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DS12C887

Name: DS12C887
Rating: 4.7 (12 reviews)

IC RTC CLK/CALENDAR PAR 24EDIP

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規格

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

概述

Description

DS12C887 is a CMOS Real-Time Clock/Calendar with nonvolatile RAM from Dallas Semiconductor (Maxim). It provides continuous timekeeping and data storage for PCs and embedded systems.
Key features:
- Real-time clock/calendar: seconds, minutes, hours, day of week, date, month, year (with optional century bit)
- Alarm and programmable periodic interrupt outputs
- 64 bytes of nonvolatile RAM for user data/configuration
- Battery-backed operation to keep time and NVRAM during power loss
- PC-compatible parallel-access interface (address/data bus with control signals), usable as a drop-in replacement for RTC/NVRAM in BIOS/ISA-era designs and many embedded applications
- Typical supply: 4.5–5.5V
Use cases:
- BIOS/system timekeeping
- Event counters and scheduled interrupts
- Small data logging or configuration storage in power-fied environments
Note: implementation details (bus protocol, register map) are designed to resemble other Dallas/Maxim RTCs (e.g., DS1287) for easy migration.

Features

DS12C887 Features (concise)
- Real-time clock/calendar with 32.768 kHz crystal input; 12/24-hour mode; BCD time/date data with leap-year support.
- 56 bytes of nonvolatile RAM (NV RAM) battery-backed for user data.
- Two programmable alarms with multiple matching modes.
- Interrupt outputs for alarms and RTC updates; configurable IRQ/SQW outputs.
- Programmable square-wave output with selectable frequencies.
- Trickle-charge input to maintain backup power (battery or capacitor) during power loss.
- Power-fail detect and automatic switchover to backup supply.
- DC supply compatible with common logic levels; suitable for microcontroller interfaces.
- Wide feature set suitable for PC/embedded RTC and data logging tasks.

Package

DS12C887 uses a 28‑pin package, available in DIP‑28 and PLCC‑28 variants.

Pinout

- Pin count: 28-pin package (DIP/SOIC)
- Function: Real-Time Clock/Calendar with non-volatile RAM. Provides timekeeping (seconds, minutes, hours, day, date, month, year, century), alarms, timer, and battery-backed RAM, commonly interfaced to system timekeeping hardware (PC RTC style).

Manufacturer

Dallas Semiconductor Corporation. It was an American semiconductor company that designed and manufactured integrated circuits (including real-time clocks, memory, and microcontrollers). It was acquired by Maxim Integrated (and is now part of Analog Devices).

Application

DS12C887 is a CMOS real-time clock/calendar with 56 bytes RAM and alarm/interrupts, battery-backed for timekeeping during power loss. Applications:
- PC motherboard BIOS timekeeping
- Embedded systems needing calendar, alarms, and periodic interrupts
- Data logging and event timestamping
- Industrial automation and process control
- Consumer electronics and appliances
- Telecommunications equipment
- Any low-power RTC needs.

Equivalent

Common equivalents to DS12C887:
- DS1287 (and DS12887) – Dallas/Maxim RTC with NVRAM
- DS12C887A – updated revision of the DS12C887
Alternative RTC+RAM families (functional substitutes):
- ST M48T02, M48T08 (timekeeper RAM)
Note: exact pinout/interfaces vary; verify compatibility for your design.