WE512K8, WE256K8,
WE128K8-XCX
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.
A polled byte write sequence would consist of the following steps:
1. write byte to EEPROM
2. store last byte and last address written
3. release a time slice to other tasks
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/O7
complemented during the programming cycle, and I/O7 true after
completion.
4. read byte from EEPROM - last address
5. compare I/O7 to stored value
a) If different, write cycle is not completed, go to step 3.
b) If same, write cycle is completed, go to step 1 or step 3.
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/O7. For example, if the data written consisted of I/O7 =
HIGH, then the data read back would consist of I/O7 = LOW.
DATA POLLING AC CHARACTERISTICS
VCC = 5.0V, VSS = 0V, -55°C ≤ TA ≤ +125°C
512Kx8 256Kx8
128Kx8
Parameter
Symbol
Unit
Min
10
Max
Min
0
Max
Min
0
Max
Data Hold Time
tDH
tOEH
tOE
ns
ns
ns
ns
Output Enable Hold Time
Output Enable To Output Delay
Write Recovery Time
10
0
0
100
100
100
tWR
0
0
0
FIGURE 8 – DATA POLLING WAVEFORMS
WE1-4
CS1-4
#
#
OE#
I/O7
ADDRESS
Microsemi Corporation reserves the right to change products or specifications without notice.
August 2011 © 2011 Microsemi Corporation. All rights reserved.
Rev. 4
8
Microsemi Corporation • (602) 437-1520 • www.microsemi.com
MERCURY [ MERCURY UNITED ELECTRONICS INC ]
