CAT28HT256 Datasheet, PDF(7/10 Page) Catalyst Semiconductor

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CAT28HT256 Datasheet, PDF (7/10 Pages) Catalyst Semiconductor – 256K-Bit CMOS PARALLEL E2PROM

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Advanced

CAT28HT256

DATA Polling

DATA polling is provided to indicate the completion of

write cycle. Once a byte write or page write cycle is

initiated, attempting to read the last byte written will

output the complement of that data on I/O7 (I/O0âI/O6

are indeterminate) until the programming cycle is com-

plete. Upon completion of the self-timed write cycle, all

I/Oâs will output true data during a read cycle.

Figure 6. Page Mode Write Cycle

Toggle Bit

In addition to the DATA Polling feature of the

CAT28HT256, the device offers an additional method

for determining the completion of a write cycle. While a

write cycle is in progress, reading data from the device

will result in I/O6 toggling between one and zero. How-

ever, once the write is complete, I/O6 stops toggling and

valid data can be read from the device.

tWP

tBLC

ADDRESS

I/O

Figure 7. DATA Polling

BYTE 0 BYTE 1

BYTE 2

BYTE n BYTE n+1

tWC

LAST BYTE

BYTE n+2

5096 FHD F10

ADDRESS

I/O7

Figure 8. Toggle Bit

tOEH

DIN = X

tOE

tWC

DOUT = X

tOES

DOUT = X

5096 FHD F11

tOEH

tOE

I/O6

(1)

tWC

Note:

(1) Beginning and ending state of I/O6 is indeterminate.

8-97

tOES

(1)

5096 FHD F12

Stock No. 21065-03 2/98

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