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LC85632
Oscillator Circuit
A 4800 Hz oscillator can be constructed by connecting a resistor and a capacitor to the CR OSC pin (pin 19). This
oscillator is used as the internal clock for detecting the loss of external power, for alarm tones, and for the dimmer duty
cycle. Therefore, it operates continuously during normal operation. In this section, we describe the operation when the
AC input to the 50/60 Hz INPUT pin falls below 1 Hz.
During a power outage, LED segment output from pins 1 to 16 is stopped. Also when power is restored and the AC input
becomes over 1 Hz, the whole LED display (except for the alarm indicator) flashes. The period of this flashing is 1 Hz.
This period is created by dividing the period of the AC input from the 50/60 Hz either by 50 when the clock is operated
at 50 Hz, i.e., when either a low or high level is applied to the MODE SELECT pin, or by 60 when the clock is operated
at 60 Hz, i.e., when the MODE SELECT pin is left open. Apply either a high level or a low level to the TIME SET
INPUT pin to stop the flashing. In either case the flashing will stop and the chip will return to normal operation, i.e.,
current time display.
Tie the CR OSC pin high if the oscillator circuit is not used. In this case the IC will not detect power loss. Also, the
alarm function will not operate correctly, but will output either no signal or an irregular signal. Furthermore, no segment
signals will be output in dimmer mode.
Note that if an oscillator circuit is not used, the high level applied to the CR OSC pin must be applied before power is
applied. If the oscillator is forcibly stopped by applying a high level in the state where the CR oscillator is operating after
power has been applied the alarm DC output may operate incorrectly.
Dual Alarms
This IC provides two 24-hour alarms systems, each of which can be set in 1 minute increments. Alarm A outputs a
2400 Hz alarm tone, and alarm B a 1200 Hz tone. (See the "Alarm" section for details on the alarm waveforms.) The
alarm tones are output continuously for 59 minutes, but can be interrupted for 6 to 7 minutes by the snooze function.
Calendar
This IC includes an on-chip full-year month and day display calendar function. The display can be switched to be either
a month/day or a day/month format. The calendar function can be set to display leap year's day (February 29) on what
would have been March 1 by applying a low level to the TIME SET INPUT pin.
Sleep Function
This IC includes a 90 minute sleep circuit (off timer) that can be set easily. The sleep function time setting can be set to
be 90, 60 , 45, 30, or 15 minutes in an "easy set" format.
No. 4659-13/34
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