MAX6702LKA+ [MAXIM]
Power Management Circuit, Adjustable, 3 Channel, BICMOS, PDSO8, LEAD FREE, MO-178BA, SOT-23, 8 PIN;
| 型号： | MAX6702LKA+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Power Management Circuit, Adjustable, 3 Channel, BICMOS, PDSO8, LEAD FREE, MO-178BA, SOT-23, 8 PIN 信息通信管理 光电二极管 |
| 文件： | 总12页 (文件大小：200K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1952; Rev 2; 8/03
Low-Voltage, SOT23 µP Supervisors with Power-
Fail In/Out, Manual Reset, and Watchdog Timer
General Description
Features
o Small 8-Pin SOT23 Package
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 accu-
racy compared to separate ICs or discrete components.
o Precision Monitoring of +5.0V, +3.3V, +3.0V, +2.5V
Supply Voltages
o 140ms Reset Timeout Delay
o Power-Fail Input with Independent Output;
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.
Monitor Inputs Down to 0.62V (MAX6704–MAX6708)
o Dual Adjustable Reset Input for Triple-Voltage
Monitoring (MAX6701(A)/MAX6702(A)/MAX6703(A))
o 1.6s Watchdog Timeout Period
(MAX6701(A)–MAX6707(A))
o Independent Watchdog Output
The MAX6701–MAX6708 family offers several pinout
options to accommodate a variety of multivoltage micro-
processor supervision applications.
(MAX6701(A)/MAX6702(A)/MAX6703(A)/
MAX6705(A)/MAX6706(A)/MAX6707(A))
o Manual Reset Input
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.
o 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)
o Guaranteed Reset Valid to V
= 1V
CC
o Immune to Short Falling V
Transients
CC
o Low Cost, Few External Components
Ordering Information
PART
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
8 SOT23-8
MAX6701_KA-T
MAX6701A_KA-T
See the Detailed Description for differences between
non-A and A versions.
8 SOT23-8
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.
Applications
Computers
Ordering Information continued at end of data sheet.
Controllers
Pin Configurations
Intelligent Instruments
Automotive Systems
Critical µP Power Monitoring
White Goods
TOP VIEW
MR
1
2
3
4
8
7
6
5
WDO
V
CC
RESET (RESET)
WDI
Networking
MAX6701(A)
MAX6702(A)
MAX6703(A)
GND
Telecommunications
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.
________________________________________________________________ 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.
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 (RESET, RESET, PFO, 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
(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
A
= -40°C to +125°C, unless otherwise specified. Typical values are at T = +25°C.) (Note 1)
A
PARAMETER
SYMBOL
CONDITIONS
= 0°C to +125°C
MIN
1.0
TYP
MAX
5.5
UNITS
T
T
A
Operating Voltage Range
V
V
CC
= -40°C to +125°C
1.2
5.5
A
V
V
V
< 5.5V, no load
12
9
25
CC
CC
CC
Supply Current
MR Unconnected
I
µA
< 3.6V, no load
20
CC
< 3.6V, no load (MAX6708 only)
6
20
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
= -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
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
(V
Reset Threshold
falling)
CC
V
V
TH
CC
Reset Threshold
Temperature Coefficient
∆V
60
ppm/°C
µs
TH
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
Reset Timeout Period
t
ms
RP
A
MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/MAX6707(A)
V
Falling to WDO Delay
5
µs
CC
T
T
= -40°C to +85°C
= -40°C to +125°C
602
593
618
634
642
PFI, RST_IN1, RST_IN2
Threshold
A
V
CC
= 1.8V to 5.5V
mV
mV
A
PFI Hysteresis
6
2
_______________________________________________________________________________________
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
A
= -40°C to +125°C, unless otherwise specified. Typical values are at T = +25°C.) (Note 1)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
-50
TYP
MAX
+50
UNITS
nA
T
A
T
A
= -40°C to +85°C
= -40°C to +125°C
PFI, RST_IN1, RST_IN2
Leakage Current
(Note 2)
-200
+200
PFI to PFO Delay
t
1
µs
PF
V
0.3 x V
CC
IL
MR Input Voltage
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
kΩ
s
CC
MR Pullup Resistance
Watchdog Timeout Period
WDI Pulse Width
25
1.12
0.96
50
50
75
T
T
= -40°C to +85°C
= -40°C to +125°C
1.6
2.4
A
t
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
WDI = 0V or V
+1
µA
WDI
CC
V
≥ 1.0V, I
= 50µA, output asserted
SINK
CC
0.3
(T = 0°C to +125°C)
A
RESET, WDO Output Low
(Push-Pull or Open Drain)
V
V
CC
V
CC
V
CC
V
CC
V
CC
V
CC
V
CC
V
CC
≥ 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
≥ 2.55V, I
≥ 4.25V, I
≥ 1.80V, I
≥ 2.55V, I
≥ 4.25V, I
SINK
SINK
SINK
PFO Output Low
(Push-Pull or Open Drain)
V
V
V
OL
SINK
SINK
≥ 2.7V, I
= 500µA, output not asserted
= 800µA, output not asserted
0.8 x V
0.8 x V
SOURCE
CC
CC
RESET, WDO, PFO Output
High (Push-Pull Only)
V
OH
≥ 4.75V, I
SOURCE
RESET, WDO, PFO Output
Open-Drain Leakage
Current
I
V
> V , output not asserted
1.0
µA
LKG
CC
TH
V
≥ 1.0V, I
= 1µA, reset asserted
= 50µA, reset asserted
CC
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
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
= 500µA, reset asserted
= 800µA, reset asserted
SOURCE
SOURCE
≥ 2.7V, I
= 1.2mA, reset not asserted
0.3
0.4
SINK
RESET Output Low
(Push-Pull Only)
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.
_______________________________________________________________________________________
3
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
V
TO RESET OUTPUT DELAY
vs. TEMPERATURE
RESET TIMEOUT PERIOD
vs. TEMPERATURE
CC
SUPPLY CURRENT vs. TEMPERATURE
20
15
10
5
210
205
200
195
190
20
16
MAX6705(A)
V
CC
= 5V
12
8
MAX6708
35
V
CC
= 3.3V
4
0
0
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
MAXIMUM V TRANSIENT DURATION
CC
vs. RESET THRESHOLD OVERDRIVE
WATCHDOG TIMEOUT PERIOD
vs. TEMPERATURE
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
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
0
40
80
120
160
-40
-15
10
35
60
85
-40
-15
10
35
60
85
RESET THRESHOLD OVERDRIVE (mV)
TEMPERATURE (°C)
TEMPERATURE (°C)
OUTPUT VOLTAGE LOW
vs. SINK CURRENT
V
- V vs. SOURCE CURRENT
CC
OH
100
75
350
300
250
200
150
100
50
V
CC
≥ 4.25V
V
≥ 4.25V
CC
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)
4
_______________________________________________________________________________________
Low-Voltage, SOT23 µP Supervisors with Power-
Fail In/Out, Manual Reset, and Watchdog Timer
Pin Description
PIN
MAX6701(A)
MAX6705(A)
NAME
FUNCTION
MAX6702(A) MAX6704 MAX6706(A) MAX6708
MAX6703(A)
MAX6707(A)
Active-Low, Manual Reset Input, Internal 50kΩ Pullup to V
.
CC
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
1
1
1
1
MR
unconnected or connect to V
if unused. WDO deasserts
CC
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 powered by V
2
3
2
3
2
3
2
3
V
CC
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;
—
—
4
5
4
5
4
5
0.62V (typ) threshold. Connect 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 a V /RST_IN1/RST_IN2 reset is asserted, the manual
CC
6
6
6
—
WDI
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, RES ET pulse asserts for the reset
timeout period after each watchdog timeout overflow. The
watchdog timer cannot be disabled.
—
—
—
6
7
N.C.
No Connection. Not internally connected.
Active-Low Reset Output (Open Drain or Push-Pull). RES ET
changes from high to low when the V input drops below the
CC
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). RES ET remains low for
the reset timeout period after the reset conditions are terminated.
7
7
7
RESET
_______________________________________________________________________________________
5
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
CC
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
8
—
8
—
WDO
delay when V , RST_IN1, and RST_IN2 rises above its
CC
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
input drops below the selected reset
CC
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
RST_IN1
RST_IN2
Input for User-Adjustable V
Monitor. High-impedance input
CC2
for second internal reset comparator. Connect this pin to an
external resistive-divider network to set the reset threshold
4
—
—
—
—
voltage; 0.62V (typ) threshold. Connect to V
when not used.
CC
Reset is asserted when either V , RST_IN1, or RST_IN2 are
CC
below threshold.
Input for User-Adjustable V
Monitor. High-impedance input
CC3
for third internal reset comparator. Connect this pin to an
external resistive-divider network to set the reset threshold
5
voltage; 0.62V (typ) threshold. Connect to V
when not used.
CC
Reset is asserted when either V , RST_IN1, or RST_IN2 are
CC
below threshold.
*RESET active-high for the MAX6702(A)/MAX6706(A).
stays low. After V , RST_IN1, or RST_IN2 rise above
CC
Detailed Description
the reset threshold, an internal timer holds RESET low
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.
for about 200ms. RESET pulses low whenever V
dips
CC
below the reset threshold, including brownout condi-
tions. 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 V
falls below
CC
Reset Output
A microprocessor’s (µP’s) reset input starts the µP in a
known state. The MAX6701–MAX6708 assert reset dur-
ing power-up and prevent code execution errors during
power-down or brownout conditions.
the reset threshold, RESET stays low and is guaranteed
to be 0.4V or less, until V drops below 1V.
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
CC
On power-up, once V
reaches 1V, RESET is a guar-
CC
down to 1V.
anteed logic low of 0.4V or less. As V
rises, RESET
CC
6
_______________________________________________________________________________________
Low-Voltage, SOT23 µP Supervisors with Power-
Fail In/Out, Manual Reset, and Watchdog Timer
V
CC
6
8
WATCHDOG
TIMER
WDI
WDO
V
CC
50kΩ
MAX6701(A)
MAX6702(A)
MAX6703(A)
50kΩ
MR
V
CC
1
2
MR
V
CC
RESET
GENERATOR
RESET (RESET)
7
5
RESET
RESET
GENERATOR
(RESET)
WDO
WDI
WATCHDOG
TIMER
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
RP
t
RP
50kΩ
8
7
RESET
RESET
V
1
2
CC
MR
RESET
RESET
GENERATOR
V
CC
0V
CC
6
WATCHDOG
TIMER
V
WDI
MR
(MAX6704 ONLY)
0V
t
MD
V
REF
V
CC
WDO
WDI
4
PFI
5
0V
PFO
MR EXTERNALLY DRIVEN LOW
V
CC
0.62V
0V
3
NOTE: THE MAX6706 RESET OUTPUT IS THE INVERSE OF THE RESET SHOWN.
GND
Figure 4. MAX6705/MAX6706/MAX6707 RESET, MR, WDO,
and WDI Timing
Figure 2. MAX6704/MAX6708 Functional Diagram
_______________________________________________________________________________________
7
Low-Voltage, SOT23 µP Supervisors with Power-
Fail In/Out, Manual Reset, and Watchdog Timer
Standard- vs. A-Version Comparison
The MAX6701/MAX6702/MAX6703/MAX6705/MAX6706/
MAX6707s’ WDO latches low when one of the following
events occurs:
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 watchdog timer times out (1.6s, typ).
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.
• V , RST_IN1, or RST_IN2 is below its reset threshold.
CC
• MR is pulled low.
• WDO only deasserts with a valid WDI transition.
Manual Reset
The manual reset input (MR) allows reset to be trig-
gered 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 threshold.
CC
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.
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.
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
V
TH
V
TH
t
t
WDI
WD
V
CC
+5V
0V
WDI
WDO
t
RP
t
RP
+5V
RESET
+5V
0V
0V
+5V
0V
+5V
0V
RESET
MR
RESET EXTERNALLY
TRIGGERED BY MR
t
RP
t
MD
+5V
0V
(RESET)
MR
t
MR
+5V
0V
+5V
WDO
0V
( ) ARE FOR MAX6702/MAX6706 ONLY.
Figure 6. MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/MAX6707(A) RESET, MR, and WDO Timing with
WDI Three-Stated
Figure 5. MAX6701/MAX6702/MAX6703/MAX6705/MAX6706/
MAX6707 Watchdog
8
_______________________________________________________________________________________
Low-Voltage, SOT23 µP Supervisors with Power-
Fail In/Out, Manual Reset, and Watchdog Timer
t
t
WD
WDI
t
WD
+5V
0V
WDI
WDO
t
WD
MAX6701(A)–
MAX6708
V
EXTERNAL
+5V
0V
R1
R2
PFI, RST_IN1, OR RST_IN2
+5V
0V
RESET
0.62V
t
RP
+5V
0V
(RESET)
MR
V
0.62
R1
R2
EXT-TH
+5V
V
=
1 +
x 0.62V
R1 = R2 x
- 1
)
EXT-TH ( )
(
0V
WHERE V
IS THE EXTERNAL VOLTAGE TRIP LEVEL.
EXT-TH
( ) ARE FOR MAX6702(A)/MAX6706(A) ONLY.
Figure 8. Calculating Adjustable Voltage Thresholds
Figure 7. MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/MAX6707(A) Watchdog Timing
Reset Input
The MAX6701(A)/MAX6702(A)/MAX6703(A) include two
adjustable reset inputs for monitoring up to a total of
Monitoring Other System Voltages
Other systems can be monitored by connecting a volt-
age-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-fre-
quency 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 out-
put 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
Generating a Reset
from Watchdog Overflow
Output Down to V
= 0
CC
When V
falls below 1V, the MAX6701–MAX6708
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.
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).
_______________________________________________________________________________________
9
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
CORE
SUPPLY
SUPPLY
RESET
V
CC
RESET
(RESET)
RESET
PFI
µP
MR
PFO
MAX6704–
MAX6708
R1 (100kΩ)
() ARE FOR MAX6704/MAX6706(A)/MAX6708 ONLY.
Figure 10. Monitoring Other System Voltages
Figure 9. RESET Valid to Ground Circuit
Selector Guide
RESET
PP LOW
RESET
PP HIGH
RESET
OD-LOW
PFI,
PFO
RST_IN1,
RST_IN2
PART
WDI
WDO
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.
10 ______________________________________________________________________________________
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
CC
V
CC
RESET (RESET)
WDI
V
CC
MAX6704
MAX6705(A)
MAX6706(A)
MAX6707(A)
MAX6708
GND
GND
GND
PFI
PFO
PFI
PFO
PFI
PFO
SOT23
SOT23
SOT23
( ) ARE FOR MAX6706(A) ONLY.
Ordering Information (continued)
Typical Operating Circuit
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
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
UNREGULATED 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
DC/DC
REGULATOR
µP
V
CC
V
RESET
WDI
WDO
PFO
CC
RESET
I/O
PFI
MAX6705(A)
MAX6706(A)
MAX6707(A)
NMI
INTERRUPT
MR
PUSHBUTTON
SWITCH
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.
Chip Information
TRANSISTOR COUNT: 716
PROCESS: BiCMOS
______________________________________________________________________________________ 11
Low-Voltage, SOT23 µP Supervisors with Power-
Fail In/Out, Manual Reset, and Watchdog Timer
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.)
SEE DETAIL "A"
SYMBOL
MIN
MAX
e
b
A
0.90
0.00
0.90
0.28
0.09
2.80
2.60
1.50
0.30
1.45
0.15
1.30
0.45
0.20
3.00
3.00
1.75
0.60
C
L
A1
A2
b
C
D
E
C
C
L
E1
L
E
E1
L
0.25 BSC.
L2
e
PIN 1
I.D. DOT
(SEE NOTE 6)
0.65 BSC.
1.95 REF.
e1
0
0
8
e1
D
C
C
L
L2
A2
A
GAUGE PLANE
A1
SEATING PLANE
C
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.
DETAIL "A"
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.
PROPRIETARY INFORMATION
TITLE:
7. SOLDER THICKNESS MEASURED AT FLAT SECTION OF LEAD
BETWEEN 0.08mm AND 0.15mm FROM LEAD TIP.
8. MEETS JEDEC MO178.
PACKAGE OUTLINE, SOT-23, 8L BODY
APPROVAL
DOCUMENT CONTROL NO.
REV.
1
21-0078
D
1
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.
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