we128k8-300cqa White Electronic Designs Corporation, we128k8-300cqa Datasheet - Page 8

• Manufacturer Part Number: we128k8-300cqa
• Description: 512kx8 Cmos Eeprom, We512k8-xcx, 5962-93091
• Manufacturer: White Electronic Designs Corporation

DATA POLLING
Operation with data polling permits a faster method of
writing to the EEPROM. The actual time to complete the
memory programming cycle is faster than the guaranteed
maximum.
The EEPROM features a method to determine when
the internal programming cycle is completed. After a
write cycle is initiated, the EEPROM will respond to read
cycles to provide the microprocessor with the status
of the programming cycle. The status consists of the
last data byte written being returned with data bit I/O
complemented during the programming cycle, and I/O
true after completion.
White Electronic Designs Corp. reserves the right to change products or specifi cations without notice.
May 2000
Rev. 1
Parameter
Data Hold Time
Output Enable Hold Time
Output Enable To Output Delay
Write Recovery Time
White Electronic Designs
ADDRESS
Symbol
WE
t
CS
t
t
t
OEH
WR
DH
OE
OE#
I/O
1-4
1-4
FIGURE 8 – DATA POLLING WAVEFORMS
DATA POLLING AC CHARACTERISTICS
#
#
7
Min
V
10
10
0
CC
= 5.0V, V
512Kx8
SS
Max
100
= 0V, -55°C ≤ T
7
7
8
Data polling allows a simple bit test operation to
determine the status of the EEPROM. During the internal
programming cycle, a read of the last byte written will
produce the complement of the data on I/O
if the data written consisted of I/O
read back would consist of I/O
A polled byte write sequence would consist of the following
steps:
1.
2.
3.
4.
5.
Min
write byte to EEPROM
store last byte and last address written
release a time slice to other tasks
read byte from EEPROM - last address
compare I/O
a) If different, write cycle is not completed, go to
b) If same, write cycle is completed, go to step 1 or
A
0
0
0
≤ +125°C
step 3.
step 3.
White Electronic Designs Corporation • [phone] • www.wedc.com
256Kx8
Max
100
7
to stored value
WE512K8, WE256K8,
Min
0
0
0
7
128Kx8
= LOW.
WE128K8-XCX
7
= HIGH, then the data
Max
100
7
. For example,
Unit
ns
ns
ns
ns