Cypress CY7C138 用户手册

4K x 8/9 Dual-Port Static RAM

with Sem, Int, Busy

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198 Champion Court

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San Jose

,

CA 95134-1709

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408-943-2600

Document #: 38-06037  Rev. *D

 Revised March 12, 2009

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True Dual-Ported memory cells that enable simultaneous reads 

of the same memory location

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4K x 8 organization (CY7C138)

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4K x 9 organization (CY7C139)

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0.65-micron CMOS for optimum speed and power

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High speed access: 15 ns

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Low operating power: I

CC

 = 160 mA (max.)

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Fully asynchronous operation

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Automatic power down

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TTL compatible

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Expandable data bus to 32/36 bits or more using 

Master/Slave chip select when using more than one 

device

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On-chip arbitration logic

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Semaphores included to permit software handshaking 

between ports 

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INT flag for port-to-port communication

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Available in 68-pin PLCC

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Pb-free packages available

The CY7C138 and CY7C139 are high speed CMOS 4K x 8 and

4K x 9 dual-port static RAMs. Various arbitration schemes are

included on the CY7C138/9 to handle situations when multiple

processors access the same piece of data. Two ports are

provided permitting independent, asynchronous access for

reads and writes to any location in memory. The CY7C138/9 can

be used as a standalone 8/9-bit dual-port static RAM or multiple

devices can be combined to function as a 16/18-bit or wider

master/slave dual-port static RAM. An M/S pin is provided for

implementing 16/18-bit or wider memory applications without the

need for separate master and slave devices or additional

discrete logic. Application areas include interprocessor/multipro-

cessor designs, communications status buffering, and dual-port

video/graphics memory. 
Each port has independent control pins: chip enable (CE), read

or write enable (R/W), and output enable (OE). Two flags are

provided on each port (BUSY and INT). BUSY signals that the

port is trying to access the same location currently being

accessed by the other port. The interrupt flag (INT) permits

communication between ports or systems by means of a mail

box. The semaphores are used to pass a flag, or token, from one

port to the other to indicate that a shared resource is in use. The

semaphore logic is comprised of eight shared latches. Only one

side can control the latch (semaphore) at any time. Control of a

semaphore indicates that a shared resource is in use. An

automatic power down feature is controlled independently on

each port by a chip enable (CE) pin or SEM pin.
The CY7C138 and CY7C139 are available in a 68-pin PLCC.

1. BUSY is an output in master mode and an input in slave mode.
2. Interrupt: push-pull output and requires no pull-up resistor.