CY7C4255-25AC Cypress Semiconductor Corp, CY7C4255-25AC Datasheet - Page 17

• Manufacturer Part Number: CY7C4255-25AC
• Manufacturer: Cypress Semiconductor Corp

Specifications of CY7C4255-25AC

• Density: 128Kb
• Word Size: 18b
• Sync/async: Synchronous
• Expandable: Yes
• Package Type: TQFP
• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (min): 4.5V
• Operating Supply Voltage (max): 5.5V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 64
• Lead Free Status / Rohs Status: Not Compliant

Document #: 38-06004 Rev. *C
Width Expansion Configuration
The CY7C4255/65 can be expanded in width to provide word
widths greater than 18 in increments of 18. During width
expansion mode all control line inputs are common and all
flags are available. Empty (Full) flags should be created by
FULL FLAG (FF)
Figure 1. Block Diagram of 8K x18/16K x 18 Synchronous FIFO Memory Used in a Width Expansion Configuration
DATA IN (D)
PROGRAMMABLE(PAE)
HALF FULL FLAG (HF)
WRITE CLOCK (WCLK)
WRITE ENABLE (WEN)
LOAD (LD)
36
18
FF
RESET (RS)
7C4255
7C4265
WRITE EXPANSION IN (WXI)
READ EXPANSION IN (RXI)
EF
FIRST LOAD (FL)
18
18
ANDing the Empty (Full) flags of every FIFO; the PAE and PAF
flags can be detected from any one device. This technique will
avoid reading data from, or writing data to the FIFO that is
“staggered” by one clock cycle due to the variations in skew
between RCLK and WCLK. Figure 1 demonstrates a 36-word
width by using two CY7C4255/65s.
FF
RESET (RS)
7C4255
7C4265
EF
READ CLOCK (RCLK)
READ ENABLE (REN)
OUTPUT ENABLE (OE)
PROGRAMMABLE (PAF)
18
DATA OUT (Q)
EMPTY FLAG (EF)
CY7C4255
CY7C4265
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