19-1078; Rev 4; 9/10
+5V, Low-Power µP Supervisory Circuits
with Adjustable Reset/Watchdog
_______________General Description
The MAX6301–MAX6304* low-power microprocessor
(µP) supervisory circuits provide maximum adjustability
for reset and watchdog functions. The reset threshold
can be adjusted to any voltage above 1.22V, using
external resistors. In addition, the reset and watchdog
timeout periods are adjustable using external capaci-
tors. A watchdog select pin extends the watchdog time-
out period to 500x. The reset function features immunity
to power-supply transients.
These four devices differ only in the structure of their reset
outputs (see the
Selector Guide).
The MAX6301–MAX6304
are available in the space-saving 8-pin µMAX
®
package,
as well as 8-pin PDIP and SO packages.
____________________________Features
Adjustable Reset Threshold
Adjustable Reset Timeout
Adjustable Watchdog Timeout
500x Watchdog Timeout Multiplier
4µA Supply Current
RESET or
RESET
Output Options
Push-Pull or Open-Drain Output Options
Guaranteed
RESET
Asserted At or Above
V
CC
= 1V (MAX6301/MAX6303)
o
Power-Supply Transient Immunity
o
Watchdog Function can be Disabled
o
PDIP/SO/µMAX Packages Available
o
o
o
o
o
o
o
o
MAX6301–MAX6304
Applications
Medical Equipment
Intelligent Instruments
Portable Equipment
Battery-Powered
Computers/Controllers
FEATURE
Active-Low
Reset
Active-High
Reset
Open-Drain
Reset Output
Push-Pull
Reset Output
Pin-Package
MAX6301
√
—
√
—
Embedded Controllers
Critical µP Monitoring
Set-Top Boxes
Computers
Ordering Information
PART
MAX6301CPA
MAX6301CSA
MAX6301CUA
MAX6301EPA
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
8 PDIP
8 SO
8 µMAX
8 PDIP
Selector Guide
MAX6302
—
√
√
—
MAX6303
√
—
—
√
MAX6304
—
√
—
√
MAX6301ESA
-40°C to +85°C
8 SO
Devices are available in both leaded and lead(Pb)-free/RoHS-
compliant packaging. Specify lead-free by adding the “+”
symbol at the end of the part number when ordering.
Ordering Information continued at end of data sheet.
Typical Operating Circuit
V
IN
MAX6301
ONLY
R1
1
RESET IN
V
CC
8
R
L
0.1µF
8-PDIP/SO/ 8-PDIP/SO/ 8-PDIP/SO/ 8-PDIP/SO/
µMAX
µMAX
µMAX
µMAX
Pin Configuration
TOP VIEW
RESET IN
1
GND
2
SRT
3
SWT
4
8
V
CC
RESET (RESET)
WDI
WDS
R2
2 GND
RESET 7
(RESET)
R
L
MAX6302
ONLY
I/O
RESET
µP
MAX6301
MAX6302
MAX6303
MAX6304
7
6
5
MAX6301
MAX6302
3
WDI 6
SRT
MAX6303
4
5
SWT
MAX6304
WDS
C
SRT
C
SWT
( ) ARE FOR MAX6302/MAX6304.
DIP/SO/µMAX
( ) ARE FOR MAX6302/MAX6304.
WDS = 0 FOR NORMAL MODE
WDS = 1 FOR EXTENDED MODE
µMAX is a registered trademark of Maxim Integrated Products, Inc.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
+5V, Low-Power µP Supervisory Circuits
with Adjustable Reset/Watchdog
MAX6301–MAX6304
ABSOLUTE MAXIMUM RATINGS
V
CC ....................................................................................
-0.3V to +7.0V
RESET IN, SWT, SRT ..................................-0.3V to (V
CC
+ 0.3V)
WDI, WDS..............................................................-0.3V to +7.0V
RESET,
RESET
MAX6301… .......................................................-0.3V to +7.0V
MAX6302/MAX6303/MAX6304...............-0.3V to (V
CC
+ 0.3V)
Input Current
V
CC
...............................................................................±20mA
GND..............................................................................±20mA
Output Current
RESET,
RESET..............................................................±20mA
Continuous Power Dissipation (T
A
= +70°C)
PDIP (derate 9.09mW/°C above +70°C) ......................727mW
SO (derate 5.88mW/°C above +70°C) .........................471mW
µMAX (derate 4.10mW/°C above +70°C) ....................330mW
Operating Temperature Range
MAX630_C_A ......................................................0°C to +70°C
MAX630_E_A ...................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow)
Lead(Pb)-free...............................................................+260°C
Containing Lead (Pb)...................................................+240°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
CC
= +2V to +5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5V and T
A
= +25°C.)
PARAMETER
Operating Voltage Range
(Note 1)
Supply Current (Note 2)
RESET TIMER
Reset Input Threshold Voltage
Reset Input Hysteresis
Reset Input Leakage Current
Reset Output-Voltage High
(MAX6302/MAX6303/MAX6304)
V
TH
V
HYST
I
RESET IN
V
CC
≥
4.5V, I
SOURCE
= 0.8mA
V
OH
V
CC
= 2V, I
SOURCE
= 0.4mA
MAX6302/MAX6304, V
CC
= 1.31V,
R
L
= 10kΩ
V
CC
≥
4.5V, I
SINK
= 3.2mA
V
CC
= 2V, I
SINK
= 1.6mA
Reset Output-Voltage Low
(MAX6301/MAX6303/MAX6304
V
OL
MAX6301/
MAX6303
t
RD
t
RI
t
RP
V
CC
= 1V, I
SINK
= 50µA,
T
A
= 0°C to +70°C
V
CC
= 1.2V, I
SINK
= 100µA,
T
A
= -40°C to +85°C
63
26
2.8
4.0
5.2
±1
±1
V
CC
-
0.3
0.4
0.4
0.3
0.3
µs
µs
ms
µA
V
V
CC
- 0.4
V
CC
- 0.4
V
V
RESET IN
falling, V
CC
= 5.0V
V
RESET IN
rising, V
CC
= 5.0V
1.195
1.220
1.240
20
±0.01
±1
1.245
1.265
V
mV
nA
SYMBOL
V
CC
I
CC
CONDITIONS
MAX6301C/MAX6303C
MAX6301E/MAX6303E
MAX6302/MAX6304
No load
MIN
1.00
1.20
1.31
4.0
TYP
MAX
5.50
5.50
5.50
7.0
µA
V
UNITS
V
CC
to Reset Delay
Reset Input Pulse Width
Reset Timeout Period (Note 3)
Reset Output Leakage Current
V
CC
= falling at 1mV/µs
Comparator overdrive = 50mV
C
SRT
= 1500pF
MAX6301, V
RESET
= V
CC
MAX6302, V
RESET
= V
GND
2
_______________________________________________________________________________________
+5V, Low-Power µP Supervisory Circuits
with Adjustable Reset/Watchdog
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +2V to +5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5V and T
A
= +25°C.)
PARAMETER
WATCHDOG TIMER
WDI, WDS Input Threshold
WDI Pulse Width
WDI, WDS Leakage Current
WDI Sink/Source Current (Note 4)
Watchdog Timeout Period
(Note 3)
t
WD
V
IH
V
IL
t
WP
V
CC
= 4.5V to 5.5V
V
CC
= 2V to 4.5V
Extended mode disabled
Extended mode enabled
WDS = GND, C
SWT
= 1500pF
WDS = V
CC
, C
SWT
= 1500pF
2.8
1.4
±70
4.0
2.0
5.2
2.6
30
60
±1
0.7 x V
CC
0.3 x V
CC
V
ns
µA
µA
ms
s
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX6301–MAX6304
Note 1:
Reset is guaranteed valid from the selected reset threshold voltage down to the minimum V
CC
.
Note 2:
WDS = V
CC
, WDI unconnected.
Note 3:
Precision timing currents of 500nA are present at both the SRT and SWT pins. Timing capacitors connected to these nodes
must have low leakage consistent with these currents to prevent timing errors.
Note 4:
The sink/source is supplied through a resistor, and is proportional to V
CC
(Figure 8). At V
CC
= 2V, it is typically ±24µA.
__________________________________________Typical Operating Characteristics
(C
SWT
= C
SRT
= 1500pF, T
A
= +25°C, unless otherwise noted.)
RESET TIMEOUT PERIOD
vs. C
SRT
MAX6301-4 toc01
10,000
EXTENDED-MODE
WATCHDOG TIMEOUT PERIOD vs. C
SWT
(WDS = V
CC
)
MAX6301-4 toc02
NORMAL-MODE
WATCHDOG TIMEOUT PERIOD vs. C
SWT
(WDS = GND)
V
CC
= 5V
MAX6301-4 toc03
V
CC
= 5V
10,000
WATCHDOG TIMEOUT PERIOD (s)
V
CC
= 5V
10,000
WATCHDOG TIMEOUT PERIOD (ms)
RESET TIMEOUT PERIOD (ms)
1000
1000
1000
100
100
100
10
10
10
1
1
1
0
0.001
0.01
0.1
1
C
SRT
(nF)
10
100
1000
0
0.001
0.01
0.1
1
C
SWT
(nF)
10
100
1000
0.1
0.001
0.01
0.1
1
C
SWT
(nF)
10
100
1000
_______________________________________________________________________________________
3
+5V, Low-Power µP Supervisory Circuits
with Adjustable Reset/Watchdog
MAX6301–MAX6304
____________________________Typical Operating Characteristics (continued)
(C
SWT
= C
SRT
= 1500pF, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6301-4 toc04
RESET AND NORMAL-MODE
WATCHDOG TIMEOUT PERIOD
vs. TEMPERATURE
MAX6301-4 toc05
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE (V
RST
)
120
110
100
TRANSIENT DURATION (µs)
90
80
70
60
50
40
30
20
10
0
V
RST
= 4.60V
0
200
400
600
800
1000
RESET OCCURS
ABOVE THE CURVE
SEE THE
NEGATIVE-GOING
V
CC
TRANSIENTS
SECTION
MAX6301-4 toc06
4.2
4.0
SUPPLY CURRENT (µA)
3.8
RESET DEASSERTED
NO LOAD
4.20
4.15
4.10
t
RP
/t
WD
(ms)
4.05
4.00
3.95
3.90
3.85
3.80
V
CC
= 5.0V
3.6
3.4
3.2
3.0
2.8
2.6
1.5
2.0 2.5 3.0 3.5 4.0
4.5 5.0 5.5 6.0
SUPPLY VOLTAGE (V)
-60
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
RESET THRESHOLD OVERDRIVE (mV)
SUPPLY CURRENT
vs. TEMPERATURE
MAX6301-4 toc07
RESET IN THRESHOLD VOLTAGE
vs. TEMPERATURE
MAX6301-4 toc08
5.00
4.75
4.50
SUPPLY CURRENT (µA)
4.25
4.00
3.75
3.50
3.25
3.00
2.75
2.50
-60
-40
-20
0
20
40
60
80
V
CC
= 2.0V
V
CC
= 5.0V
RESET DEASSERTED
NO LOAD
1.226
RESET REFERENCE VOLTAGE (V)
1.224
1.222
1.220
1.218
1.216
1.214
-60
100
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
V
CC
TO RESET DELAY
vs. TEMPERATURE (V
CC
FALLING)
V
CC
FALLING AT 1mV/µs
72
PROPAGATION DELAY (µs)
68
64
60
56
52
-60
4.00
MAX6301-4 toc09
RESET AND WATCHDOG
TIMEOUT vs. SUPPLY VOLTAGE
MAX6301-4 toc10
76
4.16
4.12
t
RP
/t
WP
(ms)
4.08
4.04
3.96
-40 -20
0
20
40
60
80
100
2
3
4
V
CC
(V)
5
6
TEMPERATURE (°C)
4
_______________________________________________________________________________________
+5V, Low-Power µP Supervisory Circuits
with Adjustable Reset/Watchdog
Pin Description
PIN
1
2
3
NAME
RESET IN
GND
SRT
FUNCTION
Reset Input. High-impedance input to the reset comparator. Connect this pin to the center point of an
external resistor voltage-divider network to set the reset threshold voltage. The reset threshold voltage is
calculated as follows: V
RST
= 1.22 x (R1 + R2)/R2 (see the
Typical Operating Circuit).
Ground
Set Reset-Timeout Input. Connect a capacitor between this input and ground to select the reset timeout
period (t
RP
). Determine the period as follows: t
RP
= 2.67 x C
SRT
, with C
SRT
in pF and t
RP
in µs (see the
Typical Operating Circuit).
Set Watchdog-Timeout Input. Connect a capacitor between this input and ground to select the basic
watchdog timeout period (t
WD
). Determine the period as follows: t
WD
= 2.67 x C
SWT
, with C
SWT
in pF and
t
WD
in µs. The watchdog function can be disabled by connecting this pin to ground.
Watchdog-Select Input. This input selects the watchdog mode. Connect to ground to select normal mode
and the basic watchdog timeout period. Connect to V
CC
to select extended mode, multiplying the basic
timeout period by a factor of 500. A change in the state of this pin resets the watchdog timer to zero.
Watchdog Input. A rising or falling transition must occur on this input within the selected watchdog timeout
period, or a reset pulse will occur. The capacitor value selected for SWT and the state of WDS determine
the watchdog timeout period. The watchdog timer clears and restarts when a transition occurs on WDI or
WDS. The watchdog timer is cleared when reset is asserted and restarted after reset deasserts. In the
extended watchdog mode (WDS = V
CC
), the watchdog function can be disabled by driving WDI with a
three-stated driver or by leaving WDI unconnected.
Open-Drain, Active-Low Reset
Output (MAX6301)
Push-Pull, Active-Low Reset
Output (MAX6303)
RESET
changes from high to low whenever the monitored voltage (V
IN
)
drops below the selected reset threshold (V
RST
).
RESET
remains low as
long as V
IN
is below V
RST
. Once V
IN
exceeds V
RST
,
RESET
remains low
for the reset timeout period and then goes high. The watchdog timer
triggers a reset pulse (t
RP
) whenever the watchdog timeout period (t
WD
)
is exceeded.
MAX6301–MAX6304
4
SWT
5
WDS
6
WDI
RESET
(MAX6301/
MAX6303)
7
RESET
(MAX6302/
MAX6304
RESET changes from low to high whenever the monitored voltage (V
IN
)
Open-Drain, Active-High Reset drops below the selected reset threshold (V
RST
). RESET remains high as
Output (MAX6302)
long as V
IN
is below V
RST
. Once V
IN
exceeds V
RST
, RESET remains high
for the reset timeout period and then goes low. The watchdog timer
Push-Pull, Active-High Reset
triggers a reset pulse (t
RP
) whenever the watchdog timeout period (t
WD
)
Output (MAX6304)
is exceeded.
Supply Voltage. Bypass to ground with a 0.1µF capacitor placed as close as possible to the pin.
8
V
CC
_______________________________________________________________________________________
5
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