DS12C887+

DS12C887+ is an enhanced CMOS real‑time clock with battery‑backed RAM and a simple two‑wire serial interface. It keeps accurate time even when main power is off by using a backup supply (battery or supercapacitor).
Key features (high level):
- Timekeeping registers: seconds, minutes, hours, day, date, month, year; supports 24/12‑hour formats and leap-year correction.
- Alarm and periodic interrupt outputs to wake up or generate timing events.
- Battery-backed RAM for non-volatile data storage and system configuration accessible over the same interface.
- Two-wire serial interface (SDA/SCL) for easy MCU integration; addressable registers.
- Trickle-charge option to maintain backup source via external components; square-wave output for timing reference.
Typical uses: PC/BIOS clock, embedded controllers, data logging systems, and any application needing reliable timekeeping with power-down retention and wake-up capability.
In short: a compact, low‑power RTC/NVRAM device with easy interface and battery backup, suitable as an enhanced successor to DS12C887‑based designs.

Common equivalents for DS12C887+ are PC-compatible RTCs with NVRAM, notably:
- DS1287 and DS1287A (Dallas/Maxim)
- DS12887
- MC146818A (Intel)
These are the standard drop-in replacements/pin-compatible alternatives in the PC RTC family. Availability may vary by supplier.

DS12C887+ features (concise):
- Real-time clock/calendar: tracks seconds, minutes, hours, day, date, month, year with leap-year correction; supports 12/24-hour formats.
- Battery-backed non-volatile RAM: preserves CMOS/BIOS data during power loss.
- Alarm function and watchdog/timer: programmable interrupt outputs for system events.
- Programmable square-wave output: selectable frequencies for peripheral timing.
- 32.768 kHz crystal oscillator input: precise time base.
- Power-fail detection: automatic switchover to backup supply to keep time intact.
- Parallel 8-bit interface: data/address bus compatible with standard CMOS RAM/RTC chips, with dedicated control lines.
- Low quiescent current in battery mode: optimized for extended battery life.

- Pin count: 28 pins (DIP/SOIC).
- Function: CMOS Real-Time Clock/Calendar with battery-backed non-volatile RAM (NVRAM), used to keep time/date and store BIOS/RTC data; includes timekeeping registers, alarm, and related I/O features, typically driven by a 32.768 kHz crystal.

- Manufacturer: Dallas Semiconductor (often abbreviated DS).
- What kind of company: A semiconductor company that designs and manufactures integrated circuits (memory, real-time clocks, analog/mixed-signal ICs). It was later acquired by Maxim Integrated, which is now part of Analog Devices.

Applications include:
- Embedded systems needing a battery-backed real-time clock/calendar with RAM
- Data recorders and environmental/industrial monitoring for time-stamped logs
- Industrial automation and PLCs for scheduling, alarms and time-based control
- Point-of-Sale, vending machines, and kiosks for timing/transaction stamping
- Computer peripherals and legacy systems requiring hardware timekeeping
- Medical devices for event logging and alarm timing
- Telecom/network gear for clocking and timed events
- Automotive electronics for timers, diagnostics and fault-time stamping

DS12C887+ uses a 28-pin package, typically offered in DIP-28 or SOIC-28 variants.