RV5C339A Datasheet, PDF (39/51 Pages) RICOH electronics devices division – 3-WIRE SERIAL INTERFACE REAL-TIME CLOCK ICs WITH VOLTAGE MONITORING FUNCTION

RV5C339A
4.2 Periodic Interrupt
Setting of the periodic selection bits (CT2 to CT0) enables periodic interrupt from the INTRA pin to the CPU. There
are two waveform modes: pulse mode and level mode. In the pulse mode, the output has a waveform duty cycle of
around 50%. In the level mode, the output is cyclically driven low and, when the CTFG bit is set to 0, the output is set
to high (OFF).
Waveform Mode, Cycle and Falling Timing
CT2 CT1 CT0
Waveform mode
Description
Cycle and falling timing
0
0
0
—
Off (“H”)
(Default setting)
0
0
1
—
Fixed at low (“L”)
0
1
0 Pulse Mode*¹ 2Hz (Duty cycle of 50%)
0
1
1 Pulse Mode*¹ 1Hz (Duty cycle of 50%)
1
0
0 Level Mode*² Once per 1 second (Synchronized with second counter increment)
1
0
1 Level Mode*² Once per minute (at 00 seconds of every minute)
1
1
0 Level Mode*² Once per hour (at 00 minutes and 00 seconds of every hour)
1
1
1 Level Mode*² Once per month (at 00 hours, 00 minutes, and 00 seconds of first day of every month)
1) Pulse Mode : 2-Hz and 1-Hz clock pulses are output in synchronization with the increment of the second counter
as illustrated in the timing chart on the next page.
2) Level Mode : periodic interrupt signals are output with selectable interrupt cycle settings of 1 second, 1 minute, 1
hour, and 1 month. The increment of the second counter is synchronized with the falling edge of
periodic interrupt signals. For example, periodic interrupt signals with an interrupt cycle setting of
1 second are output in synchronization with the increment of the second counter as illustrated in
the timing chart on the next page.
3) When the oscillation adjustment circuit is used, the interrupt cycle will fluctuate once per 20 seconds as follows:
Pulse Mode : the “L” period of output pulses will increment or decrement by a maximum of ±3.784ms.
For example, 1-Hz clock pulses will have a duty cycle of 50 ±0.3784%.
Level Mode : a periodic interrupt cycle of 1 second will increment or decrement by a maximum of ±3.784ms.
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