19-2629; Rev 3; 3/04
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
General Description
The MAX6730–MAX6735 single-/dual-/triple-voltage
microprocessor (µP) supervisors feature a watchdog
timer and manual reset capability. The MAX6730–
MAX6735 offer factory-set reset thresholds for monitor-
ing voltages from +0.9V to +5V and an adjustable reset
input for monitoring voltages down to +0.63V. The com-
bination of these features significantly improves system
reliability and accuracy when compared to separate
ICs or discrete components.
The active-low reset output asserts and remains asserted
for the reset timeout period after all the monitored volt-
ages exceed their respective thresholds. Multiple factory-
set reset threshold combinations reduce the number of
external components required. The MAX6730/MAX6731
monitor a single fixed voltage, the MAX6732/MAX6733
monitor two fixed voltages, and the MAX6734/MAX6735
monitor two fixed voltages and one adjustable voltage. All
devices are offered with six minimum reset timeout peri-
ods ranging from 1.1ms to 1120ms.
The MAX6730–MAX6735 feature a watchdog timer with
an independent watchdog output. The watchdog timer
prevents system lockup during code execution errors.
A watchdog startup delay of 54s after reset asserts
allows system initialization during power-up. The watch-
dog operates in normal mode with a 1.68s delay after
initialization. The MAX6730/MAX6732/MAX6734 provide
an active-low, open-drain watchdog output. The
MAX6731/MAX6733/MAX6735 provide an active-low,
push-pull watchdog output.
Other features include a manual reset input (MAX6730/
MAX6731/MAX6734/MAX6735) and push-pull reset out-
put (MAX6731/MAX6733/MAX6735) or open-drain reset
output (MAX6730/MAX6732/MAX6734). The MAX6730–
MAX6733 are offered in a tiny SOT23-6 package. The
MAX6734/MAX6735 are offered in a space-saving
SOT23-8 package. All devices are fully specified over
the extended -40°C to +85°C temperature range.
Features
♦
V
CC
1 (Primary Supply) Reset Threshold Voltages
from +1.575V to +4.63V
♦
V
CC
2 (Secondary Supply) Reset Threshold
Voltages from +0.79V to +3.08V
♦
Adjustable RSTIN Threshold for Monitoring
Voltages Down to +0.63V (MAX6734/MAX6735 Only)
♦
Six Reset Timeout Options
♦
Watchdog Timer with Independent Watchdog Output
35s (min) Initial Watchdog Startup Period
1.12s (min) Normal Watchdog Timeout Period
♦
Manual Reset Input
(MAX6730/MAX6731/MAX6734/MAX6735)
♦
Guaranteed Reset Valid down to
V
CC
1 or V
CC
2 = +0.8V
♦
Push-Pull
RESET
or Open-Drain
RESET
Output
♦
Immune to Short V
CC
Transients
♦
Low Supply Current: 14µA (typ) at +3.6V
♦
Small 6-Pin and 8-Pin SOT23 Packages
MAX6730–MAX6735
Ordering Information
PART*
MAX6730
UT_D_ -T
MAX6731
UT_D_ -T
MAX6732
UT_ _D_ -T
MAX6733
UT_ _D_ -T
MAX6734
KA_ _D_ -T
MAX6735
KA_ _D_ -T
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
8 SOT23-8
8 SOT23-8
Applications
Multivoltage Systems
Telecom/Networking Equipment
Computers/Servers
Portable/Battery-Operated Equipment
Industrial Equipment
Printer/Fax
Set-Top Boxes
*Note:
Insert the threshold level suffixes for V
CC
1 and V
CC
2
(Table 1) after “UT” or “KA.” For the MAX6730/MAX6731, insert
only the V
CC
1 threshold suffix after the “UT.” Insert the reset
timeout delay (Table 2) after “D” to complete the part number.
For example, the MAX6732UTLTD3-T provides a V
CC
1 threshold
of +4.625V, a V
CC
2 threshold of +3.075V, and a 210ms reset
timeout period. Sample stock is generally held on standard ver-
sions only (see the Standard Versions table). Standard versions
have an order increment requirement of 2500 pieces.
Nonstandard versions have an order increment requirement of
10,000 pieces. Contact factory for availability.
Typical Operating Circuit and Pin Configurations appear 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.
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
MAX6730–MAX6735
ABSOLUTE MAXIMUM RATINGS
V
CC
1, V
CC
2, RSTIN,
MR,
WDI to GND .....................-0.3V to +6V
RST, WDO
to GND (open drain)...............................-0.3V to +6V
RST, WDO
to GND (push-pull) .................-0.3V to (V
CC
1 + 0.3V)
Input Current/Output Current (all pins) ...............................20mA
Continuous Power Dissipation (T
A
= +70°C)
6-Pin SOT23-6 (derate 8.7mW/°C above +70°C) ........696mW
8-Pin SOT23-8 (derate 8.9mW/°C above +70°C) ........714mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature ......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°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
1 = V
CC
2 = +0.8V to +5.5V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Supply Voltage
SYMBOL
V
CC
1,
V
CC
2
V
CC
1 < +5.5V, all I/O connections
open, outputs not asserted
I
CC
1
Supply Current
V
CC
2 < +3.6V, all I/O connections
open, outputs not asserted
I
CC
2
V
CC
2 < +2.75V, all I/O connections
open, outputs not asserted
L (falling)
M (falling)
T (falling)
S (falling)
V
CC
1 Reset Threshold
V
TH
1
R (falling)
Z (falling)
Y (falling)
W (falling)
V (falling)
4.500
4.250
3.000
2.850
2.550
2.250
2.125
1.620
1.530
4
3
4.625
4.375
3.075
2.925
2.625
2.313
2.188
1.665
1.575
11
9
4.750
4.500
3.150
3.000
2.700
2.375
2.250
1.710
1.620
V
V
CC
1 < +3.6V, all I/O connections
open, outputs not asserted
CONDITIONS
MIN
0.8
15
10
TYP
MAX
5.5
39
28
µA
UNITS
V
2
_______________________________________________________________________________________
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
1 = V
CC
2 = +0.8V to +5.5V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
SYMBOL
T (falling)
S (falling)
R (falling)
Z (falling)
Y (falling)
W (falling)
V
CC
2 Reset Threshold
V
TH
2
V (falling)
I (falling)
H (falling)
G (falling)
F (falling)
E (falling)
D (falling)
Reset Threshold Tempco
Reset Threshold Hysteresis
V
HYST
Referenced to V
TH
typical
V
CC
1 = (V
TH
1 + 100mV) to
(V
TH
1 - 100mV) or
V
CC
2 = (V
TH
2 + 75mV) to
(V
TH
2 - 75mV)
D1
D2
Reset Timeout Period
t
RP
D3
D5
D6
D4
ADJUSTABLE RESET COMPARATOR INPUT (MAX6734/MAX6735)
RSTIN Input Threshold
RSTIN Input Current
RSTIN Hysteresis
RSTIN to Reset Output Delay
t
RSTIND
V
IL
V
IH
0.7
×
V
CC
1
1
100
t
MR
25
200
50
80
V
RSTIN
to (V
RSTIN
- 30mV)
MANUAL RESET INPUT (MAX6730/MAX6731/MAX6734/MAX6735)
MR
Input Threshold
MR
Minimum Pulse Width
MR
Glitch Rejection
MR
to Reset Output Delay
MR
Pullup Resistance
0.3
×
V
CC
1
V
µs
ns
ns
kΩ
V
RSTIN
I
RSTIN
611
-25
3
22
626.5
642
+25
mV
nA
mV
µs
1.1
8.8
140
280
560
1120
CONDITIONS
MIN
3.000
2.850
2.550
2.250
2.125
1.620
1.530
1.350
1.275
1.080
1.020
0.810
0.765
TYP
3.075
2.925
2.625
2.313
2.188
1.665
1.575
1.388
1.313
1.110
1.050
0.833
0.788
20
0.5
MAX
3.150
3.000
2.700
2.375
2.250
1.710
1.620
1.425
1.350
1.140
1.080
0.855
0.810
ppm/
o
C
%
V
UNITS
MAX6730–MAX6735
V
CC
_ to
RST
Output Delay
t
RD
45
µs
1.65
13.2
210
420
840
1680
2.2
17.6
280
560
1120
2240
ms
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3
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
MAX6730–MAX6735
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
1 = V
CC
2 = +0.8V to +5.5V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
WATCHDOG INPUT
Watchdog Timeout Period
WDI Pulse Width
WDI Input Voltage
WDI Input Current
RESET/WATCHDOG OUTPUT
V
CC
1 or V
CC
2
≥
+0.8V,
I
SINK
= 1µA, output asserted
V
CC
1 or V
CC
2
≥
+1.0V,
I
SINK
= 50µA, output asserted
RST
/
WDO
Output Low Voltage
(Push-Pull or Open Drain)
V
OL
V
CC
1 or V
CC
2
≥
+1.2V,
I
SINK
= 100µA, output asserted
V
CC
1 or V
CC
2
≥
+2.7V,
I
SINK
= 1.2mA, output asserted
V
CC
1 or V
CC
2
≥
+4.5V,
I
SINK
= 3.2mA, output asserted
V
CC
1
≥
+1.8V, I
SOURCE
= 200µA,
output not asserted
RST
/
WDO
Output High Voltage
(Push-Pull Only)
V
OH
V
CC
1
≥
+2.7V, I
SOURCE
= 500µA,
output not asserted
V
CC
1
≥
+4.5V, I
SOURCE
= 800µA,
output not asserted
RST
/
WDO
Output Open-Drain
Leakage Current
Output not asserted
0.8
×
V
CC
1
0.8
×
V
CC
1
0.8
×
V
CC
1
0.5
µA
V
0.3
0.3
0.3
0.3
0.4
V
t
WD-L
t
WD-S
t
WDI
V
IL
V
IH
I
WDI
WDI = 0 or V
CC
1
0.7
×
V
CC
1
-1
+1
First watchdog period after reset
timeout period
Normal mode
(Note 2)
35
1.12
50
0.3
×
V
CC
1
54
1.68
72
2.24
ns
V
µA
s
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Note 1:
Devices tested at T
A
= +25°C. Overtemperature limits are guaranteed by design and not production tested.
Note 2:
Parameter guaranteed by design.
4
_______________________________________________________________________________________
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
MAX6730–MAX6735
Typical Operating Characteristics
(V
CC
1 = +5V, V
CC
2 = +3.3V, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
(V
CC
1 = +5V, V
CC
2 = +3.3V)
MAX6730-35 toc01
SUPPLY CURRENT vs. TEMPERATURE
(V
CC
1 = +3.3V, V
CC
2 = +2.5V)
MAX6730-35 toc02
SUPPLY CURRENT vs. TEMPERATURE
(V
CC
1 = +2.5V, V
CC
2 = +1.8V)
16
SUPPLY CURRENT (µA)
14
12
10
8
6
4
2
0
I
CC
2
I
CC
1
TOTAL
MAX6730-35 toc03
18
16
SUPPLY CURRENT (µA)
14
12
10
8
6
4
2
0
-40
-15
10
35
60
I
CC
2
TOTAL
I
CC
1
18
16
SUPPLY CURRENT (µA)
14
12
10
8
6
4
2
0
I
CC
2
I
CC
1
TOTAL
18
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
SUPPLY CURRENT vs. TEMPERATURE
(V
CC
1 = +1.8V, V
CC
2 = +1.2V)
MAX6730-35 toc04
NORMALIZED THRESHOLD VOLTAGE
vs. TEMPERATURE
NORMALIZED THRESHOLD VOLTAGE
1.008
1.006
1.004
1.002
1.000
0.998
0.996
0.994
0.992
0.990
MAX6730-35 toc05
18
16
SUPPLY CURRENT (µA)
14
12
10
8
6
4
2
0
-40
-15
10
35
60
I
CC
2
TOTAL
I
CC
1
1.010
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
