CY7C1370D
CY7C1372D
Document #: 38-05555 Rev. *F
Page 7 of 28
Introduction
Functional Overview
The CY7C1370D and CY7C1372D are synchronous-pipelined
Burst NoBL SRAMs designed specifically to eliminate wait
states during Write/Read transitions. All synchronous inputs
pass through input registers controlled by the rising edge of
the clock. The clock signal is qualified with the Clock Enable
input signal (CEN). If CEN is HIGH, the clock signal is not
recognized and all internal states are maintained. All
synchronous operations are qualified with CEN. All data
outputs pass through output registers controlled by the rising
edge of the clock. Maximum access delay from the clock rise
(tCO) is 2.6 ns (250-MHz device).
Accesses can be initiated by asserting all three Chip Enables
(CE1, CE2, CE3) active at the rising edge of the clock. If Clock
Enable (CEN) is active LOW and ADV/LD is asserted LOW,
the address presented to the device will be latched. The
access can either be a read or write operation, depending on
the status of the Write Enable (WE). BWX can be used to
conduct byte write operations.
Write operations are qualified by the Write Enable (WE). All
writes are simplified with on-chip synchronous self-timed write
circuitry.
Three synchronous Chip Enables (CE1, CE2, CE3) and an
asynchronous Output Enable (OE) simplify depth expansion.
All operations (Reads, Writes, and Deselects) are pipelined.
ADV/LD should be driven LOW once the device has been
deselected in order to load a new address for the next
operation.
Single Read Accesses
A read access is initiated when the following conditions are
satisfied at clock rise: (1) CEN is asserted LOW, (2) CE1, CE2,
and CE3 are ALL asserted active, (3) the Write Enable input
signal WE is deasserted HIGH, and (4) ADV/LD is asserted
LOW. The address presented to the address inputs is latched
into the Address Register and presented to the memory core
and control logic. The control logic determines that a read
access is in progress and allows the requested data to
propagate to the input of the output register. At the rising edge
of the next clock the requested data is allowed to propagate
through the output register and onto the data bus within 2.6 ns
(250-MHz device) provided OE is active LOW. After the first
clock of the read access the output buffers are controlled by
OE and the internal control logic. OE must be driven LOW in
order for the device to drive out the requested data. During the
second clock, a subsequent operation (Read/Write/Deselect)
can be initiated. Deselecting the device is also pipelined.
Therefore, when the SRAM is deselected at clock rise by one
of the chip enable signals, its output will tri-state following the
next clock rise.
Burst Read Accesses
The CY7C1370D and CY7C1372D have an on-chip burst
counter that allows the user the ability to supply a single
address and conduct up to four Reads without reasserting the
address inputs. ADV/LD must be driven LOW in order to load
a new address into the SRAM, as described in the Single Read
Access section above. The sequence of the burst counter is
determined by the MODE input signal. A LOW input on MODE
selects a linear burst mode, a HIGH selects an interleaved
burst sequence. Both burst counters use A0 and A1 in the
burst sequence, and will wrap-around when incremented suffi-
ciently. A HIGH input on ADV/LD will increment the internal
burst counter regardless of the state of chip enables inputs or
WE. WE is latched at the beginning of a burst cycle. Therefore,
the type of access (Read or Write) is maintained throughout
the burst sequence.
Single Write Accesses
Write access are initiated when the following conditions are
satisfied at clock rise: (1) CEN is asserted LOW, (2) CE1, CE2,
and CE3 are ALL asserted active, and (3) the write signal WE
is asserted LOW. The address presented is loaded into the
Address Register. The write signals are latched into the
Control Logic block.
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 DQ and DQP
(DQa,b,c,d/DQPa,b,c,d for CY7C1370D and DQa,b/DQPa,b for
CY7C1372D). 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 DQ and DQP
(DQa,b,c,d/DQPa,b,c,d for CY7C1370D & DQa,b/DQPa,b for
CY7C1372D) (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
(BWa,b,c,d for CY7C1370D and BWa,b for CY7C1372D)
signals. The CY7C1370D/CY7C1372D provides byte write
capability that is described in the Write Cycle Description table.
VDDQ
I/O Power
Supply
Power supply for the I/O circuitry.
VSS
Ground
Ground for the device. Should be connected to ground of the system.
NC
–
No connects. This pin is not connected to the die.
NC/(36M,72M,
144M, 288M,
576M, 1G)
–
These pins are not connected. They will be used for expansion to the 36M, 72M, 144M, 288M,
576M and 1G densities.
ZZ
Input-
Asynchronous
ZZ “sleep” Input. This active HIGH input places the device in a non-time critical “sleep” condition
with data integrity preserved. During normal operation, this pin can be connected to VSS or left
floating. ZZ pin has an internal pull-down.
Pin Definitions (continued)
Pin Name
I/O Type
Pin Description
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