CMOS SyncFIFOTM
256 x 18, 512 x 18, 1,024 x 18,
2,048 x 18, and 4,096 x 18
IDT72205LB, IDT72215LB,
IDT72225LB, IDT72235LB,
IDT72245LB
writecontrols.TheseFIFOsareapplicableforawidevarietyofdatabuffering
needs, such as optical disk controllers, Local Area Networks (LANs), and
interprocessorcommunication.
FEATURES:
• 256 x 18-bit organization array (IDT72205LB)
• 512 x 18-bit organization array (IDT72215LB)
• 1,024 x 18-bit organization array (IDT72225LB)
• 2,048 x 18-bit organization array (IDT72235LB)
• 4,096 x 18-bit organization array (IDT72245LB)
• 10 ns read/write cycle time
TheseFIFOshave18-bitinputandoutputports.Theinputportiscontrolled
byafree-runningclock(WCLK),andaninputenablepin(WEN).Dataisread
intothesynchronousFIFOoneveryclockwhenWENisasserted.Theoutput
portiscontrolledbyanotherclockpin(RCLK)andanotherenablepin(REN).
Thereadclockcanbetiedtothewriteclockforsingleclockoperationorthe
twoclockscanrunasynchronousofoneanotherfordual-clockoperation. An
OutputEnablepin(OE)isprovidedonthereadportforthree-statecontrolof
theoutput.
Thesynchronous FIFOs havetwofixedflags,Empty (EF)andFull(FF),
andtwoprogrammableflags,Almost-Empty(PAE)andAlmost-Full(PAF).The
offsetloadingoftheprogrammableflagsiscontrolledbyasimplestatemachine,
andisinitiatedbyassertingtheLoadpin(LD). AHalf-Fullflag(HF)isavailable
when the FIFO is used in a single device configuration.
ThesedevicesaredepthexpandableusingaDaisy-Chaintechnique.The
XI andXO pins are usedtoexpandthe FIFOs. Indepthexpansionconfigu-
ration, FirstLoad(FL)is groundedonthe firstdevice andsettoHIGHforall
other devices in the Daisy Chain.
The IDT72205LB/72215LB/72225LB/72235LB/72245LB is fabricated
usingIDT’shigh-speedsubmicronCMOStechnology.
• Empy and Full flags signal FIFO status
• Easy expandable in depth and width
• Asynchronous or coincident read and write clocks
• Programmable Almost-Empty and Almost-Full flags with
default settings
• Half-Full flag capability
• Dual-Port zero fall-through time architecture
• Output enable puts output data bus in high-impedence state
• High-performance submicron CMOS technology
• Available in a 64-lead thin quad flatpack (TQFP/STQFP)
and plastic leaded chip carrier (PLCC)
• Industrial temperature range (–40°C to +85°C) is available
• Green parts available, see ordering information
DESCRIPTION:
The IDT72205LB/72215LB/72225LB/72235LB/72245LBare very high
speed,low-powerFirst-In,First-Out(FIFO)memorieswithclockedreadand
FUNCTIONAL BLOCK DIAGRAM
WCLK
D0-D17
INPUT REGISTER
OFFSET REGISTER
FLAG
WRITE CONTROL
LOGIC
•
•
LOGIC
RAM ARRAY
256 x 18, 512 x 18
1,024 x 18, 2,048 x 18
4,096 x 18
/(
)
READ POINTER
WRITE POINTER
•
•
READ CONTROL
LOGIC
EXPANSION LOGIC
(
)/
OUTPUT REGISTER
RESET LOGIC
2766 drw 01
RCLK
Q0-Q17
IDTandtheIDTlogoaretrademarksofIntegratedDeviceTechnology, Inc. SyncFIFOisatrademarkofIntegratedDeviceTechnology, Inc.
OCTOBER 2006
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
1
©2006 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice.
DSC-2766/1