DS1245Y-85+

DS1245Y-85+ Memory Application Field and Working Principle

The DS1245Y-85+ Nonvolatile SRAM chip is an advanced CMOS static random access memory that integrates fast static RAM with nonvolatile EEPROM technology. It offers fast (ns) access time from SRAM without sacrificing the nonvolatile characteristics of EEPROM.

The DS1245Y-85+ Nonvolatile SRAM is ideal for applications where fast access and frequent writes are required, but data must be retained under power loss emergencies. Examples include digital copiers, printers, robotics, communications equipment, SMPS and other embedded system applications such as monitoring and control devices. The DS1245Y-85+ Nonvolatile SRAM is housed in a 20-pin DIP, which permits easy drop-in replacement for existing SRAM-based designs.

Overview

The DS1245Y-85+ Nonvolatile SRAM combines the fast access time of static random access memory (SRAM) with the low-cost and small size of EEPROM. It is an 8K by 8 Nonvolatile SRAM that is primarily composed of two distinct blocks, a non-volatile EEPROM array for data storage and a static RAM array for rapid accessing.

As opposed to DRAMs, which require continuous power to maintain data, static RAM is static, or nonvolatile. This means that if power is applied or removed, data will not be lost. However, SRAMs have some drawbacks. They need to be refreshed and they require a higher current to operate. In order to overcome these drawbacks, the DS1245Y-85+ utilizes EEPROM technology.

Working Principle

The DS1245Y-85+ Nonvolatile SRAM is composed of two distinct memory blocks, an 8K by 8 static RAM and 8K by 8 EEPROM array. For read operations, the static RAM array is accessed first. When the corresponding address is accessed, the data is immediately sent to the output of the static RAM and then to the output of the device.

For write operations, the data is written to the static RAM array first and then to the EEPROM array. Writing to the static RAM array does not require any special cycles; it is written simply by providing the data and the address. Writing to the EEPROM array, on the other hand, is a more complex process. First, the data to be written must be provided along with the address. Then, a special write cycle is initiated, during which the data is programmed into the EEPROM cells.

In order to prevent the static RAM cells and the EEPROM contents from becoming corrupted over time, the DS1245Y-85+ utilizes a special refresh cycle. During this cycle, the static RAM cells are refreshed and the contents of the EEPROM are validated to ensure that they are still reliable. This ensures that the data will remain intact when the power is removed.

Conclusion

The DS1245Y-85+ Nonvolatile SRAM combines the fast access time of static RAM with the low-cost and small size of EEPROM. It is ideal for applications where fast access and frequent writes are required, but data must be retained under power loss emergencies. It utilizes fast static RAM with nonvolatile EEPROM technology to provide a reliable, low-cost solution for these types of applications.