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AM42DL16X4D ๋ฐ์ดํฐ์ํธ(HTML) 27 Page - SPANSION |
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AM42DL16X4D ๋ฐ์ดํฐ์ํธ(HTML) 27 Page - SPANSION |
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27 / 61 page 
26 Am42DL16x4D January 9, 2002 P R E L IMINARY Figure 3. Program Operation 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 algo- rithm 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 con- trols or timings during these operations. Table 14 shows the address and data requirements for the chip erase command sequence. When the Embedded Erase algorithm is complete, that bank returns to reading array data and addresses are no longer latched. The system can determine the status of the erase operation by using DQ7, DQ6, DQ2, or RY/BY#. Refer to the Write Operation Status section for information on these status bits. Any commands written during the chip erase operation are ignored. However, note that a hardware reset im- mediately terminates the erase operation. If that occurs, the chip erase command sequence should be reinitiated once that bank has returned to reading array data, to ensure data integrity. Figure 4 illustrates the algorithm for the erase opera- t i on . R e fer t o t he F l as h Er as e an d Pr ogr am Operations tables in the AC Characteristics section for pa r a meter s , and Fi gur e 20 s e c t i on for ti mi ng diagrams. 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 ad- ditional unlock cycles are written, and ar e then followed by the address of the sector to be erased, and the sector erase command. Table 14 shows the address and data requirements for the sector erase command sequence. The device does not require the system to preprogram prior to erase. The Embedded Erase algorithm auto- matically programs 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 tim- ings during these operations. After the command sequence is written, a sector erase time-out of 50 ยตs occurs. During the time-out period, additional sector addresses and sector erase com- mands may be written. Loading the sector erase buffer may be done in any sequence, and the number of sec- tors may be from one sector to all sectors. The time between these additional cycles must be less than 50 ยตs, otherwise erasure may begin. Any sector erase addre ss and c omm and fol lowin g the e xc eeded time-out may or may not be accepted. It is recom- mended 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. Any command other than Sect o r Erase o r Erase Su sp end du ring t h e time-out period resets that bank to reading array data. The system must rewrite the command se- quence and any additional addresses and commands. The system can monitor DQ3 to determine if the sec- tor erase timer has timed out (See the section on DQ3: Sector Erase Timer.). The time-out begins from the ris- ing edge of the final WE# pulse in the command sequence. When the Embedded Erase algorithm is complete, the bank returns to reading array data and addresses are no longer latched. Note that while the Embedded Erase operation is in progress, the system can read data from the non-erasing bank. The system can de- termine the status of the erase operation by reading DQ7, DQ6, DQ2, or RY/BY# in the erasing bank. START Write Program Command Sequence Data Poll from System Verify Data? No Yes Last Address? No Yes Programming Completed Increment Address Embedded Program algorithm in progress Note: See Table 14 for program command sequence. |
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