CY7C1470V33CY7C1472V33CY7C1474V33Document #: 38-05289 Rev. *I Page 7 of 29
Functional Overview
The CY7C1470V33, CY7C1472V33, and CY7C1474V33 are
synchronous-pipelined Burst NoBL SRAMs designed specifi-
cally 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 3.0 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). BW[x] 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 3.0 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 CY7C1470V33, CY7C1472V33, and CY7C1474V33
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 sufficiently. 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 accesses 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 to the address inputs
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,e,f,g,h/DQPa,b,c,d,e,f,g,h for CY7C1474V33,
DQa,b,c,d/DQPa,b,c,d for CY7C1470V33 and DQa,b/DQPa,b for
CY7C1472V33). In addition, the address for the subsequent
access (Read/Write/Deselect) is latched into the Address
Register (provided the appropriate control signals are
asserted).
TMS Test Mode Select
Synchronous This pin controls the Test Access Port state machine. Sampled on the rising edge of TCK.
TCK JTAG Clock Clock input to the JTAG circuitry.
VDD Power Supply Power supply inputs to the core of the device.
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(144M,
288M,
576M, 1G)
–These pins are not connected. They will be used for expansion to the 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 has to be LOW or left floating.
ZZ pin has an internal pull-down.
Pin Definitions (continued)
Pin Name I/O Type Pin Description
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