DS1747 Datasheet, PDF (14/18 Pages) Dallas Semiconductor – Y2K-Compliant, Nonvolatile Timekeeping RAMs

DS1747/DS1747P Y2K-Compliant, Nonvolatile Timekeeping RAMs
AC TEST CONDITIONS
Output Load: 50 pF + 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: 5 ns
NOTES:
1) Voltages are referenced to ground.
2) Typical values are at +25°C 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 +25°C.
6) Each DS1747 has a built-in switch that disconnects the lithium source until the user first applies V_CC.
The expected tDR is defined for DIP modules and assembled PowerCap modules as accumulative time
in the absence of V_CC 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 temperatures as long as temperature exposure to the lithium energy source contained
within does not exceed +85°C. Post-solder cleaning with water-washing techniques is acceptable,
provided that ultra-sonic 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) t_AH1, t_DH1 are measured from WE going high.
9) t_AH2, t_DH2 are measured from CE going high.
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