DataFlash™..."parallel goes serial"

- Densities up to 128MBit
- SPI interface speed up to 50Mbit/s
- RapidS™ interface speed up to 66Mbit/s
- two SRAM page buffer
- Very small packages SOIC8, CASON and MLF

Beside traditional serial E²PROM memories, DataFlash™ offer additional functionality to conform to user's requirements. The main special features are the two internal SRAM page buffers which are used for fast data buffering between the user interfaces (SPI) and the Flash-memory. Pages may be read from the Flash-memory into the SRAM page buffer, modified and write back while the next page is read into the other page buffer (Read-While-Write). Since speed critical erase/write operation are done while read operations are executed, the overall system performance will increase dramatically.

The key is "system cost". The total cost of a system will be basically driven by device and manufacturing cost. Parallel memories require many pins and therefore results in a big package and higher cost. Serial memories like DataFlash™ from Atmel® only need some few pins for communication. A traditional 32Mbit Flash-memory with a parallel interface needs at least 48-pins while a serial same density flash only needs 8-pins.

Cost reduction in manufacturing is the next advantage when using serial flash-memories. While parallel memories do need many traces on the PCB to be routed with the microcontroller a serial memory does not. This might result in a reduction of PCB-layer and so also in cost.

A typical DataFlash™ application exists in conjunction with a microcontroller. Like in a conventional memory system, the DataFlash™ also stores program and data information. The optimal use of a DataFlash™ will only work together with a selected microcontroller. On the left side of the block diagram a traditional microcontroller application is shown, consisting of a Flash-memory for code and non-volatile data and a SRAM memory for temporary data. Since both components are very expensive, a microcontroller has to be selected which is capable using other, more cost effective memory solutions. Atmels® AT91RM9200 has a SDRAM interface which allows the use of very low-cost SDRAM memories. The on-chip boot loader shadows the program code of the DataFlash™ into SDRAM at start-up. One positive side effect of this solution also is that the SDRAM also may be executed faster than a flash memory.