19-2530; Rev 3; 12/05
µP Reset Circuits with Capacitor-Adjustable
Reset/Watchdog Timeout Delay
General Description
Features
The MAX6746–MAX6753 low-power microprocessor
(µP) supervisory circuits monitor single/dual system
supply voltages from 1.575V to 5V and provide maxi-
mum adjustability for reset and watchdog functions.
♦ Factory-Set Reset Threshold Options from 1.575V
to 5V in ~100mV Increments
♦ Adjustable Reset Threshold Options
♦ Single/Dual Voltage Monitoring
These devices assert a reset signal whenever the V
CC
supply voltage or RESET IN falls below its reset thresh-
old or when manual reset is pulled low. The reset output
♦ Capacitor-Adjustable Reset Timeout
♦ Capacitor-Adjustable Watchdog Timeout
♦ Min/Max (Windowed) Watchdog Option
♦ Manual Reset Input Option
remains asserted for the reset timeout period after V
CC
and RESET IN rise above the reset threshold. The reset
function features immunity to power-supply transients.
The MAX6746–MAX6753 have ±±2 factory-trimmed
reset threshold voltages in approximately 100mV incre-
ments from 1.575V to 5.0V and/or adjustable reset
threshold voltages using external resistors.
♦ Guaranteed RESET Valid for V
♦ 3.7µA Supply Current
≥ 1V
CC
The reset and watchdog delays are adjustable with
external capacitors. The MAX6746–MAX6751 contain a
watchdog select input that extends the watchdog time-
out period by 1±8x. The MAX675±/MAX6753 contain a
window watchdog timer that looks for activity outside an
expected window of operation.
♦ Push-Pull or Open-Drain RESET Output Options
♦ Power-Supply Transient Immunity
♦ Small 8-Pin SOT23 Packages
The MAX6746–MAX6753 are available with a push-pull
or open-drain active-low RESET output. The MAX6746–
MAX6753 are available in an 8-pin SOT±3 package and
are fully specified over the automotive temperature
range (-40°C to +1±5°C).
Ordering Information
PART
TEMP RANGE
-40°C to +1±5°C
-40°C to +1±5°C
-40°C to +1±5°C
-40°C to +1±5°C
-40°C to +1±5°C
-40°C to +1±5°C
-40°C to +1±5°C
-40°C to +1±5°C
PIN-PACKAGE
8 SOT±3-8
8 SOT±3-8
8 SOT±3-8
8 SOT±3-8
8 SOT±3-8
8 SOT±3-8
8 SOT±3-8
8 SOT±3-8
MAX6746KA_ _-T
MAX6747KA_ _-T
MAX6748KA-T
Applications
MAX6749KA-T
Medical Equipment
Automotive
Embedded Controllers
Critical µP Monitoring
Set-Top Boxes
MAX6750KA_ _-T
MAX6751KA_ _-T
MAX6752KA_ _-T
MAX6753KA_ _-T
Intelligent Instruments
Portable Equipment
Computers
Battery-Powered
Computers/Controllers
Note: “_ _” represents the two number suffix needed when
ordering the reset threshold voltage value for the
MAX6746/MAX6747 and MAX6750–MAX6753. The reset
threshold voltages are available in approximately 100mV incre-
ments. Table 2 contains the suffix and reset factory-trimmed
voltages. All devices are available in tape-and-reel only. There
is a 2500-piece minimum order increment for standard ver-
sions (see Table 3). Sample stock is typically held on standard
versions only. Nonstandard versions require a minimum order
increment of 10,000 pieces. Contact factory for availability.
Pin Configurations
TOP VIEW
RESET IN (MR)
SWT
1
2
3
4
8
7
6
5
V
CC
RESET
WDI
MAX6746–
MAX6751
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
SRT
GND
WDS
Selector Guide appears at end of data sheet.
SOT23-8
( ) ARE FOR MAX6746 AND MAX6747 ONLY.
Typical Operating Circuit appears at end of data sheet.
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.