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A29040BV-55F Datasheet(PDF) 9 Page - AMIC Technology |
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A29040BV-55F Datasheet(HTML) 9 Page - AMIC Technology |
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9 / 29 page  A29040B Series Chip Erase Command Sequence Chip erase is a six-bus-cycle operation. The chip erase command sequence is initiated by writing two unlock cycles, followed by a set-up command. Two additional unlock write cycles are then followed by the chip erase command, which in turn invokes the Embedded Erase algorithm. The device does not require the system to preprogram prior to erase. The Embedded Erase algorithm automatically preprograms and verifies the entire memory for an all zero data pattern prior to electrical erase. The system is not required to provide any controls or timings during these operations. The Command Definitions table shows the address and data requirements for the chip erase command sequence. Any commands written to the chip during the Embedded Erase algorithm are ignored. The system can determine the status of the erase operation by using I/O7, I/O6, or I/O2. See "Write Operation Status" for information on these status bits. When the Embedded Erase algorithm is complete, the device returns to reading array data and addresses are no longer latched. Figure 2 illustrates the algorithm for the erase operation. See the Erase/Program Operations tables in "AC Characteristics" for parameters, and to the Chip/Sector Erase Operation Timings for timing waveforms. Sector Erase Command Sequence Sector erase is a six-bus-cycle operation. The sector erase command sequence is initiated by writing two unlock cycles, followed by a set-up command. Two additional unlock write cycles are then followed by the address of the sector to be erased, and the sector erase command. The Command Definitions table shows the address and data requirements for the sector erase command sequence. The device does not require the system to preprogram the memory prior to erase. The Embedded Erase algorithm automatically programs and verifies the sector for an all zero data pattern prior to electrical erase. The system is not required to provide any controls or timings during these operations. After the command sequence is written, a sector erase time- out of 50 µs begins. During the time-out period, additional sector addresses and sector erase commands may be written. Loading the sector erase buffer may be done in any sequence, and the number of sectors may be from one sector to all sectors. The time between these additional cycles must be less than 50 µs, otherwise the last address and command might not be accepted, and erasure may begin. It is recommended that processor interrupts be disabled during this time to ensure all commands are accepted. The interrupts can be re-enabled after the last Sector Erase command is written. If the time between additional sector erase commands can be assumed to be less than 50 µs, the system need not monitor I/O3. Any command other than Sector Erase or Erase Suspend during the time-out period resets the device to reading array data. The system must rewrite the command sequence and any additional sector addresses and commands. The system can monitor I/O3 to determine if the sector erase timer has timed out. (See the " I/O3: Sector Erase Timer" section.) The time-out begins from the rising edge of the final WE pulse in the command sequence. Once the sector erase operation has begun, only the Erase Suspend command is valid. All other commands are ignored. When the Embedded Erase algorithm is complete, the device returns to reading array data and addresses are no longer latched. The system can determine the status of the erase operation by using I/O7, I/O6, or I/O2. Refer to "Write Operation Status" for information on these status bits. Figure 2 illustrates the algorithm for the erase operation. Refer to the Erase/Program Operations tables in the "AC Characteristics" section for parameters, and to the Sector Erase Operations Timing diagram for timing waveforms. Erase Suspend/Erase Resume Commands The Erase Suspend command allows the system to interrupt a sector erase operation and then read data from, or program data to, any sector not selected for erasure. This command is valid only during the sector erase operation, including the 50 µs time-out period during the sector erase command sequence. The Erase Suspend command is ignored if written during the chip erase operation or Embedded Program algorithm. Writing the Erase Suspend command during the Sector Erase time-out immediately terminates the time-out period and suspends the erase operation. Addresses are "don't cares" when writing the Erase Suspend command. When the Erase Suspend command is written during a sector erase operation, the device requires a maximum of 20 µs to suspend the erase operation. However, when the Erase Suspend command is written during the sector erase time-out, the device immediately terminates the time-out period and suspends the erase operation. After the erase operation has been suspended, the system can read array data from or program data to any sector not selected for erasure. (The device "erase suspends" all sectors selected for erasure.) Normal read and write timings and command definitions apply. Reading at any address within erase-suspended sectors produces status data on I/O7 - I/O0. The system can use I/O7, or I/O6 and I/O2 together, to determine if a sector is actively erasing or is erase-suspended. See "Write Operation Status" for information on these status bits. After an erase-suspended program operation is complete, the system can once again read array data within non- suspended sectors. The system can determine the status of the program operation using the I/O7 or I/O6 status bits, just as in the standard program operation. See "Write Operation Status" for more information. The system may also write the autoselect command sequence when the device is in the Erase Suspend mode. The device allows reading autoselect codes even at addresses within erasing sectors, since the codes are not stored in the memory array. When the device exits the autoselect mode, the device reverts to the Erase Suspend mode, and is ready for another valid operation. See "Autoselect Command Sequence" for more information. The system must write the Erase Resume command (address bits are "don't care") to exit the erase suspend mode and continue the sector erase operation. Further writes of the Resume command are ignored. Another Erase Suspend command can be written after the device has resumed erasing. PRELIMINARY (December, 2004, Version 0.2) 8 AMIC Technology, Corp. |
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