The Anvo-Systems Dresden ANV22AA8WB is a 1Mb SRAM with a non-volatile SONOS storage element included with each memory cell, organized as 128k words of 8 bits each. There are 2 separate modes of operation: SRAM mode and non-volatile mode. In SRAM mode, the memory operates as an ordinary static RAM. In non-volatile operation mode, data is transferred in parallel from SRAM to the SONOS elements (STORE) or from all of them to SRAM (RECALL). In non-volatile mode SRAM functions are disabled.
The SRAM can be read and written an unlimited number of times, while independent non-volatile data resides in SONOS elements. Data transfers from the SRAM to the SONOS elements take place automatically upon power down or brown out situation (POWERSTORE) using charge stored in a small external capacitor.
Transfers from the SONOS elements to the SRAM (RECALL) take place automatically on power up or may be initiated under user control by a software sequence. Internally, RECALL is a two step procedure. First, the SRAM data is cleared and second, the non-volatile information is transferred into the SRAM cells.
STORE cycles also may be initiated under user control by a software sequence or by a single pin (HSB).
Once a STORE cycle is initiated, further input or output are disabled until the cycle is completed.
The PowerStore function can also be enabled or disabled by a software sequence.
With Read Last Successful Written Address it is possible to read out the 3 byte of address for data where last WRITE was successful.