A)/MAX6703(A) include two
adjustable reset inputs for monitoring up to a total of
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
three system voltages (including V ). The thresholds
CC
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 (V
,
be asserted on other voltages in addition to the V
CC
CC
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.
supply line. Connect PFO to MR to initiate a reset out-
put 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.
Applications Information
Ensuring a Valid RESET Output
Generating a Reset from Watchdog Overflow
Down to V
= 0
CC
Connect WDO to MR to force a watchdog timeout to gen-
erate 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 watch-
dog 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.
When V
falls below 1V, the MAX6701–MAX6708
CC
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 pull-
down 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).
Maxim Integrated
│ 9
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MAX6701-08/
MAX6701A-03A/
MAX6705A-07A
Low-Voltage, SOT23 µP Supervisors with Power-Fail
In/Out, Manual Reset, and Watchdog Timer
0.9V
3.3V
MAX6701(A)
MAX6704
MAX6705(A)
MAX6708
I/O
SUPPLY
CORE
SUPPLY
RESET
V
CC
RESET
(RESET)
RESET
PFI
µP
MAX6704–
MAX6708
MR
PFO
R1 (100kΩ)
() ARE FOR MAX6704/MAX6706(A)/MAX6708 ONLY.
Figure 9. RESET Valid to Ground Circuit
Figure 10. Monitoring Other System Voltages
Selector Guide
RESET
RESET
RESET
PFI,
RST_IN1,
RST_IN2
PART
WDI
WDO
PP LOW
PP HIGH
—
OD-LOW
PFO
—
MAX6701
—
—
—
—
✔
✔
—
—
—
—
—
✔
✔
—
✔
✔
—
—
—
—
✔
✔
✔
—
—
—
—
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
✔
—
✔PP
✔PP
✔PP
✔PP
✔OD
✔OD
—
✔
✔
✔
✔
✔
✔
—
—
—
—
—
—
—
—
MAX6701A*
MAX6702
—
—
—
✔
MAX6702A*
MAX6703
—
✔
—
—
MAX6703A*
MAX6704
—
—
✔
✔PP
✔PP
✔PP
✔PP
✔PP
✔OD
✔OD
✔PP
MAX6705
—
✔PP
✔PP
✔ PP
✔PP
✔OD
✔OD
—
MAX6705A*
MAX6706
—
✔
MAX6706A*
MAX6707
✔
—
MAX6707A*
MAX6708
—
✔
PP = push-pull, OD = open drain.
*WDO deasserts when MR is pulled low. See the Standard- vs. A-Version Comparison section for the differences on WDO.
Threshold Suffix Guide
RESET
SUFFIX
THRESHOLD (V)
L
4.63
4.38
3.08
2.93
2.63
2.32
2.19
M
T
S
R
Z
Y
Bold indicates standard version.
Maxim Integrated
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MAX6701-08/
MAX6701A-03A/
MAX6705A-07A
Low-Voltage, SOT23 µP Supervisors with Power-Fail
In/Out, Manual Reset, and Watchdog Timer
Pin Configurations (continued)
TOP VIEW
MR
1
2
3
4
8
7
6
5
RESET
RESET
WDI
MR
1
2
3
4
8
7
6
5
WDO
MR
1
2
3
4
8
7
6
5
RESET
RESET
N.C.
V
V
RESET (RESET) V
CC
CC
CC
MAX6704
MAX6705(A)
MAX6706(A)
MAX6707(A)
MAX6708
GND
GND
WDI
GND
PFI
PFO
PFI
PFO
PFI
PFO
SOT23
SOT23
SOT23
( ) ARE FOR MAX6706(A) ONLY.
Typical Operating Circuit
Ordering Information (continued)
PART
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
8 SOT23
8 SOT23
8 SOT23
8 SOT23
8 SOT23
8 SOT23
8 SOT23
8 SOT23
8 SOT23
8 SOT23
8 SOT23
8 SOT23
UNREGULATED DC
DC-DC
MAX6702_ KA-T
MAX6702A_ KA-T
MAX6703_ KA-T
MAX6703A_ KA-T
MAX6704_KA-T
MAX6705_KA-T
MAX6705A_KA-T
MAX6706_KA-T
MAX6706A_KA-T
MAX6707_KA-T
MAX6707A_KA-T
MAX6708_KA-T
REGULATOR
µP
V
CC
V
RESET
CC
RESET
I/O
WDI
WDO
PFO
PFI
MAX6705(A)
MAX6706(A)
MAX6707(A)
NMI
INTERRUPT
MR
PUSHBUTTON
SWITCH
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
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.
PACKAGE
TYPE
PACKAGE OUTLINE
CODE
LAND
PATTERN NO.
NO.
Devices are available in both leaded and lead(Pb)-free
packaging. Specify lead-free by replacing “-T” with “+T” when
ordering.
8 SOT23
K8+2
21-0078
90-0176
T = Tape and reel.
Chip Information
TRANSISTOR COUNT: 716
PROCESS: BiCMOS
Maxim Integrated
│ 11
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MAX6701-08/
MAX6701A-03A/
MAX6705A-07A
Low-Voltage, SOT23 µP Supervisors with Power-Fail
In/Out, Manual Reset, and Watchdog Timer
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
DESCRIPTION
CHANGED
4
5/14
No /V OPNs; removed Automotive reference from Applications section
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2014 Maxim Integrated Products, Inc.
│ 12
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