Cypress CY7C1245V18 用户手册

 36-Mbit QDR™-II+ SRAM 4-Word Burst

Architecture (2.0 Cycle Read Latency)

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198 Champion Court

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San Jose

,

CA 95134-1709

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408-943-2600

Document Number: 001-06365 Rev. *D

 Revised March 12, 2008

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Separate independent read and write data ports

❐

Supports concurrent transactions

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300 MHz to 375 MHz clock for high bandwidth

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4-Word Burst for reducing address bus frequency 

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Double Data Rate (DDR) interfaces on both read and write ports 
(data transferred at 750 MHz) at 375 MHz 

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Read latency of 2.0 clock cycles 

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Two input clocks (K and K) for precise DDR timing

❐

SRAM uses rising edges only

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Echo clocks (CQ and CQ) simplify data capture in high-speed 
systems

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Single multiplexed address input bus latches address inputs 
for both read and write ports

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Separate Port Selects for depth expansion

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Data valid pin (QVLD) to indicate valid data on the output

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Synchronous internally self-timed writes

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Available in x8, x9, x18, and x36 configurations

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Full data coherency providing most current data

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Core V

DD

 = 1.8V ± 0.1V; IO V

DDQ

 = 1.4V to V

DD

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HSTL inputs and variable drive HSTL output buffers

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Available in 165-ball FBGA package (15 x 17 x 1.4 mm)

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Offered in both Pb-free and non Pb-free packages

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JTAG 1149.1 compatible test access port

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Delay Lock Loop (DLL) for accurate data placement

CY7C1241V18 – 4M x 8
CY7C1256V18 – 4M x 9
CY7C1243V18 – 2M x 18
CY7C1245V18 – 1M x 36

The CY7C1241V18, CY7C1256V18, CY7C1243V18, and
CY7C1245V18 are 1.8V Synchronous Pipelined SRAMs,
equipped with Quad Data Rate-II+ (QDR-II+) architecture.
QDR-II+ architecture consists of two separate ports to access
the memory array. The read port has dedicated data outputs to
support read operations and the write port has dedicated data
inputs to support write operations. QDR-II+ architecture has
separate data inputs and data outputs to completely eliminate
the need to “turn around” the data bus required with common IO
devices. Each port can be accessed through a common address
bus. Read and write addresses are latched on alternate rising
edges of the input (K) clock. Accesses to the QDR-II+ read and
write ports are completely independent of one another. To
maximize data throughput, both read and write ports are
equipped with Double Data Rate (DDR) interfaces. Each
address location is associated with four 8-bit words
(CY7C1241V18), 9-bit words (CY7C1256V18), 18-bit words
(CY7C1243V18), or 36-bit words (CY7C1245V18), that burst
sequentially into or out of the device. Because data can be trans-
ferred into and out of the device on every rising edge of both input
clocks (K and K), memory bandwidth is maximized while simpli-
fying system design by eliminating bus “turn-arounds”.

Depth expansion is accomplished with Port Selects for each port.
Port selects enable each port to operate independently.

All synchronous inputs pass through input registers controlled by
the K or K input clocks. All data outputs pass through output
registers controlled by the K or K input clocks. Writes are
conducted with on-chip synchronous self-timed write circuitry.

Maximum Operating Frequency 

375

333

300

MHz

Maximum Operating Current 

1240

1120

1040

mA

1. The QDR consortium specification for V

DDQ

 is 1.5V + 0.1V. The Cypress QDR devices exceed the QDR consortium specification and are capable of supporting 

V

DDQ

 = 1.4V to V

DD

.