19-0605; Rev 0; 8/06
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
General Description
The MAX6730A–MAX6735A single-/dual-/triple-voltage
microprocessor (µP) supervisors feature a watchdog
timer and manual reset capability. The MAX6730A–
MAX6735A offer factory-set reset thresholds for moni-
toring voltages from +0.9V to +5V and an adjustable
reset input for monitoring voltages down to +0.63V. The
combination of these features significantly improves
system reliability and accuracy when compared to sep-
arate 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 MAX6730A/
MAX6731A monitor a single fixed voltage, the MAX6732A/
MAX6733A monitor two fixed voltages, and the
MAX6734A/MAX6735A monitor two fixed voltages and one
adjustable voltage. All devices are offered with six mini-
mum reset timeout periods ranging from 1.1ms to 1120ms.
The MAX6730A–MAX6735A 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 watchdog operates in normal mode with a 1.68s
delay after initialization. The MAX6730A/MAX6732A/
MAX6734A provide an active-low, open-drain watch-
dog output. The MAX6731A/MAX6733A/MAX6735A
provide an active-low, push-pull watchdog output.
Other features include a manual reset input (MAX6730A/
MAX6731A/MAX6734A/MAX6735A) and push-pull reset
output (MAX6731A/MAX6733A/MAX6735A) or open-
drain reset output (MAX6730A/MAX6732A/MAX6734A).
The MAX6730A–MAX6733A are offered in a tiny 6-pin
SOT23 package. The MAX6734A/MAX6735A are offered
in an 8-pin, space-saving SOT23 package. All devices
are fully specified over the extended -40°C to +125°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 (MAX6734A/MAX6735A 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 (MAX6730A/MAX6731A/
MAX6734A/MAX6735A)
♦
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
MAX6730A–MAX6735A
Ordering Information
PART*
MAX6730AUT_D_
-T
MAX6731AUT_D_
-T
MAX6732AUT_
_D_ -T
MAX6733AUT_
_D_ -T
MAX6734AKA_
_D_ -T
MAX6735AKA_
_D_ -T
PIN-PACKAGE
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
8 SOT23-8
8 SOT23-8
PKG CODE
U6-1
U6-1
U6-1
U6-1
K8S-3
K8S-3
All devices specified over the -40°C to +125°C operating tem-
perature range.
*Note:
Insert the threshold level suffixes for V
CC
1 and V
CC
2
(Table 1) after “UT” or “KA.” For the MAX6730A/MAX6731A,
insert only the V
CC
1 threshold suffix after the “UT.” Insert the
reset timeout delay (Table 2) after “D” to complete the part num-
ber. For example, the MAX6732AUTLTD3-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 versions only (see the Standard Versions table).
Standard versions have an order increment requirement of 2500
pieces. Nonstandard versions have an order increment require-
ment of 10,000 pieces. Contact factory for availability.
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “T” with “+T” when ordering.
Applications
Multivoltage Systems
Telecom/Networking Equipment
Computers/Servers
Portable/Battery-Operated Equipment
Industrial Equipment
Printer/Fax
Set-Top Boxes
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
MAX6730A–MAX6735A
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 +125°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 +125°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
MAX6730A–MAX6735A
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)
MAX6730A-35A toc01
SUPPLY CURRENT vs. TEMPERATURE
(V
CC
1 = +3.3V, V
CC
2 = +2.5V)
MAX6730A-35A toc02
SUPPLY CURRENT vs. TEMPERATURE
(V
CC
1 = +2.5V, V
CC
2 = +1.8V)
18
16
SUPPLY CURRENT (µA)
14
12
10
8
6
4
2
0
I
CC
2
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
I
CC
1
TOTAL
MAX6730A-35A toc03
MAX6730A-35A toc05
20
18
16
SUPPLY CURRENT (µA)
14
12
10
8
6
4
2
0
I
CC
2
I
CC
1
TOTAL
20
18
16
SUPPLY CURRENT (µA)
14
12
10
8
6
4
2
0
I
CC
2
I
CC
1
TOTAL
20
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SUPPLY CURRENT vs. TEMPERATURE
(V
CC
1 = +1.8V, V
CC
2 = +1.2V)
NORMALIZED THRESHOLD VOLTAGE
18
16
SUPPLY CURRENT (µA)
14
12
10
8
6
4
2
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
I
CC
2
TOTAL
I
CC
1
MAX6730A-35A toc04
NORMALIZED THRESHOLD VOLTAGE
vs. TEMPERATURE
1.008
1.007
1.006
1.005
1.004
1.003
1.002
1.001
1.000
0.999
0.998
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
20
_______________________________________________________________________________________
5
Microcontroller MCU
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