AS29LV400R-90SI 데이터 시트보기 (PDF) - Alliance Semiconductor
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AS29LV400R-90SI Datasheet PDF : 24 Pages
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January 2001
AS29LV400
®
Functional description
The AS29LV400 is an 4 megabit, 3.0 volt only 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 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 AS29LV400 offers access times of 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 and Byte mode (×8 output) is selected by BYTE = low.
The AS29LV400 is fully compatible with the JEDEC single power supply Flash standard. Write commands 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 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 (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 program and 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.
A factory shipped 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 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 AS29LV400 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 one.
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 AS29LV400 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.
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