Block Diagram

TLZ12436 – 2

Functional Description

The MCM28F256ACH is a 268435456-bit (256-Mbit) flash

memory module organized as 16 pages with 16777216

bytes (8388608 words) per page The module is segment-

ed into 512 independently lockable blocks (32 blocks per

page)

A Command User Interface (CUI) serves as the interface

between the system controller and each page of internal

memory Automation of the byteword write and block erase

functions allow these commands to be executed using a

two-write command sequence to the CUI An internal Write

State Machine (WSM) automatically executes the algo-

rithms timings and verifications necessary for the write and

erase operations thereby relieving the system controller of

these tasks

Each page of memory has three types of status registers

and a RYBY output to provide information on the progress

of the requested operation The Compatible Status Register

(CSR) is 100% compatible with status register used in previ-

ous FlashFile memory devices The Global Status Register

(GSR) informs the system of command queue status sector

buffer status and WSM status Block Status Registers (BSR)

provide block-specific status information such as the block

lock bit status A choice of four different RYBY configura-

tions can be selected via special CUI commands level-

mode (default) pulse-on-write pulse-on-erase or disabled

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