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AM29DL800B 数据表(PDF) 13 Page - Advanced Micro Devices |
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AM29DL800B 数据表(HTML) 13 Page - Advanced Micro Devices |
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13 / 43 page ![]() Am29DL800B 13 P R E L I M I NARY Table 4. Am29DL800B Autoselect Codes (High Voltage Method) Note: L = Logic Low = VIL, H = Logic High = VIH, BA = Bank Address, SA = Sector Address, X = Don’t care. Sector Protection/Unprotection The hardware sector protection feature disables both program and erase operations in any sector. The hard- ware sector unprotection feature re-enables both pro- gram and erase operations in previously protected sectors. Sector protection/unprotection can be imple- mented via two methods. The primary method requires VID on the RESET# pin only, and can be implemented either in-system or via programming equipment. Figure 2 shows the algo- rithms and Figure 24 shows the timing diagram. This method uses standard microprocessor bus cycle tim- ing. For sector unprotect, all unprotected sectors must first be protected prior to the first sector unprotect write cycle. The alternate method intended only for programming equipment requires VID on address pin A9 and OE#. This method is compatible with programmer routines written for earlier 3.0 volt-only AMD flash devices. Pub- lication number 21467 contains further details; contact an AMD representative to request a copy. The device is shipped with all sectors unprotected. AMD offers the option of programming and protecting sectors at its factory prior to shipping the device through AMD’s ExpressFlash™ Service. Contact an AMD representative for details. It is possible to determine whether a sector is protected or unprotected. See the Autoselect Mode section for details. Temporary Sector Unprotect This feature allows temporary unprotection of previ- ously protected sectors to change data in-system. The Sector Unprotect mode is activated by setting the RE- SET# pin to VID (11.5 V – 12.5 V). During this mode, formerly protected sectors can be programmed or erased by selecting the sector addresses. Once VID is removed from the RESET# pin, all the previously pro- tected sectors are protected again. Figure 1 shows the algorithm, and Figure 23 shows the timing diagrams, for this feature. Figure 1. Temporary Sector Unprotect Operation Description Mode CE# OE# WE# A18 to A12 A11 to A10 A9 A8 to A7 A6 A5 to A2 A1 A0 DQ8 to DQ15 DQ7 to DQ0 Manufacturer ID: AMD L L H BA X VID XLXL L X 01h Device ID: Am29DL800B (Top Boot Block) Word L L H BA X VID XLXL H 22h 4Ah Byte L L H X 4Ah Device ID: Am29DL800B (Bottom Boot Block) Word L L H BA X VID XLXL H 22h CBh Byte L L H X CBh Sector Protection Verification L L H SA X VID XLX H L X 01h (protected) X 00h (unprotected) START Perform Erase or Program Operations RESET# = VIH Temporary Sector Unprotect Completed (Note 2) RESET# = VID (Note 1) Notes: 1. All protected sectors unprotected. 2. All previously protected sectors are protected once again. 21519A-5 |
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