CY7C024/024A/0241
CY7C025/0251
4K x 16/18 and 8K x 16/18 Dual-Port
Static RAM with SEM, INT, BUSY
Cypress Semiconductor Corporation
•
198 Champion Court
•
San Jose
, CA 95134-1709
•
408-943-2600
Document #: 38-06035 Rev. *D
Revised December 09, 2008
Features
■ True dual-ported memory cells, which allow simultaneous
reads of the same memory location
■ 4K x 16 organization (CY7C024/024A
[1])
■ 4K x 18 organization (CY7C0241)
■ 8K x 16 organization (CY7C025)
■ 8K x 18 organization (CY7C0251)
■ 0.65 micron CMOS for optimum speed and power
■ High speed access: 15 ns
■ Low operating power: ICC = 150 mA (typ)
■ Fully asynchronous operation
■ Automatic power down
■ Expandable data bus to 32/36 bits or more using Master/Slave
chip select when using more than one device
■ On-chip arbitration logic
■ Semaphores included to permit software handshaking
between ports
■ INT flag for port-to-port communication
■ Separate upper-byte and lower-byte control
■ Pin select for Master or Slave
■ Available in 84-pin (Pb-free) PLCC, 84-pin PLCC, 100-pin
(Pb-free) TQFP, and 100-pin TQFP
Functional Description
The CY7C024/024A/0241 and CY7C025/0251 are low power
CMOS 4K x 16/18 and 8K x 16/18 dual-port static RAMs. Various
arbitration schemes are included on the CY7C024/ 0241 and
CY7C025/0251 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 CY7C024/ 0241 and
CY7C025/0251 can be used as standalone 16 or 18-bit dual-port
static RAMs or multiple devices can be combined to function as
a 32-/36-bit or wider master/ slave dual-port static RAM. An M/S
pin is provided for implementing 32-/36-bit or wider memory
applications without the need for separate master and slave
devices or additional discrete logic. Application areas include
interprocessor/multiprocessor 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 select (CE) pin.
The CY7C024/024A/0241 and CY7C025/0251 are available in
84-pin Pb-free PLCCs, 84-pin PLCCs (CY7C024 and CY7C025
only), 100-pin Pb-free Thin Quad Plastic Flatplack (TQFP), and
100-pin Thin Quad Plastic Flatpack.
Note
1. CY7C024 and CY7C024A are functionally identical.
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