CY7C1546V18
CY7C1557V18
CY7C1548V18
CY7C1550V18
Document Number: 001-06550 Rev. *D
Page 6 of 27
Pin Definitions
Pin Name
IO
Pin Description
DQ[x:0]
Input and
Output
Synchronous
Data Input or Output Signals. Inputs are sampled on the rising edge of K and K clocks during valid
write operations. These pins drive out the requested data during a read operation. Valid data is driven
out on the rising edge of both the K and K clocks during read operations. When read access is
deselected, Q[x:0] are automatically tri-stated.
CY7C1546V18
− DQ[7:0]
CY7C1557V18
− DQ[8:0]
CY7C1548V18
− DQ[17:0]
CY7C1550V18
− DQ[35:0]
LD
Input
Synchronous
Synchronous Load. Sampled on the rising edge of the K clock. This input is brought LOW when a
bus cycle sequence is defined. This definition includes address and read or write direction. All trans-
actions operate on a burst of 2 data. LD must meet the setup and hold times around edge of K.
NWS0, NWS1 Input
Synchronous
Nibble Write Select 0, 1, Active LOW (CY7C1546V18 only). Sampled on the rising edge of the K
and K clocks during write operations. Used to select the nibble that is written into the device during
the current portion of the write operations. Nibbles not written remain unaltered.
NWS0 controls D[3:0] and NWS1 controls D[7:4].
All the Nibble Write Selects are sampled on the same edge as the data. Deselecting a Nibble Write
Select ignores the corresponding nibble of data and does not write into the device.
BWS0, BWS1,
BWS2, BWS3
Input
Synchronous
Byte Write Select 0, 1, 2, and 3, Active LOW. Sampled on the rising edge of the K and K clocks
during write operations. Used to select the byte written into the device during the current portion of
the write operations. Bytes not written remain unaltered.
CY7C1557V18
− BWS0 controls D[8:0]
CY7C1548V18
− BWS0 controls D[8:0] and BWS1 controls D[17:9].
CY7C1550V18
− BWS0 controls D[8:0], BWS1 controls D[17:9], BWS2 controls D[26:18] and BWS3
controls D[35:27].
All the Byte Write Selects are sampled on the same edge as the data. Deselecting a Byte Write Select
ignores the corresponding byte of data and does not write into the device.
A
Input
Synchronous
Address Inputs. Sampled on the rising edge of the K clock during active read and write operations.
These address inputs are multiplexed for both read and write operations. Internally, the device is
organized as 8M x 8 (2 arrays each of 4M x 8) for CY7C1546V18, 8M x 9 (2 arrays each of 4M x 9)
for CY7C1557V18, 4M x 18 (2 arrays each of 2M x 18) for CY7C1548V18, and 2M x 36 (2 arrays
each of 1M x 36) for CY7C1550V18.
R/W
Input
Synchronous
Synchronous Read or Write Input. When LD is LOW, this input designates the access type (read
when R/W is HIGH, write when R/W is LOW) for loaded address. R/W must meet the setup and hold
times around edge of K.
QVLD
Valid output
indicator
Valid Output Indicator. The Q Valid indicates valid output data. QVLD is edge aligned with CQ and
CQ.
K
Input
Clock
Positive Input Clock Input. The rising edge of K is used to capture synchronous inputs to the device
and to drive out data through Q[x:0] when in single clock mode. All accesses are initiated on the rising
edge of K.
K
Input
Clock
Negative Input Clock Input. K is used to capture synchronous data presented to the device and to
drive out data through Q[x:0] when in single clock mode.
CQ
Clock Output Synchronous Echo Clock Outputs. This is a free running clock and is synchronized to the input
clock (K) of the DDR-II+. The timing for the echo clocks is shown in “Switching Characteristics” on
page 22.
CQ
Clock Output Synchronous Echo Clock Outputs. This is a free running clock and is synchronized to the input
clock (K) of the DDR-II+. The timing for the echo clocks is shown in “Switching Characteristics” on
page 22.
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