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AM29PDL128G データシート(PDF) 12 Page - SPANSION |
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AM29PDL128G データシート(HTML) 12 Page - SPANSION |
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12 / 69 page ![]() July 29, 2002 Am29PDL128G 11 P R E L I M I NARY inputs (assuming the addresses have been stable for at least t ACC–tOE time). Page Mode Read The device is capable of fast page mode read and is compatible with the page mode Mask ROM read oper- ation. This mode provides faster read access speed for random locations within a page. The page size of the device is 8 words, or 4 double words, with the ap- propriate page being selected by the higher address bits A21–A2 and the LSB bits A1–A0 (in the double word mode) and A1 to A-1 (in the word mode) deter- mining the specific word/double word within that page. This is an asynchronous operation with the micropro- cessor supplying the specific word or double word lo- cation. The random or initial page access is equal to t ACC or t CE and subsequent page read accesses (as long as the locations specified by the microprocessor falls within that page) is equivalent to t PACC. When CE# is deasserted and reasserted for a subsequent access, the access time is t ACC or tCE. Here again, CE# selects the device and OE# is the output control and should be used to gate data to the output inputs if the device is selected. Fast page mode accesses are obtained by keeping A21–A2 constant and changing A1 to A0 to select the specific double word, or changing A1 to A-1 to select the specific word, within that page. Table 2. Page Select, Double Word Mode Table 3. Page Select, Word Mode Simultaneous Operation The device is capable of reading data from one bank of memory while a program or erase operation is in progress in another bank of memory (simultaneous operation), in addition to the conventional features (read, program, erase-suspend read, and erase-sus- pend program). The bank selected can be selected by bank addresses (A21–A19) with zero latency. The simultaneous operation can execute multi-func- tion mode in the same bank. Table 4. Bank Select Writing Commands/Command Sequences To write a command or command sequence (which in- cludes programming data to the device and erasing sectors of memory), the system must drive WE# and CE# to V IL, and OE# to VIH. For program operations, the WORD# pin determines whether the device accepts program data in double words or words. Refer to “Word/Double Word Configu- ration” for more information. The device features an Unlock Bypass mode to facil- itate faster programming. Once a bank enters the Un- lock Bypass mode, only two write cycles are required to program a double word or word, instead of four. The “Double Word/Word Program Command Sequence” section has details on programming data to the device using both standard and Unlock Bypass command se- quences. An erase operation can erase one sector, multiple sec- tors, or the entire device. Table 5 indicates the address space that each sector occupies. A “bank address” is the address bits required to uniquely select a bank. Similarly, a “sector address” refers to the address bits required to uniquely select a sector. The “Command Definitions” section has details on erasing a sector or the entire chip, or suspending/resuming the erase op- eration. I CC2 in the DC Characteristics table represents the ac- tive current specification for the write mode. The AC Characteristics section contains timing specification tables and timing diagrams for write operations. Word A1 A0 Double Word 0 0 0 Double Word 1 0 1 Double Word 2 1 0 Double Word 3 1 1 Word A1 A0 A-1 Word 0 0 0 0 Word 1 0 0 1 Word 2 0 1 0 Word 3 0 1 1 Word 4 1 0 0 Word 5 1 0 1 Word 6 1 1 0 Word 7 1 1 1 Bank A21–A19 Bank 1 000 Bank 2 001, 010, 011 Bank 3 100, 101, 110 Bank 4 111 |
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