MT28F004B5 Micron, MT28F004B5 Datasheet - Page 7

• Manufacturer Part Number: MT28F004B5
• Description: FLASH MEMORY
• Manufacturer: Micron

FUNCTIONAL DESCRIPTION
incorporate a number of features ideally suited for
system firmware. The memory array is segmented into
individual erase blocks. Each block may be erased
without affecting data stored in other blocks. These
memory blocks are read, written and erased with com-
mands to the command execution logic (CEL). The CEL
controls the operation of the internal state machine
(ISM), which completely controls all WRITE, BLOCK
ERASE and VERIFY operations. The ISM protects each
memory location from over-erasure and optimizes each
memory location for maximum data retention. In addi-
tion, the ISM greatly simplifies the control necessary
for writing the device in-system or in an external
programmer.
mation on the operation of the MT28F004B5 and
MT28F400B5 and is organized into these sections:
OVERVIEW
SMART 5 TECHNOLOGY (B5)
in-system READ, WRITE and ERASE operations. For 5V-
only systems, WRITE and ERASE operations may be
executed with a V
technology advances, 5V V
and production programming. For backward compat-
ibility with SmartVoltage technology, 12V V
ported for a maximum of 100 cycles and may be
connected for up to 100 cumulative hours. However,
no performance increase will be realized. For any opera-
tion, V
SEVEN INDEPENDENTLY ERASABLE MEMORY
BLOCKS
into seven independently erasable memory blocks that
allow portions of the memory to be erased without
affecting the rest of the memory data. A special boot
block is hardware-protected against inadvertent era-
sure or writing by requiring either a super-voltage on
4Mb Smart 5 Boot Block Flash Memory
F44_B.p65 – Rev. 7/02
The MT28F004B5 and MT28F400B5 flash memory
The Functional Description provides detailed infor-
• Overview
• Memory Architecture
• Output (READ) Operations
• Input Operations
• Command Set
• ISM Status Register
• Command Execution
• Error Handling
• WRITE/ERASE Cycle Endurance
• Power Usage
• Power-Up
Smart 5 technology allows maximum flexibility for
The MT28F004B5 and MT28F400B5 are organized
CC
may be at 5V.
PP
voltage of 5V. Due to process
PP
is optimal for application
PP
is sup-
SMART 5 BOOT BLOCK FLASH MEMORY
7
the RP# pin or driving the WP# pin HIGH. One of these
two conditions must exist along with the V
(5V or 12V) on the V
be performed on the boot block. The remaining blocks
require that only the V
pin before writing or erasing.
HARDWARE-PROTECTED BOOT BLOCK
written only when the RP# pin is taken to V
the WP# pin is brought HIGH. This provides additional
security for the core firmware during in-system firm-
ware updates should an unintentional power fluctua-
tion or system reset occur. The MT28F004B5 and
MT28F400B5 are available with the boot block starting
at the bottom of the address space (“B” suffix) or the top
of the address space (“T” suffix).
SELECTABLE BUS SIZE (MT28F400B5 ONLY)
(512K x 8) or 16-bit (256K x 16) data bus for reading and
writing the memory. The BYTE# pin is used to select the
bus width. In the x16 configuration, control data is read
or written only on the lower eight bits (DQ0-DQ7).
data pins for the selected configuration. When the x8
configuration is selected, data is written in byte form;
when the x16 configuration is selected, data is written
in word form.
INTERNAL STATE MACHINE (ISM)
simplified with an ISM that controls all erase and write
algorithms in the memory array. The ISM ensures
protection against overerasure and optimizes write
margin to each cell.
increments and monitors WRITE attempts, verifies write
margin on each memory cell and updates the ISM status
register. When BLOCK ERASE is performed, the ISM
automatically overwrites the entire addressed block
(eliminates overerasure), increments and monitors
ERASE attempts, and sets bits in the ISM status register.
ISM STATUS REGISTER
to monitor the status of the ISM during WRITE and
ERASE operations. Two bits of the 8-bit status register
are set and cleared entirely by the ISM. These bits
indicate whether the ISM is busy with a WRITE or
ERASE task and when an ERASE has been suspended.
Additional error information is set in three other bits:
V
PP
This block of the memory array can be erased or
The MT28F400B5 allows selection of an 8-bit
Data written to the memory array utilizes all active
BLOCK ERASE and BYTE/WORD WRITE timing are
During WRITE operations, the ISM automatically
The ISM status register allows an external processor
status, write status and erase status.
Micron Technology, Inc., reserves the right to change products or specifications without notice.
PP
pin before a WRITE or ERASE will
PP
voltage be present on the V
©2002, Micron Technology, Inc.
HH
PP
4Mb
or when
voltage
PP