DS17285 Datasheet, PDF (34/38 Pages) Dallas Semiconductor – 3V/5V Real-Time Clock

BURST MODE TIMING WAVEFORM
DS17285/DS17287
NOTES:
1) Typical values are at +25°C and nominal supplies.
2) Outputs are open.
3) Write-protection trip point occurs during power-fail prior to switchover from V_CC to V_BAT.
4) Applies to the AD0 to AD7 pins, and the SQW pin when each is in a high-impedance state.
5) The IRQ and PWR pins are open-drain.
6) Measured with a load of 50pF + 1 TTL gate.
7) Wake-up kickstart timeout generated only when the oscillator is enabled and the countdown chain is
not reset.
8) V_SW is determined by the larger of V_BAT and V_BAUX.
9) The DS17287 keeps time to an accuracy of ±1 minute per month during data retention time for the
period of t_DR.
10) t_DR is the amount of time that the internal battery can power the internal oscillator and internal
registers of the DS17287.
11) I_BAT1 and I_BAT2 are measured at V_BAT = 3.5V, with a 32.768kHz crystal attached to X1 and X2
(DS17285).
12) RTC modules 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.
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