Intel E3815 FH8065301567411 Data Sheet

Intel

®

 Atom™ Processor E3800 Product Family

4544

Datasheet

The Real Time Clock (RTC) module provides a battery backed-up date and time keeping 
device. Three interrupt features are available: time of day alarm with once a second to 
once a month range, periodic rates of 122 us to 500 ms, and end of update cycle 
notification. Seconds, minutes, hours, days, day of week, month, and year are counted. 

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Crystal Input 1: This signal is connected to the 32.768 
kHz crystal. If no external crystal is used, the signal can 
be driven with the desired clock rate.

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Crystal Input 2: This signal is connected to the 32.768 
kHz crystal. If no external crystal is used, the signal 
should be left floating.

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RTC Reset: An external RC circuit creates a time delay for 
the signal such that it will go high (de-assert) sometime 
after the battery voltage is valid. The RC time delay should 
be in the 10-20 ms range. Contact your Intel 
representative for details.
When asserted, this signal resets all register bits in the 
RTC well except for GEN_PMCON1.RPS.
NOTE: Unless registers are being cleared (only to be done 

in the G3 power state), the signal input must 
always be high when all other RTC power planes 
are on.

NOTE: In the case where the RTC battery is dead or 

missing on the platform, the signal should be 
deasserted before the PMC_RSMRST# signal is 
deasserted.

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RTC Battery Test: An external RC circuit creates a time 
delay for the signal such that it will go high (de-assert) 
sometime after the battery voltage is valid. The RC time 
delay should be in the 10-20 ms range. Contact your Intel 
representative for details. If the battery is missing/weak, 
this signal appears low (asserted) at boot just after the 
suspend power rail (V3P3A) is up since it will not have 
time to meet Vih when V3P3A is high. The weak/missing 
battery condition is reported in the GEN_PMCON1.RPS 
(RTC Power Status) register. When asserted, BIOS may 
clear the RTC CMOS RAM.
NOTE: Unless CMOS is being cleared (only to be done in 

the G3 power state) or the battery is low, the 
signal input must always be high when all other 
RTC power planes are on.

NOTE: This signal may also be used for debug purposes, 

as part of a XDP port. Contact your Intel 
representative for details.

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