MAX6814 5-Pin Watchdog Timer Circuit General Description Features The MAX6814 is a low-power watchdog circuit in a 4A Operating Current tiny 5-pin SC70 package. This device improves system Watchdog Timer with 1.6s Timeout reliability by monitoring the system for software code 140ms (min) WDO Pulse Period execution errors. When the watchdog input detects a transitional edge, the internal watchdog timer clears and Push-Pull Active-Low WDO restarts, then begins counting again. If the watchdog Fully Specified Over Extended Temperature Range timer exceeds the watchdog timeout period (1.6s typ), No External Components the active-low, push-pull watchdog output asserts for the watchdog pulse period (140ms min) to alert the system of the fault. The MAX6814 consumes only 4A of supply current and is fully specified over the extended temperature range. Applications Ordering Information Computers and Controllers TEMP PIN- TOP PART Embedded Controllers RANGE PACKAGE MARK Intelligent Instruments MAX6814XK-T -40C to +85C 5 SC70 AEK Critical P Monitoring Devices are available in both leaded and lead(Pb)-free/RoHS- compliant packaging. Specify lead-free by replacing -T with +T when ordering. Typical Operating Circuit Pin Configuration V CC TOP VIEW WDO 1 5 V V CC V CC CC WDO NMI MAX6814 2 GND MAX6814 P I/O WDI N.C. 3 4 WDI GND GND SC70-5 19-2804 Rev 3 7/14MAX6814 5-Pin Watchdog Timer Circuit Absolute Maximum Ratings V .......................................................................-0.3V to +6.0V Operating Temperature Range ........................... -40C to +85C CC All Other Pins ........................................... -0.3V to (V + 0.3V) Storage Temperature Range ............................ -65C to +150C CC Input Current, WDI .............................................................20mA Junction Temperature ......................................................+150C Output Current, WDO .........................................................20mA Lead Temperature (soldering, 10s) .................................+300C Continuous Power Dissipation (T = +70C) A 5-Pin SC70 (derate 3.1mW/C above +70C) .............247mW 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 = +2.25V to +5.5V, T = T to T , T = -40C to +85C, unless otherwise noted. Typical values are at T = +25C.) CC A MIN MAX A A (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Operating Voltage Range V T = 0C to +70C 2.25 5.5 V CC A V = 5.5V 10 24 CC Supply Current I WDI unconnected A SUPPLY V = 2.5V 4 12 CC Undervoltage Lockout Threshol UVLO (Note 2) 2.19 V d Watchdog Pulse Period t (Note 3) 140 200 280 ms PP V I = 30A, V = 2.3V 0.8 V OH SOURCE CC CC WDO Output Voltage V V I = 1.2mA, V = 2.1V 0.3 OL SINK CC WDO Output Short-Circuit Current I V = 3.6V (Note 4) 400 A SOURCE CC Watchdog Timeout Period t 1.12 1.60 2.40 s WD WDI Pulse Width t V = 0.4V, V = 0.8 V 50 ns WDI IL IH CC V 0.3 V IL CC WDI Input Voltage (Note 5) V V 0.7 V IH CC WDI = V , time average 120 160 CC WDI Input Current (Note 6) A WDI = 0, time average -20 -15 Note 1: Overtemperature limits are guaranteed by design, production testing performed at +25C only. Note 2: WDO is low when V falls below the undervoltage threshold. When V rises above the undervoltage threshold, WDO goes CC CC high after the watchdog pulse period. Note 3: Watchdog pulse period occurs when the watchdog times out or after V rises above the undervoltage threshold. CC Note 4: The WDO short-circuit current is the maximum pullup current when WDO is driven low. Note 5: WDI is internally serviced within the watchdog period if WDI is left unconnected. Note 6: The WDI input current is specified as the average input current when the WDI input is driven high or low. The WDI input is designed to drive a three-stated output device with a 10A maximum leakage current and a maximum capacitive load of 200pF. This output device must be able to source and sink at least 200A when active. Maxim Integrated 2 www.maximintegrated.com