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CY7C291A
CY7C292A/CY7C293A
6
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 inten-
sity 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 ex-
posed 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 pack-
ages, please see the PROM Programming Information located
at the end of this section. Programming algorithms can be ob-
tained from any Cypress representative.
Table 1. Mode Selection
Pin Function
[7]
Read or Output Disable A
10
− A
0
CS
3
CS
2
CS
1
O
7
− O
0
Mode Other A
10
− A
0
PGM VFY V
PP
D
7
− D
0
Read A
10
− A
0
V
IH
V
IH
V
IL
O
7
− O
0
Output Disable
[8]
A
10
− A
0
X X V
IH
High Z
Output Disable A
10
− A
0
X V
IL
X High Z
Output Disable A
10
− A
0
V
IL
X X High Z
Program A
10
− A
0
V
ILP
V
IHP
V
PP
D
7
− D
0
Program Verify A
10
− A
0
V
IHP
V
ILP
V
PP
O
7
− O
0
Program Inhibit A
10
− A
0
V
IHP
V
IHP
V
PP
High Z
Intelligent Program A
10
− A
0
V
ILP
V
IHP
V
PP
D
7
− D
0
Blank Check Zeros A
10
− A
0
V
IHP
V
ILP
V
PP
Zeros
Notes:
7. X = “don’t care” but not to exceed V
CC
+5%.
8. The power-down mode for the CY7C293A is activated by deselecting CS
1
.
Figure 1. Programming Pinouts
C291A-8
C291A-9
1
2
3
4
5
6
7
8
9
10
11
12
16
17
18
19
20
24
23
22
21
13
14
A
8
A
7
A
6
A
5
A
4
A
3
A
2
A
1
A
0
D
0
D
1
D
2
GND
V
CC
D
7
D
6
D
4
D
5
D
3
15
A
9
A
10
V
PP
VFY
PGM
28
4
5
6
7
8
9
10
321 27
1314151617
26
25
24
23
22
21
20
11
12
19D
0
18
NC
A
0
A
4
A
3
D
7
D
6
A
2
A
1
A
10
V
PP
VFY
PGM
NC
DIP LCC/PLCC (Opaque Only)
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7C291A
7C291A
7C292A
7C293A
7C293A