5
COMMERCIALTEMPERATURERANGE
IDT72V3624/72V3634/72V3644 3.3V CMOS SyncBiFIFOTM WITH BUS-MATCHING
256 x 36 x 2, 512 x 36 x 2, 1,024 x 36 x 2
Symbol
Name
I/O
Description
FS1/
SEN FlagOffsetSelect1/
I
FS1/
SEN and FS0/SD are dual-purpose inputs used for flag offset register programming. During Master
Serial Enable,
Reset, FS1/
SEN andFS0/SD,togetherwith SPM,selecttheflagoffsetprogrammingmethod.Threeoffset
register programming methods are available: automatically load one of three preset values (8, 16, or 64),
FS0/SD
Flag Offset Select 0/
I
parallel load from Port A, and serial load.
Serial Data
When serial load is selected for flag offset register programming, FS1/
SEN is used as an enable synchronous
to the LOW-to-HIGH transition of CLKA. When FS1/
SEN is LOW, a rising edge on CLKA load the bit present
on FS0/SD into the X and Y registers. The number of bit writes required to program the offset registers is 32
for the 72V3624, 36 for the 72V3634, and 40 for the 72V3644. The first bit write stores the Y-register (Y1)
MSB and the last bit write stores the X-register (X2) LSB.
MBA
Port A Mailbox
I
A HIGH level on MBA chooses a mailbox register for a Port A read or write operation. When the A0-A35
Select
outputs are active, a HIGH level on MBA selects data from the mail2 register for output and a LOW level
selects FIFO2 output register data for output.
MBB
Port B Mailbox
I
A HIGH level on MBB chooses a mailbox register for a Port B read or write operation. When the B0-B35
Select
outputs are active, a HIGH level on MBB selects data from the mail1 register for output and a LOW level
selects FIFO1 output register data for output.
MBF1
Mail1 Register
O
MBF1 is set LOW by a LOW-to-HIGH transition of CLKA that writes data to the mail1 register. Writes to
Flag
the mail1 register are inhibited while
MBF1 is LOW. MBF1 is set HIGH by a LOW-to-HIGH transition of CLKB
when a Port B read is selected and MBB is HIGH.
MBF1 is set HIGH following either a Master or Partial
Reset of FIFO1.
MBF2
Mail2 Register
O
MBF2 is set LOW by a LOW-to-HIGH transition of CLKB that writes data to the mail2 register. Writes to the
Flag
mail2 register are inhibited while
MBF2 is LOW. MBF2 is set HIGH by a LOW-to-HIGH transition of CLKA
when a Port A read is selected and MBA is HIGH.
MBF2 is set HIGH following either a Master or Partial
Reset of FIFO2.
MRS1
FIFO1 Master
I
A LOW on this pin initializes the FIFO1 read and write pointers to the first location of memory and sets the
Reset
Port B output register to all zeroes. A LOW-to-HIGH transition on
MRS1selectstheprogrammingmethod(serial
or parallel) and one of three programmable flag default offsets for FIFO1 and FIFO2. It also configures Port
Bforbussizeandendianarrangement. FourLOW-to-HIGHtransitionsofCLKA andfourLOW-to-HIGHtransitions
of CLKB must occur while
MRS1 is LOW.
MRS2
FIFO2 Master
I
A LOW on this pin initializes the FIFO2 read and write pointers to the first location of memory and sets the
Reset
PortAoutputregistertoallzeroes. ALOW-to-HIGHtransitionon
MRS2,toggledsimultaneouslywithMRS1,selects
theprogrammingmethod(serialorparallel)andoneoftheprogrammableflagdefaultoffsetsforFIFO2. FourLOW-
to-HIGH transitions of CLKA and four LOW-to-HIGH transitions of CLKB must occur while
MRS2 is LOW.
PRS1
FIFO1 Partial
I
A LOW on this pin initializes the FIFO1 read and write pointers to the first location of memory and sets the
Reset
Port B output register to all zeroes. During Partial Reset, the currently selected bus size, endian arrangement,
programming method (serial or parallel), and programmable flag settings are all retained.
PRS2
FIFO2 Partial
I
A LOW on this pin initializes the FIFO2 read and write pointers to the first location of memory and sets the Port
Reset
A output register to all zeroes. During Partial Reset, the currently selected bus size, endian arrangement,
programming method (serial or parallel), and programmable flag settings are all retained.
SIZE
Bus Size Select
I
A HIGH on this pin when BM is HIGH selects byte bus (9-bit) size on Port B. A LOW on this pin when BM is HIGH
selects word (18-bit) bus size. SIZE works with BM andBEtoselectthebussizeandendianarrangementforPort
B. The level of SIZE must be static throughout device operation.
SPM
Serial Programming
I
ALOWonthispinselectsserialprogrammingofpartialflagoffsets. AHIGHonthispinselectsparallelprogramming
Mode
or default offsets (8, 16, or 64).
W/
RA
Port-AWrite/
I
A HIGH selects a write operation and a LOW selects a read operation on Port A for a LOW-to-HIGH transition of
Read Select
CLKA. The A0-A35 outputs are in the HIGH impedance state when W/
RA is HIGH.
W/RB
Port-BWrite/
I
A LOW selects a write operation and a HIGH selects a read operation on Port B for a LOW-to-HIGH transition of
Read Select
CLKB. The B0-B35 outputs are in the HIGH impedance state when
W/RB is LOW.
PIN DESCRIPTIONS (CONTINUED)