High-Voltage Watchdog Timers with Adjustable Timeout Delay

Highest Input Voltage Watchdog Consumes Only 18µA Supply Current

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The MAX16997/MAX16998 are microprocessor (µP) supervisory circuits for high-input-voltage and low-quiescent-current applications. These devices detect downstream circuit failures and provide switchover to redundant circuitry. See the Selector Guide in the full data sheet for the different 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 watchdog 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, active-low RESET and active-low ENABLE. Active-low 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, active-low RESET remains low for the reset timeout period, tRESET, and then goes high. The MAX16997A generates one output signal (active-low ENABLE) based on the voltage level at EN and the signal at WDI.<.p>

The MAX16997A does not have a active-low RESET output. The watchdog is disabled if the voltage at EN is below its threshold. The MAX16997A watchdog timer starts timing 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 (tWP).

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.

MAX16997, MAX16998: Functional Diagram MAX16997, MAX16998: Functional Diagram Enlarge+

Key Features

  • Wide 5V to 40V Input Voltage Range
  • 18µA Quiescent Current (Typical at +125°C)
  • Capacitor-Adjustable Timeout Period for Watchdog and Reset
  • Windowed Watchdog Timer Options (MAX16998B/D)
  • External Voltage Monitoring (RESETIN for the MAX16998A/B/D and EN for the MAX16997A)
  • Car Battery-Compatible EN Input
  • TTL- and CMOS-Compatible Open-Drain Outputs
  • 18V Maximum Open-Drain Reset Output Voltage
  • 28V Maximum Open-Drain Enable Output Voltage
  • Power-On/Power-Off Reset Functionality (MAX16998A/B/D Only)
  • AEC-Q100 Qualified
  • -40°C to +125°C Operating Temperature Range
  • Small (3mm x 3mm) µMAX Package
  • WDI Narrow Pulse Immunity


  • Automotive
  • Industrial
Part NumberWatchdog FeatureWatchdog TimeoutWatchdog Startup DelayWatchdog OutputICC
Package/PinsOper. Temp.
minmaxSee Notes
MAX16997 Input (WDI)Adjustable-Open-Drain60
-40 to +125$1.08 @1k
MAX16998 <60s
$1.17 @1k
See All Watchdog Timers (10)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Technical Documents

App Note 4210 High-Voltage Watchdog Timers Enhance Automotive System Safety

Quality and Environmental Data

Product Reliability Reports: MAX16997.pdf 
Lead-Free Package Tin (Sn) Whisker Reports
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

Quality Management System >
Environmental Management System >


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