The M5M5408B is a family of 4-Mbit static RAMs organized as 524,288-words by 8-bit, fabricated by Mitsubishis high performance 0.25µm CMOS technology.

The M5M5408B is suitable for memory applications where a simple interfacing , battery operating and battery backup are the important design objectives. M5M5408B is packaged in 32-pin plastic SOP, 32-pin plastic TSOP and 32-pin 8mm x 13.4mm STSOP packages. Two types of TSOPs and two types of STSOPs are available , M5M5408BTP (normal-lead-bend TSOP) , M5M5408BRT (reverse-lead-bend TSOP) , M5M5408BKV (normal-lead-bend STSOP) and M5M5408BKR (reverse-lead-bend STSOP).

These two types TSOPs and two types STSOPs are suitable for a surface mounting on double-sided printed circuit boards. From the point of operating temperature, the family is divided into three versions; "Standard", " W-version", and "I-version". Those are summarized in the part name table below.