DESCRIPTION OF OPERATIONS
50/60 Hz Input:
Built-in Shumidt circuits enable noise elimination at 50/60Hz commercial
frequencies with use of a simple CR filter. Built-in pull-up resistor.
When the AC power supply is interrupted, the time counter switches to a holding
state and a built-in oscillator promptly begins operation. If 50/60Hz input
continuous for 3 clocks without arriving, this oscillator’s output is activated and
functions as the time counter clock in place of 50/60Hz input. The frequency
level of this clock oscillator is determined according to the CK Value. While the
above mentioned oscillator is operating using backup mode, all segment output
is switched to OFF. (Note) When the backup oscillator is in use due to an AC
power supply interruption, the 50/60Hz input pin must be maintained open or at
a Vss level.
50/60Hz Selective Input
Display Mode Selective Input
(Alarm Select/Sleep Select )
When 50/60 selective input is connected to Vss,50Hz use is enable. When 50/60
selective input is left open, VDD is activated using an internal pull-down resistor
and the setting is switched to enable use at 60Hz.
Since the pull-down resistor is built-in, selection from four display modes is
possible using two SPST switches (single-pole and single-throw switches). Table
l shows these display mode selections.
Time Setting Input
12/24H Select Input
Power Failure Detection
There are two setting inputs for use with “hour” and “minute”. Time content
settings shown in Table 2 are possible by activating Vss to these pins. A pull-
down resister is built-in.
Leaving this pin unconnected (VDD) causes the 12-hour basis to be selected,
connecting this pin to VSS cause the 24-hour basis to be selected .An internal
pull-down resistor is provided.
If the power supply voltage drops and is applied again, all the on-segments flash
and the power failure indication mode is entered. The power failure indication
mode is released by applying VSS to “hour set” or “ minutes set”.
Alarm Operation and Alarm
The alarm signal outputs when alarm content marches the time .When not reset
by either snooze input or alarm off input, output continues after l hour and 59
minutes. This output signal consists of 900 Hz 2 Hz intermittent (50% duty)
modulation signals. When the need arises, a filter can be applied to alter the
alarm signal to a DC signal.
When the alarm is sounding and instantly activating Vss to this pin, alarm output
is set to OFF for a period between 8 and 9 minutes after which time the alarm
signal is once again output .The snooze function can be used repeatedly in l
hour and 59 minutes intervals. A pull-down resist is built-in. Activating Vss to the
snooze pin when the alarm is OFF resets the sleep timer counter to [0:00].(This
is known as the one-touch sleep timer reset function.)
Alarm Off Input
Activating this input pin to Vss instantly sets alarm output to OFF. A pull-down
resistor is built-in.
Sleep output can turn on the radio and can be set for time intervals of 59
minutes or l hour and 59 minutes. Refer to Table 2 for the proper selection
procedure (59 minutes or l hour and 59 minute selection). This sleep timer
constructed using a down counter and when the counter content arrives at
output is set to off and the radio turns off .Adding Vss to snooze input turns sleep
output off, when sleep output is on.
HANGZHOU SILAN MICROELECTRONICS CO.,LTD
REV: 1.1 2008.06.02
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