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COMMERCIALTEMPERATURERANGE

IDT723624/723634/723644 CMOS SyncBiFIFO™ WITH BUS-MATCHING

256 x 36 x 2, 512 x 36 x 2, 1,024 x 36 x 2

PIN DESCRIPTIONS

Symbol

Name

I/O

Description

A0-A35

Port A Data

I/O

36-bitbidirectionaldataportforsideA.

AEA

PortAAlmost-

O

Programmable Almost-Empty flag synchronized to CLKA. It is LOW when the number of words in FIFO2 is less

EmptyFlag

thanorequal to the value in the Almost-Empty A Offset register, X2.

AEB

PortBAlmost-

O

Programmable Almost-Empty flag synchronized to CLKB. It is LOW when the number of words in FIFO1 is less

EmptyFlag

thanorequal to the value in the Almost-Empty B Offset register, X1.

AFA

PortAAlmost-

O

ProgrammableAlmost-FullflagsynchronizedtoCLKA.ItisLOWwhenthenumberofemptylocationsinFIFO1

Full Flag

is less than or equal to the value in the Almost-Full A Offset register, Y1.

AFB

PortBAlmost-

O

ProgrammableAlmost-FullflagsynchronizedtoCLKB.ItisLOWwhenthenumberofemptylocationsinFIFO2

Full Flag

FIFO2 is less than or equal to the value in the Almost-Full B Offset register, Y2.

B0-B35

Port A Data

I/O

36-bitbidirectionaldataportforsideB.

BE/FWFT

Big-Endian/

I

This is a dual purpose pin. During Master Reset, a HIGH on BE will select Big Endian operation. In this case,

FirstWord

depending on the bus size, the most significant byte or word on Port A is read from Port B first (A-to-B data

Fall Through

flow) or written to Port B first (B-to-A data flow). A LOW on BE will select Little-Endian operation. In this case,

Select

the least significant byte or word on Port A is read from Port B first (for A-to-B data flow) or written to Port B first

(B-to-A data flow). After Master Reset, this pin selects the timing mode. A HIGH on FWFT selects IDT

Standard mode, a LOW selects First Word Fall Through mode. Once the timing mode has been

selected,thelevelon FWFTmustbestaticthroughoutdeviceoperation.

BM(1)

Bus-Match

I

A HIGH on this pin enables either byte or word bus width on Port B, depending on the state of SIZE. A LOW

Select

selects long word operation. BM works with SIZE and BE to select the bus size and endian arrangement for

(Port B)

Port B. The level of BM must be static throughout device operation.

CLKA

Port A Clock

I

CLKA is a continuous clock that synchronizes all data transfers through Port A and can be asynchronous or

coincident to CLKB. FFA/IRA, EFA/ORA, AFA, and AEA are all synchronized to the LOW-to-HIGH transition of

CLKA.

CLKB

Port B Clock

I

CLKB is a continuous clock that synchronizes all data transfers through Port B and can be asynchronous or

coincident to CLKA. FFB/IRB, EFB/ORB, AFB, and AEB are synchronized to the LOW-to-HIGH transition of

CLKB.

CSA

Port A Chip

I

CSA must be LOW to enable to LOW-to-HIGH transition of CLKA to read or write on Port A. The A0-A35

Select

outputs are in the high-impedance state when CSA is HIGH.

CSB

Port B Chip

I

CSB must be LOW to enable a LOW-to-HIGH transition of CLKB to read or write on Port B. The B0-B35

Select

outputs are in the high-impedance state when CSB is HIGH.

EFA/ORA

PortAEmpty/

O

This is a dual function pin. In the IDT Standard mode, the EFA function is selected. EFA indicates whether or

OutputReady

not the FIFO2 memory is empty. In the FWFT mode, the ORA function is selected. ORA indicates the presence

Flag

of valid data on A0-A35 outputs, available for reading. EFA/ORA is synchronized to the LOW-to-HIGH

transitionofCLKA.

EFB/ORB

PortBEmpty/

O

This is a dual function pin. In the IDT Standard mode, the EFB function is selected. EFB indicates whether or

OutputReady

not the FIFO1 memory is empty. In the FWFT mode, the ORB function is selected. ORB indicates the presence

Flag

ofvaliddataontheB0-B35outputs,availableforreading.EFB/ORBissynchronizedtotheLOW-to-HIGHtransition

ofCLKB.

ENA

Port A Enable

I

ENA must be HIGH to enable a LOW-to-HIGH transition of CLKA to read or write data on Port A.

ENB

Port B Enable

I

ENB must be HIGH to enable a LOW-to-HIGH transition of CLKB to read or write data on Port B.

FFA/IRA

Port A Full/

O

This is a dual function pin. In the IDT Standard mode, the FFA function is selected. FFA indicates whether or

Input Read

not the FIFO1 memory is full. In the FWFT mode, the IRA function is selected. IRA indicates whether or not

Flag

there is space available for writing to the FIFO1 memory. FFA/IRA is synchronized to the LOW-to-HIGH

transitionofCLKA.

FFB/IRB

Port B Full/

O

This is a dual function pin. In the IDT Standard mode, the FFB function is selected. FFB indicates whether or

Input Ready

not the FIFO2 memory is full. In the FWFT mode, the IRB function is selected. IRB indicates whether or not

Flag

there is space available for writing to the FIFO memory. FFB/IRB is synchronized to the LOW-to-HIGH transition

of CLKB.