AS29LV800
March 2001
®
Functional description
The AS29LV800 is an 8 megabit, 3.0 volt Flash memory organized as 1 Megabyte of 8 bits/512Kbytes of 16 bits each. For
flexible erase and program capability, the 8 megabits of data is divided into nineteen sectors: one 16K, two 8K, one 32K, and
fifteen 64k byte sectors; or one 8K, two 4K, one 16K, and fifteen 32K word sectors. The ×8 data appears on DQ0–DQ7; the
×16 data appears on DQ0–DQ15. The AS29LV800 is offered in JEDEC standard 48-pin TSOP and 44-pin SOP packages. This
device is designed to be programmed and erased in-system with a single 3.0V VCC supply. The device can also be
reprogrammed in standard EPROM programmers.
The AS29LV800 offers access times of 70/80/90/120 ns, allowing 0-wait state operation of high speed microprocessors. To
eliminate bus contention the device has separate chip enable (CE), write enable (WE), and output enable (OE) controls. Word
mode (×16 output) is selected by BYTE = high. Byte mode (×8 output) is selected by BYTE = low.
The AS29LV800 is fully compatible with the JEDEC single power supply Flash standard. Write commands are sent to the
command register using standard microprocessor write timings. An internal state-machine uses register contents to control the
erase and programming circuitry. Write cycles also internally latch addresses and data needed for the programming and erase
operations. Read data from the device occurs in the same manner as other Flash or EPROM devices. Use the program command
sequence to invoke the automated on-chip programming algorithm that automatically times the program pulse widths and
verifies proper cell margin. Use the erase command sequence to invoke the automated on-chip erase algorithm that
preprograms the sector (if it is not already programmed before executing the erase operation), times the erase pulse widths,
and verifies proper cell margin.
Boot sector architecture enables the system to boot from either the top (AS29LV800T) or the bottom (AS29LV800B) sector.
Sector erase architecture allows specified sectors of memory to be erased and reprogrammed without altering data in other
sectors. A sector typically erases and verifies within 1.0 seconds. Hardware sector protection disables both program and erase
operations in all, or any combination of, the nineteen sectors. The device provides true background erase with Erase Suspend,
which puts erase operations on hold to either read data from, or program data to, a sector that is not being erased. The chip
erase command will automatically erase all unprotected sectors.
A factory shipped AS29LV800 is fully erased (all bits = 1). The programming operation sets bits to 0. Data is programmed into
the array one byte at a time in any sequence and across sector boundaries. A sector must be erased to change bits from 0 to 1.
Erase returns all bytes in a sector to the erased state (all bits = 1). Each sector is erased individually with no effect on other
sectors.
The device features single 3.0V power supply operation for Read, Write, and Erase functions. Internally generated and
regulated voltages are provided for the Program and Erase operations. A low VCC detector automatically inhibits write
operations during power transtitions. The RY/BY pin, DATA polling of DQ7, or toggle bit (DQ6) may be used to detect end of
program or erase operations. The device automatically resets to the read mode after program/erase operations are completed.
DQ2 indicates which sectors are being erased.
The AS29LV800 resists accidental erasure or spurious programming signals resulting from power transitions. Control register
architecture permits alteration of memory contents only after successful completion of specific command sequences. During
power up, the device is set to read mode with all program/erase commands disabled when VCC is less than VLKO (lockout
voltage). The command registers are not affected by noise pulses of less than 5 ns on OE, CE, or WE. To initiate write
commands, CE and WE must be logical zero and OE a logical 1.
When the device’s hardware RESET pin is driven low, any program/erase operation in progress is terminated and the internal
state machine is reset to read mode. If the RESET pin is tied to the system reset circuitry and a system reset occurs during an
automated on-chip program/erase algorithm, data in address locations being operated on may become corrupted and requires
rewriting. Resetting the device enables the system’s microprocessor to read boot-up firmware from the Flash memory.
The AS29LV800 uses Fowler-Nordheim tunnelling to electrically erase all bits within a sector simultaneously. Bytes are
programmed one at a time using EPROM programming mechanism of hot electron injection.
3/22/01; V.1.0
Alliance Semiconductor
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