65
CY7C265
8K x 8 Registered PROM
Features
鈥?CMOS for optimum speed/power
鈥?High speed (Commercial)
鈥?15 ns address set-up
鈥?12 ns clock to output
鈥?Low power
鈥?660 mW (Commercial)
鈥?On-chip edge-triggered registers
鈥?Ideal for pipelined microprogrammed systems
鈥?EPROM technology
鈥?100% programmable
鈥?Reprogrammable (CY7C265W)
鈥?5V
鹵10%
V
CC
, commercial and military
鈥?Capable of withstanding >2001V static discharge
鈥?Slim 28-pin, 300-mil plastic or hermetic DIP
If the asynchronous enable (E) is being used, the outputs may
be disabled at any time by switching the enable to a logic
HIGH, and may be returned to the active state by switching the
enable to a logic LOW.
If the synchronous enable (E
S
) is being used, the outputs will
go to the OFF or high-impedance state upon the next positive
clock edge after the synchronous enable input is switched to
a HIGH level. If the synchronous enable pin is switched to a
logic LOW, the subsequent positive clock edge will return the
output to the active state. Following a positive clock edge, the
address and synchronous enable inputs are free to change
since no change in the output will occur until the next
LOW-to-HIGH transition of the clock. This unique feature al-
lows the CY7C265 decoders and sense amplifiers to access
the next location while previously addressed data remains sta-
ble on the outputs.
If the E/I pin is used for INIT (asynchronous), then the outputs
are permanently enabled. The initialize function is useful
during power-up and time-out sequences, and can facilitate
implementation of other sophisticated functions such as a
built-in 鈥渏ump start鈥?address. When activated, the initialize
control input causes the contents of a user programmed
8193rd 8-bit word to be loaded into the on-chip register. Each
bit is programmable and the initialize function can be used to
load any desired combination of 1鈥檚 and 0鈥檚 into the register.
In the unprogrammed state, activating INIT will generate a
register clear (all outputs LOW). If all the bits of the initialize
word are programmed to be a 1, activating INIT performs a
register preset (all outputs HIGH).
Applying a LOW to the INIT input causes an immediate load
of the programmed initialize word into the pipeline register and
onto the outputs. The INIT LOW disables clock and must
return HIGH to enable clock independent of all other inputs,
including the clock.
Functional Description
The CY7C265 is a 8192 x 8 registered PROM. It is organized
as 8,192 words by 8 bits wide, and has a pipeline output
register. In addition, the device features a programmable
initialize byte that may be loaded into the pipeline register with
the initialize signal. The programmable initialize byte is the
8,193rd byte in the PROM and its value is programmed at the
time of use.
Packaged in 28 pins, the PROM has 13 address signals (A
0
through A
12
), 8 data out signals (O
0
through O
7
), E/I (enable
or initialize), and CLOCK.
CLOCK functions as a pipeline clock, loading the contents of
the addressed memory location into the pipeline register on
each rising edge. The data will appear on the outputs if they
are enabled. One pin on the CY7C265 is programmed to
perform either the enable or the initialize function.
Cypress Semiconductor Corporation
Document #: 38-04012 Rev. *A
鈥?/div>
3901 North First Street
鈥?/div>
San Jose
鈥?/div>
CA 95134 鈥?408-943-2600
Revised October 9, 2002
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