• Free-running CLKA and CLKB may be asynchronous or
coincident (simultaneous reading and writing of data on a
single clock edge is permitted)
• Two independent clocked FIFOs buffering data in opposite directions
• Memory storage capacity:
IDT723622–256 x 36 x 2
IDT723632–512 x 36 x 2
IDT723642–1024 x 36 x 2
• Mailbox bypass register for each FIFO
• Programmable Almost-Full and Almost-Empty flags
• Microprocessor Interface Control Logic
• IRA, ORA,
• IRB, ORB,
AEAAEB
, and
, and
AFA
flags synchronized by CLKA
AFB
flags synchronized by CLKB
• Supports clock frequencies up to 67MHz
FUNCTIONAL BLOCK DIAGRAM
Mail 1
CLKA
CSA
W/RA
ENA
MBA
RST1
Port-A
Control
Logic
FIFO1,
Mail1
Reset
Logic
Input
Register
36
Pointer
Register
256 x 36
512 x 36
1024 x 36
SRAM
Write
• Fast access times of 11ns
• Available in 132-pin Plastic Quad Flatpack (PQF) or
space-saving 120-pin Thin Quad Flatpack (PF)
• Low-power 0.8-Micron Advanced CMOS technology
• Industrial temperature range (-40oC to +85oC) is available, tested to military electrical specifications
DESCRIPTION:
The IDT723622/723632/723642 is a monolithic, high-speed,
low-power, CMOS Bidirectional SyncFIFO (clocked) memory
which supports clock frequencies up to 67MHz and have read
access times as fast as 11ns. Two independent 256/512/
1024x36 dual-port SRAM FIFOs on board each chip buffer
data in opposite directions. Each FIFO has flags to indicate
empty and full conditions and two programable flags (almost
MBF1
Output
Register
Read
Pointer
36
IRA
AFA
FS
0
FS1
A0 - A35
ORA
AEA
36
MBF2
SyncFIFO is a trademark and the IDT logo is a registered trademark of Integrated Device Technology, Inc.
For latest information contact IDT's web site at www.idt.com or fax-on-demand at 408-492-8391.
5.22
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2 COMMERCIAL TEMPERATURE RANGE
DESCRIPTION (CONTINUED)
Full and almost Empty) to indicate when a selected number of
words is stored in memory. Communication between each
port may bypass the FIFOs via two 36-bit mailbox registers.
Each mailbox register has a flag to signal when new mail has
been stored. Two or more devices may be used in parallel to
create wider data paths.
The IDT723622/723632/723642 is a synchronous (clocked)
FIFO, meaning each port employs a synchronous interface.
All data transfers through a port are gated to the LOW-toHIGH transition of a port clock by enable signals. The clocks
for each port are independent of one another and can be
PIN CONFIGURATION
/RB
NC
B
B34
B33
B32
GND
B
B30
B29
B28
B27
B26
VCC
B25
B24
GND
B
B22
B21
B20
B19
B18
GND
B
B16
VCC
B15
B14
B13
B12
GND
NC
NC
CC
NC
V
ENB
CLKB
W
GND
IRB
CSB
987654321
10
NC
17161514131211
18
35
19
20
21
22
23
31
24
25
26
27
28
29
30
31
32
33
23
34
35
36
37
38
39
40
17
41
42
43
44
45
46
47
48
49
50
51525354555657
585960
ORB
AFB
61
CC
AEB
MBF1
V
626364
MBB
PQ132-1
65
asynchronous or coincident. The enables for each port are
arranged to provide a simple bidirectional interface between
microprocessors and/or buses with synchronous control.
The Input Ready (IRA, IRB) and Almost-Full (
AFA, AFB
flags of a FIFO are two-stage synchronized to the port clock
that writes data into its array. The Output Ready (ORA, ORB)
and Almost-Empty (
AEA, AEB
) flags of a FIFO are two-stage
synchronized to the port clock that reads data from its array.
Offset values for the Almost-Full and Almost-Empty flags of
both FIFOs can be programmed from Port A.
The IDT723622/723632/723642 is characterized for op-
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2 COMMERCIAL TEMPERATURE RANGE
PIN DESCRIPTIONS
SymbolNameI/ODescription
A0-A35Port-A DataI/036-bit bidirectional data port for side A.
AEA
AEB
AFA
AFB
B0 - B35Port-B DataI/O36-bit bidirectional data port for side B.
CLKAPort-A Clock ICLKA is a continuous clock that synchronizes all data transfers through port A
CLKBPort-B Clock ICLKB is a continuous clock that synchronizes all data transfers through port B
CSA
CSB
ENAPort-A EnableIENA must be HIGH to enable a LOW-to-HIGH transition of CLKA to read or
ENBPort-B EnableIENB must be HIGH to enable a LOW-to-HIGH transition of CLKB to read or
FS1,Flag OffsetIThe LOW-to-HIGH transition of a FlFO’s reset input latches the values of FSO
FS0Selectsand FS1. If either FSO or FS1 is HIGH when a reset input goes HIGH, one
IRAInput-ReadyOIRA is synchronized to the LOW-to-HIGH transition of CLKA. When IRA is
IRBInput-ReadyO IRB is synchronized to the LOW-to-HIGH transition of CLKB. When IRB is
MBAPort-A MailboxIA HIGH level on MBA chooses a mailbox register for a port-A read or
Port-A AlmostOProgrammable almost-empty flag synchronized to CLKA. It is LOW
-Empty Flag(Port A)when the number of words in FIF02 is less than or equal to the value in the
almost-empty A offset register, X2.
Port-B AlmostOProgrammable almost-empty flag synchronzed to CLKB. It is LOW
-Empty Flag(Port B)when the number of words in FIF01 is less than or equal to the value in the
almost-empty B offset register, X1.
Port-A AlmostOProgrammable almost-full flag synchronized to CLKA. It is LOW when
-Full Flag(Port A)the number of empty locations in FIF01 is less than or equal to the value in
the almost-full A offset register, Y1.
Port-B Almost OProgrammable almost-full flag synchronized to CLKB. It is LOW when
-Full Flag(Port B)the number of empty locations in FIF02 is less than or equal to the value in
the almost-full B offset register, Y2.
and can be asynchronous or coincident to CLKB. IRA, ORA,
AFA
, and
AEA
are all synchronized to the LOW-to-HIGH transition of CLKA.
and can be asynchronous or coincident to CLKA. IRB, ORB,
AFB
, and
AEB
are synchronized to the LOW-to-HIGH transition of CLKB.
Port-A ChipI
CSA
must be LOW to enable to LOW-to-HIGH transition of CLKA to read or
Selectwrite on port A. The AO-A35 outputs are in the high-impedance state when
CSA
is HIGH.
Port-B Chip I
CSB
must be LOW to enable a LOW-to-HIGH transition of CLKB to read or
Selectwrite data on port B. The BO- B35 outputs are in the high-impedance state
when
CSB
is HIGH.
write data on port A.
write data on port B.
of the three preset values is selected as the offset for the FlFOs almost-full
and almost-empty flags. If both FIFOs are reset simultaneously and both FSO
and FS1 are LOW when RST1 and RST2 go HIGH, the first four writes to
FIFO1 almost empty offsets for both FlFOs.
Flag(Port A)LOW, FIFO1 is full and writes to its array are disabled. IRA is set LOW
when FIFO1 is reset and is set HIGH on the second LOW-to-HIGH transition
of CLKA after reset.
Flag(Port B)LOW, FIFO2 is full and writes to its array are disabled. IRB is set LOW when
FIFO2 is reset and is set HIGH on the second LOW-to-HIGH transition of
CLKB after reset.
Selectwrite operation. When the AO-A35 outputs are active, a HIGH level on MBA
selects data from the mail2 register for output and a LOW level selects FIF02
output-register data for output.
5.224
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2 COMMERCIAL TEMPERATURE RANGE
PIN DESCRIPTIONS (CONT.)
SymbolNameI/ODescription
MBBPort-B MailboxIA HIGH level on MBB chooses a mailbox register for a port-B read or
Selectwrite operation. When the B0-B35 outputs are active, a HIGH level on
MBB selects data from the mail1 register or output and a LOW level selects
FIFO1 output-register data for output.
MBF1
MBF2
ORAOutput-ReadyOORA is synchronized to the LOW-to-HIGH transition of CLKA. When ORA is
ORBOutput-Ready OORB is synchronized to the LOW-to-HIGH transition of CLKB. When ORB
RST1
RST2
W/RAPort-A Write/IA HIGH selects a write operation and a LOW selects a read operation on port A
W
/RBPort-B Write/IA LOW selects a write operation and a HIGH selects a read operation on port B
Mail1 RegisterO
Flagto the mail1 register. Writes to the mail1 register are inhibited while
Mail2 RegisterO
Flagmail2 register. Writes to the mail2 register are inhibited while
MBF1
is set LOW by a LOW-to-HIGH transition of CLKA that writes data
LOW.
read is selected and MBB is HIGH.
MBF2
MBF1
is set HIGH by a LOW-to-HIGH transition of CLKB when a port-B
MBF1
is set HIGH when FIFO1 is reset.
is set LOW by a LOW-to-HIGH transition of CLKB that writes data to the
MBF2
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 also set HIGH when FIFO2 is reset.
MBF1
is
is LOW.
Flag(Port A)LOW, FIFO2 is empty and reads from its memory are disabled. Ready data
is present on the output register of FIFO2 when ORA is HIGH. ORA is
forced LOW when FlFO2 is reset and goes HIGH on the third LOW-to-HIGH
transition of CLKA after a word is loaded to empty memory.
Flag(Port B)is LOW, FlFO1 is empty and reads from its memory are disabled. Ready data
is present on the output register of FIFO1 when ORB is HIGH. ORB is forced LOW
when FIFO1 is reset and goes HIGH on the third LOW-to-HIGH transition of CLKB
after a word is loaded to empty memory.
FIFO1 ResetITo reset FIFO1, four LOW-to-HIGH transitions of CLKA and four LOW-to-HIGH
transitions of CLKB must occur while
of
RST1
latches the status of FSO and FS1 for
RST1
is LOW. The LOW-to-HIGH transition
AFA
and
AEB
offset selection.
FIFO1 must be reset upon power up before data is written to its RAM.
FIFO2 Reset ITo reset FIFO2, four LOW-to-HIGH transitions of CLKA and four LOW-to-HIGH
transitions of CLKB must occur while
of
RST2
latches the status of FSO and FS1 for
RST2
is LOW. The LOW-to-HIGH transition
AFB
and
AEA
offset selection.
FIFO2 must be reset upon power up before data is written to its RAM.
Read Selectfor a LOW-to-HIGH transition of CLKA. The AO-A35 outputs are in
the HIGH impedance state when W/RA is HIGH.
Read Selectfor a LOW-to-HIGH transition of CLKB. The BO-B35 outputs are in the HIGH
impedance state when W/RB is LOW.
5.225
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2 COMMERCIAL TEMPERATURE RANGE
ABSOLUTE MAXIMUM RATINGS OVER OPERATING FREE-AIR TEMPERATURE RANGE (UNLESS OTHERWISE NOTED)
SymbolRatingCommercialUnit
CCSupply Voltage Range-0.5 to 7V
V
(2)
V
I
O
V
I
IKInput Clamp Current (VI < 0 or VI > VCC)±20 mA
OKOutput Clamp Current (VO = < 0 or VO > VCC)±50mA
I
OUTContinuous Output Current (VO = 0 to VCC)±50mA
I
I
CCContinuous Current Through VCC or GND±400mA
AOperating Free Air Temperature Range0 to 70°C
T
T
STGStorage Temperature Range-65 to 150°C
NOTES:
1. Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only and functional
operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to
absolute-maximum-rated conditions for extended periods may affect device reliability.
2. The input and output voltage ratings may be exceeded provided the input and output current ratings are observed.
Input Voltage Range-0.5 to VCC+0.5V
(2)
Output Voltage Range-0.5 to VCC+0.5V
(1)
RECOMMENDED OPERATING CONDITIONS
SymbolParameterMin. Max. Unit
V
CCSupply Voltage4.55.5V
IHHigh-Level Input Voltage2V
V
ILLow-Level Input Voltage0.8V
V
I
OHHigh-Level Output Current-4mA
OLLow-Level Output Current8mA
I
AOperating Free-Air070°C
T
Temperature
5.226
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2 COMMERCIAL TEMPERATURE RANGE
ELECTRICAL CHARACTERISTICS OVER RECOMMENDED OPERATING FREE-AIR TEMPERATURE RANGE (UNLESS OTHERWISE NOTED)
IDT723622
IDT723632
IDT723642
Commerical
A = 15, 20, 30 ns
t
ParameterTest ConditionsMin.Typ.
OHVCC = 4.5V,IOH = -4 mA2.4V
V
OLVCC = 4.5 V,IOL = 8 mA0.5V
V
I
LIVCC = 5.5 V,VI = VCC or 0±5µA
LOVCC = 5.5 V,VO = VCC or 0±5µA
I
I
CCVCC = 5.5 V,VI = VCC -0.2 V or 0400µA
(2)
∆I
CC
VCC = 5.5 V,One Input at 3.4 V,
Other Inputs at V
CC or GND
CSA
= VIHA0-A350mA
CSB
= VIHB0-B350
CSA
= VILA0-A351
CSB
= VILB0-351
All Other Inputs1
C
INVI = 0,f = 1 MHz4pF
OUTVO = 0,f = 1 MHZ8pF
C
(1)
Max.Unit
NOTES:
1. All typical values are at V
2. This is the supply current when each input is at least one of the specified TTL voltage levels rather than 0V or V
CC = 5V, TA = 25°C.
CC.
5.227
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2 COMMERCIAL TEMPERATURE RANGE
TIMING REQUIREMENTS OVER RECOMMENDED RANGES OF SUPPLY VOLTAGE AND OPERATING FREE-AIR TEMPERATURE
DHHold Time, A0-A35 after CLKA↑ and B0-B35 after111ns
CLKB↑
ENHHold Time,
t
CSB, W
t
RSTHHold Time,
CLKB↑
tFSHHold Time, FS0 and FS1 after
(2)
SKEW1
t
Skew Time, between CLKA↑ and CLKB↑ for ORA,7.5911ns
ORB, IRA, and IRB
(2)
t
SKEW2
Skew Time, between CLKA↑ and CLKB↑ for
AEB, AFA
CSA
, W/RA, ENA, and MBA before4.556ns
CSB, W
/RB, ENB, and MBB before CLKB↑
RST1
or
RST2
(1)
LOW before CLKA↑567ns
RST1
CSA
, W/RA, ENA, and MBA after CLKA↑;111ns
/RB, ENB, and MBB after CLKB↑
RST1
or
RST2
(1)
, and
AFB
LOW after CLKA↑ or445ns
RST1
and
and
RST2
RST2
7.58.59.5ns
HIGH233ns
AEA
,121620ns
NOTES:
1. Requirement to count the clock edge as one of at least four needed to reset a FIFO.
2. Skew time is not a timing constraint for proper device operation and is only included to illustrate the timing relationship between CLKA cycle and CLKB
cycle.
5.228
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