GENERAL DESCRIPTION
The MT28F004B3 (x8) and MT28F400B3 (x16/x8) are nonvolatile, electrically block-erasable (flash), programmable memory devices containing 4,194,304 bits organized as 262,144 words (16 bits) or 524,288 bytes (8 bits). Writing or erasing the device is done with either a 3.3V or 5V VPP voltage, while all operations are performed with a 3.3V VCC. Due to process technology advances, 5V VPP is optimal for application and production programming. These devices are fabricated with Micron’s advanced 0.18µm CMOS floating-gate process.
The MT28F004B3 and MT28F400B3 are organized into seven separately erasable blocks. To ensure that critical firmware is protected from accidental erasure or overwrite, the devices feature a hardware-protected boot block. Writing or erasing the boot block requires either applying a super-voltage to the RP# pin or driving WP# HIGH in addition to executing the normal write or erase sequences. This block may be used to store code implemented in low-level system recovery. The remaining blocks vary in density and are written and erased with no additional security measures.

FEATURES
• Seven erase blocks:
   16KB/8K-word boot block (protected)
   Two 8KB/4K-word parameter blocks
   Four main memory blocks
• Smart 3 technology (B3):
   3.3V ±0.3V VCC
   3.3V ±0.3V VPP application programming
   5V ±10% VPP application/production programming1
• Compatible with 0.3µm Smart 3 device
• Advanced 0.18µm CMOS floating-gate process
• Address access time: 80ns
• 100,000 ERASE cycles
• Industry-standard pinouts
• Inputs and outputs are fully TTL-compatible
• Automated write and erase algorithm
• Two-cycle WRITE/ERASE sequence
• Byte- or word-wide READ and WRITE
   (MT28F400B3, 256K x 16/512K x 8)
• Byte-wide READ and WRITE only
   (MT28F004B3, 512K x 8)
• TSOP and SOP packaging options