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AM29PDL640G 数据表(PDF) 13 Page - SPANSION |
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AM29PDL640G 数据表(HTML) 13 Page - SPANSION |
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13 / 61 page ![]() 12 Am29PDL640G February 26, 2003 P R E L I M INARY 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–A3 constant and changing A2 to A0 to select the specific word within that page. Table 2. Page Select 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 3. 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. 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 word, instead of four. The “Word Pro- gram Command Sequence” section has details on programming data to the device using both standard and Unlock Bypass command sequences. An erase operation can erase one sector, multiple sec- tors, or the entire device. Table 4 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. Accelerated Program Operation The device offers accelerated program operations through the ACC function. This function is primarily in- tended to allow faster manufacturing throughput at the factory. If the system asserts V HH on this pin, the device auto- matically enters the aforementioned Unlock Bypass mode, temporarily unprotects any protected sectors, and uses the higher voltage on the pin to reduce the time required for program operations. The system would use a two-cycle program command sequence as required by the Unlock Bypass mode. Removing V HH from the WP#/ACC pin returns the device to nor- mal operation. Note that V HH must not be asserted on WP#/ACC for operations other than accelerated pro- gramming, or device damage may result. In addition, the WP#/ACC pin should be raised to V CC when not in use. That is, the WP#/ACC pin should not be left float- ing or unconnected; inconsistent behavior of the de- vice may result. Autoselect Functions If the system writes the autoselect command se- quence, the device enters the autoselect mode. The system can then read autoselect codes from the inter- nal register (which is separate from the memory array) on DQ15–DQ0. Standard read cycle timings apply in this mode. Refer to the Autoselect Mode and Autose- lect Command Sequence sections for more informa- tion. Standby Mode When the system is not reading or writing to the de- vice, it can place the device in the standby mode. In this mode, current consumption is greatly reduced, and the outputs are placed in the high impedance state, independent of the OE# input. Word A2 A1 A0 Word 0 000 Word 1 001 Word 2 010 Word 3 011 Word 4 100 Word 5 101 Word 6 110 Word 7 111 Bank A21–A19 Bank A 000 Bank B 001, 010, 011 Bank C 100, 101, 110 Bank D 111 |
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