DS1644-120 Nonvolatile Timekeeping RAM 32KB DIP-28 Package

The DS1644-120 is a 32K x 8 nonvolatile static RAM integrated with a full-function real-time clock (RTC), accessible in a byte-wide format. This device functions as a standard 32K x 8 SRAM but with the added benefit of nonvolatile data retention and timekeeping capabilities. The RTC maintains timekeeping information, including year, month, date, day, hours, minutes, and seconds, all in 24-hour BCD format, with automatic corrections for day of the month and leap years up to the year 2100. The DS1644-120 features an automatic power-fail detection and switch circuitry, ensuring data integrity during power disruptions by seamlessly switching to the internal lithium energy source. This design provides over 10 years of data retention without external power. The device is housed in a 28-pin encapsulated DIP package, integrating the crystal, lithium energy source, and silicon, simplifying board design and reducing component count. Its standard JEDEC bytewide 32K x 8 static RAM pinout allows for easy substitution in existing designs requiring nonvolatile memory with real-time clock functionality.​

Key Features:

• Integrated NV SRAM and RTC: Combines 32KB nonvolatile static RAM with a full-function real-time clock.​
• Automatic Data Protection: Ensures data integrity during power failures with built-in lithium energy source.​
• BCD-Coded Timekeeping: Tracks year, month, date, day, hours, minutes, and seconds with leap year compensation valid up to 2100.​
• Standard JEDEC Pinout: Compatible with standard 32k x 8 static RAM pin configurations for easy integration.​
• Power-Fail Protection: Provides ±10% VCC power supply tolerance with power-fail write protection.​
• Long-Term Data Retention: Offers over 10 years of data retention in the absence of power.​

Additional Specifications:

• Memory Type: Nonvolatile Static RAM (NV SRAM) with integrated Real-Time Clock (RTC).
• Interface Type: Parallel interface.
• Supply Voltage: 4.5V to 5.5V
• Memory Size: 32KB