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AM29SL160C 数据表(PDF) 18 Page - Advanced Micro Devices |
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AM29SL160C 数据表(HTML) 18 Page - Advanced Micro Devices |
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18 / 52 page ![]() 16 Am29SL160C 21635C5 January 23, 2007 D A TA SH EE T The primary method requires V ID on the RESET# pin only, and is implemented either in-system or via pro- gramming equipment. Figure 1, on page 17 shows the algorithms and Figure 24, on page 43 shows the timing diagram. This method uses standard microprocessor bus cycle timing. 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 V ID 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 21622 contains further details. Contact an AMD representative to request the document con- taining further details. 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 “Autoselect Mode” on page 14 for details. Write Protect (WP#) The write protect function provides a hardware method of protecting certain boot sectors without using V ID. This function is one of two provided by the WP#/ACC pin. If the system asserts V IL on the WP#/ACC pin, the device disables program and erase functions in the two “outermost” 8 Kbyte boot sectors independently of whether those sectors were protected or unprotected using the method described in “Sector/Sector Block Protection and Unprotection” on page 15. The two out- ermost 8 Kbyte boot sectors are the two sectors containing the lowest addresses in a bottom-boot-con- figured device, or the two sectors containing the highest addresses in a top-boot-configured device. If the system asserts V IH on the WP#/ACC pin, the device reverts to whether the two outermost 8 Kbyte boot sectors were last set to be protected or unpro- tected. That is, sector protection or unprotection for these two sectors depends on whether they were last protected or unprotected using the method described in “Sector/Sector Block Protection and Unprotection” on page 15. Note that if the system asserts V HH on the WP#/ACC pin, all sectors, including the two outermost sectors, are unprotected. V HH is intended for accelerated in- system programming of the device during system pro- duction. It is advisable, therefore, not to assert V HH on this pin after the system has been placed in the field for use. If faster programming is desired, the system may use the unlock bypass program command sequence. 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 RESET# pin to V ID. During this mode, formerly pro- tected sectors can be programmed or erased by selecting the sector addresses. Once V ID is removed from the RESET# pin, all the previously protected sectors are protected again. Figure 2, on page 18 shows the algorithm, and Figure 22, on page 42 shows the timing diagrams, for this feature. |
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