DS1251YP-70

Overview

The DS1251YP-70+ is a nonvolatile SRAM integrated with a phantom clock real-time calendar, housed in a 34-pin PowerCap module. It provides 512K x 8 bits of memory and operates on a 5V supply within the commercial temperature range of 0°C to +70°C. The device features parallel interface access with a 70ns cycle time. An embedded lithium cell maintains data retention for over 10 years when VCC is absent. The phantom clock tracks time using a serial bit stream pattern recognition method, supporting both 12-hour and 24-hour formats.

Feature Summary

• Integrated 512K x 8 NV SRAM with automatic leap year compensation valid through 2100
• Phantom clock uses transparent serial bit stream (64-bit pattern) for timekeeping without dedicated pins
• 34-pin PowerCap Module board allows surface mount assembly before attaching the replaceable battery cap
• Automatic write protection and power-fail detection prevent data corruption during voltage transitions

Applications

• Industrial control systems requiring persistent time-stamping and data logging
• Telecommunications equipment needing reliable backup memory and calendar functions
• Embedded controllers replacing volatile RAM or EEPROM with integrated timing capabilities

Procurement Notes

Verify that the specific suffix 'IND' is not required if operation below 0°C is needed, as the base model covers 0°C to +70°C. Confirm the separate ordering of the DS9034PCX+ PowerCap module, which contains the necessary crystal and lithium battery. Ensure the design accommodates the surface-mount footprint for the 34-pin module base prior to final assembly.

Selection Notes

Select this component when a parallel interface is preferred over serial protocols like I2C or SPI. The 70ns access speed suits standard microprocessor buses. Consider the PowerCap package only if surface mounting is mandatory; otherwise, the EDIP variant offers a self-contained solution. Verify that the system can support the 64-cycle pattern recognition sequence required to access the clock registers.

Part Context

This part belongs to the Maxim Integrated DS1251 family of nonvolatile RAMs with phantom clocks. It is upward compatible with the DS1248 series. The 'P' designation indicates the PowerCap surface-mount package, while 'Y' specifies the 5V operating voltage and 70ns speed grade. The '+' suffix denotes lead-free/RoHS compliance.

Replacement Considerations

The DS1251W-120IND+ serves as a functional equivalent for 3.3V applications with slower 120ns speeds. For direct pin-for-pin replacement in 5V designs, verify compatibility with other densities in the DS124xP Phantom Clock series.