AS7C252MFT18A
®
Write enable truth table (per byte)
Function
GWE BWE
BWa
X
BWb
X
L
H
H
H
H
H
X
L
L
L
H
L
Write All Bytes
L
L
Write Byte a
Write Byte b
L
H
H
L
X
X
Read
H
H
Key: X = don’t care, L = low, H = high, n = a, b; BWE
,
BWn = internal write signal.
Asynchronous Truth Table
Operation
Snooze mode
ZZ
H
L
OE
X
I/O Status
High-Z
L
Dout
Read
L
H
High-Z
Write
L
X
Din, High-Z
High-Z
Deselected
L
X
Notes:
1. X means “Don’t Care”
2. ZZ pin is pulled down internally
3. For write cycles that follows read cycles, the output buffers must be disabled with OE, otherwise data bus contention will occur.
4. Snooze mode means power down state of which stand-by current does not depend on cycle times
5. Deselected means power down state of which stand-by current depends on cycle times
Burst sequence table
Interleaved burst address (LBO = 1)
A1 A0 A1 A0 A1 A0 A1 A0
Linear burst address (LBO = 0)
A1 A0 A1 A0 A1 A0 A1 A0
1st Address
2nd Address
3rd Address
4th Address
0 0
0 1
1 0
1 1
0 1
0 0
1 1
1 0
1 0
1 1
0 0
0 1
1 1
1 0
0 1
0 0
1st Address
2nd Address
3rd Address
4th Address
0 0
0 1
1 0
1 1
0 1
1 0
1 1
1 0
1 0
1 1
0 0
0 1
1 1
0 0
0 1
1 0
1/17/05, v 1.2
Alliance Semiconductor
6 of 19
ISSI [ INTEGRATED SILICON SOLUTION, INC ]
