CMOS SyncBiFIFO
TM
256 x 36 x 2, 512 x 36 x 2,
1,024 x 36 x 2
.EATURES:
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IDT723622
IDT723632
IDT723642
•
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Memory storage capacity:
IDT723622 – 256 x 36 x 2
IDT723632 – 512 x 36 x 2
IDT723642 – 1,024 x 36 x 2
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
Mailbox bypass register for each FIFO
Programmable Almost-Full and Almost-Empty flags
Microprocessor Interface Control Logic
IRA, ORA,
AEA,
and
AFA
flags synchronized by CLKA
IRB, ORB,
AEB,
and
AFB
flags synchronized by CLKB
Supports clock frequencies up to 83MHz
Fast access times of 8ns
Available in 132-pin Plastic Quad Flatpack (PQFP) or space-
saving 120-pin Thin Quad Flatpack (TQFP)
Low-power 0.8-Micron Advanced CMOS technology
Industrial temperature range (–40°C to +85°C) is available
°
°
DESCRIPTION:
The IDT723622/723632/723642 are a monolithic, high-speed, low-power,
CMOS Bidirectional SyncFIFO (clocked) memory which supports clock fre-
quencies up to 83MHz and have read access times as fast as 8ns. Two
independent 256/512/1,024 x 36 dual-port SRAM FIFOs on board each chip
buffer data in opposite directions. 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.
These devices are a synchronous (clocked) FIFO, meaning each port
employs a synchronous interface. All data transfers through a port are gated
to the LOW-to-HIGH transition of a port clock by enable signals. The clocks for
each port are independent of one another and can be asynchronous or
.UNCTIONAL BLOCK DIAGRAM
MBF1
CLKA
CSA
W/RA
ENA
MBA
Mail 1
Register
Input
Register
RAM
ARRAY
256 x 36
512 x 36
1,024 x 36
Output
Register
Port-A
Control
Logic
RST1
FIFO1,
Mail1
Reset
Logic
36
36
Write
Pointer
Read
Pointer
ORB
AEB
IRA
AFA
FIFO 1
Status Flag
Logic
FS
0
FS
1
A
0
- A
35
ORA
AEA
Programmable Flag
Offset Registers
10
FIFO 2
B
0
- B
35
Status Flag
Logic
Write
Pointer
36
IRB
AFB
36
Read
Pointer
RAM
ARRAY
256 x 36
512 x 36
1,024 x 36
Mail 2
Register
Output
Register
FIFO2,
Mail2
Reset
Logic
Input
Register
RST2
Port-B
Control
Logic
CLKB
CSB
W/RB
ENB
MBB
3022 drw 01
MBF2
IDT, the IDT logo are registered trademarks of Integrated Device Technology, Inc. SyncBiFIFO is a trademark of Integrated Device Technology, Inc.
COMMERCIAL TEMPERATURE RANGE
DECEMBER 2001
DSC-3022/3
1
2001 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice.
IDT723622/723632/723642 CMOS SyncBiFIFO™
256 x 36 x 2, 512 x 36 x 2, 1,024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
DESCRIPTION (CONTINUED)
coincident. The enables for each port are arranged to provide a simple
bidirectional interface between microprocessors and/or buses with synchro-
nous control.
Each FIFO has a programmable Almost-Empty flag (AEA and
AEB)
and a
progammable Almost-Full flag (AFA and
AFB). AEA
and
AEB
indicate when
a selected number of words remain in the FIFO memory.
AFA
and
AFB
indicate
when the FIFO contains more than a selected number of words.
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.
Two or more devices may be used in parallel to create wider data paths.
If, at any time, the FIFO is not actively performing a function, the chip will
automatically power down. During the power down state, supply current
consumption (I
CC
) is at a minimum. Initiating any operation (by activating control
inputs will immediately take the device out of the power down state.
The 723622/723632/723642 are characterized for operation from 0°C to
70°C. Industrial temperature range (-40°C to +85°C) is available by special
order. They are fabricated using IDT's high speed, submicron CMOS technology.
PIN CON.IGURATION
NC
NC
V
CC
CLKB
ENB
W/RB
CSB
GND
IRB
ORB
AFB
AEB
V
CC
MBF1
MBB
RST2
FS1
GND
FS0
RST1
MBA
MBF2
AEA
AFA
V
CC
ORA
IRA
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
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
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
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
3022 drw 02
PQFP (PQ132-1, order code: PQF)
TOP VIEW
NOTES:
1. NC – no internal connection
2. Uses Yamaichi socket IC51-1324-828
2
IDT723622/723632/723642 CMOS SyncBiFIFO™
256 x 36 x 2, 512 x 36 x 2, 1,024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
PIN CON.IGURATION (CONTINUED)
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
GND
CLKA
ENA
W/RA
CSA
IRA
ORA
V
CC
AFA
AEA
MBF2
MBA
RST1
FS0
GND
FS1
RST2
MBB
MBF1
V
CC
AEB
AFB
ORB
IRB
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
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
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
3022 drw 03
TQFP (PN120-1, order code: PF)
TOP VIEW
3
IDT723622/723632/723642 CMOS SyncBiFIFO™
256 x 36 x 2, 512 x 36 x 2, 1,024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
PIN DESCRIPTIONS
Symbol
A0-A35
AEA
AEB
AFA
AFB
B0 - B35
CLKA
Name
Port A Data
Port A Almost-
Empty Flag
Port B Almost-
Empty Flag
Port A Almost-
Full Flag
Port B Almost-
Full Flag
Port B Data
Port A Clock
I/O
I/0
O
(Port A)
O
(Port B)
O
(Port A)
O
(Port B)
I/O
I
36-bit bidirectional data port for side A.
Programmable Almost-Empty flag synchronized to CLKA. It is LOW when the number of words
in FIFO2 is less than or equal to the value in the Almost-Empty A Offset register, X2.
Programmable Almost-Empty flag synchronized to CLKB. It is LOW when the number of words
in FIFO1 is less than or equal to the value in the Almost-Empty B Offset register, X1.
Programmable Almost-Full flag synchronized to CLKA. It is LOW when the number of empty
locations in FIFO1 is less than or equal to the value in the Almost-Full A Offset register, Y1.
Programmable Almost-Full flag synchronized to CLKB. It is LOW when the number of empty
locations in FIFO2 is less than or equal to the value in the Almost-Full B Offset register, Y2.
36-bit bidirectional data port for side B.
CLKA is a continuous clock that synchronizes all data transfers through port A and can be
asynchronous or coincident to CLKB. IRA, ORA,
AFA,
and
AEA
are all synchronized to the
LOW-to-HIGH transition of CLKA.
CLKB is a continuous clock that synchronizes all data transfers through port B and can be
asynchronous or coincident to CLKA. IRB, ORB,
AFB,
and
AEB
are synchronized to the LOW-
to-HIGH transition of CLKB.
CSA
must be LOW to enable a LOW-to-HIGH transition of CLKA to read or write on port A.
The A0-A35 outputs are in the high-impedance state when
CSA
is HIGH.
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.
ENA must be HIGH to enable a LOW-to-HIGH transition of CLKA to read or write data on port A.
ENB must be HIGH to enable a LOW-to-HIGH transition of CLKB to read or write data on port B.
The LOW-to-HIGH transition of a FlFO’s Reset input latches the values of FS0 and FS1.
If either FS0 or FS1 is HIGH when a Reset goes HIGH, one of 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 FS0 and FS1 are LOW when
RST1
and
RST2
go HIGH, the first four writes to FIFO1
load the Almost-Empty and Almost-Full offsets for both FlFOs.
IRA is synchronized to the LOW-to-HIGH transition of CLKA. When IRA is 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.
IRB is synchronized to the LOW-to-HIGH transition of CLKB. When IRB is 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.
A HIGH level on MBA chooses a mailbox register for a port A read or write operation.
When the A0-A35 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.
A HIGH level on MBB 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 or output and
a LOW level selects FIFO1 output register data for output.
MBF1
is set LOW by a LOW-to-HIGH transition of CLKA that writes data to the mail1
register. Writes to 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 when FIFO1 is reset.
MBF2
is set LOW by a LOW-to-HIGH transition of CLKB that writes data to the mail2 register.
Writes to the 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 also
set HIGH when FIFO2 is reset.
Description
CLKB
Port B Clock
I
CSA
CSB
ENA
ENB
FS1, FS0
Port A Chip
Select
Port B Chip
Select
Port A Enable
Port B Enable
Flag Offset
Selects
I
I
I
I
I
IRA
Input Ready
Flag
Input Ready
Flag
Port A Mailbox
Select
Port B Mailbox
Select
Mail1 Register
Flag
O
(Port A)
O
(Port B)
I
IRB
MBA
MBB
I
MBF1
O
MBF2
Mail2 Register
Flag
O
4
IDT723622/723632/723642 CMOS SyncBiFIFO™
256 x 36 x 2, 512 x 36 x 2, 1,024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
PIN DESCRIPTIONS (CONTINUED)
Symbol
ORA
Name
Output Ready
Flag
I/O
O
(Port A)
Description
ORA is synchronized to the LOW-to-HIGH transition of CLKA. When ORA is 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.
ORB is synchronized to the LOW-to-HIGH transition of CLKB. When ORB 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.
To reset FIFO1, four LOW-to-HIGH transitions of CLKA and four LOW-to-HIGH transitions of CLKB
must occur while
RST1
is LOW. The LOW-to-HIGH transition of
RST1
latches the status of FS0
and FS1 for
AFA
and
AEB
offset selection. FIFO1 must be reset upon power up before data is
written to its RAM.
To reset FIFO2, four LOW-to-HIGH transitions of CLKA and four LOW-to-HIGH transitions of CLKB
must occur while
RST2
is LOW. The LOW-to-HIGH transition of
RST2
latches the status of FS0
and FS1 for
AFB
and
AEA
offset selection. FIFO2 must be reset upon power up before data is
written to its RAM.
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.
ORB
Output Ready
Flag
O
(Port B)
RST1
FIFO1 Reset
I
RST2
FIFO2 Reset
I
W/RA
W/RB
Port A Write/
Read Select
Port B Write/
Read Select
I
I
5
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