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參數(shù)資料
| 型號(hào)： | XM28C020MHR-20 |
| 英文描述： | 5 Volt, Byte Alterable E2PROM |
| 中文描述： | 5伏，可變E2PROM的字節(jié) |
| 文件頁數(shù)： | 3/16頁 |
| 文件大?。?/td> | 74K |
| 代理商： | XM28C020MHR-20 |
XM28C020
3
DEVICE OPERATION
Read
Read operations are initiated by both
OE
and
CE
LOW.
The read operation is terminated by either
CE
or
OE
returning HIGH. This 2-line control architecture elimi-
nates 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 XM28C020 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
, which-
ever occurs first. A byte write operation, once initiated,
will automatically continue to completion, typically within
5ms (see Note 4).
Page Write Operation
The page write feature of the XM28C020 allows the
entire memory to be written in 10 seconds. Page write
allows two to 128 bytes of data to be consecutively
written to the XM28C020 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 (A
7
through A
17
) for each subsequent
valid write cycle to the part during this operation must be
the same as the initial page address.
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 127 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 100
μ
s of the falling edge of
the preceding
WE
. If a subsequent
WE
HIGH to LOW
transition is not detected within 100
μ
s, 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 100
μ
s.
Write Operation Status Bits
The XM28C020 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
5
TB
DP
4
3
2
1
0
I/O
RESERVED
TOGGLE BIT
DATA POLLING
3872 FHD F09
DATA
Polling (I/O
7
)
The XM28C020 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
XM28C020, 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/O
7
(i.e., write
data = 0xxx xxxx, read data = 1xxx xxxx). Once the
programming cycle is complete, I/O
7
will reflect true
data. Note: If the XM28C020 is in the protected state and
an illegal write operation is attempted,
DATA
Polling will
not operate.
Toggle Bit (I/O
6
)
The XM28C020 also provides another method for deter-
mining when the internal write cycle is complete. During
the internal programming cycle I/O
6
will toggle from “1”
to “0” and “0” to “1” on subsequent attempts to read the
last byte written. When the internal cycle is complete the
toggling will cease and the device will be accessible for
additional read or write operations.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| XM28C020MHR-25 | 5 Volt, Byte Alterable E2PROM |
| XM28C020M-12 | 5 Volt, Byte Alterable E2PROM |
| XM28C020M-15 | 5 Volt, Byte Alterable E2PROM |
| XM28C020M-20 | 5 Volt, Byte Alterable E2PROM |
| XM28C020M-25 | 5 Volt, Byte Alterable E2PROM |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| XM28C020MHR-25 | 制造商:XICOR 制造商全稱:Xicor Inc. 功能描述:5 Volt, Byte Alterable E2PROM |
| XM28C020P-12 | 制造商:XICOR 制造商全稱:Xicor Inc. 功能描述:5 Volt, Byte Alterable E2PROM |
| XM28C020P-15 | 制造商:XICOR 制造商全稱:Xicor Inc. 功能描述:5 Volt, Byte Alterable E2PROM |
| XM28C020P-20 | 制造商:XICOR 制造商全稱:Xicor Inc. 功能描述:5 Volt, Byte Alterable E2PROM |
| XM28C020P-25 | 制造商:XICOR 制造商全稱:Xicor Inc. 功能描述:5 Volt, Byte Alterable E2PROM |
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