DS1682_13 Datasheet, PDF (4/14 Pages) Dallas Semiconductor – Total-Elapsed-Time Recorder with Alarm

DS1682 Total-Elapsed-Time Recorder with Alarm
The V_CC holding capacitor value of 30μF is calculated using the maximum EEPROM write current and
EEPROM write time. This assumes that the V_CC slew rate allows time from EVENT trip point to V_CC at
2.5V on the DS1682 is at least t_EW.
Figure 4 shows the DS1682 in a total time-of-use application with power that can be removed at the same
time as the end of the event. In this application, the V_CC slew rate at power-down is slow with respect to
t_EW. The external RST IC ends the event as V_CC begins to drop. V_CC must remain above 2.5V until the
end of t_EW.
Figure 3. Total Time-of-Use Application with Fast V_CC Slew Rate
Figure 4. Total Time-of-Use Application with Slow V_CC Slew Rate
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