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.
www.DTahteaaShcetievte4-Ulo.cwomreset 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.
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.
Features
♦ VCC1 (Primary Supply) Reset Threshold Voltages
from +1.575V to +4.63V
♦ VCC2 (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
VCC1 or VCC2 = +0.8V
♦ Push-Pull RESET or Open-Drain RESET Output
♦ Immune to Short VCC Transients
♦ Low Supply Current: 14µA (typ) at +3.6V
♦ Small 6-Pin and 8-Pin SOT23 Packages
Ordering Information
PART*
PIN-PACKAGE PKG CODE
MAX6730AUT_D_ -T
MAX6731AUT_D_ -T
MAX6732AUT_ _D_ -T
6 SOT23-6
6 SOT23-6
6 SOT23-6
U6-1
U6-1
U6-1
MAX6733AUT_ _D_ -T
MAX6734AKA_ _D_ -T
MAX6735AKA_ _D_ -T
6 SOT23-6
8 SOT23-8
8 SOT23-8
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 VCC1 and VCC2
(Table 1) after “UT” or “KA.” For the MAX6730A/MAX6731A,
insert only the VCC1 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 VCC1
threshold of +4.625V, a VCC2 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.
________________________________________________________________ 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.
