CMOS SyncBiFIFO
™
256 x 36 x 2, 512 x 36 x 2,
1024 x 36 x 2
Integrated Device Technology, Inc.
IDT723622
IDT723632
IDT723642
FEATURES:
• 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 oppo-
site 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,
AEA
, and
AFA
flags synchronized by CLKA
• IRB, ORB,
AEB
, and
AFB
flags synchronized by CLKB
• Supports clock frequencies up to 67MHz
• 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 (-40
o
C to +85
o
C) is avail-
able, 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
FUNCTIONAL BLOCK DIAGRAM
CLKA
MBF1
Mail 1
Register
256 x 36
512 x 36
1024 x 36
SRAM
Input
Register
Output
Register
W/
R
A
ENA
MBA
CSA
Port-A
Control
Logic
RST1
FIFO1,
Mail1
Reset
Logic
36
36
Write
Pointer
Read
Pointer
Status Flag
Logic
ORB
AFA
FS
0
FS
1
A
0
- A
35
IRA
FIFO 1
AEB
Programmable Flag
Offset Registers
9
FIFO 2
B
0
- B
35
ORA
AEA
36
Status Flag
Logic
Write
Pointer
36
IRB
AFB
FIFO2,
Mail2
Reset
Logic
Read
Pointer
RST2
Output
Register
256 x 36
512 x 36
1024 x 36
SRAM
Mail 2
Register
Input
Register
Port-B
Control
Logic
CLKB
CSB
W
/RB
ENB
MBB
MBF2
SyncFIFO is a trademark and the IDT logo is a registered trademark of Integrated Device Technology, Inc.
3022 drw 01
COMMERCIAL TEMPERATURE RANGE
©1996
Integrated Device Technology, Inc.
For latest information contact IDT's web site at www.idt.com or fax-on-demand at 408-492-8391.
DECEMBER 1996
DSC-3022/3
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-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 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-
eration from 0°C to 70°C.
PIN CONFIGURATION
NC
NC
V
CC
CLKB
ENB
W
/RB
MBF1
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
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
MBF2
AEA
AFA
RST1
CSA
W/
R
A
FS1
GND
FS0
V
CC
ORA
IRA
CSB
V
CC
ENA
CLKA
GND
NC
RST2
GND
IRB
ORB
MBB
MBA
AFB
AEB
PQ132-1
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
3022 drw 02
PQF Package
TOP VIEW
NOTES:
1. NC – no internal connection
2. Uses Yamaichi socket IC51-1324-828
5.22
2
IDT723622/723632/723642 CMOS SyncBiFIFO™
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
PIN CONFIGURATION
GND
CLKA
ENA
W/
R
A
RST2
MBB
MBF1
FS0
GND
FS1
IRA
ORA
V
CC
CSA
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
V
CC
ENB
CLKB
V
CC
AFA
AEA
MBF2
MBA
RST1
CSB
W
/RB
ORB
IRB
GND
AEB
AFB
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
PN120-1
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
TOP VIEW
5.22
3
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
Symbol
A0-A35
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
Description
36-bit bidirectional data port for side A.
Programmable almost-empty flag synchronized to CLKA. It is LOW
when the number of words in FIF02 is less than or equal to the value in the
almost-empty A offset register, X2.
Programmable almost-empty flag synchronzed to CLKB. It is LOW
when the number of words in FIF01 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 FIF01 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 FIF02 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.
AEA
AEB
AFA
AFB
B0 - B35
CLKA
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
CSA
must be LOW to enable to LOW-to-HIGH transition of CLKA to read or
write on port A. The AO-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 BO- B35 outputs are in the high-impedance state
when
CSB
is HIGH.
I
I
I
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 FSO
and FS1. If either FSO or FS1 is HIGH when a reset input goes HIGH, one
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.
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 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.
IRA
Input-Ready
Flag
O
(Port A)
IRB
Input-Ready
Flag
O
(Port B)
MBA
Port-A Mailbox
Select
I
5.22
4
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.)
Symbol
MBB
Name
Port-B Mailbox
Select
I/O
I
Description
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.
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.
MBF1
Mail1 Register
Flag
O
MBF1
MBF2
Mail2 Register
Flag
O
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.
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 FSO 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 FSO 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 AO-A35 outputs are in
the HIGH impedance state when W/
R
A 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 BO-B35 outputs are in the HIGH
impedance state when
W
/RB is LOW.
ORA
Output-Ready
Flag
O
(Port A)
ORB
Output-Ready
Flag
O
(Port B)
RST1
FIFO1 Reset
I
RST2
FIFO2 Reset
I
W/
R
A
Port-A Write/
Read Select
Port-B Write/
Read Select
I
W
/RB
I
5.22
5
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