DS1817R-20+T&R Analog Devices

DS1817 Active High 3.3V EconoReset www.maxim-ic.com FEATURES PIN ASSIGNMENT Automatically restarts a microprocessor after 3 power failure DALLAS DS1817 Maintains reset for 150 ms after V returns CC Econo Reset to an in-tolerance condition Reduces need for discrete components Precision temperature-compensated voltage 12 reference and voltage sensor TOP VIEW SOT-23 PACKAGE Accurate 5%, 10% or 20% power monitoring See Mech. Drawings Section 20% tolerance for use with 3.0-volt systems On Website 1 2 3 Low-cost TO-92 or space saving surface mount SOT-23 packages available 1 2 3 Push-pull active high output Operating temperature -40C to +85C BOTTOM VIEW TO-92 PACKAGE See Mech. Drawings Section On Website PIN DESCRIPTION TO-92 1 RST Active High Reset Output 2 V Power Supply CC 3 GND Ground SOT-23 1 RST Active High Reset Output 2 V Power Supply CC 3 GND Ground DESCRIPTION The DS1817 EconoReset uses a precision temperature reference and comparator circuit to monitor the status of the power supply (V ). When an out-of-tolerance condition is detected, an internal power-fail CC signal is generated which forces reset to the active state. When V returns to an in-tolerance condition, CC the reset signal is kept in the active state for approximately 150 ms to allow the power supply and processor to stabilize. 1 of 5 041002DS1817 OPERATION - POWER MONITOR The DS1817 provides the function 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 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 (CMOS OUTPUT) Figure 1 APPLICATION EXAMPLE Figure 2 2 of 5