參數(shù)資料
型號: CY27C256-45WC
廠商: CYPRESS SEMICONDUCTOR CORP
元件分類: DRAM
英文描述: 32K x 8-Bit CMOS EPROM
中文描述: 32K X 8 UVPROM, 45 ns, CDIP28
封裝: 0.600 INCH, WINDOWED, CERDIP-28
文件頁數(shù): 5/11頁
文件大?。?/td> 260K
代理商: CY27C256-45WC
CY27C256
5
Erasure Characteristics
Wavelengths of light less than 4000 begin to erase the
27C256 in the windowed package. For this reason, an opaque
label should be placed over the window if the EPROM is ex-
posed to sunlight or fluorescent lighting for extended periods
of time.
The recommended dose of ultraviolet light for erasure is a
wavelength of 2537 for a minimum dose (UV intensity mul-
tiplied by exposure time) of 25 Wsec/cm2. For an ultraviolet
lamp with a 12 mW/cm
2
power rating, the exposure time would
be approximately 35 minutes. The CY27C256 needs to be
within 1 inch of the lamp during erasure. Permanent damage
may result if the EPROM is exposed to high-intensity UV light
for an extended period of time. 7258 Wsec/cm
2
is the recom-
mended maximum dosage.
Programming Modes
Programming support is available from Cypress as well as
from a number of third-party software vendors. For detailed
programming information, including a listing of software pack-
ages, please see the EPROM Programming Information locat-
ed at the end of this section. Programming algorithms can be
obtained from any Cypress representative.
Switching Waveform
t
OH
t
PU
t
PD
t
AA
27c256–8
(t
OE
)
t
ACE
50%
50%
A
- A
ADDRESS
I
SUPPLY
CURRENT
OE, CE
O
0
- O
7
PREVIOUS DATA VALID
DATA VALID
POWER–DOWN CONTROLLED BY CE
(t
HZOE
)
t
HZCE
HIGH Z
Table 1. CY27C256 Mode Selection.
Mode
Pin Function
[8]
A
14
-A
0
OE
CE
V
PP
X
[9]
O
7
-O
0
Read
A
14
-A
0
V
IL
V
IL
O
7
-O
0
Output Disable
A
14
-A
0
V
IH
V
IL
X
High Z
Power Down
A
14
-A
0
X
V
IH
X
High Z
Notes:
8.
9.
X can be V
or V
V
PP
should not exceed V
CC
in read mode.
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