DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
AC TEST CONDITIONS
Output Load: 50pF + 1TTL Gate
Input Pulse Levels: 0 to 3.0V
Timing Measurement Reference Levels:
Input: 1.5V
Output: 1.5V
Input Pulse Rise and Fall Times: 5ns
NOTES:
1) Voltages are referenced to ground.
2) Typical values are at +25LC and nominal supplies.
3) Outputs are open.
4) Battery switchover occurs at the lower of either the battery terminal voltage or VPF
.
5) Data-retention time is at +25LC.
6) Each DS1744 has a built-in switch that disconnects the lithium source until the user first applies VCC.
The expected tDR is defined for DIP modules and assembled PowerCap modules as a cumulative time
in the absence of VCC starting from the time power is first applied by the user.
7) RTC modules (DIP) can be successfully processed through conventional wave-soldering techniques as
long as temperature exposure to the lithium energy source contained within does not exceed +85LC.
Post-solder cleaning with water-washing techniques is acceptable, provided that ultrasonic vibration is
not used.
In addition, for the PowerCap:
a.) Dallas Semiconductor recommends that PowerCap module bases experience one pass through
solder reflow oriented with the label side up (“live-bug”).
b.) Hand soldering and touch-up: Do not touch or apply the soldering iron to leads for more than
3 seconds. To solder, apply flux to the pad, heat the lead frame pad, and apply solder. To
remove the part, apply flux, heat the lead frame pad until the solder reflows, and use a solder
wick to remove solder.
8) tAH1, tDH1 are measured from WE going high.
9) tAH2, tDH2 are measured from CE going high.
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