S29AS008J70BHI040(Cypress Semiconductor) 描述
Additional information about the S29AS008J70BHI040: The S29AS008J is a 8 Mbit, 1.8 Volt-only Flash memory organized as 1,048,576 bytes or 524,288 words with a x8/x16 bus and
either top or bottom boot sector architecture. The device is offered in 48-pin TSOP and 48-ball FBGA packages. The word-wide
data (x16) appears on DQ15–DQ0; the byte-wide (x8) data appears on DQ7–DQ0. This device is designed to be programmed
and erased in-system with the standard system 1.8 volt VCC supply. A 12.0 V VPP or 5.0 VCC are not required for program or
erase operations. The device can also be programmed in standard EPROM programmers.
The device offers access time of 70 ns allowing high speed microprocessors to operate without wait states. To eliminate bus
contention the device has separate chip enable (CE#), write enable (WE#) and output enable (OE#) controls.
The device requires only a single 1.8 volt power supply for both read and write functions. Internally generated and regulated
voltages are provided for the program and erase operations.
The S29AS008J is entirely command set compatible with the JEDEC single-power-supply Flash standard. Commands are
written to the command register using standard microprocessor write timings. Register contents serve as input to an internal
state-machine that controls the erase and programming circuitry. Write cycles also internally latch addresses and data needed
for the programming and erase operations. Reading data out of the device is similar to reading from other Flash or EPROM
Device programming occurs by executing the program command sequence. This initiates the Embedded Program algorithm—
an internal algorithm that automatically times the program pulse widths and verifies proper cell margin. The Unlock Bypass
mode facilitates faster programming times by requiring only two write cycles to program data instead of four.
Device erasure occurs by executing the erase command sequence. This initiates the Embedded Erase algorithm—an internal
algorithm that automatically preprograms the array (if it is not already programmed) before executing the erase operation.
During erase, the device automatically times the erase pulse widths and verifies proper cell margin.
The host system can detect whether a program or erase operation is complete by observing the RY/BY# pin, or by reading the
DQ7 (Data# Polling) and DQ6 (toggle) status bits. After a program or erase cycle has been completed, the device is ready to
read array data or accept another command.
The sector erase architecture allows memory sectors to be erased and reprogrammed without affecting the data contents of
other sectors. The device is fully erased when shipped from the factory.
Hardware data protection measures include a low VCC detector that automatically inhibits write operations during power
transitions. The hardware sector group protection feature disables both program and erase operations in any combination of
the sectors of memory. This can be achieved in-system or via programming equipment.
The Erase Suspend/Erase Resume feature enables the user to put erase on hold for any period of time to read data from, or
program data to, any sector that is not selected for erasure. True background erase can thus be achieved.
The hardware RESET# pin terminates any operation in progress and resets the internal state machine to reading array data.
The RESET# pin may be tied to the system reset circuitry. A system reset would thus also reset the device, enabling the system
microprocessor to read the boot-up firmware from the Flash memory.
The device offers two power-saving features. When addresses have been stable for a specified amount of time, the device
enters the automatic sleep mode. The system can also place the device into the standby mode. Power consumption is
greatly reduced in both these modes.
Cypress Flash technology combines years of Flash memory manufacturing experience to produce the highest levels of quality,
reliability and cost effectiveness. The device electrically erases all bits within a sector simultaneously via Fowler-Nordheim
tunneling. The data is programmed using hot electron injection.