The AT49BV040B is a 2.7V to 5.5V in-system reprogrammable Flash Memory. Its 4 megabits of memory is organized as 524,288 words by 8 bits. Manufactured with Atmel's advanced nonvolatile CMOS technology, the device offers an access time of 70 ns (VCC = 2.7V to 3.6V) and an access time of 55 ns (VCC = 4.5V to 5.5V). The power dissipation over the industrial temperature range with VCC = 2.7V to 3.6V is 72 mW and is 110 mW with VCC = 4.5V to 5.5V. When the device is deselected, the CMOS standby current is less than 30 A. To allow for simple in-system reprogrammability, the AT49BV040B does not require high input voltages for programming. Reading data out of the device is similar to reading from an EPROM; it has standard CE, OE, and WE inputs to avoid bus contention. Reprogramming the AT49BV040B is performed by erasing a sector of data and then programming on a byte by byte basis. The byte programming time is a fast 10 s. The end of a program or erase cycle can be optionally detected by the DATA polling or toggle bit feature. Once the end of a byte program cycle has been detected, a new access for a read or program can begin. The typical number of program and erase cycles is in excess of 100,000 cycles. The device is erased by executing a chip erase or a sector erase command sequence; the device internally controls the erase operations. The memory array of the AT49BV040B is organized into two 8K byte parameter sectors, eight main memory sectors, and one boot sector.