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PDF CY7C1298H Data sheet ( Hoja de datos )
| Número de pieza | CY7C1298H | |
| Descripción | 1-Mbit (64K x 18) Pipelined DCD Sync SRAM | |
| Fabricantes | Cypress Semiconductor | |
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CY7C1298H
1-Mbit (64K x 18) Pipelined DCD Sync SRAM
Features
• Registered inputs and outputs for pipelined operation
• Optimal for performance (Double-Cycle deselect)
— Depth expansion without wait state
• 64K × 18-bit common I/O architecture
• 3.3V core power supply (VDD)
• 2.5V/3.3V I/O power supply (VDDQ)
• Fast clock-to-output times
— 3.5 ns (for 166-MHz device)
• Provide high-performance 3-1-1-1 access rate
• User-selectable burst counter supporting Intel®
Pentium® interleaved or linear burst sequences
• Separate processor and controller address strobes
• Synchronous self-timed writes
• Asynchronous Output Enable
• Available in JEDEC-standard lead-free 100-Pin TQFP
package
• “ZZ” Sleep Mode option
Selection Guide
Maximum Access Time
Maximum Operating Current
Maximum CMOS Standby Current
Functional Description[1]
The CY7C1298H SRAM integrates 64K x 18 SRAM cells with
advanced synchronous peripheral circuitry and a two-bit
counter for internal burst operation. All synchronous inputs are
gated by registers controlled by a positive-edge-triggered
Clock Input (CLK). The synchronous inputs include all
addresses, all data inputs, address-pipelining Chip Enable
(CE1), depth-expansion Chip Enables (CE2 and CE3), Burst
Control inputs (ADSC, ADSP, and ADV), Write Enables
(BW[A:B], and BWE), and Global Write (GW). Asynchronous
inputs include the Output Enable (OE) and the ZZ pin.
Addresses and chip enables are registered at rising edge of
clock when either Address Strobe Processor (ADSP) or
Address Strobe Controller (ADSC) are active. Subsequent
burst addresses can be internally generated as controlled by
the Advance pin (ADV).
Address, data inputs, and write controls are registered on-chip
to initiate a self-timed Write cycle.This part supports Byte Write
operations (see Pin Descriptions and Truth Table for further
details). Write cycles can be one to two bytes wide as
controlled by the byte write control inputs. GW active LOW
causes all bytes to be written. This device incorporates an
additional pipelined enable register which delays turning off
the output buffers an additional cycle when a deselect is
executed.This feature allows depth expansion without penal-
izing system performance.
The CY7C1298H operates from a +3.3V core power supply
while all outputs operate either with a +2.5V or +3.3V supply.
All inputs and outputs are JEDEC-standard
JESD8-5-compatible.
166 MHz
3.5
240
40
133 MHz
4.0
225
40
Unit
ns
mA
mA
Note:
1. For best-practices recommendations, please refer to the Cypress application note System Design Guidelines on www.cypress.com.
Cypress Semiconductor Corporation • 198 Champion Court • San Jose, CA 95134-1709 • 408-943-2600
Document #: 38-05665 Rev. *B
Revised July 5, 2006
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CY7C1298H
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.
The CY7C1298H 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.
Byte write operations are qualified with the Byte Write Enable
(BWE) and Byte Write Select (BW[A:B]) 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.
Synchronous Chip Selects CE1, CE2, CE3 and an
asynchronous Output Enable (OE) provide for easy bank
selection and output tri-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)
chip selects 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 is
stored into the address advancement logic and the Address
Register while being presented to the memory core. The corre-
sponding 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 tco 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 tri-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.
The CY7C1298H is a double-cycle deselect part. Once the
SRAM is deselected at clock rise by the chip select and either
ADSP or ADSC signals, its output will tri-state immediately
after the next clock rise.
Single Write Accesses Initiated by ADSP
This access is initiated when both of the following conditions
are satisfied at clock rise: (1) ADSP is asserted LOW, and
(2) chip select is asserted active. The address presented is
loaded into the address register and the address
advancement logic while being delivered to the memory core.
The write signals (GW, BWE, and BW[A:B]) 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 DQx inputs is written into the corre-
sponding address location in the memory core. If GW is HIGH,
then the write operation is controlled by BWE and BW[A:B]
Document #: 38-05665 Rev. *B
signals. The CY7C1298H provides byte write capability that
is described in the Write Cycle Description table. Asserting the
Byte Write Enable input (BWE) with the selected Byte Write
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 CY7C1298H is a common I/O device, the Output
Enable (OE) must be deasserted HIGH before presenting data
to the DQ inputs. Doing so will tri-state the output drivers. As
a safety precaution, DQ are automatically tri-stated whenever
a write cycle is detected, regardless of the state of OE.
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) chip select is asserted active, and (4)
the appropriate combination of the write inputs (GW, BWE,
and BW[A:B]) 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 is
loaded into the address register and the address
advancement logic while being delivered to the memory core.
The ADV input is ignored during this cycle. If a global write is
conducted, the data presented to the DQX 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.
Because the CY7C1298H is a common I/O device, the Output
Enable (OE) must be deasserted HIGH before presenting data
to the DQX inputs. Doing so will tri-state the output drivers. As
a safety precaution, DQX are automatically tri-stated
whenever a write cycle is detected, regardless of the state of
OE.
Burst Sequences
The CY7C1298H provides a two-bit wraparound counter, fed
by A[1:0], that implements either an interleaved or linear burst
sequence. The interleaved burst sequence is designed specif-
ically 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. Both read and write burst operations
are supported
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.
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. CEs, ADSP, and ADSC must remain
inactive for the duration of tZZREC after the ZZ input returns
LOW.
Page 5 of 16
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CY7C1298H
Switching Waveforms
Read Timing[16]
CLK
ADSP
ADSC
ADDRESS
GW, BWE,BW
[A:B]
CE
ADV
OE
Data Out (Q)
tCYC
tCH tCL
tADS tADH
tADS tADH
tAS tAH
A1
tWES tWEH
A2
tCES tCEH
A3
Burst continued with
new base address
Deselect
cycle
tADVS tADVH
ADV suspends burst
High-Z
t
CLZ
tCO
tOEHZ
Q(A1)
Single READ
tOEV
tOELZ
tCO
tDOH
Q(A2) Q(A2 + 1)
Q(A2 + 2)
Q(A2 + 3)
BURST READ
tCHZ
Q(A2) Q(A2 + 1)
Burst wraps around
to its initial state
Q(A3)
DON’T CARE
UNDEFINED
Note:
16. On this diagram, when CE is LOW, CE1 is LOW, CE2 is HIGH and CE3 is LOW. When CE is HIGH, CE1 is HIGH or CE2 is LOW or CE3 is HIGH.
Document #: 38-05665 Rev. *B
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