DS1554 Datasheet, PDF (17/21 Pages) Dallas Semiconductor – 256K NV Y2KC Timekeeping RAM

AC TEST CONDITIONS
Output Load:
100 pF + 1TTL Gate
Input Pulse Levels:
0.0 to 3.0 Volts
Timing Measurement Reference Levels:
Input: 1.5V
Output: 1.5V
Input Pulse Rise and Fall Times: 5 ns
DS1554
NOTES:
1. Voltage referenced to ground.
2. Typical values are at 25°C and nominal supplies.
3. Outputs are open.
4. Battery switch over occurs at the lower of either the battery voltage or V_PF.
5. The IRQ /FT and RST outputs are open drain.
6. Data retention time is at 25°C.
7. Each DS1554 has a built-in switch that disconnects the lithium source until V_CC is first applied by the
user. The expected t_DR is defined for DIP modules and PowerCap modules as a cumulative time in
the absence of V_CC starting from the time power is first applied by the user.
8. Real Time Clock 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 +85°C. 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 reflow and use a solder wick to
remove solder.
9. t_AH1, t_DH1 are measured from WE going high.
10. t_AH1, t_DH1 are measured from CE going high.
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