CY7C1546V18, CY7C1557V18
CY7C1548V18, CY7C1550V18
Document Number: 001-06550 Rev. *E
Page 10 of 28
Truth Table
The truth table for CY7C1546V18, CY7C1557V18, CY7C1548V18, and CY7C1550V18 follows.
[3, 4, 5, 6, 7, 8]
Operation
K
LD
R/W
DQ
DQ
Write Cycle:
Load address; wait one cycle;
input write data on consecutive K and K rising edges.
L-H
L
L
D(A) at K(t + 1)
↑
D(A+1) at K(t + 1)
↑
Read Cycle: (2.0 cycle Latency)
Load address; wait two cycle;
read data on consecutive K and K rising edges.
L-H
L
H
Q(A) at K(t + 2)
↑
Q(A+1) at K(t + 2)
↑
NOP: No Operation
L-H
H
X
High Z
High Z
Standby: Clock Stopped
Stopped
X
X
Previous State
Previous State
Write Cycle Descriptions
The write cycle description table for CY7C1546V18 and CY7C1548V18 follows.
[3, 9]
BWS
0
/
NWS
0
BWS
1
/
NWS
1
K
K
Comments
L
L
L–H
–
During the data portion of a write sequence
:
CY7C1546V18
−
both nibbles (D
[7:0]
) are written into the device.
CY7C1548V18
−
both bytes (D
[17:0]
) are written into the device.
L
L
–
L-H During the data portion of a write sequence
:
CY7C1546V18
−
both nibbles (D
[7:0]
) are written into the device.
CY7C1548V18
−
both bytes (D
[17:0]
) are written into the device.
L
H
L–H
–
During the data portion of a write sequence
:
CY7C1546V18
−
only the lower nibble (D
[3:0]
) is written into the device, D
[7:4]
remains unaltered.
CY7C1548V18
−
only the lower byte (D
[8:0]
) is written into the device, D
[17:9]
remains unaltered.
L
H
–
L–H During the data portion of a write sequence
:
CY7C1546V18
−
only the lower nibble (D
[3:0]
) is written into the device, D
[7:4]
remains unaltered.
CY7C1548V18
−
only the lower byte (D
[8:0]
) is written into the device, D
[17:9]
remains unaltered.
H
L
L–H
–
During the data portion of a write sequence
:
CY7C1546V18
−
only the upper nibble (D
[7:4]
) is written into the device, D
[3:0]
remains unaltered.
CY7C1548V18
−
only the upper byte (D
[17:9]
) is written into the device, D
[8:0]
remains unaltered.
H
L
–
L–H During the data portion of a write sequence
:
CY7C1546V18
−
only the upper nibble (D
[7:4]
) is written into the device, D
[3:0]
remains unaltered.
CY7C1548V18
−
only the upper byte (D
[17:9]
) is written into the device, D
[8:0]
remains unaltered.
H
H
L–H
–
No data is written into the devices during this portion of a write operation.
H
H
–
L–H No data is written into the devices during this portion of a write operation.
Notes
3. X = “Don’t Care,” H = Logic HIGH, L = Logic LOW,
↑
represents rising edge.
4. Device powers up deselected with the outputs in a tri-state condition.
5. “A” represents address location latched by the devices when transaction was initiated. A + 1 represents the address sequence in the burst.
6. “t” represents the cycle at which a read/write operation is started. t + 1 and t + 2 are the first and second clock cycles succeeding the “t” clock cycle.
7. Data inputs are registered at K and K rising edges. Data outputs are delivered on K and K rising edges.
8. Cypress recommends that K = K = HIGH when clock is stopped. This is not essential but permits most rapid restart by overcoming transmission line charging
symmetrically.
9. Is based on a write cycle is initiated as per the
Write Cycle Descriptions
table. NWS
0
, NWS
1
,
BWS
0
, BWS
1
, BWS
2
,
and BWS
3
is altered on different portions of a write
cycle, as long as the setup and hold requirements are met.
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