General Description
The MAX16997/MAX16998 are microprocessor (µP)
supervisory circuits for high-input-voltage and low-qui-
escent-current applications. These devices detect
downstream circuit failures and provide switchover to
redundant circuitry. See the
Selector Guide
for the dif-
ferent versions of this product family.
The MAX16997/MAX16998 family has four independent
inputs for reset and watchdog functions. SWT and SRT
inputs independently set the timeout periods of watch-
dog and reset timers through external capacitors.
RESETIN/EN monitor voltages at respective inputs. A
resistive voltage-divider sets the reset threshold.
The MAX16998A/B/D generate two output signals,
RESET and ENABLE. RESET asserts whenever
RESETIN drops below its threshold voltage or when the
watchdog timer detects a timing fault at WDI. Once
asserted, and after all reset conditions are removed,
RESET remains low for the reset timeout period, t
RESET
,
and then goes high. The MAX16997A generates one
output signal (ENABLE) based on the voltage level at
EN and the signal at WDI.
The MAX16997A does not have a RESET output. The
watchdog is disabled if the voltage at EN is below its
threshold. The MAX16997A watchdog timer starts tim-
ing when the voltage at EN becomes higher than the
preset threshold voltage level. Each time EN rises
above the preset threshold voltage, the initial watchdog
timeout period is 8 times the normal watchdog timeout
period (t
WP
).
The MAX16997/MAX16998 are available in 8-pin lead-
free µMAX
®
packages and are fully specified over the
-40°C to +125°C automotive temperature range.
Applications
Automotive
Industrial
Features
o Wide 5V to 40V Input Voltage Range
o 18µA Quiescent Current (Typical at +125°C)
o Capacitor-Adjustable Timeout Period for
Watchdog and Reset
o Windowed Watchdog Timer Options
(MAX16998B/D)
o External Voltage Monitoring (RESETIN for the
MAX16998A/B/D and EN for the MAX16997A)
o Car Battery-Compatible EN Input
o TTL- and CMOS-Compatible Open-Drain Outputs
o 18V Maximum Open-Drain Reset Output Voltage
o 28V Maximum Open-Drain Enable Output Voltage
o Power-On/Power-Off Reset Functionality
(MAX16998A/B/D Only)
o AEC-Q100 Qualified
o -40°C to +125°C Operating Temperature Range
o Small (3mm x 3mm) µMAX Package
o WDI Narrow Pulse Immunity
MAX16997/MAX16998
High-Voltage Watchdog Timers with
Adjustable Timeout Delay
________________________________________________________________
Maxim Integrated Products
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