CAT28C256
Page Write
(which can be loaded in any order) during the first and
subsequent write cycles. Each successive byte load
cycle must begin within tBLC MAX of the rising edge of the
preceding WE pulse. There is no page write window
The page write mode of the CAT28C256 (essentially an
extended BYTE WRITE mode) allows from 1 to 64 bytes
of data to be programmed within a single E2PROM write
cycle. This effectively reduces the byte-write time by a
factor of 64.
limitation as long as WE is pulsed low within tBLC MAX
.
Upon completion of the page write sequence, WE must
stay high a minimum of tBLC MAX for the internal auto-
matic program cycle to commence. This programming
cycle consists of an erase cycle, which erases any data
that existed in each addressed cell, and a write cycle,
whichwritesnewdatabackintothecell. Apagewritewill
only write data to the locations that were addressed and
will not rewrite the entire page.
FollowinganinitialWRITEoperation(WEpulsedlow,for
tWP, and then high) the page write mode can begin by
issuing sequential WE pulses, which load the address
anddatabytesintoa64bytetemporarybuffer. Thepage
address where data is to be written, specified by bits A6
to A14, is latched on the last falling edge of WE. Each
byte within the page is defined by address bits A0 to A5
Figure 5. Byte Write Cycle [CE Controlled]
t
WC
ADDRESS
t
t
t
BLC
AS
AH
t
CW
CE
OE
WE
t
OEH
t
OES
t
t
CH
CS
HIGH-Z
DATA OUT
DATA IN
DATA VALID
DS
t
t
DH
5096 FHD F07
Figure 6. Page Mode Write Cycle
OE
CE
WE
t
t
BLC
WP
ADDRESS
I/O
t
WC
LAST BYTE
BYTE n+2
BYTE 0 BYTE 1
BYTE 2
7
BYTE n
BYTE n+1
5096 FHD F10
Doc. No. 25020-0A 2/98
CATALYST [ CATALYST SEMICONDUCTOR ]
