CY7C271 Datasheet, PDF (4/11 Pages) Cypress Semiconductor – 32K x 8 Power Switched and Reprogrammable PROM

CY7C271
CY7C274
Switching Waveform
V_CC
SUPPLY
CURRENT
A₀ − A₁₄
ADDRESS
t_PD
50%
t_{PU POWER-DOWN CONTROLLED BY CE}
50%
CS₂
OE, CE, CS₁^[7]
t_AA
t_OH
O₀ - O_{7 PREVIOUS DATA VALID}
(t_HZOE)
t_HZCS(E)
DATA VALID
(t_OE)
t_ACS(E)
HIGH Z
Note:
7. CS₂ and CS₁ are used on the 7C271 only. OE is used on the 7C274 only.
Erasure Characteristics
Wavelengths of light less than 4000 angstroms begin to erase
the CY7C271 and CY7C274 in the windowed package. 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 × exposure time) of 25 Wsec/cm². For an ultraviolet lamp
with a 12 mW/cm² power rating, the exposure time would be approx-
imately 35 minutes. The CY7C271 or CY7C274 needs 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/cm² is the recommended 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
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. CY7C271 Mode Selection
Pin Function^[8]
Read or Output Disable
Mode
Other
Read
Power Down
Output Disable
Output Disable
Program
Program Verify
Program Inhibit
Blank Check
A₁₄–A₀
A₁₄–A₀
A₁₄–A₀
A₁₄–A₀
A₁₄–A₀
A₁₄–A₀
A₁₄–A₀
A₁₄–A₀
A₁₄–A₀
A₁₄–A₀
CE
VFY
V_IL
V_IH
X
X
V_IHP
V_ILP
V_IHP
V_ILP
CS₂
PGM
V_IH
X
V_IL
X
V_ILP
V_IHP/V_ILP
V_IHP
V_IHP/V_ILP
CS₁
V_PP
V_IL
X
X
V_IH
V_PP
V_PP
V_PP
V_PP
O₇–O₀
D₇–D₀
O₇–O₀
High Z
High Z
High Z
D₇–D₀
O₇–O₀
High Z
O₇–O₀
Document #: 38-04008 Rev. *B
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