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CY7C1350G
Document #: 38-05524 Rev. *F Page 5 of 15
On the subsequent clock rise the data lines are automatically
tri-stated regardless of the state of the OE
input signal. This
allows the external logic to present the data on DQs
and
DQP
[A:D]
. In addition, the address for the subsequent access
(Read/Write/Deselect) is latched into the Address Register
(provided the appropriate control signals are asserted).
On the next clock rise the data presented to DQs
and DQP
[A:D]
(or a subset for Byte Write operations, see Write Cycle
Description table for details) inputs is latched into the device
and the write is complete.
The data written during the Write operation is controlled by
BW
[A:D]
signals. The CY7C1350G provides byte write
capability that is described in the Write Cycle Description table.
Asserting the Write Enable input (WE) with the selected Byte
Write Select (BW
[A:D]
) input will selectively write to only the
desired bytes. Bytes not selected during a Byte Write
operation will remain unaltered. A synchronous self-timed
write mechanism has been provided to simplify the write
operations. Byte write capability has been included in order to
greatly simplify Read/Modify/Write sequences, which can be
reduced to simple byte write operations.
Because the CY7C1350G is a common I/O device, data
should not be driven into the device while the outputs are
active. The Output Enable (OE
) can be deasserted HIGH
before presenting data to the DQs
and DQP
[A:D]
inputs. Doing
so will tri-state the output drivers. As a safety precaution, DQs
and DQP
[A:D]
are automatically tri-stated during the data
portion of a write cycle, regardless of the state of OE
.
Burst Write Accesses
The CY7C1350G has an on-chip burst counter that allows the
user the ability to supply a single address and conduct up to
four Write operations without reasserting the address inputs.
ADV/LD
must be driven LOW in order to load the initial
address, as described in the Single Write Access section
above. When ADV/LD is driven HIGH on the subsequent clock
rise, the chip enables (CE
1
, CE
2
, and CE
3
) and WE inputs are
ignored and the burst counter is incremented. The correct
BW
[A:D]
inputs must be driven in each cycle of the burst write
in order to write the correct bytes of data.
Sleep Mode
The ZZ input pin is an asynchronous input. Asserting ZZ
places the SRAM in a power conservation “sleep” mode. Two
clock cycles are required to enter into or exit from this “sleep”
mode. While in this mode, data integrity is guaranteed.
Accesses pending when entering the “sleep” mode are not
considered valid nor is the completion of the operation
guaranteed. The device must be deselected prior to entering
the “sleep” mode. CE
1
, CE
2
, and CE
3
, must remain inactive
for the duration of t
ZZREC
after the ZZ input returns LOW.
Interleaved Burst Address Table
(MODE = Floating or V
DD
)
First Address
A1, A0
Second
Address
A1, A0
Third
Address
A1, A0
Fourth
Address
A1, A0
00 01 10 11
01 00 11 10
10 11 00 01
11 10 01 00
Linear Burst Address Table (MODE = GND)
First Address
A1, A0
Second
Address
A1, A0
Third
Address
A1, A0
Fourth
Address
A1, A0
00 01 10 11
01 10 11 00
10 11 00 01
11 00 01 10
Truth Table
[2, 3, 4, 5, 6, 7, 8]
Operation Address Used CE ZZ ADV/LD WE BW
x
OE CEN CLK DQ
Deselect Cycle None H L L X X X L L-H Tri-State
Continue Deselect Cycle None X L H X X X L L-H Tri-State
Read Cycle (Begin Burst) External L L L H X L L L-H Data Out (Q)
Read Cycle (Continue Burst) Next X L H X X L L L-H Data Out (Q)
NOP/Dummy Read (Begin Burst) External L L L H X H L L-H Tri-State
Dummy Read (Continue Burst) Next X L H X X H L L-H Tri-State
Write Cycle (Begin Burst) External L L L L L X L L-H Data In (D)
Write Cycle (Continue Burst) Next X L H X L X L L-H Data In (D)
Notes:
2. X =”Don't Care.” H = Logic HIGH, L = Logic LOW. CE
stands for ALL Chip Enables active. BW
x
= L signifies at least one Byte Write Select is active, BW
x
= Valid
signifies that the desired byte write selects are asserted, see Write Cycle Description table for details.
3. Write is defined by BW
X
, and WE. See Write Cycle Descriptions table.
4. When a write cycle is detected, all DQs are tri-stated, even during byte writes.
5. The DQ and DQP pins are controlled by the current cycle and the OE
signal. OE is asynchronous and is not sampled with the clock.
6. CEN
= H, inserts wait states.
7. Device will power-up deselected and the DQs in a tri-state condition, regardless of OE
.
8. OE
is asynchronous and is not sampled with the clock rise. It is masked internally during write cycles. During a read cycle DQs and DQP
[A:D]
= tri-state when
OE
is inactive or when the device is deselected, and DQs and DQP
[A:D]
= data when OE is active.
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