SpecificationsThe autoselect mode allows the reading of a binarycode from the device and will identify its manufacturer and type. This mode is intended for use by programming equipment for the purpose of automatically matching the device to be programmed with its corresponding programming algorithm. This mode is functional over the entire temperature range of the device.
To activate this mode, the programming equipment must force VID (11.5 V to 12.5 V) on address pin A9.Two identifier bytes may then be sequenced from the device outputs by toggling address A0 from VIL to VIH.All addresses are don't cares except A0, A1, and A6(see Table 3).
The manufacturer and device codes may also be read via the command register, for instances when theAm29F400A is erased or programmed in a systemwithout access to high voltage on the A9 pin. The command sequence is illustrated in Table 4 (see Autoselect Command Sequence).
Byte 0 (A0 = VIL) represents the manufacturer's code (AMD=01H) and byte 1 (A0 = VIH) the device identifier code (Am29F400AT = 23H and Am29F400AB = ABH for x8 momode;Am29F400AT = 2223H and Am29F400AB= 22ABH for x16 mode). These two bytes/words are given in the table below. All identifiers for manufacturer and device will exhibit odd parity with DQ7 defined as the parity bit. In order to read the proper device codes when executing the Autoselect, A1 must be VIL(see Tables 3 and 4).
The autoselect mode also facilitates the determination of sector protection in the system. By performing a read operation at the address location XX02H with the higher order address bits A12A17 set to the desired sector address, the device will return 01H for a protected sector and 00H for a non-protected sector.
DescriptionThe Am29F400AB is a 4 Mbit, 5.0 Volt-only Flash memory organized as 512 Kbytes of 8 bits each or 256 Kwords of 16 bits each. The 4 Mbits of data is divided into 11 sectors of one 16 Kbyte, two 8 Kbyte, one 32 Kbyte,and seven 64 Kbytes, for flexible erase capability. The 8 bits of data will appear on DQ0DQ7 or 16 bits on DQ0DQ15. Am29F400A is offered in 44-pin SO and 48-pin TSOP packages. This device is designed to be programmed in-system with thestandard system5.0 Volt VCC supply. 12.0 Volt VPPis not required for program or erase operations. Am29F400AB can also be reprogrammed in standard EPROM programmers.
The standard Am29F400A offers access times of 60 ns, 70 ns, 90 ns, 120 ns and 150 ns, allowing highspeedmicroprocessors to operate without wait states.To eliminate bus contention the device has separate chip enable (CE), write enable (WE) and output enable (OE) controls.The Am29F400AB is entirely command set compatible
with the JEDEC single-power-supply Flash standard.Commands are written to the command register using standard microprocessor write timings. Register contents serve as input to an internal state-machine which controls the erase and programming circuitry
Am29F400AB Data Sheet
