cy27c256-120zc Cypress Semiconductor Corporation., cy27c256-120zc Datasheet - Page 5

• Manufacturer Part Number: cy27c256-120zc
• Description: 32k X 8-bit Cmos Eprom Semiconductor
• Manufacturer: Cypress Semiconductor Corporation.

Switching Waveform
Erasure Characteristics
Wavelengths of light less than 4000 Å 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 Å for a minimum dose (UV intensity mul-
tiplied by exposure time) of 25 Wsec/cm2. For an ultraviolet
lamp with a 12 mW/cm
be approximately 35 minutes. The CY27C256 needs to be
Table 1. CY27C256 Mode Selection.
CURRENT
ADDRESS
Mode
Read
Output Disable
Power Down
Notes:
A
8.
9.
O
SUPPLY
0
OE, CE
0
- A
- O
X can be V
V
PP
I
CC
14
7
should not exceed V
PREVIOUS DATA VALID
IL
or V
IH
A
A
A
A
2
power rating, the exposure time would
14
14
14
14
CC
-A
-A
-A
-A
in read mode.
0
0
0
0
t
OH
t
AA
OE
V
V
X
IL
IH
DATA VALID
t
PD
(t
t
HZOE
HZCE
)
50%
5
CE
V
V
V
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
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.
IL
IL
IH
Pin Function
t
PU
HIGH Z
[8]
50%
(t
t
POWER–DOWN CONTROLLED BY CE
ACE
OE
V
X
X
X
)
PP
[9]
O
O
High Z
High Z
CY27C256
7
7
-O
-O
0
0
2
is the recom-
27c256–8