DS1643P-70+

Real Time Clock Overview

The DS1643P-70+ is a nonvolatile static RAM integrated with a real-time clock, crystal, and power-fail control circuit. It features an 8K x 8 byte-wide SRAM architecture where the RTC registers occupy the eight top memory locations. The device operates on a 5.0V supply (4.5V to 5.5V) within a 0°C to +70°C temperature range. It provides access times of 85ns or 100ns and includes BCD-coded timekeeping with leap year compensation valid until 2100. The PowerCap module version allows surface mounting and connects to a separate battery/crystal unit.

Real Time Clock Feature Summary

• Integrated NV SRAM, Real-Time Clock, Crystal, Power-Fail Control Circuit, and Lithium Energy Source
• BCD-Coded Year, Month, Date, Day, Hours, Minutes, and Seconds with Leap Year Compensation Valid Up to 2100
• Power-Fail Write Protection Allows for ±10% VCC Power Supply Tolerance
• DS1643P Only: Surface Mountable PowerCap Module Board for Direct Connection to PowerCap Containing Battery and Crystal

Real Time Clock Applications

• Systems requiring nonvolatile timekeeping RAM with direct replacement capability for standard SRAM sockets
• Applications needing automatic date correction including leap years up to the year 2100
• Embedded systems requiring power-fail write protection to prevent data corruption during voltage drops

Real Time Clock Procurement Notes

Verify that the required PowerCap component (DS9034PCX or DS9034I-PCX+) is ordered separately, as it is not included with the DS1643P-70+. Confirm the specific access time requirement (85ns vs 100ns) matches the system timing constraints before procurement.

Real Time Clock Selection Notes

Select the DS1643P variant when surface mount assembly is required, ensuring compatibility with the separate PowerCap module. Choose between 85ns and 100ns access speeds based on the host microcontroller's timing requirements. Ensure the application environment stays within the 0°C to +70°C operating temperature range.

Real Time Clock Part Context

The DS1643P is part of the DS164x family of nonvolatile timekeeping RAMs. It is functionally equivalent to JEDEC standard 8K x 8 SRAM but adds real-time clock functionality in the upper memory addresses. The 'P' suffix denotes the PowerCap module package, which differs from the standard DIP module by allowing the battery and crystal to be mounted after soldering.

Real Time Clock Replacement Considerations

Pin-for-pin compatible with other densities of DS164XP Timekeeping RAM.