4-MBIT SmartVoltage BOOT BLOCK FAMILY
E
For program and erase operations, 5V VPP
operation eliminates the need for in system voltage
converters, while 12V VPP operation provides faster
program and erase for situations where 12V is
available, such as manufacturing or designs where
12V is in-system. For design simplicity, however,
just hook up VCC and VPP to the same 5V ± 10%
source.
Each byte or word in the flash memory can be
programmed independently of other memory
locations, unlike erases, which erase all locations
within a block simultaneously.
The 4-Mbit SmartVoltage boot block flash memory
family is also designed with an Automatic Power
Savings (APS) feature which minimizes system
battery current drain, allowing for very low power
designs. To provide even greater power savings,
the boot block family includes a deep power-down
mode which minimizes power consumption by
turning most of the flash memory’s circuitry off.
This mode is controlled by the RP# pin and its
usage is discussed in Section 3.5, along with other
power consumption issues.
The 28F400/28F004B boot block flash memory
family is a high-performance, 4-Mbit (4,194,304 bit)
flash memory family organized as either
256 Kwords of 16 bits each (28F400 only) or
512 Kbytes of 8 bits each (28F400 and 28F004B).
Separately erasable blocks, including a hardware-
lockable boot block (16,384 bytes), two parameter
blocks (8,192 bytes each) and main blocks (one
block of 98,304 bytes and three blocks of 131,072
bytes), define the boot block flash family
architecture. See Figures 7 and 8 for memory
maps. Each block can be independently erased and
programmed 100,000 times at commercial
temperature or 10,000 times at extended
temperature.
Additionally, the RP# pin provides protection
against unwanted command writes due to invalid
system bus conditions that may occur during
system reset and power-up/down sequences. For
example, when the flash memory powers-up, it
automatically defaults to the read array mode, but
during
a
warm system reset, where power
continues uninterrupted to the system components,
the flash memory could remain in a non-read mode,
such as erase. Consequently, the system Reset
signal should be tied to RP# to reset the memory to
normal read mode upon activation of the Reset
signal. See Section 3.6.
The boot block is located at either the top (denoted
by -T suffix) or the bottom (-B suffix) of the address
map in order to accommodate different
microprocessor protocols for boot code location.
The hardware-lockable boot block provides
complete code security for the kernel code required
for system initialization. Locking and unlocking of
the boot block is controlled by WP# and/or RP#
(see Section 3.4 for details).
The 28F400 provides both byte-wide or word-wide
input/output, which is controlled by the BYTE# pin.
Please see Table 2 and Figure 16 for a detailed
description of BYTE# operations, especially the
usage of the DQ
15/A–1 pin.
The Command User Interface (CUI) serves as the
interface
between
the
microprocessor
or
The 28F400 products are available in
a
microcontroller and the internal operation of the
boot block flash memory products. The internal
Write State Machine (WSM) automatically executes
the algorithms and timings necessary for program
and erase operations, including verifications,
thereby unburdening the microprocessor or
microcontroller of these tasks. The Status Register
(SR) indicates the status of the WSM and whether it
successfully completed the desired program or
erase operation.
ROM/EPROM-compatible pinout and housed in the
44-lead PSOP (Plastic Small Outline) package, the
48-lead TSOP (Thin Small Outline, 1.2 mm thick)
package and the 56-lead TSOP as shown in
Figures 4,
5 and 6, respectively. The 28F004
products are available in the 40-lead TSOP
package as shown in Figure 3.
Refer to the DC Characteristics Table, Section 5.2
(commercial temperature) and Section 6.2
(extended temperature), for complete current and
voltage specifications. Refer to the AC
Characteristics Table, Section 5.3 (commercial
Program and Erase Automation allows program and
erase operations to be executed using an industry-
standard two-write command sequence to the CUI.
Data writes are performed in word (28F400 family)
or byte (28F400 or 28F004B families) increments.
temperature)
and
Section
6.3
(extended
temperature), for read, write and erase performance
specifications.
6
PRELIMINARY
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