AS29LV400T-70TC 查看數據表（PDF） - Alliance Semiconductor
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AS29LV400T-70TC Datasheet PDF : 25 Pages
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March 2001
AS29LV400
®
Functional description
The AS29LV400 is an 4 megabit, 3.0 volt Flash memory organized as 512Kbyte of 8 bits/256Kbytes of 16 bits each. For
flexible Erase and Program capability, the 4 megabits of data is divided into eleven sectors: one 16K, two 8K, one 32K, and
seven 64k byte sectors; or one 8K, two 4K, one 16K, and seven 32K word sectors. The ×8 data appears on DQ0–DQ7; the ×16
data appears on DQ0–DQ15. The AS29LV400 is offered in JEDEC standard 48-pin TSOP. A 44-pin SOP package may be offered
in the future. This device is designed to be programmed and erased with a single 3.0V VCC supply. The device can also be
reprogrammed in standard EPROM programmers.
The AS29LV400 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 (C E ), write enable (W E), and output enable (OE ) controls. Word
mode (×16 output) is selected by B Y T E = high. Byte mode (×8 output) is selected by B Y T E = low.
The AS29LV400 is fully compatible with the JEDEC single power supply Flash standard. The device uses standard
microprocessor write timings to send Write commands to the register. 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. Data is read in the same manner as other Flash or EPROM devices. Use the Program command sequence
to invoke the 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 when
it is not already programmed before executing the erase operation. The Erase command also times the erase pulse widths and
verifies the proper cell margins.
Boot sector architecture enables the system to boot from either the top (AS29LV400T) or the bottom (AS29LV400B) 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 the Program and the
Erase operations in all, or any combination of the eleven 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.
When shipped from the factory, AS29LV400 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 a 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 V CC detector automatically inhibits write
operations during power transtitions. The RY/B Y pin, DATA polling of DQ7, or toggle bit (DQ6) may be used to detect the
end of the program or to erase operations. The device automatically resets to the Read mode after the Program or Erase
operations are completed. DQ2 indicates which sectors are being erased.
The AS29LV400 resists accidental erasure or spurious programming signals resulting from power transitions. The Control
register architecture permits alteration of memory contents only when successful completion of specific command sequences
has occured. During power up, the device is set to Read mode with all Program/Erase commands disabled if VCC is less than
VLKO (lockout voltage). The command registers are not affected by noise pulses of less than 5 ns on OE , C E , or W E. To initiate
Write commands, C E and W E must be a logical zero and O E a logical 1.
When the device’s hardware RE S ET pin is driven low, any Program/Erase operation in progress is terminated and the internal
state machine is reset to Read mode. If the RE S ET pin is tied to the system reset circuitry and a system reset occurs during an
automated on-chip Program/Erase algorithm, the operating data in the address locations may become corrupted and require
rewriting. Resetting the device enables the system’s microprocessor to read boot-up firmware from the Flash memory.
The AS29LV400 uses Fowler-Nordheim tunnelling to electrically erase all bits within a sector simultaneously. Bytes are
programmed one at a time using the EPROM programming mechanism of hot electron injection.
3/20/01; V.0.9.3
Alliance Semiconductor
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