LH28F800BG Sharp Electrionic Components, LH28F800BG Datasheet - Page 8

• Manufacturer Part Number: LH28F800BG
• Description: 8 M-bit (512 kB x 16) SmartVoltage Flash Memory
• Manufacturer: Sharp Electrionic Components

2 PRINCIPLES OF OPERATION
The LH28F800BG-L SmartVoltage flash memory
includes an on-chip WSM to manage block erase
and word write functions. It allows for : 100% TTL-
level control inputs, fixed power supplies during
block erasure and word write, and minimal
processor overhead with RAM-like interface timings.
After initial device power-up or return from deep
power-down mode (see Table 2 "Bus Operations"),
the
Manipulation of external memory control pins allow
array read, standby and output disable operations.
Status register and identifier codes can be
accessed through the CUI independent of the V
voltage. High voltage on V
block erasure and word writing. All functions
associated with altering memory contents—block
erase, word write, status and identifier codes—are
accessed via the CUI and verified through the
status register.
Commands are written using standard micro-
processor write timings. The CUI contents serve as
input to the WSM, which controls the block erase
and word write. The internal algorithms are
regulated by the WSM, including pulse repetition,
internal verification and margining of data.
Addresses and data are internally latched during
write cycles. Writing the appropriate command
outputs array data, accesses the identifier codes or
outputs status register data.
Interface software that initiates and polls progress
of block erase and word write can be stored in any
block. This code is copied to and executed from
system RAM during flash memory updates. After
successful completion, reads are again possible via
the Read Array command. Block erase suspend
allows system software to suspend a block erase to
read/write data from/to blocks other than that which
is suspended. Word write suspend allows system
device
defaults
to
PP
read
enables successful
array
mode.
PP
- 8 -
software to suspend a word write to read data from
any other flash memory array location.
2.1 Data Protection
Depending on the application, the system designer
may choose to make the V
switchable (available only when memory block
erases or word writes are required) or hardwired to
V
practice and encourages optimization of the
processor-memory interface.
When V
altered. The CUI, with two-step block erase or word
write command sequences, provides protection
from unwanted operations even when high voltage
is applied to V
when V
or when RP# is at V
locking capability for RP# provides additional
protection from inadvertent code or data alteration
by block erase and word write operations. Refer to
Table 5 for write protection alternatives.
3 BUS OPERATION
The local CPU reads and writes flash memory in-
system. All bus cycles to or from the flash memory
conform to standard microprocessor bus cycles.
3.1 Read
Information can be read from any block, identifier
codes or status register independent of the V
voltage. RP# can be at either V
The first task is to write the appropriate read mode
command (Read Array, Read Identifier Codes or
Read Status Register) to the CUI. Upon initial
device power-up or after exit from deep power-
down mode, the device automatically resets to read
array mode. Four control pins dictate the data flow
in and out of the component : CE#, OE#, WE# and
RP#. CE# and OE# must be driven active to obtain
PPH1/2/3
CC
PP
. The device accommodates either design
is below the write lockout voltage V
≤ V
PP
PPLK
. All write functions are disabled
LH28F800BG-L (FOR SOP)
, memory contents cannot be
IL
. The device’s boot blocks
IH
PP
or V
power supply
HH
.
LKO
PP