Cypress Semiconductor CY7C1350G Scheda tecnica - Pagina 5

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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
. In addition, the address for the subsequent access
[A:D]
(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
(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
signals. The CY7C1350G provides byte write
[A:D]
capability that is described in the Write Cycle Description table.
Asserting the Write Enable input (WE) with the selected Byte
Write Select (BW
) input will selectively write to only the
[A:D]
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
so will tri-state the output drivers. As a safety precaution, DQs
and DQP
are automatically tri-stated during the data
[A:D]
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
, CE
1
[2, 3, 4, 5, 6, 7, 8]
Truth Table
Operation
Deselect Cycle
Continue Deselect Cycle
Read Cycle (Begin Burst)
Read Cycle (Continue Burst)
NOP/Dummy Read (Begin Burst)
Dummy Read (Continue Burst)
Write Cycle (Begin Burst)
Write Cycle (Continue Burst)
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
, and WE. See Write Cycle Descriptions table.
X
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
OE is inactive or when the device is deselected, and DQs and DQP
Document #: 38-05524 Rev. *F
[A:D]
inputs. Doing
[A:D]
, and CE
) and WE inputs are
2
3
Address Used
CE
None
H
None
X
External
L
Next
X
External
L
Next
X
External
L
Next
X
= data when OE is active.
[A:D]
ignored and the burst counter is incremented. The correct
BW
inputs must be driven in each cycle of the burst write
[A:D]
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
, CE
1
2
for the duration of t
after the ZZ input returns LOW.
ZZREC
Interleaved Burst Address Table
(MODE = Floating or V
Second
First Address
Address
A1, A0
A1, A0
00
01
01
00
10
11
11
10
Linear Burst Address Table (MODE = GND)
Second
First Address
Address
A1, A0
A1, A0
00
01
01
10
10
11
11
00
ZZ
ADV/LD
WE BW
x
L
L
X
X
L
H
X
X
L
L
H
X
L
H
X
X
L
L
H
X
L
H
X
X
L
L
L
L
L
H
X
L
CY7C1350G
, and CE
, must remain inactive
3
)
DD
Third
Fourth
Address
Address
A1, A0
A1, A0
10
11
11
10
00
01
01
00
Third
Fourth
Address
Address
A1, A0
A1, A0
10
11
11
00
00
01
01
10
OE CEN
CLK
DQ
X
L
L-H
Tri-State
X
L
L-H
Tri-State
L
L
L-H
Data Out (Q)
L
L
L-H
Data Out (Q)
H
L
L-H
Tri-State
H
L
L-H
Tri-State
X
L
L-H
Data In (D)
X
L
L-H
Data In (D)
= tri-state when
[A:D]
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