RS5C348B_95 Просмотр технического описания (PDF) - RICOH Co.,Ltd.

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RS5C348B_95

4-WIRE SERIAL INTERFACE REAL-TIME CLOCK ICS WITH VOLTAGE MONITORING FUNCTION

RICOH Co.,Ltd. 

R×5C348A/B

5. Oscillation Halt Sensing Function and Supply Voltage Monitoring Function

The R×5C348A/B incorporate an oscillation halt sensing circuit equipped with internal registers configured to

record any past oscillation halt, thereby identifying whether they are powered on from 0 volts or battery backed-up.

As such, the oscillation halt sensing circuit is useful for judging the validity of time data.

The R×5C348A/B also incorporate a supply voltage monitoring circuit equipped with internal registers configured

to record any drop in supply voltage below a certain threshold value. Supply voltage monitoring threshold settings

can be selected between 2.1 and 1.6 volts through internal register settings.

The oscillation halt sensing circuit is configured to confirm the established invalidation of time data in contrast to

the supply voltage monitoring circuit intended to confirm the potential invalidation of time data. Further, the supply

voltage monitoring circuit can be applied to battery supply voltage monitoring.

6. Periodic Interrupt Function

The R×5C348A/B incorporate a periodic interrupt circuit configured to generate periodic interrupt signals aside

from interrupt signals generated by the alarm circuit for output from the INTR pin. Periodic interrupt signals have

five selectable frequency settings of 2Hz (once per 0.5 seconds), 1Hz (once per 1 second), 1/60Hz (once per 1

minute), 1/3600Hz (once per 1 hour), and monthly (the first day of every month). Further, periodic interrupt

signals also have two selectable waveforms of a normal pulse form (with a frequency of 2Hz or 1Hz) and special

form adapted to interruption from the CPU in the level mode (with second, minute, hour, and month interrupts).

The register records of periodic interrupt signals can be monitored by using a polling function.

7. 32-kHz Clock Output Function

The R×5C348A/B incorporate a 32-kHz clock circuit configured to generate clock pulses with the oscillation

frequency of a 32.768-kHz crystal oscillator for output from the 32KOUT pin (Nch. open drain output). For the

R×5C348A, the 32-kHz clock output can be disabled by certain register settings. But it cannot be disabled without

manipulation of any two registers with different addresses, to prevent disabling in such events as the runaway of the

CPU. For the R×5C348B, however, the 32-kHz clock circuit cannot be disabled by any register settings. For both

the R×5C348A and the R×5C348B alike, the 32-kHz clock circuit is enabled at power-on.

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