DS17885 datasheet(34/38 Pages) DALLAS

34 / 38 page

DS17885/DS17887

34 of 38

BURST MODE TIMING WAVEFORM

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 VCC to VBAT.

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) VSW is determined by the larger of VBAT and VBAUX.

9) The DS17887 keeps time to an accuracy of ±1 minute per month during data retention time for the

period of tDR.

10) tDR is the amount of time that the internal battery can power the internal oscillator and internal

registers of the DS17887.

11) IBAT1 and IBAT2 are measured at VBAT = 3.5V.

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.

DS17885 Datenblatt(PDF) 34 Page - Dallas Semiconductor