Free-running CLKA and CLKB can be asynchronous or coinci-
dent (permits simultaneous reading and writing of data on a
single clock edge)
Clocked FIFO buffering data from Port A to Port B
Synchronous read retransmit capability
Mailbox register in each direction
Programmable Almost-Full and Almost-Empty flags
Microprocessor interface control logic
Input Ready (IR) and Almost-Full (AF) flags synchronized by
CLKA
Output Ready (OR) and Almost-Empty (AE) flags synchronized
by CLKB
Available in 132-pin plastic quad flat package (PQFP) or space-
saving 120-pin thin quad flat package (TQFP)
Pin and functionally compatible versions of the 5V operating
IDT723631/723641/723651
Easily expandable in width and depth
Industrial temperature range (–40°C to +85°C) is available
°
°
DESCRIPTION
The IDT72V3631/72V3641/72V3651 are pin and functionally compatible
versons of the IDT723631/723641/723651, designed to run off a 3.3V supply
for exceptionally low-power consumption. These devices are monolithic high-
speed, low-power, CMOS clocked FIFO memory. It supports clock frequencies
up to 67 MHz and has read access times as fast as 10ns. The 512/1,024/2,048
x 36 dual-port SRAM FIFO buffers data from port A to Port B. The FIFO memory
has retransmit capability, which allows previously read data to be accessed
again. The FIFO operates in First Word Fall Through mode and has flags to
indicate empty and full conditions and conditions and two programmable flags
(Almost-Full and Almost-Empty) to indicate when a selected number of words
is stored in memory. Communication between each port may take place with
FUNCTIONAL BLOCK DIAGRAM
MBF1
Mail 1
Register
Input
Register
RAM ARRAY
512 x 36
1,024 x 36
2,048 x 36
Sync
Retransmit
Logic
RST
Reset
Logic
Output
Register
CLKA
CSA
W/RA
ENA
MBA
Port-A
Control
Logic
RTM
RFM
B
0
- B
35
OR
AE
36
A
0
- A
35
IR
AF
Write
Pointer
Read
Pointer
Status Flag
Logic
FS
0
/SD
FS
1
/SEN
10
Flag Offset
Registers
Port-B
Control
Logic
CLKB
CSB
W/RB
ENB
MBB
4658 drw 01
Mail 2
Register
MBF2
IDT and the IDT logo are trademark of Integrated Device Technology, Inc. SyncFIFO is a trademark of Integrated Device Technology, Inc.
COMMERCIAL TEMPERATURE RANGE
1
1
2003 Integrated Device Technology, Inc.
All rights reserved.
Product specifications subject to change without notice.
NOVEMBER 2003
DSC-4658/2
IDT72V3631/72V3641/72V3651
3.3V CMOS SYNCFIFO™ 512 x 36, 1,024 x 36 and 2,048 x 36
COMMERCIAL TEMPERATURE RANGE
DESCRIPTION (CONTINUED)
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. Expansion is also possible in word depth.
These devices are a clocked FIFO, which means each port employs a
synchronous interface. All data transfers through a port are gated to the LOW-
to-HIGH transition of a continuous (free-running) port clock by enable signals.
The continuous clocks for each port are independent of one another and can
be asynchronous or coincident. The enables for each port are arranged to
provide a simple interface between microprocessors and/or buses with
synchronous control.
The Input Ready (IR) flag and Almost-Full (AF) flag of the FIFO are two-stage
synchronized to CLKA. The Output Ready (OR) flag and Almost-Empty (AE)
flag of the FIFO are two-stage synchronized to CLKB. Offset values for the
Almost-Full and Almost-Empty flags of the FIFO can be programmed from port
A or through a serial input.
The IDT72V3631/72V3641/72V3651 are characterized for operation from
0°C to 70°C. Industrial temperature range (-40°C to +85°C) is available by
special order. These devices are fabricated using IDT's high speed, submicron
CMOS technology.
PIN CONFIGURATION
NC
NC
V
CC
CLKB
ENB
W/RB
CSB
GND
MBF1
GND
MBB
NC
V
CC
RFM
RTM
FS1/SEN
FS0/SD
GND
RST
MBA
MBF2
V
CC
AE
AF
V
CC
OR
IR
CSA
W/RA
ENA
CLKA
GND
NC
NC
B
35
B
34
B
33
B
32
GND
B
31
B
30
B
29
B
28
B
27
B
26
V
CC
B
25
B
24
GND
B
23
B
22
B
21
B
20
B
19
B
18
GND
B
17
B
16
V
CC
B
15
B
14
B
13
B
12
GND
NC
NC
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
132
131
130
129
128
127
126
125
124
123
122
121
120
119
118
117
*
NC
B
11
B
10
B
9
B
8
B
7
V
CC
B
6
GND
B
5
B
4
B
3
B
2
B
1
B
0
GND
A
0
A
1
A
2
V
CC
A
3
A
4
A
5
GND
A
6
A
7
A
8
A
9
A
10
A
11
GND
NC
NC
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
116
115
114
113
112
111
110
109
108
107
106
105
104
103
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
NC
NC
A
35
A
34
A
33
A
32
V
CC
A
31
A
30
GND
A
29
A
28
A
27
A
26
A
25
A
24
A
23
GND
A
22
V
CC
A
21
A
20
A
19
A
18
GND
A
17
A
16
A
15
A
14
A
13
V
CC
A
12
NC
4658 drw 02
*
Electrical pin 1 in center of beveled edge. Pin 1 identifier in corner.
NOTES:
1. NC – No internal connection.
2. Uses Yamaichi socket IC51-1324-828.
PQFP (PQ132-1, order code: PQF)
TOP VIEW
2
IDT72V3631/72V3641/72V3651
3.3V CMOS SYNCFIFO™ 512 x 36, 1,024 x 36 and 2,048 x 36
COMMERCIAL TEMPERATURE RANGE
PIN CONFIGURATION (CONTINUED)
GND
CLKA
ENA
W/RA
CSA
IR
OR
V
CC
AF
AE
VCC
MBF2
MBA
RST
GND
FS0/SD
FS1/SEN
RTM
RFM
V
CC
NC
MBB
GND
MBF1
GND
CSB
W/RB
ENB
CLKB
V
CC
A
35
A
34
A
33
A
32
V
CC
A
31
A
30
GND
A
29
A
28
A
27
A
26
A
25
A
24
A
23
GND
A
22
V
CC
A
21
A
20
A
19
A
18
GND
A
17
A
16
A
15
A
14
A
13
V
CC
A
12
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
120
119
118
117
116
115
114
113
112
111
110
109
108
107
106
105
104
103
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
B
35
B
34
B
33
B
32
GND
B
31
B
30
B
29
B
28
B
27
B
26
V
CC
B
25
B
24
GND
B
23
B
22
B
21
B
20
B
19
B
18
GND
B
17
B
16
V
CC
B
15
B
14
B
13
B
12
GND
GND
A
11
A
10
A
9
A
8
A
7
A
6
GND
A
5
A
4
A
3
V
CC
A
2
A
1
A
0
GND
B
0
B
1
B
2
B
3
B
4
B
5
GND
B
6
V
CC
B
7
B
8
B
9
B
10
B
11
4658 drw 03
NOTE:
1. NC – No internal connection.
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
TQFP (PN120-1, order code: PF)
TOP VIEW
3
IDT72V3631/72V3641/72V3651
3.3V CMOS SYNCFIFO™ 512 x 36, 1,024 x 36 and 2,048 x 36
COMMERCIAL TEMPERATURE RANGE
PIN DESCRIPTION
Symbol
Name
A0-A35 Port-A Data
AE
Almost-Empty
Flag
AF
Almost-Full
Flag
B0-B35 Port-B Data
CLKA
Port-A Clock
CLKB
CSA
CSB
ENA
ENB
FS1/
SEN,
Port-B Clock
Port-A Chip
Select
Port-B Chip
Select
Port-A Enable
Port-B Enable
Flag-Offset
Select 1/
Serial Enable
Flag Offset 0/
Serial Data
I/O
Description
I/O 36-bit bidirectional data port for side A.
O Programmable flag synchronized to CLKB. It is LOW when the number of words in the FIFO is less than or equal to
the value in the Almost-Empty register (X).
O Programmable flag synchronized to CLKA. It is LOW when the number of empty locations in the FIFO is less than or
equal to the value in the Almost-Full Offset register (Y).
I/O 36-bit bidirectional data port for side B.
I CLKA is a continuous clock that synchronizes all data transfers through port-A and may be asynchronous or
coincident to CLKB. IR and
AF
are synchronous to the LOW-to-HIGH transition of CLKA.
I CLKB is a continuous clock that synchronizes all data transfers through port-B and may be asynchronous or
coincident to CLKA. OR and
AE
are synchronous to the LOW-to-HIGH transition of CLKB.
I
CSA
must be LOW to enable a LOW-to-HIGH transition of CLKA to read or write data on port-A. The A0-A35
outputs are in the high-impedance state when
CSA
is HIGH.
I
CSB
must be LOW to enable a LOW-to-HIGH transition of CLKB to read or write data on port-B. The B0-B35
outputs are in the high-impedance state when
CSB
is HIGH.
I ENA must be HIGH to enable a LOW-to-HIGH transition of CLKA to read or write data on port-A.
I ENB must be HIGH to enable a LOW-to-HIGH transition of CLKB to read or write data on port-B.
I FS1/SEN and FS0/SD are dual-purpose inputs used for flag Offset register programming. During a device reset,
FS1/SEN and FS0/SD selects the flag offset programming method. Three Offset register programming methods are
available: automatically load one of two preset values, parallel load from port A, and serial load.
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 18/20/22 for the
IDT72V3631/72V3641/72V3651 respectively. The first bit write stores the Y-register MSB and the last bit write stores
the X-register LSB.
IR is synchronized to the LOW-to-HIGH transition of CLKA. When IR is LOW, the FIFO is full and writes to its
array are disabled. When the FIFO is in retransmit mode, IR indicates when the memory has been filled to the point
of the retransmit data and prevents further writes. IR is set LOW during reset and is set HIGH after reset.
A HIGH level chooses a mailbox register for a port-A read or write operation.
A HIGH level chooses a mailbox register for a port-B read or write operation. When the B0-B35 outputs are active,
a HIGH level on MBB selects data from the mail1 register for output and a LOW level selects FIFO data for output.
MBF1
is set LOW by the LOW-to-HIGH transition of CLKA that writes data to the mail1 register.
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 by a
reset.
MBF2
is set LOW by the LOW-to-HIGH transition of CLKB that writes data to the mail2 register.
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 by a
reset.
OR is synchronized to the LOW-to-HIGH transition of CLKB. When OR is LOW, the FIFO is empty and reads are
disabled. Ready data is present in the output register of the FIFO when OR is HIGH. OR is forced LOW during the
reset and goes HIGH on the third LOW-to-HIGH transition of CLKB after a word is loaded to empty memory.
When the FIFO is in retransmit mode, a HIGH on RFM enables a LOW-to-HIGH transition of CLKB to reset the read
pointer to the beginning retransmit location and output the first selected retransmit data.
To reset the device, four LOW-to-HIGH transitions of CLKA and four LOW-to-HIGH transitions of CLKB must occur
while
RST
is LOW. The LOW-to-HIGH transition of
RST
latches the status of FS0 and FS1 for
AF
and
AE
offset
selection.
When RTM is HIGH and valid data is present in the FIFO output register (OR is HIGH), a LOW-to-HIGH transition
of CLKB selects the data for the beginning of a retransmit and puts the FIFO in retransmit mode. The selected word
remains the initial retransmit point until a LOW- to-HIGH transition of CLKB occurs while RTM is LOW, taking the FIFO
out of retransmit mode.
A HIGH selects a write operation and a LOW selects a read operation on port A for a LOW-to-HIGH transition of
CLKA. The A0-A35 outputs are in the high-impedance state when W/RA is HIGH.
A LOW selects a write operation and a HIGH selects a read operation on port B for a LOW-to-HIGH transition of
CLKB. The B0-B35 outputs are in the high-impedance state when
W/RB
is LOW.
FS0/SD
IR
MBA
MBB
MBF1
MBF2
OR
RFM
RST
RTM
Input Ready
Flag
Port-A Mailbox
Select
Port-B Mailbox
Select
Mail1 Register
Flag
Mail2 Register
Flag
Output Ready
Flag
Read From
Mark
Reset
Retransmit
Mode
O
I
I
O
O
O
I
I
I
W/RA
W/RB
Port-A Write/
Read Select
Port-B Write/
Read Select
I
I
4
IDT72V3631/72V3641/72V3651
3.3V CMOS SYNCFIFO™ 512 x 36, 1,024 x 36 and 2,048 x 36
COMMERCIAL TEMPERATURE RANGE
ABSOLUTE MAXIMUM RATINGS OVER OPERATING FREE-AIR
TEMPERATURE RANGE (Unless otherwise noted)
(2)
Symbol
V
CC
V
I
(2)
V
O
(2)
I
IK
I
OK
I
OUT
I
CC
T
STG
Supply Voltage Range
Input Voltage Range
Output Voltage Range
Input Clamp Current, (V
I
< 0 or V
I
> V
CC
)
Output Clamp Current, (V
O
= < 0 or V
O
> V
CC
)
Continuous Output Current, (V
O
= 0 to V
CC
)
Continuous Current Through V
CC
or GND
Storage Temperature Range
Rating
Commercial
–0.5 to +4.6
–0.5 to V
CC
+0.5
(3)
–0.5 to V
CC
+0.5
±20
±50
±50
±400
–65 to 150
Unit
V
V
V
mA
mA
mA
mA
°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.
3. Control Inputs: maximum V
I
= 5.0V.
RECOMMENDED OPERATING
CONDITIONS
Symbol
V
CC
V
IH
V
IL
I
OH
I
OL
T
A
Parameter
Supply Voltage
HIGH Level Input Voltage
LOW-Level Input Voltage
HIGH-Level Output Current
LOW-Level Output Current
Operating Free-air
Temperature
Min.
3.0
2
—
—
—
0
Typ.
3.3
—
—
—
—
—
Max.
3.6
V
CC
+0.5
0.8
–4
8
70
Unit
V
V
V
mA
mA
°
C
ELECTRICAL CHARACTERISTICS OVER RECOMMENDED OPERATING
FREE-AIR TEMPERATURE RANGE (Unless otherwise noted)
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