Datasheet

PCA8565 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 4 — 5 December 2014 20 of 48
NXP Semiconductors
PCA8565
Real time clock/calendar
8.11 STOP bit function
The function of the STOP bit is to allow for accurate starting of the time circuits. The STOP
bit function will cause the upper part of the prescaler (F
2
to F
14
) to be held in reset and
thus no 1 Hz ticks will be generated (see Figure 10
). The time circuits can then be set and
will not increment until the STOP bit is released (see Figure 11
and Table 30).
The STOP bit function will not affect the output of 32.768 kHz but will stop 1.024 kHz,
32 Hz and 1 Hz.
The lower two stages of the prescaler (F
0
and F
1
) are not reset and because the I
2
C-bus
is asynchronous to the crystal oscillator, the accuracy of re-starting the time circuits will be
between zero and one 8.192 kHz cycle (see Figure 11
).
Fig 10. STOP bit functional diagram
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Fig 11. STOP bit release timing
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