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DS1813 5V EconoReset with Pushbutton www.maxim-ic.com GENERAL DESCRIPTION PIN CONFIGURATIONS The DS1813 EconoReset uses a precision temperature reference and comparator circuit to 3 DALLAS DS1813 monitor the status of the power supply (V ). CC Econo Reset When an out-of-tolerance condition is detected, an internal power-fail signal is generated which forces reset to the active state. When V returns CC 12 to an in-tolerance condition, the reset signal is TOP VIEW SOT-23 PACKAGE kept in the active state for approximately 150ms See Mech. to allow the power supply and processor to Drawings Section On Website 1 2 3 stabilize. 1 2 3 The DS1813 also monitors a pushbutton on the reset output. If the reset line is pulled low, a reset BOTTOM VIEW is generated upon release and will be held in reset TO-92 PACKAGE See Mech. output low for typically 150ms. Drawings Section On Website FEATURES Automatically Restarts a Microprocessor After Power Failure PIN DESCRIPTION Monitors Pushbutton for External Override PIN NAME FUNCTION Maintains Reset for Typically 150ms After TO-92 SOT-23 V Returns to an In-Tolerance Condition CC Active-Low 1 1 RST Reduces Need for Discrete Components Reset Output Precision Temperature-Compensated Voltage 2 2 V Power Supply CC Reference and Voltage Sensor Low-Cost TO-92 or Space-Saving Surface- 3 3 GND Ground Mount SOT-23 Packages Available Efficient Open-Drain Output with Internal 5.5k Pullup Resistor -40C to +85C Operating Temperature 1 of 5 REV: 022306 DS1813 OPERATIONPOWER MONITOR The DS1813 provides the functions of detecting out-of-tolerance power-supply conditions and warning a processor-based system of impending power failure. When V is detected as out-of-tolerance, the RST CC signal is asserted. On power-up, RST is kept active for approximately 150ms after the power supply has reached the selected tolerance. This allows the power supply and microprocessor to stabilize before RST is released. OPERATIONPUSHBUTTON RESET The DS1813 provides for a pushbutton switch for manual reset control. When the DS1813 is not in a reset cycle, a pushbutton reset can be generated by pulling the RST pin low for at least 1s. When the pushbutton is held low, the RST is forced active low and will remain active low for about 150ms after the pushbutton is released. See Figure 2 for an application example and Figure 3 for the timing diagram. Figure 1. Block Diagram (Open-Drain Output) Figure 2. Application Example 2 of 5
