Am29SL400D

The Am29SL400D is an 4Mbit, 1.8 V volt-only Flash memory organized as 524,288 bytes or 262,144 words. The device is offered in a 48-ball FBGA package. The word-wide data (x16) appears on DQ15DQ0; the byte-wide (x8) data appears on DQ7DQ0. This device is designed to be programmed and erased in-system with a single 1.8 volt VCC supply. No VPP is required for write or erase operations. The device can also be programmed in standard EPROM programmers.

The standard device offers access times of 90, 100, and 120 ns, allowing high speed microprocessors to operate without wait states. To eliminate bus contention Am29SL400D 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 device 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 devices. 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. Am29SL400D 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 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 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. Am29SL400D 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. AMD's Flash technology combines years of Flash memory manufacturing experience to produce the highest levels of quality, reliability and cost effectiveness. Am29SL400D electrically erases all bits within a sector simultaneously via Fowler-Nordheim tunneling. The data is programmed using hot electron injection.