DS1251WP-120+

Real Time Clock, Non-Volatile, 0 Timer(s), CMOS

DS1251WP-120+ – Phantom Time Chip with NVSRAM – Analog Devices

Ensure continuous, accurate timekeeping and critical data retention in your embedded systems with the DS1251WP-120+ from Analog Devices (Maxim Integrated). This integrated Real Time Clock (RTC) combines a high-precision clock calendar with a robust 512KB Non-Volatile SRAM (NVSRAM), providing reliable operation and zero data loss during power interruptions. PCX is your trusted source for this specialized component, backed by our commitment to quality and fast delivery.

Key Features

Type: Phantom Time Chip with Integrated NVSRAM
Memory Size: 512KB Non-Volatile SRAM
Time Format: HH:MM:SS:hh (12/24 hour selectable)
Date Format: YY-MM-DD-dd (Day of week included)
Interface: Parallel
Supply Voltage: 2.97V to 3.63V
Battery Voltage: 3V
Max Timekeeping Current: 7mA @ 3.3V
Operating Temperature: 0°C to 70°C
Features: Automatic Leap Year Compensation
Mounting: Surface Mount
Package: 34-PowerCap™ Module

Technical Details
The DS1251WP-120+ integrates a sophisticated real-time clock/calendar with a large 512KB static RAM array featuring non-volatile storage. Utilizing Analog Devices’ “Phantom Clock” technology, the RTC continuously monitors the main VCC supply. Should VCC fall out of tolerance, the device instantaneously and transparently switches to the backup battery supply, ensuring uninterrupted timekeeping and preserving the entire SRAM contents. The parallel interface facilitates straightforward integration into various system designs. This device is supplied in a robust 34-PowerCap Module package, designed for reliable surface mount assembly.

Common Applications

Industrial Automation and Control Systems
Medical Monitoring and Diagnostic Equipment
Point-of-Sale (POS) Terminals and Kiosks
Data Loggers and Instrumentation
Telecommunications Infrastructure

About Analog Devices / Maxim Integrated
Analog Devices Inc. (ADI), including its acquired subsidiary Maxim Integrated, is a global leader in high-performance semiconductor solutions. The company is renowned for its innovation in analog, mixed-signal, and power management technologies. ADI consistently sets industry benchmarks for precision, reliability, and efficiency across a vast portfolio of components.
Their commitment to rigorous quality control and deep technical expertise makes Analog Devices / Maxim Integrated a preferred partner for engineers designing mission-critical systems in demanding sectors like industrial, automotive, healthcare, and communications. Choosing an ADI component signifies choosing proven performance and long-term dependability.

About Real Time Clocks (RTCs) with NVSRAM
Real Time Clocks are essential integrated circuits that provide accurate time and date information to electronic systems, even when main power is absent, by utilizing a backup battery. This functionality is crucial for applications requiring event timestamping, scheduled operations, or maintaining chronological data integrity.
Integrating NVSRAM with the RTC, as seen in the DS1251WP-120+, offers a significant advantage. NVSRAM combines the speed and ease of use of standard SRAM with the non-volatility of EEPROM or Flash. Crucially, it provides zero write-time delay during a power failure, ensuring critical data is never lost unexpectedly. This makes RTC/NVSRAM combos ideal for systems where preserving configuration settings, calibration data, or transaction logs during power loss is absolutely essential.

Packaging
This DS1251WP-120+ Real Time Clock IC is supplied in Tube packaging, suitable for automated manufacturing processes.
Note: Product image is representational. Refer to the datasheet for exact dimensions and pinout.

Frequently Asked Questions (FAQs)
Question: Is the DS1251WP-120+ obsolete? What does that mean for availability?
Answer: Yes, Analog Devices has classified the DS1251WP-120+ as obsolete (End-of-Life). However, PCX specializes in sourcing and supplying such critical components. We maintain reliable stock levels to support your ongoing production and maintenance needs.

Question: How does the battery backup work on this Phantom Time Chip?
Answer: The device continuously monitors the VCC supply. If VCC drops below a specified threshold, it automatically and seamlessly switches to the connected 3V backup battery, ensuring the real-time clock continues running and the contents of the 512KB NVSRAM are preserved without any data loss or system intervention.

Question: What is the purpose of the NVSRAM in this RTC?
Answer: The integrated 512KB NVSRAM provides fast, read/write memory that retains its data during power loss, thanks to the battery backup. It’s used to store critical system data (like configuration, logs, or calibration constants) that must be preserved immediately and reliably when main power fails.

Question: Can I interface this RTC with a microcontroller?
Answer: Yes. The DS1251WP-120+ uses a parallel interface, which is compatible with many microcontrollers. You will need to implement the appropriate control signals (Chip Enable, Output Enable, Write Enable) and data bus connections as detailed in the datasheet.

Question: What is the operating temperature range?
Answer: The DS1251WP-120+ is specified for operation from 0°C to 70°C, making it suitable for standard commercial and industrial environments.

Question: Why should I source this obsolete RTC from PCX?