IDT IDT723632L15PF Cmos syncbififoo 256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2 Datasheet

CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2,
1024 x 36 x 2
IDT723622
IDT723632
IDT723642
Integrated Device Technology, Inc.
FEATURES:
• 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
• 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, AEA, and AFA flags synchronized by CLKA
• IRB, ORB, AEB, and AFB flags synchronized by CLKB
• Supports clock frequencies up to 67MHz
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
RST1
256 x 36
512 x 36
1024 x 36
SRAM
FIFO1,
Mail1
Reset
Logic
Write
Pointer
36
36
Read
Pointer
Status Flag
Logic
IRA
AFA
Output
Register
Port-A
Control
Logic
FIFO 1
ORB
AEB
Programmable Flag
Offset Registers
FS0
FS1
A0 - A35
B0 - B35
9
FIFO 2
ORA
AEA
Status Flag
Logic
Read
Pointer
Output
Register
36
IRB
AFB
36
Write
Pointer
256 x 36
512 x 36
1024 x 36
SRAM
FIFO2,
Mail2
Reset
Logic
Input
Register
CSA
W/RA
ENA
MBA
Mail 1
Register
Input
Register
CLKA
MBF1
Port-B
Control
Logic
Mail 2
Register
MBF2
RST2
CLKB
CSB
W/RB
ENB
MBB
3022 drw 01
SyncFIFO is a trademark and the IDT logo is a registered trademark of Integrated Device Technology, Inc.
COMMERCIAL TEMPERATURE RANGE
1996 Integrated Device Technology, Inc.
DECEMBER 1996
For latest information contact IDT's web site at www.idt.com or fax-on-demand at 408-492-8391.
5.22
DSC-3022/3
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
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 operation from 0°C to 70°C.
ENA
CLKA
GND
NC
CSA
W/RA
VCC
ORA
IRA
MBA
MBF2
AEA
AFA
RST1
RST2
FS1
GND
FS0
MBB
VCC
AFB
AEB
GND
IRB
ORB
MBF1
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
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
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
NC
B11
B10
B9
B8
B7
VCC
B6
GND
B5
B4
B3
B2
B1
B0
GND
A0
A1
A2
VCC
A3
A4
A5
GND
A6
A7
A8
A9
A10
A11
GND
NC
NC
NC
B35
B34
B33
B32
GND
B31
B30
B29
B28
B27
B26
VCC
B25
B24
GND
B23
B22
B21
B20
B19
B18
GND
B17
B16
VCC
B15
B14
B13
B12
GND
NC
NC
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
CSB
NC
NC
VCC
CLKB
ENB
W/RB
PIN CONFIGURATION
NC
NC
A35
A34
A33
A32
VCC
A31
A30
GND
A29
A28
A27
A26
A25
A24
A23
GND
A22
VCC
A21
A20
A19
A18
GND
A17
A16
A15
A14
A13
VCC
A12
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
ENB
CLKB
VCC
CSB
W/RB
ORB
IRB
GND
AEB
AFB
VCC
RST2
MBB
MBF1
FS0
GND
FS1
AFA
AEA
MBF2
MBA
RST1
IRA
ORA
VCC
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
CSA
GND
CLKA
ENA
W/RA
PIN CONFIGURATION
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
B35
B34
B33
B32
GND
B31
B30
B29
B28
B27
B26
VCC
B25
B24
GND
B23
B22
B21
B20
B19
B18
GND
B17
B16
VCC
B15
B14
B13
B12
GND
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
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
GND
A11
A10
A9
A8
A7
A6
GND
A5
A4
A3
VCC
A2
A1
A0
GND
B0
B1
B2
B3
B4
B5
GND
B6
VCC
B7
B8
B9
B10
B11
A35
A34
A33
A32
VCC
A31
A30
GND
A29
A28
A27
A26
A25
A24
A23
GND
A22
VCC
A21
A20
A19
A18
GND
A17
A16
A15
A14
A13
VCC
A12
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
AEA
AEB
AFA
AFB
Name
Port-A Data
I/O
I/0
Description
36-bit bidirectional data port for side A.
Port-A Almost
-Empty Flag
O
(Port 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.
Port-B Almost
-Empty Flag
O
(Port B)
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.
Port-A Almost
-Full Flag
O
(Port A)
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.
Port-B Almost
-Full Flag
O
(Port B)
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.
B0 - B35
Port-B Data
I/O
CLKA
Port-A Clock
I
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
Port-B Clock
I
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.
Port-A Chip
Select
I
Port-B Chip
Select
I
ENA
Port-A Enable
I
ENA must be HIGH to enable a LOW-to-HIGH transition of CLKA to read or
write data on port A.
ENB
Port-B Enable
I
ENB must be HIGH to enable a LOW-to-HIGH transition of CLKB to read or
write data on port B.
FS1,
FS0
Flag Offset
Selects
I
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
Input-Ready
Flag
O
(Port A)
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
Input-Ready
Flag
O
(Port B)
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.
MBA
Port-A Mailbox
Select
I
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.
CSA
CSB
36-bit bidirectional data port for side B.
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.
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.
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
Name
I/O
Port-B Mailbox
Select
I
Mail1 Register
Flag
O
Mail2 Register
Flag
O
ORA
Output-Ready
Flag
O
(Port A)
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
Output-Ready
Flag
O
(Port B)
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.
RST1
FIFO1 Reset
I
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.
RST2
FIFO2 Reset
I
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.
Port-A Write/
Read Select
I
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/RA is HIGH.
Port-B Write/
Read Select
I
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.
MBB
MBF1
MBF2
W/RA
W/RB
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.
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.
5.22
5
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)(1)
Symbol
VCC
(2)
VI
VO
(2)
Rating
Commercial
Unit
-0.5 to 7
V
Input Voltage Range
-0.5 to VCC+0.5
V
Output Voltage Range
-0.5 to VCC+0.5
V
Supply Voltage Range
IIK
Input Clamp Current (VI < 0 or VI > VCC)
±20
mA
IOK
Output Clamp Current (VO = < 0 or VO > VCC)
±50
mA
IOUT
Continuous Output Current (VO = 0 to VCC)
±50
mA
ICC
Continuous Current Through VCC or GND
±400
mA
TA
Operating Free Air Temperature Range
0 to 70
°C
TSTG
Storage 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.
RECOMMENDED OPERATING CONDITIONS
Symbol
Parameter
Min. Max. Unit
VCC
Supply Voltage
VIH
High-Level Input Voltage
VIL
Low-Level Input Voltage
0.8
V
IOH
High-Level Output Current
-4
mA
IOL
Low-Level Output Current
8
mA
TA
Operating Free-Air
Temperature
70
°C
4.5
5.5
2
0
V
V
5.22
6
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
tA = 15, 20, 30 ns
Parameter
Test Conditions
Min.
2.4
Typ.(1)
Max.
Unit
VOH
VCC = 4.5V,
IOH = -4 mA
VOL
VCC = 4.5 V,
IOL = 8 mA
0.5
V
ILI
VCC = 5.5 V,
VI = VCC or 0
±5
µA
ILO
VCC = 5.5 V,
VO = VCC or 0
±5
µA
ICC
VCC = 5.5 V,
VI = VCC -0.2 V or 0
400
µA
∆ICC
VCC = 5.5 V,
One Input at 3.4 V,
(2)
Other Inputs at VCC or GND
CSA = VIH
CSB = VIH
CSA = VIL
CSB = VIL
V
A0-A35
0
B0-B35
0
mA
A0-A35
1
B0-35
1
All Other Inputs
1
CIN
VI = 0,
f = 1 MHz
4
pF
COUT
VO = 0,
f = 1 MHZ
8
pF
NOTES:
1. All typical values are at VCC = 5V, TA = 25°C.
2. This is the supply current when each input is at least one of the specified TTL voltage levels rather than 0V or VCC.
5.22
7
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
723622-15
723622-20
723622-30
723632-15
723632-20
723632-30
723642-15
Symbol
Parameter
Min.
Max.
723642-20
Min.
723642-30
Min.
Unit
33.4
MHz
Clock Frequency, CLKA or CLKB
tCLK
Clock Cycle Time, CLKA or CLKB
15
20
30
ns
tCLKH
Pulse Duration, CLKA or CLKB HIGH
6
8
10
ns
tCLKL
Pulse Duration, CLKA and CLKB LOW
6
8
10
ns
Setup Time, A0-A35 before CLKA↑ and B0-B35
before CLKB↑
4
5
6
ns
4.5
5
6
ns
5
6
7
ns
7.5
8.5
9.5
ns
1
1
1
ns
1
1
1
ns
Hold Time, RST1 or RST2 LOW after CLKA↑ or
CLKB↑(1)
4
4
5
ns
Hold Time, FS0 and FS1 after RST1 and RST2 HIGH
2
3
3
ns
7.5
9
11
ns
12
16
20
ns
Setup Time, CSA, W/RA, ENA, and MBA before
CLKA↑; CSB, W/RB, ENB, and MBB before CLKB↑
tENS
tRSTS
Setup Time, RST1 or RST2 LOW before CLKA↑
or CLKB↑(1)
tFSS
Setup Time, FS0 and FS1 before RST1 and RST2
HIGH
tDH
Hold Time, A0-A35 after CLKA↑ and B0-B35 after
CLKB↑
Hold Time, CSA, W/RA, ENA, and MBA after CLKA↑;
CSB, W/RB, ENB, and MBB after CLKB↑
tENH
tRSTH
tFSH
tSKEW1
(2)
Skew Time, between CLKA↑ and CLKB↑ for ORA,
ORB, IRA, and IRB
tSKEW2(2) Skew Time, between CLKA↑ and CLKB↑ for AEA,
AEB, AFA, and AFB
50
Max.
fS
tDS
66.7
Max.
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.
5.22
8
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
SWITCHING CHARACTERISTICS OVER RECOMMENDED RANGES OF SUPPLY VOLTAGE
AND OPERATING FREE-AIR TEMPERATURE, CL = 30 pF
Symbol
Parameter
723622L15
723622L20
723622L30
723632L15
723632L20
723632L30
723642L15
723642L20
723642L30
Min.
Max.
Min.
Max.
Min.
Max.
Unit
tA
Access Time, CLKA↑ to A0-A35 and CLKB↑
to B0-B35
3
11
3
13
3
15
ns
tPIR
Propagation Delay Time, CLKA↑ to IRA and
CLKB↑ to IRB
2
8
2
10
2
12
ns
tPOR
Propagation Delay Time, CLKA↑ to ORA and
CLKB↑ to ORB
1
8
1
10
1
12
ns
1
8
1
10
1
12
ns
1
8
1
10
1
12
ns
0
8
0
10
0
12
ns
tPAE
tPAF
tPMF
Propagation Delay Time, CLKA↑ to AEA and
CLKB↑ to AEB
Propagation Delay Time, CLKA↑ to AFA and
and CLKB↑ to AFB
Propagation Delay Time, CLKA↑ to MBF1 LOW or
MBF2 HIGH and CLKB↑ to MBF2 LOW or MBF1
HIGH
tPMR
Propagation Delay Time, CLKA↑ to B0-B35(1) and
CLKB↑ to A0-A35(2)
3
13.5
3
15
3
17
ns
tMDV
Propagation Delay Time, MBA to A0-A35 valid and
MBB to B0-B35 Valid
3
11
3
13
3
15
ns
1
15
1
20
1
30
ns
2
12
2
13
2
14
ns
1
8
1
10
1
11
ns
tPRF
tEN
tDIS
Propagation Delay Time, RST1 LOW to AEB LOW,
AFA HIGH, and MBF1 HIGH, and RST2 LOW to
AEA LOW, AFB HIGH, and MBF2 HIGH
Enable Time, CSA and W/RA LOW to A0-A35 Active
and CSB LOW and W/RB HIGH to B0-B35 Active
Disable Time, CSA or W/RA HIGH to A0-A35 at
high impedance and CSB HIGH or W/RB LOW
to B0-B35 at HIGH impedance
NOTES:
1. Writing data to the mail1 register when the B0-B35 outputs are active and MBB is HIGH.
2. Writing data to the mail2 register when the A0-A35 outputs are active and MBA is HIGH.
5.22
9
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
during the LOW-to-HIGH transition of its reset input. For
example, to load the preset value of 64 into X1 and Y1, FS0
and FS1 must be HIGH when FlFO1 reset (RST1) returns
HIGH. Flag-offset registers associated with FIFO2 are loaded
with one of the preset values in the same way with FIFO2 reset
(RST2). When using one of the preset values for the flag
offsets, the FlFOs can be reset simultaneously or at different
times.
To program the X1, X2, Y1, and Y2 registers from port A,
both FlFOs should be reset simultaneously with FS0 and FS1
LOW during the LOW-to-HIGH transition of the reset inputs.
After this reset is complete, the first four writes to FIFO1 do not
store data in RAM but load the offset registers in the order Y1,
X1, Y2, X2. The port A data inputs used by the offset registers
are (A7-A0), (A8-A0), or (A9-A0) for the IDT723622,
IDT723632, or IDT723642, respectively. The highest numbered input is used as the most significant bit of the binary
number in each case. Valid programming values for the
registers ranges from 1 to 252 for the IDT723622; 1 to 508 for
the IDT723632; and 1 to 1020 for the IDT723642. After all the
offset registers are programmed from port A, the port-B inputready flag (IRB) is set HIGH, and both FIFOs begin normal
operation.
SIGNAL DESCRIPTION
RESET
The FIFO memories of the IDT723622/723632/723642
are reset separately by taking their reset (RST1, RST2) inputs
LOW for at least four port-A clock (CLKA) and four port-B clock
(CLKB) LOW-to-HIGH transitions. The reset inputs can switch
asynchronously to the clocks. A FIFO reset initializes the
internal read and write pointers and forces the input-ready flag
(IRA, IRB) LOW, the output-ready flag (ORA, ORB) LOW, the
almost-empty flag (AEA, AEB) LOW, and the almost-full flag
(AFA, AFB) HIGH. Resetting a FIFO also forces the mailbox
flag (MBF1, MBF2) of the parallel mailbox register HIGH. After
a FlFO is reset, its input-ready flag is set HIGH after two clock
cycles to begin normal operation. A FIFO must be reset after
power up before data is written to its memory.
A LOW-to HIGH transition on a FlFO reset (RST1, RST2)
input latches the value of the flag-select (FS0, FS1) inputs for
choosing the almost-full and almost-empty offset programming method (see almost-empty and almost-full flag offset
programming below).
ALMOST-EMPTY FLAG AND ALMOST-FULL FLAG OFFSET PROGRAMMING
Four registers in the IDT723622/723632/723642 are used
to hold the offset values for the almost-empty and almost-full
flags. The port-B almost-empty flag (AEB) offset register is
labeled X1 and the port-A almost-empty flag (AEA) offset
register is labeled X2. The port-A almost-full flag (AFA) offset
register is labeled Y1 and the port-B almost-full flag (AFB)
offset register is labeled Y2. The index of each register name
corresponds to its FIFO number. The offset registers can be
loaded with preset values during the reset of a FIFO or they
can be programmed from port A (see Table 1 ) .
To load a FIFO almost-empty flag and almost-full flag
offset registers with one of the three preset values listed in
Table1, at least one of the flag-select inputs must be HIGH
FIFO WRITE/READ OPERATION
The state of the port-A data (A0-A35) outputs is controlled
by port-A chip select (CSA) and port-A write/read select (W/
RA). The A0-A35 outputs are in the High-impedance state
when either CSA or W/RA is HIGH. The A0-A35 outputs are
active when both CSA and W/RA are LOW.
Data is loaded into FIFO1 from the A0-A35 inputs on a
LOW-to-HIGH transition of CLKA when CSA is LOW, W/RA is
HIGH, ENA is HIGH , MBA is LOW, and IRA is HIGH. Data is
read from FIFO2 to the A0-A35 outputs by a LOW-to-HIGH
transition of CLKA when CSA is LOW, W/RA is LOW, ENA is
HIGH, MBA is LOW, and ORA is HIGH (see Table 2). FIFO
reads and writes on port A are independent of any concurrent
FS1
FS0
RST1
RST2
X1 AND Y1 REGlSTERS(1)
X2 AND Y2 REGlSTERS(2)
H
H
↑
X
64
X
H
H
X
↑
X
64
H
L
↑
X
16
X
H
L
X
↑
X
16
L
H
↑
X
8
X
L
H
X
↑
X
8
L
L
↑
↑
Programmed from port A
Programmed from port A
NOTES:
1. X1 register holds the offset for AEB; Y1 register holds the offset for AFA.
2. X2 register holds the offset tor AEA; Y2 register holds the offset for AFB.
Table 1. Flag Programming
5.22
10
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
port-B operation.
The port-B control signals are identical to those of port A
with the exception that the port-B write/read select (W/RB) is
the inverse of the port-A write/read select (W/RA). The state
of the port-B data (B0-B35) outputs is controlled by the portB chip select (CSB) and port-B write/read select (W/RB). The
B0-B35 outputs are in the high-impedance state when either
CSB is HIGH or W/RB is LOW. The B0-B35 outputs are active
when CSB is LOW and W/RB is HIGH.
Data is loaded into FIFO2 from the B0-B35 inputs on a
LOW-to-HIGH transition of CLKB when CSB is LOW, W/RB is
LOW, ENB is HIGH, MBB is LOW, and IRB is HIGH. Data is
read from FIFO1 to the B0-B35 outputs by a LOW-to-HIGH
transition of CLKB when CSB is LOW, W/RB is HIGH, ENB is
HIGH, MBB is LOW, and ORB is HIGH (see Table 3) . FIFO
reads and writes on port B are independent of any concurrent
port-A operation.
The setup and hold time constraints to the port clocks for
the port chip selects and write/read selects are only for
enabling write and read operations and are not related to highimpedance control of the data outputs. If a port enable is LOW
during a clock cycle, the port’s chip select and write/read
select may change states during the setup and hold time
window of the cycle.
When a FIFO output-ready flag is LOW, the next data
word is sent to the FIFO output register automatically by the
LOW-to-HIGH transition of the port clock that sets the outputready flag HIGH. When the output-ready flag is HIGH, an
available data word is clocked to the FIFO output register only
when a FIFO read is selected by the port’s chip select, write/
read select, enable, and mailbox select.
SYNCHRONIZED FIFO FLAGS
Each FIFO is synchronized to its port clock through at
least two flip-flop stages. This is done to improve flag-signal
reliability by reducing the probability of metastable events
when CLKA and CLKB operate asynchronously to one another. ORA, AEA, IRA, and AFA are synchronized to CLKA.
ORB, AEB, IRB, and AFB are synchronized to CLKB. Tables
4 and 5 show the relationship of each port flag to FIFO1 and
FIF02.
CSA
W/RA
ENA
MBA
CLKA
A0-A35 OUTPUTS
PORT FUNCTION
H
X
X
X
X
In high-impedance state
None
L
H
L
X
X
In high-impedance state
None
L
H
H
L
↑
In high-impedance state
FIFO1 write
L
H
H
H
↑
In high-impedance state
Mail1 write
L
L
L
L
X
Active, FIFO2 output register
None
L
L
H
L
↑
Active, FIFO2 output register
FIFO2 read
L
L
L
H
X
Active, mail2 register
None
L
L
H
H
↑
Active, mail2 register
Mail2 read (set MBF2 HIGH)
Table 2. Port-A Enable Functlon Table
CSB
W/RB
ENB
MBB
CLKB
B0-B35 OUTPUTS
PORT FUNCTION
H
X
X
X
X
In high-impedance state
None
L
L
L
X
X
In high-impedance state
None
L
L
H
L
↑
In high-impedance state
FIFO2 write
L
L
H
H
↑
In high-impedance state
Mail2 write
L
H
L
L
X
Active, FIFO1 output register
None
L
H
H
L
↑
Active, FIFO1 output register
FIFO1 read
L
H
L
H
X
Active, mail1 register
None
L
H
H
H
↑
Active, mail1 register
Mail1 read (set MBF1 HIGH)
Table 3. Port-B Enable Function Table
5.22
11
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
OUTPUT-READY FLAGS (ORA, ORB)
The output-ready flag of a FIFO is synchronized to the port
clock that reads data from its array. When the output-ready
flag is HIGH, new data is present in the FIFO output register.
When the output-ready flag is LOW, the previous data word is
present in the FIFO output register and attempted FIFO reads
are ignored.
A FIFO read pointer is incremented each time a new word
is clocked to its output register. The state machine that
controls an output-ready flag monitors a write pointer and read
pointer comparator that indicates when the FIFO SRAM
status is empty, empty+1, or empty+2. From the time a word
is written to a FIFO, it can be shifted to the FIFO output register
in a minimum of three cycles of the output-ready flag synchronizing clock. Therefore, an output-ready flag is LOW if a word
in memory is the next data to be sent to the FlFO output
register and three cycles of the port Clock that reads data from
the FIFO have not elapsed since the time the word was
written. The output-ready flag of the FIFO remains LOW until
the third LOW-to-HIGH transition of the synchronizing clock
occurs, simultaneously forcing the output-ready flag HIGH
and shifting the word to the FIFO output register.
A LOW-to-HIGH transition on an output-ready flag synchronizing clock begins the first synchronization cycle of a
write if the clock transition occurs at time tSKEW1 or greater
after the write. Otherwise, the subsequent clock cycle can be
the first synchronization cycle (see Figures 7 and 8).
INPUT-READY FLAGS (IRA, IRB)
The input-ready flag of a FlFO is synchronized to the port
clock that writes data to its array. When the input-ready flag
is HIGH, a memory location is free in the SRAM to receive new
data. No memory locations are free when the input-ready flag
is LOW and attempted writes to the FIFO are ignored.
Each time a word is written to a FIFO, its write pointer is
incremented. The state machine that controls an input-ready
flag monitors a write pointer and read pointer comparator that
indicates when the FlFO SRAM status is full, full-1, or full-2.
From the time a word is read from a FIFO, its previous memory
location is ready to be written in a minimum of two cycles of the
S ynchronized
to CLKB
ORB
AEB
L
L
IDT723622(1,2)
0
Number of Words in FIFO
IDT723632(1,2)
0
IDT723642(1,2)
0
1 to X1
1 to X1
1 to X1
(X1+1) to [256-(Y1+1)]
(X1+1) to [512-(Y1+1)]
(X1+1) to [1024-(Y1+1)]
(256-Y1) to 255
(512-Y1) to 511
(1024-Y1) to 1023
256
512
1024
H
H
Synchronized
to CLKA
AFA
IRA
H
H
L
H
H
H
H
H
H
H
H
L
H
H
L
L
Table 4. FIF01 Flag Operatlon
Notes:
1. X1 is the almost-empty offset for FIFO1 used by AEB. Y1 is the almost-full offset for FIFO1 used by AFA. Both X1
and Y1 are selected during a reset of FIFO1 or programmed from port A.
2. When a word loaded to an empty FIFO is shifted to the output register, its previous FIFO memory location is free.
S ynchronized
to CLKA
ORA
AEA
L
L
Synchronized
to CLKB
AFB
IRB
H
H
IDT723622(1,2)
0
Number of Words in FIFO
IDT723632(1,2)
0
IDT723642(1,2)
0
1 to X2
1 to X2
1 to X2
H
L
H
H
(X2+1) to [256-(Y2+1)]
(X2+1) to [512-(Y2+1)]
(X2+1) to [1024-(Y2+1)]
H
H
H
H
(256-Y2) to 255
(512-Y2) to 511
(1024-Y2) to 1023
H
H
L
H
256
512
1024
H
H
L
L
Table 5. FIF02 Flag Operatlon
Notes:
1. X2 is the almost-empty offset for FIFO2 used by AEA. Y2 is the almost-full offset for FIFO2 used by AFB. Both X2 and
Y2 are selected during a reset of FIFO2 or programmed from port A.
2. When a word loaded to an empty FIFO is shifted to the output register, its previous FIFO memory location is free.
5.22
12
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
input-ready flag synchronizing clock. Therefore, an inputready flag is LOW if less than two cycles of the input-ready flag
synchronizing clock have elapsed since the next memory
write location has been read. The second LOW-to-HIGH
transition on the input-ready flag synchronizing Clock after the
read sets the input-ready flag HIGH.
A LOW-to-HIGH transition on an input-ready flag synchronizing clock begins the first synchronization cycle of a
read if the clock transition occurs at time tSKEW1 or greater
after the read. Otherwise, the subsequent clock cycle can be
the first synchronization cycle (see Figures 9 and 10).
ALMOST-EMPTY FLAGS (AEA, AEB)
The almost-empty flag of a FIFO is synchronized to the
port clock that reads data from its array. The state machine
that controls an almost-empty flag monitors a write pointer and
read pointer comparator that indicates when the FIFO SRAM
status is almost empty, almost empty+1, or almost empty+2.
The almost-empty state is defined by the contents of register
X1 for AEB and register X2 for AEA. These registers are
loaded with preset values during a FIFO reset or programmed
from port A (see almost-empty flag and almost-full flag offset
programming above). An almost empty Flag is LOW when its
FIFO contains X or less words and is HIGH when its FIFO
contains (X+1) or more words. A data word present in the FIFO
output register has been read from memory.
Two LOW-to-HIGH transitions of the almost-empty flag
synchronizing clock are required after a FIFO write for its
almost-empty flag to reflect the new level of fill. Therefore, the
almost-full flag of a FIFO containing (X+1) or more words
remains LOW if two cycles of its synchronizing clock have not
elapsed since the write that filled the memory to the (X+1)
level. An almost-empty flag is set HIGH by the second LOWto-HIGH transition of its synchronizing clock after the FIFO
write that fills memory to the (X+1) level. A LOW-to-HIGH
transition of an almost-empty flag synchronizing clock begins
the first synchronization cycle if it occurs at time tSKEW2 or
greater after the write that fills the FIFO to (X+1) words.
Otherwise, the subsequent synchronizing clock cycle may be
the first synchronization cycle. (See Figures 11 and 12).
ALMOST-FULL FLAGS (AFA, AFB)
The almost-full flag of a FIFO is synchronized to the port
clock that writes data to its array. The state machine that
controls an almost-full flag monitors a write pointer and read
pointer comparator that indicates when the FIFO SRAM
status is almost full, almost full-1, or almost full-2. The almostfull state is defined by the contents of register Y1 for AFA and
register Y2 for AFB. These registers are loaded with preset
values during a FlFO reset or programmed from port A (see
almost-empty flag and almost-full flag offset programming
above). An almost-full flag is LOW when the number of words
in its FIFO is greater than or equal to (256-Y), (512-Y), or
(1024-Y) for the IDT723622, IDT723632, or IDT723642 respectively. An almost-full flag is HIGH when the number of
words in its FIFO is less than or equal to [256-(Y+1)], [512(Y+1)], or [1024-(Y+1)] for the IDT723622, IDT723632, or
IDT723642 respectively. Note that a data word present in the
FIFO output register has been read from memory.
Two LOW-to-HIGH transitions of the almost-full flag synchronizing clock are required after a FIFO read for its almostfull flag to reflect the new level of fill. Therefore, the almost-full
flag of a FIFO containing [256/512/1024-(Y+1)] or less words
remains LOW if two cycles of its synchronizing clock have not
elapsed since the read that reduced the number of words in
memory to [256/512/1024-(Y+1)]. An almost-full flag is set
HIGH by the second LOW-to-HIGH transition of its synchronizing clock after the FIFO read that reduces the number of
words in memory to [256/512/1024-(Y+1)]. A LOW-to-HIGH
transition of an almost-full flag synchronizing clock begins the
first synchronization cycle if it occurs at time tSKEW2 or greater
after the read that reduces the number of words in memory to
[256/512/1024-(Y+1)]. Otherwise, the subsequent synchronizing clock cycle may be the first synchronization cycle (see
Figures 13 and 14).
MAILBOX REGISTERS
Each FIFO has a 36-bit bypass register to pass command
and control information between port A and port B without
putting it in queue. The mailbox-select (MBA, MBB) inputs
choose between a mail register and a FIFO for a port data
transfer operation. A LOW-to-HIGH transition on CLKA writes
A0-A35 data to the mail1 register when a port-A write is
selected by CSA, W/RA, and ENA and with MBA HIGH. A
LOW-to-HIGH transition on CLKB writes BO-B35 data to the
mail2 register when a port-B write is selected by CSB, W/RB,
and ENB and with MBB HIGH. Writing data to a mail register
sets its corresponding flag (MBF1 or MBF2) LOW. Attempted
writes to a mail register are ignored while the mail flag is LOW.
When data outputs of a port are active, the data on the bus
comes from the FIFO output register when the port mailbox
select input is LOW and from the mail register when the portmailbox select input is HIGH. The mail1 register flag (MBF1 )
is set HIGH by a LOW-to-HIGH transition on CLKB when a
port-B read is selected by CSB, W/RB, and ENB and with MBB
HIGH. The mail2 register flag (MBF2) is set HIGH by a LOWto-HIGH transition on CLKA when a port-A read is selected by
CSA, W/RA, and ENA and with MBA HIGH. The data in a mail
register remains intact after it is read and changes only when
new data is written to the register.
5.22
13
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
CLKA
tRSTH
CLKB
tRSTS
tFSS
tFSH
RST1
FS1,FS0
0,1
tPIR
tPIR
IRA
tPOR
ORB
tRSF
AEB
tRSF
AFA
tRSF
MBF1
3022 drw 04
Figure 1. FIFO1 Reset Loading X1 and Y1 with a Preset Value of
NOTE:
1. FIFO2 is reset in the same manner to load X2 and Y2 with a preset value.
CLKA
4
tFSS
RST1,
RST2
FS1,FS0
Eight(1).
tFSH
0,0
tPIR
IRA
tENS
tSKEW1(1)
tENH
ENA
tDS
tDH
A0 - A35
AFA Offset
(Y1)
AEB Offset
(X1)
CLKB
AFB Offset
(Y2)
AEA Offset
First Word to FIFO1
(X2)
1
2
tPIR
IRB
3022 drw 05
NOTES:
1. tSKEW1 is the minimum time between the rising CLKA edge and a rising CLKB edge for IRB to transition HIGH in the next cycle. If the time between the
rising edge of CLKA and rising edge of CLKB is less than tSKEW1, then IRB may transition HIGH one cycle later than shown.
2. CSA = LOW, W/RA = HIGH, MBA = LOW. It is not necessary to program offset register on consecutive clock cycles.
Figure 2. Programming the Almost-Full Flag and Almost-Empty Flag Offset Values after Reset.
5.22
14
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
tCLK
tCLKH
tCLKL
CLKA
IRA
tENS
tENH
CSA
tENS
tENH
tENS
tENH
tENS
tENH
W/RA
MBA
tENS
tENH
tENH
tENS
ENA
tDH
tDS
A0 - A35
W1(1)
No Operation
W2(1)
3022 drw 06
NOTE:
1. Written to FIFO1.
Figure 3. Port-A Write Cycle Timing for FIFO1
tCLK
tCLKH
tCLKL
CLKB
IRB
CSB
W/RB
tENH
tENS
tENS
tENH
tENH
MBB
tENS
tENS
tENH
tENS
tENH
tENS
tENH
ENB
B0 - B35
tDS
W1(1)
tDH
W2(1)
No Operation
3022 drw 07
NOTE:
1. Written to FIFO2.
Figure 4. Port-B Write Cycle Timing for FIFO2.
5.22
15
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
tCLK
tCLKH
tCLKL
CLKB
ORB
CSB
W/RB
tENS
MBB
tENH
tENS
tENH
tENH
tENS
ENB
tMDV
tA
tEN
B0 - B35
W1(1)
No
Operation
tA
W2(1)
tDIS
W3 (1)
3022 drw 08
NOTE:
1. Read From FIFO1.
Figure 5. Port-B Read Cycle Timing for FIFO1.
tCLK
tCLKH
tCLKL
CLKA
ORA
CSA
W/RA
tENS
MBA
tENH
tENS
tENH
ENA
tDMV
tA
tA
tEN
A0 - A35
W1(1)
tENH
tENS
W2(1)
No
Operation
tDIS
W3(1)
3022 drw 09
NOTE:
1. Read From FIFO2.
Figure 6. Port-A Read Cycle Timing for FIFO2.
5.22
16
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
tCLK
tCLKH
tCLKL
CLKA
CSA
LOW
WR A
HIGH
tENS
tENH
tENS
tENH
tDS
tDH
MBA
ENA
IRA
HIGH
A0 - A35
W1
tSKEW1
CLKB
(1)
tCLKH
1
tCLK
tCLKL
2
3
tPOR
tPOR
Old Data in FIFO1 Output Register
ORB
CSB
LOW
W/RB
HIGH
MBB
LOW
tENS
tENH
ENB
tA
B0 -B35
Old Data in FIFO1 Output Register
W1
3022 drw 10
NOTE:
1. tSKEW1 is the minimum time between a rising CLKA edge and a rising CLKB edge for ORB to transition HIGH and to clock the next word to the FIFO1 output
register in three CLKB cycles. If the time between the rising CLKA edge and rising CLKB edge is less than tSKEW1, then the transition of ORB HIGH and
load of the first word to the output register may occur one CLKB cycle later than shown.
Figure 7. ORB Flag Timing and First Data Word Fallthrough when FIFO1 is Empty.
5.22
17
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
tCLK
tCLKH
tCLKL
CLKB
CSB
LOW
W/RB
LOW
tENS
tENH
tENS
tENH
tDS
tDH
MBB
ENB
IRB
HIGH
B0 - B35
W1
tSKEW1
(1)
tCLKH
tCLK
tCLKL
1
CLKA
2
3
tPOR
tPOR
Old Data in FIFO2 Output Register
ORA
CSA
LOW
W/RA
LOW
MBA
LOW
tENS
tENH
ENA
tA
A0 -A35
Old Data in FIFO2 Output Register
W1
3022 drw 11
NOTE:
1. tSKEW1 is the minimum time between a rising CLKB edge and a rising CLKA edge for ORA to transition HIGH and to clock the next word to the FIFO2 output
register in three CLKA cycles. If the time between the rising CLKB edge and rising CLKA edge is less than tSKEW1, then the transition of ORA HIGH and
load of the first word to the output register may occur one CLKA cycle later than shown.
Figure 8. ORA Flag Timing and First Data Word Fallthrough when FIFO2 is Empty.
5.22
18
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
tCLK
tCLKH
tCLKL
CLKB
CSB
LOW
W/RB
HIGH
MBB
LOW
tENS
tENH
ENB
ORB
HIGH
tA
B0 -B35
Previous Word in FIFO1 Output Register
tSKEW1
Next Word From FIFO1
(1)
tCLK
tCLKH
tCLKL
1
CLKA
2
tPIR
tPIR
IRA
FIFO1 Full
CSA
LOW
WR A
HIGH
tENH
tENS
MBA
tENS
tENH
ENA
tDS
tDH
A0 - A35
To FIFO1
3022 drw 12
NOTE:
1. tSKEW1 is the minimum time between a rising CLKB edge and a rising CLKA edge for IRA to transition HIGH in the next CLKA cycle. If the time between
the rising CLKB edge and rising CLKA edge is less than tSKEW1, then IRA may transition HIGH one CLKA cycle later than shown.
Figure 9. IRA Flag Timing and First Available Write when FIFO1 is Full.
5.22
19
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
tCLK
tCLKH
tCLKL
CLKA
CSA
LOW
W/RA
LOW
MBA
LOW
tENS
tENH
ENA
ORA
HIGH
tA
A0 -A35
Previous Word in FIFO2 Output Register
Next Word From FIFO2
tSKEW1 (1)
tCLK
tCLKH
tCLKL
1
CLKB
2
tPIR
tPIR
IRB
FIFO2 FULL
CSB
LOW
WRB
LOW
tENS
tENH
tENS
tENH
tDS
tDH
MBB
ENB
B0 - B35
To FIFO2
3022 drw 13
NOTE:
1. tSKEW1 is the minimum time between a rising CLKA edge and a rising CLKB edge for IRB to transition HIGH in the next CLKB cycle. If the time between
the rising CLKA edge and rising CLKB edge is less than tSKEW1, then IRB may transition HIGH one CLKB cycle later than shown.
Figure 10. IRB Flag Timing and First Available Write when FIFO2 is Full.
CLKA
tENS
tENH
ENA
tSKEW2
(1)
1
CLKB
2
tPAE
tPAE
AEB
X1 Word in FIFO1
(X1+1) Words in FIFO1
tENS
tENH
ENB
3022 drw 14
NOTES:
1. tSKEW2 is the minimum time between a rising CLKA edge and a rising CLKB edge for AEB to transition HIGH in the next CLKB cycle. If the time between
the rising CLKA edge and rising CLKB edge is less than tSKEW2, then AEB may transition HIGH one CLKB cycle later than shown.
2. FIFO1 Write (CSA = LOW, W/RA = LOW, MBA = LOW), FIFO1 read (CSB = LOW, W/RB = HIGH, MBB = LOW). Data in the FIFO1 output register has
been read from the FIFO.
Figure 11. Timing for AEB when FIFO2 is Almost Empty.
5.22
20
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
CLKB
tENS
tENH
ENB
tSKEW2
(1)
1
CLKA
2
tPAE
tPAE
AEA
X2 Words in FIFO2
(X2+1) Words in FIFO2
tENS
tENH
ENA
3022 drw 15
NOTES:
1. tSKEW2 is the minimum time between a rising CLKB edge and a rising CLKA edge for AEA to transition HIGH in the next CLKA cycle. If the time between
the rising CLKB edge and rising CLKA edge is less than tSKEW2, then AEA may transition HIGH one CLKA cycle later than shown.
2. FIFO2 Write (CSB = LOW, W/RB = LOW, MBB = LOW), FIFO2 read (CSA = LOW, W/RA = LOW, MBA = LOW). Data in the FIFO2 output register has
been read from the FIFO.
Figure 12. Timing for AEA when FIFO2 is Almost Empty.
tSKEW2
(1)
1
CLKA
tENS
2
tENH
ENA
tPAF
tPAF
AFA
[D-(Y1+1)] Words in FIFO1
(D-Y1) Words in FIFO1
CLKB
tENH
tENS
ENB
3022 drw 16
NOTES:
1. tSKEW2 is the minimum time between a rising CLKA edge and a rising CLKB edge for AFA to transition HIGH in the next CLKA cycle. If the time between
the rising CLKA edge and rising CLKB edge is less than tSKEW2, then AFA may transition HIGH one CLKB cycle later than shown.
2. FIFO1 Write (CSA = LOW, W/RA = HIGH, MBA = LOW), FIFO1 read (CSB = LOW, W/RB = HIGH, MBB = LOW). Data in the FIFO1 output register has
been read from the FIFO.
3. D = Maximum FIFO Depth = 256 for the 723622, 512 for the 723632, 1024 for the 723642.
Figure 13. Timing for AFA when FIFO1 is Almost Full.
5.22
21
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
tSKEW2
(1)
1
CLKB
2
tENH
tENS
ENB
tPAF
AFB
tPAF
(D-Y2) Words in FIFO2
[D-(Y2+1)] Words in FIFO2
CLKA
tENS
tENH
ENA
3022 drw 17
NOTES:
1. tSKEW2 is the minimum time between a rising CLKB edge and a rising CLKA edge for AFB to transition HIGH in the next CLKB cycle. If the time between
the rising CLKB edge and rising CLKA edge is less than tSKEW2, then AFB may transition HIGH one CLKA cycle later than shown.
2. FIFO2 write (CSB = LOW, W/RB = LOW, MBB = LOW), FIFO2 read (CSA = LOW, W/RA = LOW, MBA = LOW). Data in the FIFO2 output register has
been read from the FIFO.
3. D = Maximum FIFO Depth = 256 for the 723622, 512 for the 723632, 1024 for the 723642.
Figure 14. Timing for AFB when FIFO2 is Almost Full.
CLKA
tENH
tENS
CSA
W/RA
MBA
ENA
tDS
W1
A0 - A35
tDH
CLKB
tPMF
MBF1
tPMF
CSB
W/RB
MBB
tENS
tENH
ENB
tEN
tMDV
tDIS
tPMR
B0 - B35
W1 (Remains valid in Mail1 Register after read)
FIFO1 Output Register
3022 drw 18
Figure 15. Timing for Mail1 Register and MBF1 Flag.
5.22
22
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
CLKB
COMMERCIAL TEMPERATURE RANGE
tENH
tENS
CSB
W/RB
MBB
ENB
tDS
W1
B0 - B35
tDH
CLKA
tPMF
MBF2
tPMF
CSA
W/RA
MBA
tENS
tENH
ENA
tEN
tMDV
tDIS
tPMR
W1 (Remains valid in Mail 2 Register after read)
A0 - A35
FIFO2 Output Register
3022 drw 19
Figure 16. Timing for Mail2 Register and MBF2 Flag.
5.22
23
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
TYPICAL CHARACTERISTICS
SUPPLY CURRENT
vs
CLOCK FREQUENCY
300
f data = 1/2 f s
TA = 25°C
C L = 0pF
250
V CC = 5.5 V
I CC(f) - Supply Current - mA
V CC = 5.0 V
200
150
V CC = 4.5 V
100
50
0
0
10
20
30
40
50
60
70
3022 drw 18
fs – Clock Frequency – MHz
Figure 17.
CALCULATING POWER DISSIPATION
The ICC(f) current for the graph in Figure 17 was taken while simultaneously reading and writing a FIFO on the
IDT723622/723632/723642 with CLKA and CLKB set to fs. All data inputs and data outputs change state during each
clock cycle to consume the highest supply current. Data outputs were disconnected to normalize the graph to a zero
capacitance load. Once the capacitance load per data-output channel and the number of IDT723622/723632/723642
inputs driven by TTL HIGH levels are known, the power dissipation can be calculated with the equation below.
With ICC(f) taken from Figure 17, the maximum power dissipation (PT) of the IDT723622/723632/723642 may be
calculated by:
PT = VCC x [ICC(f) + (N x ∆ICC x dc)] + ∑(CL x VCC2 X fo)
where:
N
=
number of inputs driven by TTL levels
∆ICC=
increase in power supply current for each input at a TTL HIGH level
dc =
duty cycle of inputs at a TTL HIGH level of 3.4 V
CL =
output capacitance load
fo
=
switching frequency of an output
When no read or writes are occurring on the IDT723632, the power dissipated by a single clock (CLKA or CLKB) input
running at frequency fs is calculated by:
PT = VCC x fs x 0.184 mA/MHz
5.22
24
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
PARAMETER MEASUREMENT INFORMATION
5V
1.1 k Ω
From Output
Under Test
30 pF
680 Ω
(1)
PROPAGATION DELAY
LOAD CIRCUIT
GND
3V
Timing
Input
1.5 V
GND
tS
th
GND
tW
3V
1.5 V
1.5 V
1.5 V
1.5 V
3V
Data,
Enable
Input
Low-Level
Input
GND
VOLTAGE WAVEFORMS
SETUP AND HOLD TIMES
1.5 V
1.5 V
VOLTAGE WAVEFORMS
PULSE DURATIONS
3V
Output
Enable
1.5 V
tPLZ
1.5 V
tPZL
GND
≈3 V
1.5 V
Low-Level
Output
Input
3V
1.5 V
1.5 V
tPD
tPD
VOL
tPZH
VOH
High-Level
Output
3V
High-Level
Input
1.5 V
tPHZ
≈ OV
VOLTAGE WAVEFORMS
ENABLE AND DISABLE TIMES
GND
VOH
In-Phase
Output
1.5 V
VOLTAGE WAVEFORMS
PROPAGATION DELAY TIMES
1.5 V
VOL
3022 drw 20
NOTE:
1. Includes probe and jig capacitance.
Figure 18. Load Circuit and Voltage Waveforms.
5.22
25
IDT723622/723632/723642 CMOS SyncBiFIFO
256 x 36 x 2, 512 x 36 x 2, 1024 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
ORDERING INFORMATION
IDT
XXXXXX
Device Type
X
Power
XX
Speed
X
Package
X
Process/
Temperature
Range
BLANK
Commercial (0°C to +70°C)
PF
PQF
Thin Quad Flat Pack
Plastic Quad Flat Pack
15
20
30
Commercial Only
Clock Cycle Time (t CLK)
Speed in Nanoseconds
L
Low Power
723622 256 x 36 Synchronous BiFIFO
723632 512 x 36 Synchronous BiFIFO
723642 1024 x 36 Synchronous BiFIFO
5.22
3022 drw 22
26
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