DS1818-10+ Analog Devices

DS1818 3.3V EconoReset with Pushbutton BENEFITS AND FEATURES PIN ASSIGNMENT Improves Reliability of Processor Operation 3 o Temperature-Compensated Voltage DALLAS DS1818 Monitor for Precise, Automated Power- Econo Reset Fail Detection o Automatically Restarts a Microprocessor After Power Failure 1 2 o Maintains Reset for 150ms After V CC TOP VIEW SOT-23 PACKAGE Returns to Tolerance for Processor See Mech. Drawings Section Stabilization On Website 1 2 3 o Monitors Pushbutton for External Override 1 2 3 o Active-Low Reset Output Efficient Open-Drain Output with Internal BOTTOM VIEW TO-92 PACKAGE 5.5k Pullup Resistor Saves Power and Space See Mech. Drawings Section o 35A (max) Quiescent Current On Website Allows for Easy Design with No Complicated Settings PIN DESCRIPTION o Fixed 3.3V Reset Threshold TO-92 o 5%, 10%, and 20% Tolerance Versions 1 RST Active Low Reset Output Available 2 V Power Supply CC Operates in Most Commercial and Industrial 3 GND Ground Environments o -40C to +85C Operating Temperature SOT-23 Range 1 RST Active Low Reset Output MXD1818 Offers Improved Performance over 2 V Power Supply CC the DS1818 3 GND Ground DESCRIPTION The DS1818 EconoReset uses a precision temperature-compensated reference and comparator circuit to monitor the status of the power supply (V ). When an out-of-tolerance condition is detected, an internal CC power-fail signal is generated which forces reset to the active state. When V returns to an in-tolerance CC condition, the reset signal is kept in the active state for approximately 150 ms to allow the power supply and processor to stabilize. The DS1818 also monitors a pushbutton on the reset output. If the reset line is pulled low, a reset is generated upon release and the DS1818 output will be held in reset output low for typically 150 ms. 1 of 5 19-7559 Rev 1 3/15 DS1818 OPERATION - POWER MONITOR The DS1818 provides the functions of detecting out-of-tolerance power supply conditions and warning a processor-based system of impending power failures. When V is detected as out-of-tolerance, the RST CC signal is asserted. On power-up, RST is kept active for approximately 150 ms after the power supply has reached the selected tolerance. This allows the power supply and microprocessor to stabilize before RST is released. BLOCK DIAGRAM (OPEN-DRAIN OUTPUT) Figure 1 APPLICATION EXAMPLE Figure 2 OPERATION - PUSHBUTTON RESET The DS1818 provides a pushbutton switch for manual reset control. When the DS1818 is not in a reset cycle, a pushbutton reset can be generated by pulling the RST pin low for at least 1 s. When the pushbutton is held low, the RST is forced active low and will remain active low for about 150 ms after the pushbutton is released. See Figure 2 for an application example and Figure 3 for the timing diagram. TIMING DIAGRAM: PUSHBUTTON RESET Figure 3 2 of 6