AS28C010 Просмотр технического описания (PDF) - Micross Components
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AS28C010 Datasheet PDF : 15 Pages
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EEPROM
AS28C010
FUNCTIONAL DESCRIPTION
READ
Read operations are initiated by both OE\ and CE\
LOW. The read operation is terminated by either CE\ or OE\
returning HIGH. This two line control architecture eliminates
bus contention in a system environment. The data bus will be
in a high impedance state when either OE\ or CE\ is HIGH.
WRITE
Write operations are initiated when both CE\ and WE\ are
LOW and OE\ is HIGH. The AS28C010 supports both a CE\
and WE\ controlled write cycle. That is, the address is latched
by the falling edge of either CE\ or WE\, whichever occurs
last. Similarly, the data is latched internally by the rising edge
of either CE\ or WE\, whichever occurs first. A byte write
operation, once initiated, will automatically continue to
completion, typically within 5ms.
PAGE WRITE
The page write feature of the AS28C010 allows the entire
memory to be written in 5 seconds. Page write allows two to
two hundred fifty-six bytes of data to be consecutively written
to the AS28C010 prior to the commencement of the internal
programming cycle. The host can fetch data from another
device within the system during a page write operation (change
the source address), but the page address (A8 through A16)
for each subsequent valid write cycle to the part during this
operation must be the same as the initial page address.
I/O
DP
TB
5
4
3
2
1
0
RESERVED
TOGGLE BIT
DATA\ POLLING
DATA\ POLLING
The AS28C010 features DATA\ Polling as a method to
indicate to the host system that the byte write or page write
cycle has completed. DATA\ Polling allows a simple bit
test operation to determine the status of the AS28C010,
eliminating additional interrupt inputs or external hardware.
During the internal programming cycle, any attempt to
read the last byte written will produce the complement of that
data on I/O7 (i.e., write data = 0xxx xxxx, read data = 1xxx
xxxx). Once the programming cycle is complete, I/O7 will reflect
true data. Note: If the AS28C010 is in the protected state and
an illegal write operation is attempted DATA\ Polling will not
operate.
TOGGLE BIT
The AS28C010 also provides another method for
determining when the internal write cycle is complete. During
the internal programming cycle, I/O6 will toggle from HIGH to
LOW and LOW to HIGH on subsequent attempts to read the
device. When the internal cycle is complete the toggling will
cease and the device will be accessible for additional read or
write operations.
The page write mode can be initiated during any write operation.
Following the initial byte write cycle, the host can write an
additional one to two hundred fifty six bytes in the same manner
as the first byte was written. Each successive byte load cycle,
started by the WE\ HIGH to LOW transition, must begin within
100μs of the falling edge of the preceding WE\. If a subsequent
WE\ HIGH to LOW transition is not detected within 100μs, the
internal automatic programming cycle will commence. There
is no page write window limitation. Effectively the page write
window is infinitely wide, so long as the host continues to access
the device within the byte load cycle time of 100μs.
WRITE
The AS28C010 provides the user two write operation
status bits. These can be used to optimize a system write cycle
time. The status bits are mapped onto the I/O bus as shown in
Figure 1.
Figure 1: Status Bit Assignment
AS28C010
Rev. 1.7 01/12
Micross Components reserves the right to change products or specifications without notice.
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