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DS12C887

Name: DS12C887
Rating: 4.7 (12 reviews)

IC RTC CLK/CALENDAR PAR 24EDIP

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Mfr。パート #DS12C887
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仕様

Part Status	Obsolete
DigiKey Programmable	Not Verified
Type	Clock/Calendar
Features	Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output
Memory Size	113B
Time Format	HH:MM:SS (12/24 hr)
Date Format	YY-MM-DD-dd
Interface	Parallel
Voltage - Supply	4.5V ~ 5.5V
Voltage - Supply, Battery	2.5V ~ 4V
Current - Timekeeping (Max)	15mA @ 4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C
Mounting Type	Through Hole
Package / Case	24-DIP Module (0.600", 15.24mm)
Supplier Device Package	24-EDIP
Base Product Number	DS12C887

概要

Description

The DS12C887 is a Dallas Semiconductor (now Maxim) CMOS Real-Time Clock/Calendar with non-volatile RAM (NVRAM). It provides timekeeping and calendar functions (seconds, minutes, hours, day, date, month, year with leap-year handling, 12/24-hour modes) and runs from a 32.768 kHz crystal. It is battery-backed, so it keeps time during power loss. It also offers a programmable square-wave output and interrupt/alarm features, plus user NVRAM for data storage. The device is accessed via a simple register-based bus (read/write to RTC and NVRAM registers) and is commonly used as a PC-compatible RTC replacement in embedded systems.

Features

Key features of DS12C887 (Dallas/Maxim Serial RTC with NV RAM):
- Real-time clock/calendar: seconds, minutes, hours, day, date, month, year; 12/24-hour mode; leap-year aware; year 00–99 with century support.
- Time data in user-friendly format (BCD is typical).
- 32.768 kHz crystal input for accurate timekeeping.
- Battery backup with VBAT to maintain time when VCC is off; includes trickle-charge option for backup source.
- 56 bytes of NV RAM accessible via the same serial interface for user data storage.
- I2C-like two-wire serial interface with addressable registers.
- Alarm functionality and interrupt outputs for events/timers.
- Square-wave/ periodic interrupt output with selectable frequency.
- Low-power CMOS operation; wide supply range (typically 3V–5.5V).
- Available in DIP8/SOIC packages for easy integration.
Note: Always verify exact register map and voltage ranges in the specific datasheet for your device revision.

Package

DS12C887 is a 28-pin RTC. It’s available in DIP-28, SOIC-28, and PLCC-28 package options.

Pinout

- Pin count: 28-pin package (DIP/SOIC).
- Function: Real-Time Clock/Calendar with CMOS RAM (RTC plus nonvolatile RAM), including alarm and periodic interrupt capability; used as the PC BIOS clock with a multiplexed address/data bus and battery backup.

Manufacturer

- Manufacturer: Dallas Semiconductor (Dallas Semiconductor Corp.).
- About the company: A semiconductor company that designed and produced integrated circuits (ICs), memory, and timing devices. It was acquired by Maxim Integrated in 2001, and Maxim is now part of Analog Devices.

Application

Typical application areas of DS12C887:
- PC motherboards/BIOS timekeeping (battery-backed RTC)
- Embedded systems needing accurate real-time clocks (industrial controllers, data loggers, POS terminals)
- Consumer electronics requiring time stamping (digital cameras, set-top boxes, appliances)
- Networking/communication gear for timestamping and scheduled tasks
- Automotive and portable devices needing a reliable, low-power RTC

Equivalent

Direct equivalents (drop-in): Dallas/Maxim DS1287 and DS12887, RTCs with NV RAM and pin-compatible with DS12C887 in many PC designs. Other vendors offer similar RTC+RAM devices (not pin-compatible): Intersil ISL1208/ISL1209 and Microchip MCP7940N/MCP7941.