CY7C1360B
CY7C1362B
then the Write operation is controlled by BWE and BWX
signals. The CY7C1360B/CY7C1362B provides Byte Write
capability that is described in the Write Cycle Descriptions
table. Asserting the Byte Write Enable input (BWE) with the
selected Byte Write (BWX) 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.
Because the CY7C1360B/CY7C1362B is a common I/O
device, the Output Enable (OE) must be deasserted HIGH
before presenting data to the DQs inputs. Doing so will
three-state the output drivers. As a safety precaution, DQs are
automatically three-stated whenever a Write cycle is detected,
regardless of the state of OE.
Functional Overview
All synchronous inputs pass through input registers controlled
by the rising edge of the clock. 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
(200-MHz device).
The CY7C1360B/CY7C1362B supports secondary cache in
systems utilizing either a linear or interleaved burst sequence.
The interleaved burst order supports Pentium and i486
processors. The linear burst sequence is suited for processors
that utilize a linear burst sequence. The burst order is user
selectable, and is determined by sampling the MODE input.
Accesses can be initiated with either the Processor Address
Strobe (ADSP) or the Controller Address Strobe (ADSC).
Address advancement through the burst sequence is
controlled by the ADV input. A two-bit on-chip wraparound
burst counter captures the first address in a burst sequence
and automatically increments the address for the rest of the
burst access.
Single Write Accesses Initiated by ADSC
ADSC Write accesses are initiated when the following condi-
tions are satisfied: (1) ADSC is asserted LOW, (2) ADSP is
deasserted HIGH, (3) CE1, CE2, CE3[2] are all asserted active,
and (4) the appropriate combination of the Write inputs (GW,
BWE, and BWX) are asserted active to conduct a Write to the
desired byte(s). ADSC-triggered Write accesses require a
single clock cycle to complete. The address presented to A is
loaded into the address register and the address
advancement logic while being delivered to the memory array.
The ADV input is ignored during this cycle. If a global Write is
conducted, the data presented to the DQs is written into the
corresponding address location in the memory core. If a Byte
Write is conducted, only the selected bytes are written. 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 operations are qualified with the Byte Write Enable
(BWE) and Byte Write Select (BWX) inputs. A Global Write
Enable (GW) overrides all Byte Write inputs and writes data to
all four bytes. All writes are simplified with on-chip
synchronous self-timed Write circuitry.
Three synchronous Chip Selects (CE1, CE2, CE3[2]) and an
asynchronous Output Enable (OE) provide for easy bank
selection and output three-state control. ADSP is ignored if
CE1 is HIGH.
Single Read Accesses
This access is initiated when the following conditions are
satisfied at clock rise: (1) ADSP or ADSC is asserted LOW, (2)
Because the CY7C1360B/CY7C1362B is a common I/O
device, the Output Enable (OE) must be deasserted HIGH
before presenting data to the DQs inputs. Doing so will
three-state the output drivers. As a safety precaution, DQs are
automatically three-stated whenever a Write cycle is detected,
regardless of the state of OE.
[2]
CE1, CE2, CE3 are all asserted active, and (3) the Write
signals (GW, BWE) are all deasserted HIGH. ADSP is ignored
if
CE1 is HIGH. The address presented to the address inputs
(A) is stored into the address advancement logic and the
address register while being presented to the memory array.
The corresponding data is allowed to propagate to the input of
the output registers. At the rising edge of the next clock the
data is allowed to propagate through the output register and
onto the data bus within 3.0 ns (200-MHz device) if OE is
active LOW. The only exception occurs when the SRAM is
emerging from a deselected state to a selected state, its
outputs are always three-stated during the first cycle of the
access. After the first cycle of the access, the outputs are
controlled by the OE signal. Consecutive single Read cycles
are supported. Once the SRAM is deselected at clock rise by
the chip select and either ADSP or ADSC signals, its output
will three-state immediately.
Burst Sequences
The CY7C1360B/CY7C1362B provides a two-bit wraparound
counter, fed by A1, A0, that implements either an interleaved
or linear burst sequence. The interleaved burst sequence is
designed specifically to support Intel Pentium applications.
The linear burst sequence is designed to support processors
that follow a linear burst sequence. The burst sequence is user
selectable through the MODE input.
Asserting ADV LOW at clock rise will automatically increment
the burst counter to the next address in the burst sequence.
Both Read and Write burst operations are supported.
Single Write Accesses Initiated by ADSP
Sleep Mode
This access is initiated when both of the following conditions
are satisfied at clock rise: (1) ADSP is asserted LOW, and
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
[2]
(2) CE1, CE2, CE3 are all asserted active. The address
presented to A is loaded into the address register and the
address advancement logic while being delivered to the
memory array. The Write signals (GW, BWE, and BWX) and
ADV inputs are ignored during this first cycle.
ADSP-triggered Write accesses require two clock cycles to
complete. If GW is asserted LOW on the second clock rise, the
data presented to the DQs inputs is written into the corre-
sponding address location in the memory array. If GW is HIGH,
“sleep” mode. CE1, CE2, CE3[2], ADSP, and ADSC must
the
remain inactive for the duration of tZZREC after the ZZ input
returns LOW.
Document #: 38-05291 Rev. *C
Page 12 of 34
CYPRESS [ CYPRESS ]
