MBM29LV080A-12PTN Просмотр технического описания (PDF) - Fujitsu

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MBM29LV080A-12PTN

8M (1M x 8) BIT

Fujitsu 

MBM29LV080A-70/-90/-12

Write

Device erasure and programming are accomplished via the command register. The contents of the register serve

as inputs to the internal state machine. The state machine outputs dictate the function of the device.

The command register itself does not occupy any addressable memory location. The register is a latch used to

store the commands, along with the address and data information needed to execute the command. The com-

mand register is written by bringing WE to VIL, while CE is at VIL and OE is at VIH. Addresses are latched on the

falling edge of WE or CE, whichever happens later; while data is latched on the rising edge of WE or CE,

whichever happens first. Standard microprocessor write timings are used.

Refer to AC Write Characteristics and the Erase/Programming Waveforms for specific timing parameters.

Sector Protection

The MBM29LV080A features hardware sector protection. This feature will disable both program and erase

operations in any number of sectors (0 through 15). The sector protection feature is enabled using programming

equipment at the user’s site. The device is shipped with all sectors unprotected.

To activate this mode, the programming equipment must force VID on address pin A9 and control pin OE, (suggest

VID = 11.5 V), CE = VIL, A0 = A6 = VIL, and A1 = VIH. The sector addresses (A19, A18, A17,and A16) should be set to

the sector to be protected. Tables 4 and 5 define the sector address for each of the sixteen (16) individual sectors.

Programming of the protection circuitry begins on the falling edge of the WE pulse and is terminated with the

rising edge of the same. Sector addresses must be held constant during the WE pulse. See figures 13 and 21

for sector protection waveforms and algorithm.

To verify programming of the protection circuitry, the programming equipment must force VID on address pin A9

with CE and OE at VIL and WE at VIH. Scanning the sector addresses (A19, A18, A17,and A16) while (A10, A6, A1,

A0) = (0, 0, 1, 0) will produce a logical “1” code at device output DQ0 for a protected sector. Otherwise the devices

will read 00H for unprotected sector. In this mode, the lower order addresses, except for A0, A1, A6, and A10 are

DON’T CARES. Address locations with A1 = VIL are reserved for Autoselect manufacturer and device codes.

It is also possible to determine if a sector is protected in the system by writing an Autoselect command. Performing

a read operation at the address location XX02H, where the higher order addresses (A19, A18, A17,and A16). are

the sector address will produce a logical “1” at DQ0 for a protected sector. See Tables 3.1 and 3.2 for Autoselect

codes.

Temporary Sector Unprotection

This feature allows temporary unprotection of previously protected sectors of the MBM29LV080A device in order

to change data. The Sector Unprotection mode is activated by setting the RESET pin to high voltage (12 V).

During this mode, formerly protected sectors can be programmed or erased by selecting the sector addresses.

Once the 12 V is taken away from the RESET pin, all the previously protected sectors will be protected again.

See figure 15 and 22.

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