CY7C291A
Erasure Characteristics
Wavelengths of light less than 4000 Angstroms begin to erase
these PROMs. For this reason, an opaque label should be
placed over the window if the PROM is exposed to sunlight or
fluorescent lighting for extended periods of time.
The recommended dose of ultraviolet light for erasure is a
wavelength of 2537 Angstroms for a minimum dose (UV
intensity x 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.
These PROMs need to be within 1 inch of the lamp during
erasure. Permanent damage may result if the PROM is
exposed to high-intensity UV light for an extended period of
time. 7258 Wsec/cm
2
is the recommended maximum dosage.
Programming Information
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
packages, please see the PROM Programming Information
located at the end of this section. Programming algorithms can
be obtained from any Cypress representative.
Table 1. Mode Selection
Pin Function
[5]
Read or Output Disable
Mode
Read
Output Disable
[6]
Output Disable
Output Disable
Program
Program Verify
Program Inhibit
Intelligent Program
Blank Check Zeros
Other
A
10
−A
0
A
10
−A
0
A
10
−A
0
A
10
−A
0
A
10
−A
0
A
10
−A
0
A
10
−A
0
A
10
−A
0
A
10
−A
0
A
10
−A
0
A
10
−A
0
CS
3
PGM
V
IH
X
X
V
IL
V
ILP
V
IHP
V
IHP
V
ILP
V
IHP
CS
2
VFY
V
IH
X
V
IL
X
V
IHP
V
ILP
V
IHP
V
IHP
V
ILP
CS
1
V
PP
V
IL
V
IH
X
X
V
PP
V
PP
V
PP
V
PP
V
PP
O
7
−O
0
D
7
−D
0
O
7
−O
0
High Z
High Z
High Z
D
7
−D
0
O
7
−O
0
High Z
D
7
−D
0
Zeros
Figure 1. Programming Pinouts
DIP
Top View
A
7
A
6
A
5
A
4
A
3
A
2
A
1
A
0
D
0
D
1
D
2
GND
1
24
V
CC
A
8
A
9
A
10
V
PP
VFY
PGM
D
7
D
6
D
5
D
4
D
3
A
4
A
3
A
2
A
1
A
0
NC
D
0
5
6
7
8
9
10
11
LCC/PLCC (Opaque Only)
Top View
A5
A6
A7
NC
V
CC
A8
A9
4 3 2 1 28 27 26
25
24
7C291A
23
22
21
20
19
121314151617 18
A
10
V
PP
VFY
PGM
NC
D
7
D
6
D1
D2
GND
NC
D3
D4
D5
23
2
22
3
7C291A 21
4
20
5
19
6
7
8
9
10
11
12
18
17
16
15
14
13
Notes
5. X = “don’t care” but not to exceed V
CC
+5%.
6. The power-down mode for the CY7C293A is activated by deselecting CS
1
.
Document #: 38-04011 Rev. *B
Page 6 of 13
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