UPD4991A Datasheet, PDF (10/32 Pages) NEC – 4-BIT PARALLEL I/O CALENDAR CLOCK

µPD4991A
FUNCTION SPECIFICATIONS
• Reference frequency (X’tal OSC) ........... 32.768 kHz
• Data format .............................................. BCD format
• Data function
Year, month, day, date, hour, minute, and second counters
Leap year and months are automatically identified.
Leap year is identified every 4 years and can be set to any year.
Year is set in 2 digits.
Hour can be displayed in 12- or 24-hour mode.
• Data input/output (D3, D2, D1, D0)
4-bit parallel input/output format
Data is written by WE signal and read by OE signal.
• Function mode selection
With ADDRESS = “FH” (A3, A2, A1, A0 = 1, 1, 1, 1), a mode is selected by DATA (D3, D2, D1, D0) input, and set
by input of WE signal.
A function is selected by ADDRESS input.
• Timing pulse outputs (TP1, TP2)
TP1 ... Alarm coincidence signal.
One of the following is selectable:
2048 Hz
1024 Hz
64 Hz
16 Hz
1 Hz
1 pulse output (H → L)
TP2 ... Interval timer signal output.
One of the following is selectable:
60 s
30 s
10 s
1s
0.1 s
• Chip select (CS1, CS2)
When CS1 = “H” or CS2 = “L,” all inputs except XIN are disabled (non-select).
When CS1 = “L” and CS2 = “H,” all inputs are selected.
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