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AM29F040B-70EF Datasheet(PDF) 11 Page - Advanced Micro Devices |
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AM29F040B-70EF Datasheet(HTML) 11 Page - Advanced Micro Devices |
11 / 36 page November 1, 2006 21445E5 Am29F040B 9 D A TA SH EE T Autoselect Mode The autoselect mode provides manufacturer and de- vice identification, and sector protection verification, through identifier codes output on DQ7–DQ0. This mode is primarily intended for programming equipment to automatically match a device to be programmed with its corresponding programming algorithm. However, the autoselect codes can also be accessed in-system through the command register. When using programming equipment, the autoselect mode requires VID (11.5 V to 12.5 V) on address pin A9. Address pins A6, A1, and A0 must be as shown in Autoselect Codes (High Voltage Method) table. In addi- tion, when verifying sector protection, the sector address must appear on the appropriate highest order address bits. Refer to the corresponding Sector Ad- dress Tables. The Command Definitions table shows the remaining address bits that are don’t care. When all necessary bits have been set as required, the program- ming equipment may then read the corresponding identifier code on DQ7–DQ0. To access the autoselect codes in-system, the host system can issue the autoselect command via the command register, as shown in the Command Defini- tions table. This method does not require VID. See “Command Definitions” for details on using the autose- lect mode. Table 3. Am29F040B Autoselect Codes (High Voltage Method) 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 program and erase operations in previously protected sectors. Sector protection/unprotection must be implemented using programming equipment. The procedure re- quires a high voltage (VID) on address pin A9 and the control pins. Details on this method are provided in a supplement, publication number 19957. Contact an AMD representative to obtain a copy of the appropriate document. 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” for details. Hardware Data Protection The command sequence requirement of unlock cycles for programming or erasing provides data protection against inadvertent writes (refer to the Command Defi- nitions table). In addition, the following hardware data protection measures prevent accidental erasure or pro- gramming, which might otherwise be caused by spurious system level signals during VCC power-up and power-down transitions, or from system noise. Low VCC Write Inhibit When VCC is less than VLKO, the device does not ac- cept any write cycles. This protects data during VCC power-up and power-down. The command register and all internal program/erase circuits are disabled, and the device resets. Subsequent writes are ignored until VCC is greater than VLKO. The system must provide the proper signals to the control pins to prevent uninten- tional writes when VCC is greater than VLKO. Write Pulse “Glitch” Protection Noise pulses of less than 5 ns (typical) on OE#, CE# or WE# do not initiate a write cycle. Logical Inhibit Write cycles are inhibited by holding any one of OE# = VIL, CE# = VIH or WE# = VIH. To initiate a write cycle, CE# and WE# must be a logical zero while OE# is a logical one. Power-Up Write Inhibit If WE# = CE# = VIL and OE# = VIH during power up, the device does not accept commands on the rising edge of WE#. The internal state machine is automatically reset to reading array data on power-up. Description A18–A16 A15–A10 A9 A8–A7 A6 A5–A2 A1 A0 Identifier Code on DQ7-DQ0 Manufacturer ID: AMD X X VID X VIL X VIL VIL 01h Device ID: Am29F040B X X VID X VIL X VIL VIH A4h Sector Protection Verification Sector Address X VID X VIL X VIH VIL 01h (protected) 00h (unprotected) |
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