UPD4991A is an integrated circuit (IC) designed by NEC Electronics Corporation. It serves as a 4-bit parallel I/O (Input/Output) calendar clock, commonly used in various electronic devices requiring timekeeping functionality
Part Number: UPD4991ACX, UPD4991AGS
Function: 4-BIT PARALLEL I/O CALENDAR CLOCK
Package: DIP 18 Pin or SOP 20 Pin Type
Manufacturers: NEC
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Description
The µPD4991A is a CMOS integrated circuit that has the ability to input/output 4-bit parallel time data and calendar data to/from a microcomputer and includes an alarm function.
Its reference oscillation frequency is 32.768 kHz. Hour, minute, second, year, month, day, and date data is stored internally.
The IC features a 4-bit parallel input/output interface, enabling communication with external devices or microcontrollers. This interface allows users to read and write data to the calendar clock registers.
Features
• Time (hour, minute, and second) and calendar (leap year, year, month, day, and date) counters
• Leap year can be automatically identified or set
• 12- and 24-hour modes selectable
• 4-bit parallel input/output in BCD data format
• Alarm function (hour, minute, second, month, day, date)
• One of 0.1, 1.0, 10, 30, and 60-s interval timer outputs selectable
• One of 2048, 1024, 64, 16, 1 Hz, 1-pulse output, and H→L output selectable as alarm coincidence output
• Upward compatible with µPD4991
• Low power consumption: 2 µA typ. (VDD = 2.4 V)
Pinouts
Applications
1. Digital clocks, watches, electronic organizers
2. Other devices requiring timekeeping and calendar functions.
UPD4991A Technical Datasheet (PDF)
