White Electronic Designs
WRITE
Write operations are initiated when both CS# and WE#
are low and OE# is high. The EEPROM devices support
both a CS# and WE# controlled write cycle. The address is
latched by the falling edge of either CS# or WE#, whichever
occurs last.
The data is latched internally by the rising edge of either
CS# or WE#, whichever occurs first. A byte write operation
will automatically continue to completion.
WE512K8, WE256K8,
WE128K8-XCX
WRITE CYCLE TIMING
Figures 6 and 7 show the write cycle timing relationships.
A write cycle begins with address application, write enable
and chip select. Chip select is accomplished by placing
the CS# line low. Write enable consists of setting the WE
line low. The write cycle begins when the last of either CS#
or WE# goes low.
The WE# line transition from high to low also initiates
an internal 150µsec delay timer to permit page mode
operation. Each subsequent WE# transition from high to
low that occurs before the completion of the 150µsec time
out will restart the timer from zero. The operation of the
timer is the same as a retriggerable one-shot.
AC WRITE CHARACTERISTICS
V
CC
= 5.0V, V
SS
= 0V, -55°C ≤ T
A
≤ +125°C
Parameter
Write Cycle Time, TYP = 6mS
Address Set-up Time
Write Pulse Width (WE# or CS#)
Chip Select Set-up Time
Address Hold Time (1)
Data Hold Time
Chip Select Hold Time
Data Set-up Time
Output Enable Set-up Time
Output Enable Hold Time
Write Pulse Width High
Symbol
t
WC
t
AS
t
WP
t
CS
t
AH
t
DH
t
CH
t
DS
t
OES
t
OEH
t
WPH
512K x 8
Min
10
150
0
125
10
0
100
10
10
50
Max
10
256K x 8
Min
30
150
0
50
0
0
100
30
0
50
Max
10
128K x 8
Min
30
150
0
50
0
0
100
30
0
50
Max
10
Unit
ms
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
NOTES:
1. A17 and A18 must remain valid through WE# and CS# low pulse, for 512K x 8.
A15, A16, and A17 must remain valid through WE# and CS# low pulse, for 256K x 8.
A15 and A16 must remain valid through WE# and CS# low pulse, for 128K x 8.
White Electronic Designs Corp. reserves the right to change products or specifications without notice.
May 2000
Rev. 1
6
White Electronic Designs Corporation • (602) 437-1520 • www.wedc.com
WEDC [ WHITE ELECTRONIC DESIGNS CORPORATION ]
