IDT IDT723653 Cmos syncfifo with bus-matching Datasheet

CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36
4,096 x 36
8,192 x 36
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FEATURES
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Memory storage capacity:
IDT723653 – 2,048 x 36
IDT723663 – 4,096 x 36
IDT723673 – 8,192 x 36
Clock frequencies up to 83 MHz (8 ns access time)
Clocked FIFO buffering data from Port A to Port B
IDT Standard timing (using EF and FF) or First Word Fall
Through Timing (using OR and IR flag functions)
Programmable Almost-Empty and Almost-Full flags; each has
five default offsets (8, 16, 64, 256 and 1,024)
Serial or parallel programming of partial flags
Port B bus sizing of 36 bits (long word), 18 bits (word) and 9 bits
(byte)
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IDT723653
IDT723663
IDT723673
Big- or Little-Endian format for word and byte bus sizes
Retransmit Capability
Reset clears data and configures FIFO, Partial Reset clears data
but retains configuration settings
Mailbox bypass registers for each FIFO
Free-running CLKA and CLKB may be asynchronous or
coincident (simultaneous reading and writing of data on a single
clock edge is permitted)
Easily expandable in width and depth
Auto power down minimizes power dissipation
Available in a space-saving 128-pin Thin Quad Flatpack (TQFP)
Pin compatible with the lower density parts, IDT723623/723633/
723643
Industrial temperature range (–40°°C to +85°°C) is available
FUNCTIONAL BLOCK DIAGRAM
MBF1
RS1
RS2
PRS
FIFO1
Mail1,
Mail2,
Reset
Logic
RAM ARRAY
36
36
2,048 x 36
4,096 x 36
8,192 x 36
Output
Register
Port-A
Control
Logic
BusMatching
CLKA
CSA
W/RA
ENA
MBA
Input
Register
Mail 1
Register
36
36
RT
RTM
FIFO
Retransmit
Logic
Write
Pointer
Read
Pointer
A0-A35
B0-B35
36
FS2
FS0/SD
FS1/SEN
EF/OR
AE
Status Flag
Logic
FF/IR
AF
36
Programmable Flag
Offset Registers
Timing
Mode
13
Port-B
Control
Logic
Mail 2
Register
MBF2
FWFT
CLKB
CSB
W/RB
ENB
MBB
BE
BM
SIZE
5610 drw01
IDT and the IDT logo are registered trademarks of Integrated Device Technology, Inc. SyncFIFO is a trademark of Integrated Device Technology, Inc.
NOVEMBER 2003
COMMERCIAL TEMPERATURE RANGE
1
 2003 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice.
DSC-5610/4
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
DESCRIPTION
COMMERCIAL TEMPERATURE RANGE
These devices are synchronous (clocked) FIFOs, 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 IDT723653/723663/723673 is a monolithic, high-speed, low-power,
CMOS unidirectional Synchronous (clocked) FIFO memory which supports
clock frequencies up to 83 MHz and has read access times as fast as 8ns. The
2,048/4,096/8,192 x 36 dual-port SRAM FIFO buffers data from Port A to Port
B. FIFO data on Port B can output in 36-bit, 18-bit, or 9-bit formats with a choice
of Big- or Little-Endian configurations.
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
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
31
32
33
34
35
36
37
38
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
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
W/RA
ENA
CLKA
GND
A35
A34
A33
A32
Vcc
A31
A30
GND
A29
A28
A27
A26
A25
A24
A23
BE/FWFT
GND
A22
Vcc
A21
A20
A19
A18
GND
A17
A16
A15
A14
A13
Vcc
A12
GND
A11
A10
A9
A8
A7
A6
GND
A5
A4
A3
FS2
Vcc
A2
A1
A0
GND
B0
B1
B2
B3
B4
B5
GND
B6
Vcc
B7
B8
B9
INDEX
CSA
FF/IR
NC
PRS/RT
Vcc
AF
NC
MBF2
MBA
RS1
FS0/SD
GND
GND
FS1/SEN
RS2
MBB
MBF1
Vcc
AE
NC
EF/OR
NC
GND
CSB
W/RB
ENB
PIN CONFIGURATION
TQFP (PK128-1, order code: PF)
TOP VIEW
2
CLKB
Vcc
Vcc
B35
B34
B33
B32
RTM
GND
B31
B30
B29
B28
B27
B26
Vcc
B25
B24
BM
GND
B23
B22
B21
B20
B19
B18
GND
B17
B16
SIZE
Vcc
B15
B14
B13
B12
GND
B11
B10
5610 drw02
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
Communication between each port may bypass the FIFO via two mailbox
registers. The mailbox registers' width matches the selected Port B bus width.
Each mailbox register has a flag (MBF1 and MBF2) to signal when new mail
has been stored.
Two kinds of reset are available on these FIFOs: Reset and Partial Reset.
Reset initializes the read and write pointers to the first location of the memory array
and selects serial flag programming, parallel flag programming, or one of five
possible default flag offset settings, 8, 16, 64, 256 or 1,024.
Partial Reset also sets the read and write pointers to the first location of the
memory. Unlike Reset, any settings existing prior to Partial Reset (i.e.,
programming method and partial flag default offsets) are retained. Partial Reset
is useful since it permits flushing of the FIFO memory without changing any
configuration settings.
The FIFO has Retransmit capability, a Retransmit is performed after four clock
cycles of CLKA and CLKB, by taking the Retransmit pin, RT LOW while the
Retransmit Mode pin, RTM is HIGH. When a Retransmit is performed the read
pointer is reset to the first memory location.
These devices have two modes of operation: In the IDT Standard mode, the
first word written to an empty FIFO is deposited into the memory array. A read
operation is required to access that word (along with all other words residing
in memory). In the First Word Fall Through mode (FWFT), the first word written
to an empty FIFO appears automatically on the outputs, no read operation
required (Nevertheless, accessing subsequent words does necessitate a
formal read request). The state of the BE/FWFT pin during Reset determines
the mode in use.
The FIFO has a combined Empty/Output Ready Flag (EF/OR ) and a
combined Full/Input Ready Flag (FF/IR). The EF and FF functions are selected
in the IDT Standard mode. EF indicates whether or not the FIFO memory is
empty. FF shows whether the memory is full or not. The IR and OR functions
are selected in the First Word Fall Through mode. IR indicates whether or not
COMMERCIAL TEMPERATURE RANGE
the FIFO has available memory locations. OR shows whether the FIFO has data
available for reading or not. It marks the presence of valid data on the outputs.
The FIFO has a programmable Almost-Empty flag (AE) and a programmable
Almost-Full flag (AF). AE indicates when a selected number of words remain
in the FIFO memory. AF indicates when the FIFO contains more than a selected
number of words.
FF/IR and AF are two-stage synchronized to the port clock that writes data
into its array. EF/OR and AE are two-stage synchronized to the port clock that
reads data from its array. Programmable offsets for AE and AF are loaded in
parallel using Port A or in serial via the SD input. Five default offset settings are
also provided. The AE threshold can be set at 8, 16, 64, 256 or 1,024 locations
from the empty boundary and the AF threshold can be set at 8, 16, 64, 256 or
1,024 locations from the full boundary. All these choices are made using the FS0,
FS1 and FS2 inputs during Reset.
Interspersed Parity is available and can be selected during a Master Reset
of the FIFO. If Interspersed Parity is selected then during parallel programming
of the flag offset values, the device will ignore data line A8 . If Non-Interspersed
Parity is selected then data line A8 will become a valid bit.
Two or more devices may be used in parallel to create wider data paths. In
First Word Fall Through mode, more than one device may be connected in
series to create greater word depths. The addition of external components is
unnecessary.
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 (ICC) is at a minimum. Initiating any operation (by activating control
inputs) will immediately take the device out of the Power Down state.
The IDT723653/723663/723673 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.
3
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
PIN DESCRIPTIONS
Symbol
Name
I/O
Description
A0-A35
Port A Data
I/O
36-bit bidirectional data port for side A.
AE
Almost-Empty Flag
(Port B)
O
Programmable Almost-Empty 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 B offset register, X.
AF
Almost-Full Flag
(Port A)
O
Programmable Almost-Full 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 A offset register, Y.
B0-B35
Port B Data
I/O
36-bit bidirectional data port for side B.
BE/FWFT
Big-Endian/
First Word
Fall Through
I
BM(1)
Bus-Match Select
(Port B)
I
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. FF/IR and AF are 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. EF/OR and AE are synchronized to the LOW-to-HIGH
transition of CLKB.
CSA
Port A Chip
Select
I
CSA must be LOW to enable to 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
Port B Chip
Select
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.
EF/OR
Empty/Output
Ready Flag
(Port B)
O
This is a dual function pin. In the IDT Standard mode, the EF function is selected. EF indicates
whether or not the FIFO memory is empty. In the FWFT mode, the OR function is selected. OR indicates
the presence of valid data on the B0-B35 outputs, available for reading. EF/OR is synchronized to the
LOW-to-HIGH transition of CLKB.
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.
FF/IR
Full/Input
Ready Flag
(Port A)
O
This is a dual function pin. In the IDT Standard mode, the FF function is selected. FF indicates
whether or not the FIFO memory is full. In the FWFT mode, the IR function is selected. IR indicates
whether or not there is space available for writing to the FIFO memory. FF/IR is synchronized to the
LOW-to-HIGH transition of CLKA.
This is a dual purpose pin. During Master Reset, a HIGH on BE will select Big-Endian operation. In
this case, depending on the bus size, the most significant byte or word written to Port A is read from
Port B first. A LOW on BE will select Little-Endian operation. In this case, the least significant byte or
word written to Port A is read from Port B first. After Master Reset, this pin selects the timing mode. A
HIGH on FWFT selects IDT Standard mode, a LOW selects First Word Fall Through mode. Once
the timing mode has been selected, the level on FWFT must be static throughout device operation.
A HIGH on this pin enables either byte or word bus width on Port B, depending on the state of
SIZE. A LOW selects long word operation. BM works with SIZE and BE to select the bus size and
endian arrangement for Port B. The level of BM must be static throughout device operation.
FS0/SD
Flag Offset Select 0/
Serial Data,
I
FS1/SEN and FS0/SD are dual-purpose inputs used for flag offset register programming. During
Reset, FS1/SEN and FS0/SD, together with FS2 select the flag offset programming method. Three
offset register programming methods are available: automatically load one of five preset values (8,
16, 64, 256 or 1,024), parallel load from Port A, and serial load.
FS1/SEN
Flag Offset Select 1/
Serial Enable
I
FS2(1)
Flag Offset Select 2
I
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 22 for the IDT723653, 24 for the IDT723663, and 26 for the IDT723673.
The first bit write stores the Y-register MSB and the last bit write stores the X-register LSB.
MBA
Port A Mailbox
Select
I
A HIGH level on MBA chooses a mailbox register for a Port A read or write operation.
MBB
Port B Mailbox
Select
I
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 for output and
a LOW level selects FIFO data for output.
4
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
PIN DESCRIPTIONS (CONTINUED)
Symbol
MBF1
Name
Mail1 Register Flag
I/O
O
Description
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-toHIGH transition of CLKB when a Port B read is selected and MBB is HIGH. MBF1 is set HIGH
following either a Reset (RS1) or Partial Reset (PRS).
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-toHIGH transition of CLKA when a Port A read is selected and MBA is HIGH. MBF2 is set HIGH
following either a Reset (RS2) or Partial Reset (PRS).
RS1, RS2
Resets
I
A LOW on both pins initializes the FIFO read and write pointers to the first location of memory and
sets the Port B output register to all zeroes. A LOW-to-HIGH transition on RS1 selects the programming
method (serial or parallel) and one of five programmable flag default offsets. It also configures Port
B for bus size and endian arrangement. Four LOW-to-HIGH transitions of CLKA and four LOW-toHIGH transitions of CLKB must occur while RS1 is LOW.
PRS/
RT
Partial Reset/
Retransmit
I
This pin muxed for both Partial Reset and Retransmit operations, it is used in conjunction with the RTM
pin. If RTM is LOW, then a LOW on this pin initializes the FIFO read and write pointers to the first location
of memory and sets the Port B output register to all zeroes. During Partial Reset, the currently
selected bus size, endian arrangement, programming method (serial or parallel), and programmable
flag settings are all retained. If RTM is HIGH, then a LOW on this pin performs a Retransmit and initializes
the read pointer only, to the first memory location.
RTM
Retransmit Mode
I
This pin is used in conjunction with the RT pin. When RTM is HIGH a Retransmit is performed when
RT is taken HIGH.
SIZE(1)
Bus Size Select
(Port B)
I
A HIGH on this pin when BM is HIGH selects byte bus (9-bit) size on Port B. A LOW on this pin
when BM is HIGH selects word (18-bit) bus size. SIZE works with BM and BE to select the bus size
and endian arrangement for Port B. The level of SIZE must be static throughout device operation.
W/RA
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 A0-A35 outputs are in the HIGH impedance state when W/RA is HIGH.
W/RB
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 B0-B35 outputs are in the HIGH impedance state when W/RB is LOW.
NOTE:
1. FS2, BM and SIZE inputs are not TTL compatible. These inputs should be tied to GND or VCC.
5
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 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 +7.0
V
Input Voltage Range
–0.5 to VCC+0.5
V
Output Voltage Range
–0.5 to VCC+0.5
V
±20
mA
Supply Voltage Range
IIK
Input Clamp Current (VI < 0 or VI > VCC)
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
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
4.5
5.5
V
VIH
High-Level Input Voltage
2
—
V
VIL
Low-Level Input Voltage
—
0.8
V
IOH
High-Level Output Current
—
–4
mA
IOL
Low-Level Output Current
—
8
mA
TA
Operating Temperature
0
70
°C
ELECTRICAL CHARACTERISTICS OVER RECOMMENDED OPERATING FREEAIR TEMPERATURE RANGE (Unless otherwise noted)
Symbol
Parameter
Test Conditions
IDT723653
IDT723663
IDT723673
Commercial
tCLK = 12, 15 ns
Max.
Min.
Typ.(1)
2.4
VOH
Output Logic "1" Voltage
VCC = 4.5V,
IOH = –4 mA
—
—
Unit
V
VOL
Output Logic "0" Voltage
VCC = 4.5V,
IOL = 8 mA
—
—
0.5
V
ILI
Input Leakage Current (Any Input)
VCC = 5.5V,
VI = VCC or 0
—
—
±10
µA
ILO
Output Leakage Current
VCC = 5.5V,
VO = VCC or 0
—
—
±10
µA
ICC2(2)
Standby Current (with CLKA & CLKB running)
VCC = 5.5V,
VI = VCC –0.2V or 0V
—
—
8
mA
ICC3(2)
Standby Current (no clocks running)
VCC = 5.5V,
VI = VCC –0.2V or 0V
—
—
1
mA
CIN
(3)
COUT(3)
Input Capacitance
VI = 0,
f = 1 MHz
—
4
—
pF
Output Capacitance
VO = 0,
f = 1 MHZ
—
8
—
pF
NOTES:
1. All typical values are at VCC = 5V, TA = 25°C.
2. For additional ICC information, see Figure 1, Typical Characteristics: Supply Current (ICC) vs. Clock Frequency (fS).
3. Characterized values, not currently tested.
4. Industrial temperature range is available by special order.
6
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
CALCULATING POWER DISSIPATION
The ICC(f) current for the graph in Figure 1 was taken while simultaneously reading and writing a FIFO on the IDT723653/723663/723673 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 IDT723653/723663/723673 inputs
driven by TTL HIGH levels are known, the power dissipation can be calculated with the equation below.
With ICC(f) taken from Figure 1, the maximum power dissipation (PT) of these FIFOs may be calculated by:
PT = VCC x [ICC(f) + (N x ∆ICC x dc)] + Σ(CL x VCC2 X fo)
where:
N
∆I CC
dc
CL
fo
ICC(f)
Supply Current
mA
300
=
=
=
=
=
number of inputs driven by TTL levels
increase in power supply current for each input at a TTL HIGH level
duty cycle of inputs at a TTL HIGH level of 3.4 V
output capacitance load
switching frequency of an output
fdata = 1/2 fS
TA = 25oC
CL = 0 pF
250
VCC = 5.5V
VCC = 5.0V
200
VCC = 4.5V
150
100
50
0
0
10
20
30
40
50
60
70
fS  Clock Frequency  MHz
Figure 1. Typical Characteristics: Supply Current (ICC) vs. Clock Frequency (fS)
7
80
90
5610 drw03
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
TIMING REQUIREMENTS OVER RECOMMENDED RANGES OF SUPPLY
VOLTAGE AND OPERATING FREE-AIR TEMPERATURE
(Commercial: VCC = 5V ± 10%, TA = 0°C to +70°C)
Commercial
IDT723653L12
IDT723653L15
IDT723663L12
IDT723663L15
IDT723673L12
IDT723673L15
Symbol
Parameter
Min.
Max.
Min.
Max.
Unit
fS
Clock Frequency, CLKA or CLKB
—
83
—
66.7
MHz
tCLK
Clock Cycle Time, CLKA or CLKB
12
—
15
—
ns
tCLKH
Pulse Duration, CLKA or CLKB HIGH
5
—
6
—
ns
tCLKL
Pulse Duration, CLKA and CLKB LOW
5
—
6
—
ns
tDS
Setup Time, A0-A35 before CLKA↑ and B0-B35 before CLKB↑
3
—
4
—
ns
tENS1
Setup Time, CSA and W/RA before CLKA↑; CSB and W/RB before CLKB↑
4
—
4.5
—
ns
tENS2
Setup Time, ENA, and MBA before CLKA↑; ENB and MBB before CLKB↑
3
—
4.5
—
ns
tRSTS
Setup Time, RS1 or PRS LOW before CLKA↑ or CLKB↑
5
—
5
—
ns
tFSS
Setup Time, FS0, FS1 and FS2 before RS1 HIGH
7.5
—
7.5
—
ns
tBES
Setup Time, BE/FWFT before RS1 HIGH
7.5
—
7.5
—
ns
tSDS
Setup Time, FS0/SD before CLKA↑
3
—
4
—
ns
tSENS
Setup Time, FS1/SEN before CLKA↑
3
—
4
—
ns
tFWS
Setup Time, FWFT before CLKA↑
0
—
0
—
ns
tDH
Hold Time, A0-A35 after CLKA↑ and B0-B35 after CLKB↑
0.5
—
1
—
ns
tRTMS
Setup Time, RTM before RT1; RTM before RT2
5
—
5
—
ns
tENH
Hold Time, CSA, W/RA, ENA, and MBA after CLKA↑; CSB, W/RB, ENB,
and MBB after CLKB↑
0.5
—
1
—
ns
tRSTH
Hold Time, RS1 or PRS LOW after CLKA↑ or CLKB↑(1)
4
—
4
—
ns
tFSH
Hold Time, FS0, FS1 and FS2 after RS1 HIGH
2
—
2
—
ns
tBEH
Hold Time, BE/FWFT after RS1 HIGH
2
—
2
—
ns
tSDH
Hold Time, FS0/SD after CLKA↑
0.5
—
1
—
ns
tSENH
Hold Time, FS1/SEN HIGH after CLKA↑
0.5
—
1
—
ns
tSPH
Hold Time, FS1/SEN HIGH after RS1 HIGH
2
—
2
—
ns
(1)
Hold Time, RTM after RT1; RTM after RT2
5
—
5
—
ns
(2)
tSKEW1
Skew Time between CLKA↑ and CLKB↑ for EF/OR and FF/IR
5
—
7.5
—
ns
tSKEW2
(2,3)
Skew Time between CLKA↑ and CLKB↑ for AE and AF
12
—
12
—
ns
tRTMH
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.
3. Design simulated, not tested.
4. Industrial temperature range is available by special order.
8
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
SWITCHING CHARACTERISTICS OVER RECOMMENDED RANGES OF SUPPLY
VOLTAGE AND OPERATING FREE-AIR TEMPERATURE, CL = 30 pF
(Commercial: VCC = 5V ± 10%, TA = 0°C to +70°C)
Commercial
IDT723653L12
IDT723653L15
IDT723663L12
IDT723663L15
IDT723673L12
IDT723673L15
Symbol
Parameter
Min.
Max.
Min.
Max.
Unit
tA
Access Time, CLKA↑ to A0-A35 and CLKB↑ to B0-B35
2
8
2
10
ns
tWFF
Propagation Delay Time, CLKA↑ to FF/IR
2
8
2
8
ns
tREF
Propagation Delay Time, CLKB↑ to EF/OR
1
8
1
8
ns
tPAE
Propagation Delay Time, CLKB↑ to AE
1
8
1
8
ns
tPAF
Propagation Delay Time, CLKA↑ to AF
1
8
1
8
ns
tPMF
Propagation Delay Time, CLKA↑ to MBF1 LOW or MBF2 and CLKB↑ to MBF2
LOW or MBF1 HIGH
0
8
0
8
ns
tPMR
Propagation Delay Time, CLKA↑ to B0-B35(1) and CLKB↑ to A0-A35(2)
2
8
2
10
ns
tMDV
Propagation Delay Time, MBA to A0-A35 valid and MBB to B0-B35 Valid
2
8
2
10
ns
tRSF
Propagation Delay Time, RS1 or PRS LOW to AE LOW, AF HIGH, MBF1 HIGH
and MBF2 HIGH
1
10
1
15
ns
tEN
Enable Time, CSA and W/RA LOW to A0-A35 Active and CSB LOW and W/RB HIGH to
B0-B35 Active
2
6
2
10
ns
tDIS
Disable Time, CSA or W/RA HIGH to A0-A35 at highimpedance and CSB HIGH
or W/RB LOW to B0-B35 at high impedance
1
6
1
8
ns
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.
3. Industrial temperature range is available by special order.
9
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
SIGNAL DESCRIPTION
BIG-ENDIAN/FIRST WORD FALL THROUGH (BE/FWFT)
RESET (RS1, RS2)
After power up, a Reset operation must be performed by providing a LOW
pulse to RS1 and RS2 simultaneously. Afterwards, the FIFO memory of the
IDT723653/723663/723673 undergoes a complete reset by taking its Reset
(RS1 and RS2) input 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 Reset initializes the internal read and write
pointers and forces the Full/Input Ready flag (FF/IR) LOW, the Empty/Output
Ready flag (EF/OR) LOW, the Almost-Empty flag (AE) LOW, and the AlmostFull flag (AF) HIGH. A Reset (RS1) also forces the Mailbox flag (MBF1) of the
parallel mailbox register HIGH, and at the same time the RS2 and MBF2 operate
likewise. After a Reset, the FIFO’s Full/Input Ready flag is set HIGH after two
write clock cycles to begin normal operation.
A LOW-to-HIGH transition on the FlFO Reset (RS1) input latches the value
of the Big-Endian (BE) input for determining the order by which bytes are
transferred through Port B.
A LOW-to-HIGH transition on the FlFO Reset (RS1) input also latches the
values of the Flag Select (FS0, FS1 and FS2) inputs for choosing the AlmostFull and Almost-Empty offset programming method ( for details see Table 1, Flag
Programming, and Almost-Empty and Almost-Full flag offset programming
section). The relevant Reset timing diagram can be found in Figure 3.
— ENDIAN SELECTION
This is a dual purpose pin. At the time of Reset, the BE select function is active,
permitting a choice of Big- or Little-Endian byte arrangement for data read from
Port B. This selection determines the order by which bytes (or words) of data
are transferred through this port. For the following illustrations, assume that a
byte (or word) bus size has been selected for Port B. (Note that when Port B
is configured for a long word size, the Big-Endian function has no application
and the BE input is a “don’t care”1.)
A HIGH on the BE/FWFT input when the Reset (RS1) input goes from LOW
to HIGH will select a Big-Endian arrangement. In this case, the most significant
byte (word) of the long word written to Port A will be read from Port B first; the
least significant byte (word) of the long word written to Port A will be read from
Port B last.
A LOW on the BE/FWFT input when the Reset (RS1) input goes from LOW
to HIGH will select a Little-Endian arrangement. In this case, the least significant
byte (word) of the long word written to Port A will be read from Port B first; the
most significant byte (word) of the long word written to Port A will be read from
Port B last. Refer to Figure 2 for an illustration of the BE function. See Figure
3 (Reset) for an Endian select timing diagram.
— TIMING MODE SELECTION
After Reset, the FWFT select function is active, permitting a choice between
two possible timing modes: IDT Standard mode or First Word Fall Through
(FWFT) mode. Once the Reset (RS1) input is HIGH, a HIGH on the BE/FWFT
input during the next LOW-to-HIGH transition of CLKA and CLKB will select IDT
Standard mode. This mode uses the Empty Flag function (EF) to indicate
whether or not there are any words present in the FIFO memory. It uses the
Full Flag function (FF) to indicate whether or not the FIFO memory has any free
space for writing. In IDT Standard mode, every word read from the FIFO,
including the first, must be requested using a formal read operation.
Once the Reset (RS1) input is HIGH, a LOW on the BE/FWFT input during
the next LOW-to-HIGH transition of CLKA and CLKB will select FWFT mode.
This mode uses the Output Ready function (OR) to indicate whether or not there
is valid data at the data outputs (B0-B35). It also uses the Input Ready function
(IR) to indicate whether or not the FIFO memory has any free space for writing.
In the FWFT mode, the first word written to an empty FIFO goes directly to data
outputs, no read request necessary. Subsequent words must be accessed by
performing a formal read operation.
Following Reset, the level applied to the BE/FWFT input to choose the
desired timing mode must remain static throughout FIFO operation. Refer to
Figure 3 (Reset) for a First Word Fall Through select timing diagram.
PARTIAL RESET (PRS)
The FIFO memory of the IDT723653/723663/723673 undergoes a limited
reset by taking its Partial Reset (PRS) input LOW for at least four Port A clock
(CLKA) and four Port B clock (CLKB) LOW-to-HIGH transitions. The RTM pin
must be LOW during the time of Partial Reset. The Partial Reset input can switch
asynchronously to the clocks. A Partial Reset initializes the internal read and
write pointers and forces the Full/Input Ready flag (FF/IR) LOW, the Empty/
Output Ready flag (EF/OR) LOW, the Almost-Empty flag (AE) LOW, and the
Almost-Full flag (AF) HIGH. A Partial Reset also forces the Mailbox flag (MBF1,
MBF2) of the parallel mailbox register HIGH. After a Partial Reset, the FIFO’s
Full/Input Ready flag is set HIGH after two Write Clock cycles to begin normal
operation. See Figure 4, Partial Reset (IDT Standard and FWFT Modes) for
the relevant timing diagram.
Whatever flag offsets, programming method (parallel or serial), and timing
mode (FWFT or IDT Standard mode) are currently selected at the time a Partial
Reset is initiated, those settings will be remain unchanged upon completion of
the reset operation. A Partial Reset may be useful in the case where
reprogramming a FIFO following a Reset would be inconvenient.
RETRANSMIT (RT)
The FIFO memory of these devices undergoes a Retransmit by taking its
associated Retransmit (RT) input LOW for at least four Port A Clock (CLKA) and
four Port B Clock (CLKB) LOW-to-HIGH transitions. The Retransmit initializes
the read pointer of FIFO to the first memory location.
The RTM pin must be HIGH during the time of Retransmit. Note that the RT
input is muxed with the PRS input, the state of the RTM pin determining whether
this pin performs a Retransmit or a Partial Reset. See Figure 19 for Retransmit
(Standard IDT mode) and Figure 20 for Retransmit (FWFT mode) timing
diagrams.
PROGRAMMING THE ALMOST-EMPTY AND ALMOST-FULL FLAGS
Two registers in the IDT723653/723663/723673 are used to hold the offset
values for the Almost-Empty and Almost-Full flags. The Almost-Empty flag (AE)
Offset register is labeled X and Almost-Full flag (AF) Offset register is labeled
Y. The offset registers can be loaded with preset values during the reset of the
FIFO, programmed in parallel using the FIFO’s Port A data inputs, or
programmed in serial using the Serial Data (SD) input (see Table 1). FS2 FS0/
SD, and FS1/SEN function the same way in both IDT Standard and FWFT
modes.
NOTE:
1. Either a HIGH or LOW can be applied to a “don’t care” input with no change to the logical operation of the FIFO. Nevertheless, inputs that are temporarily “don’t care” (along with
unused inputs) must not be left open, rather they must be either HIGH or LOW.
10
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
TABLE 1 — FLAG PROGRAMMING
FS2
FS1/SEN
FS0/SD
RS1
X AND Y REGlSTERS(1)
H
H
H
↑
64
H
H
L
↑
16
H
L
H
↑
8
L
H
H
↑
256
L
L
H
↑
1,024
L
H
L
↑
Serial programming via SD
H
L
L
↑
Parallel programming via Port A(2,4)
L
L
L
↑
IP Mode(3,4)
NOTES:
1. X register holds the offset for AE; Y register holds the offset for AF.
2. When this method of parallel programming is selected, Port A will assume Non-Interspersed Parity.
3. When IP Mode is selected, only parallel programming of the offset values via Port A, can be performed and Port A will assume Interspersed Parity.
4. IF parallel programming is selected during a Master Reset, then FS0 & FS1 must remain LOW during FIFO operation.
— PRESET VALUES
To load a FIFO’s Almost-Empty flag and Almost-Full flag Offset registers with
one of the five preset values listed in Table 1, the flag select inputs must be HIGH
or LOW during a reset. For example, to load the preset value of 64 into X and
Y, FS0, FS1 and FS2 must be HIGH when RS1 returns HIGH. For the relevant
preset value loading timing diagram, see Figure 3.
values. If Interspersed Parity is selected then during parallel programming of
the flag offset values, the device will ignore data line A8. If Non-Interspersed
Parity is selected then data line A8 will become a valid bit. If Interspersed Parity
is selected serial programming of the offset values is not permitted, only parallel
programming can be done.
— SERIAL LOAD
To program the X and Y registers serially, initiate a Reset with FS2 LOW, FS0/
SD LOW and FS1/SEN HIGH during the LOW-to-HIGH transition of RS1. After
this reset is complete, the X and Y register values are loaded bit-wise through
the FS0/SD input on each LOW-to-HIGH transition of CLKA that the FS1/SEN
input is LOW. There are 22-, 24- or 26-bit writes needed to complete the
programming for the IDT723653, IDT723663 or the IDT723673, respectively.
The two registers are written in the order Y, X. Each register value can be
programmed from 1 to 2,044 (IDT723653), 1 to 4,092 (IDT723663) or 1 to
8,188 (IDT723673).
When the option to program the offset registers serially is chosen, the Full/
Input Ready (FF/IR) flag remains LOW until all register bits are written. FF/IR
is set HIGH by the LOW-to-HIGH transition of CLKA after the last bit is loaded
to allow normal FIFO operation.
See Figure 6, Serial Programming of the Almost-Full Flag and AlmostEmpty Flag Offset Values after Reset (IDT Standard and FWFT Modes).
— PARALLEL LOAD FROM PORT A
To program the X and Y registers from Port A, perform a Reset with FS2 HIGH
or LOW and FS0 and FS1 LOW during the LOW-to-HIGH transition of RS1.
The state of FS2 at this point of reset will determine whether the parallel
programming method has Interspersed Parity or Non-Interspersed Parity.
Refer to Table 1 for Flag Programming Flag Offset setup. It is important to note
that once parallel programming has been selected during a Master Reset by
holding both FS0 & FS1 LOW, these inputs must remain LOW during all
subsequent FIFO operation. They can only be toggled HIGH when future
Master Resets are performed and other programming methods are desired.
After this reset is complete, the first two writes to the FIFO do not store data
in RAM. The first two write cycles load the offset registers in the order Y, X. On
the third write cycle the FIFO is ready to be loaded with a data word. See Figure
5, Parallel Programming of the Almost-Full Flag and Almost-Empty Flag
Offset Values after Reset (IDT Standard and FWFT modes), for a detailed
timing diagram. For Non-Interspersed Parity mode the Port A data inputs used
by the Offset registers are (A10-A0), (A11-A0), or (A12-A0) for the IDT723653,
IDT723663, or IDT723673, respectively. For Interspersed Parity mode the
Port A data inputs used by the Offset registers are (A11-A9, A7-A0), (A12-A9,
A7-A0), or (A13-A9, A7-A0) for the IDT723653, IDT723663, or IDT723673,
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
range from 1 to 2,044 for the IDT723653; 1 to 4,092 for the IDT723663; and
1 to 8,188 for the IDT723673. After all the offset registers are programmed from
Port A, the FIFO begins normal operation.
FIFO WRITE/READ OPERATION
The state of the Port A data (A0-A35) lines is controlled by Port A Chip Select
(CSA) and Port A Write/Read select (W/RA). The A0-A35 lines are in the Highimpedance state when either CSA or W/RA is HIGH. The A0-A35 lines are active
outputs when both CSA and W/RA are LOW.
Data is loaded into the FIFO 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 FF/IR is HIGH (see Table 2). FIFO writes on Port A are independent
of any concurrent reads on Port B.
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) lines is controlled by the
Port B Chip Select (CSB) and Port B Write/Read select (W/RB). The B0-B35
lines are in the high-impedance state when either CSB is HIGH or W/RB is LOW.
The B0-B35 lines are active outputs when CSB is LOW and W/RB is HIGH.
INTERSPERSED PARITY
Interspersed Parity is selected during a Master Reset of the FIFO. Refer
to Table 1 for the set-up configuration of Interspersed Parity. The Interspersed
Parity function allows the user to select the location of the parity bits in the word
loaded into the parallel port (A0-An) during programming of the flag offset
11
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
TABLE 2 — PORT-A ENABLE FUNCTION TABLE
CSA
W/RA
ENA
MBA
CLKA
Data A (A0-A35) I/O
Port Functions
H
X
X
X
X
High-Impedance
None
L
H
L
X
X
Input
None
L
H
H
L
↑
Input
FIFO Write
L
H
H
H
↑
Input
Mail1 Write
L
L
L
L
X
Output
None
L
L
H
L
↑
Output
None
L
L
L
H
X
Output
None
L
L
H
H
↑
Output
Mail2 Read (Set MBF2 HIGH)
TABLE 3 — PORT-B ENABLE FUNCTION TABLE
CSB
W/RB
ENB
MBB
CLKB
Data B (B0-B35) I/O
Port Functions
H
X
X
X
X
High-Impedance
None
L
L
L
X
X
Input
None
L
L
H
L
↑
Input
None
L
L
H
H
↑
Input
Mail2 Write
L
H
L
L
X
Output
None
L
H
H
L
↑
Output
FIFO read
L
H
L
H
X
Output
None
L
H
H
H
↑
Output
Mail1 Read (Set MBF1 HIGH)
TABLE 4 — FIFO FLAG OPERATION (IDT STANDARD AND FWFT MODES)
IDT723653(3)
Number of Words in FIFO(1,2)
IDT723663(3)
IDT723673(3)
Synchronized
to CLKB
EF/OR
AE
Synchronized
to CLKA
AF
FF/IR
0
0
0
L
L
H
H
1 to X
1 to X
1 to X
H
L
H
H
(X+1) to [2,048-(Y+1)]
(X+1) to [4,096-(Y+1)]
(X+1) to [8,192-(Y+1)]
H
H
H
H
(2,048-Y) to 2,047
(4,096-Y) to 4,095
(8,192-Y) to 8,191
H
H
L
H
2,048
4,096
8,192
H
H
L
L
NOTES:
1. When a word loaded to an empty FIFO is shifted to the output register, its previous FIFO memory location is free.
2. Data in the output register does not count as a "word in FIFO memory". Since in FWFT mode, the first word written to an empty FIFO goes unrequested to the output
register (no read operation necessary), it is not included in the memory count.
3. X is the Almost-Empty offset used by AE. Y is the Almost-Full offset used by AF. Both X and Y are selected during a FIFO reset or Port A programming.
Data is read from the FIFO 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 EF/OR is HIGH (see Table 3). FIFO reads on Port B are
independent of any concurrent writes on Port A.
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 high-impedance 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 operating the FIFO in FWFT mode and the Output Ready flag is LOW,
the next word written is automatically sent to the FIFO’s output register by the
LOW-to-HIGH transition of the port clock that sets the Output Ready flag HIGH.
When the Output Ready flag is HIGH, data residing in the FIFO’s memory array
is clocked to the output register only when a read is selected using the port’s
Chip Select, Write/Read select, Enable, and Mailbox select.
When operating the FIFO in IDT Standard mode, regardless of whether
the Empty Flag is LOW or HIGH, data residing in the FIFO’s memory array is
clocked to the output register only when a read is selected using the port’s
Chip Select, Write/Read select, Enable, and Mailbox select. Port A Write
timing diagram can be found in Figure 7. Relevant Port B Read timing
diagrams together with Bus-Matching and Endian select can be found in
Figure 8, 9 and 10.
12
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
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. FF/IR, and AF are synchronized to CLKA. EF/OR and AE are
synchronized to CLKB. Table 4 shows the relationship of each port flag to the
number of words stored in memory.
EMPTY/OUTPUT READY FLAGS (EF/OR)
These are dual purpose flags. In the FWFT mode, the Output Ready (OR)
function is selected. 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.
In the IDT Standard mode, the Empty Flag (EF) function is selected. When
the Empty Flag is HIGH, data is available in the FIFO’s memory for reading to
the output register. When the Empty Flag is LOW, the previous data word is
present in the FIFO output register and attempted FIFO reads are ignored.
The Empty/Output Ready flag of a FIFO is synchronized to the port clock that
reads data from its array (CLKB). For both the FWFT and IDT Standard modes,
the 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 memory status
is empty, empty+1, or empty+2.
In FWFT mode, 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 LOWto-HIGH transition of the synchronizing clock occurs, simultaneously forcing the
Output Ready flag HIGH and shifting the word to the FIFO output register.
In IDT Standard mode, from the time a word is written to a FIFO, the Empty
Flag will indicate the presence of data available for reading in a minimum of two
cycles of the Empty Flag synchronizing clock. Therefore, an Empty Flag is LOW
if a word in memory is the next data to be sent to the FlFO output register and
two cycles of the port Clock that reads data from the FIFO have not elapsed since
the time the word was written. The Empty Flag of the FIFO remains LOW until
the second LOW-to-HIGH transition of the synchronizing clock occurs, forcing
the Empty Flag HIGH; only then can data be read.
A LOW-to-HIGH transition on an Empty/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 11 and 12).
FULL/INPUT READY FLAGS (FF/IR)
This is a dual purpose flag. In FWFT mode, the Input Ready (IR) function is
selected. In IDT Standard mode, the Full Flag (FF) function is selected. For both
timing modes, when the Full/Input Ready flag is HIGH, a memory location is free
in the FIFO to receive new data. No memory locations are free when the Full/
Input Ready flag is LOW and attempted writes to the FIFO are ignored.
The Full/Input Ready flag of a FlFO is synchronized to the port clock that writes
data to its array (CLKA). For both FWFT and IDT Standard modes, each time
a word is written to a FIFO, its write pointer is incremented. The state machine
that controls a Full/Input Ready flag monitors a write pointer and read pointer
comparator that indicates when the FlFO memory status is full, full-1, or full-2.
From the time a word is read from a FIFO, its previous memory location is ready
13
COMMERCIAL TEMPERATURE RANGE
to be written to in a minimum of two cycles of the Full/Input Ready flag
synchronizing clock. Therefore, an Full/Input Ready flag is LOW if less than two
cycles of the Full/Input Ready flag synchronizing clock have elapsed since the
next memory write location has been read. The second LOW-to-HIGH
transition on the Full/Input Ready flag synchronizing clock after the read sets
the Full/Input Ready flag HIGH.
A LOW-to-HIGH transition on a Full/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 13 and 14).
ALMOST-EMPTY FLAG (AE)
The Almost-Empty flag of a FIFO is synchronized to the port clock that reads
data from its array (CLKB). The state machine that controls an Almost-Empty
flag monitors a write pointer and read pointer comparator that indicates when
the FIFO memory status is almost-empty, almost-empty+1, or almost-empty+2.
The Almost-Empty state is defined by the contents of register X. These registers
are loaded with preset values during a FIFO reset, programmed from Port A,
or programmed serially (see Almost-Empty flag and Almost-Full flag offset
programming section). 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. Note
that 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-Empty 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 LOW-to-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 Figure 15).
ALMOST-FULL FLAG (AF)
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
memory status is almost-full, almost-full-1, or almost-full-2. The Almost-Full state
is defined by the contents of register Y. These registers are loaded with preset
values during a FlFO reset or, programmed from Port A, or programmed
serially (see Almost-Empty flag and Almost-Full flag offset programming
section). An Almost-Full flag is LOW when the number of words in its FIFO is
greater than or equal to (2,048-Y), (4,096-Y), or (8,192-Y) for the IDT723653,
IDT723663, or IDT723673 respectively. An Almost-Full flag is HIGH when the
number of words in its FIFO is less than or equal to [2,048-(Y+1)], [4,096-(Y+1)],
or [8,192-(Y+1)] for the IDT723653, IDT723663, or IDT723673 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 Almost-Full flag to reflect the new level of fill.
Therefore, the Almost-Full flag of a FIFO containing [2,048/4,096/8,192-(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 [2,048/
4,096/8,192-(Y+1)]. An Almost-Full flag is set HIGH by the second LOW-toHIGH transition of its synchronizing clock after the FIFO read that reduces the
number of words in memory to [2,048/4,096/8,192-(Y+1)]. A LOW-to-HIGH
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
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 [2,048/4,096/8,192-(Y+1)]. Otherwise, the
subsequent synchronizing clock cycle may be the first synchronization cycle
(see Figure 16).
on A0-A8. (In this case, A9-A35 are indeterminate.)
The data in a mail register remains intact after it is read and changes only when
new data is written to the register. The Endian select feature has no effect on
mailbox data. For mail register and mail register flag timing diagrams, see Figure
17 and 18.
MAILBOX REGISTERS
Two 36-bit bypass registers are on the IDT723653/723663/723673 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. The usable width of both
the Mail1 and Mail2 Registers matches the selected bus size for Port B.
A LOW-to-HIGH transition on CLKA writes data to the Mail1 Register when
a Port A write is selected by CSA, W/RA, and ENA with MBA HIGH. If the
selected Port B bus size is 36 bits, the usable width of the Mail1 Register employs
data lines A0-A35. If the selected Port B bus size is 18 bits, then the usable width
of the Mail1 Register employs data lines A0-A17. (In this case, A18-A35 are
don’t care inputs.) If the selected Port B bus size is 9 bits, then the usable width
of the Mail1 Register employs data lines A0-A8. (In this case, A9-A35 are don’t
care inputs.)
A LOW-to-HIGH transition on CLKB writes B0-B35 data to the Mail2 Register
when a Port B write is selected by CSB, W/RB, and ENB with MBB HIGH. If
the selected Port B bus size is 36 bits, the usable width of the Mail2 employs
data lines B0-B35. If the selected Port B bus size is 18 bits, then the usable width
of the Mail2 Register employs data lines B0-B17. (In this case, B18-B35 are
don’t care inputs.) If the selected Port B bus size is 9 bits, then the usable width
of the Mail2 Register employs data lines B0-B8. (In this case, B9-B35 are don’t
care inputs.)
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 port Mailbox 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 with MBB
HIGH. For a 36-bit bus size, 36 bits of mailbox data are placed on B0-B35. For
an 18-bit bus size, 18 bits of mailbox data are placed on B0-B17. (In this case,
B18-B35 are indeterminate.) For a 9-bit bus size, 9 bits of mailbox data are
placed on B0-B8. (In this case, B9-B35 are indeterminate.)
The Mail2 Register Flag (MBF2) is set HIGH by a LOW-to-HIGH transition
on CLKA when a Port A read is selected by CSA, W/RA, and ENA with MBA
HIGH.
For a 36-bit bus size, 36 bits of mailbox data are placed on A0-A35. For an
18-bit bus size, 18 bits of mailbox data are placed on A0-A17. (In this case, A18A35 are indeterminate.) For a 9-bit bus size, 9 bits of mailbox data are placed
BUS SIZING
The Port B bus can be configured in a 36-bit long word, 18-bit word, or 9bit byte format for data read from the FIFO. The levels applied to the Port B Bus
Size select (SIZE) and the Bus-Match select (BM) determine the Port B bus size.
These levels should be static throughout FIFO operation. Both bus size
selections are implemented at the completion of Reset, by the time the Full/Input
Ready flag is set HIGH, as shown in Figure 2.
Two different methods for sequencing data transfer are available for Port B
when the bus size selection is either byte-or word-size. They are referred to
as Big-Endian (most significant byte first) and Little-Endian (least significant byte
first). The level applied to the Big-Endian select (BE) input during the LOW-toHIGH transition of RS1 selects the endian method that will be active during FIFO
operation. BE is a don’t care input when the bus size selected for Port B is long
word. The endian method is implemented at the completion of Reset, by the time
the Full/Input Ready flag is set HIGH, as shown in Figure 2.
Only 36-bit long word data is written to or read from the FIFO memory on the
IDT723653/723663/723673. Bus-matching operations are done after data is
read from the FIFO RAM. These bus-matching operations are not available
when transferring data via mailbox registers. Furthermore, both the word- and
byte-size bus selections limit the width of the data bus that can be used for mail
register operations. In this case, only those byte lanes belonging to the selected
word- or byte-size bus can carry mailbox data. The remaining data outputs will
be indeterminate. The remaining data inputs will be don’t care inputs. For
example, when a word-size bus is selected, then mailbox data can be transmitted
only between A0-A17 and B0-B17. When a byte-size bus is selected, then
mailbox data can be transmitted only between A0-A8 and B0-B8. (See Figures
17 and 18).
BUS-MATCHING FIFO READS
Data is read from the FIFO RAM in 36-bit long word increments. If a long word
bus size is implemented, the entire long word immediately shifts to the FIFO output
register. If byte or word size is implemented on Port B, only the first one or two
bytes appear on the selected portion of the FIFO output register, with the rest
of the long word stored in auxiliary registers. In this case, subsequent FIFO
reads output the rest of the long word to the FIFO output register in the order
shown by Figure 2.
When reading data from FIFO in byte or word format, the unused B0-B35
outputs are indeterminate.
14
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
BYTE ORDER ON PORT A:
BYTE ORDER ON PORT B:
BE
X
BM
SIZE
L
X
COMMERCIAL TEMPERATURE RANGE
A35  A27
A26  A18
A17  A9
A8  A0
A
B
C
D
B35  B27
B26  B18
B17  B9
B8  B0
A
B
C
D
Write to FIFO
Read from FIFO
(a) LONG WORD SIZE
B35  B27
BE
BM
H
H
B26  B18
SIZE
B17  B9
A
B
B17  B9
B8  B0
C
D
L
B35  B27
B26  B18
B8  B0
1st: Read from FIFO
2nd: Read from FIFO
(b) WORD SIZE  BIG-ENDIAN
B35  B27
BE
BM
L
H
B26  B18
SIZE
B17  B9
C
D
B17  B9
B8  B0
A
B
L
B35  B27
B26  B18
B8  B0
1st: Read from FIFO
2nd: Read from FIFO
(c) WORD SIZE  LITTLE-ENDIAN
B35  B27
BE
BM
H
H
B26  B18
B17  B9
SIZE
B8  B0
A
1st: Read from FIFO
H
B35  B27
B26  B18
B17  B9
B8  B0
B
B35  B27
B26  B18
B17  B9
B8  B0
C
B35  B27
B26  B18
B17  B9
2nd: Read from FIFO
3rd: Read from FIFO
B8  B0
D
4th: Read from FIFO
(d) BYTE SIZE  BIG-ENDIAN
B35  B27
BE
L
BM
H
B26  B18
B17  B9
SIZE
H
B8  B0
D
B35  B27
B26  B18
B17  B9
B8  B0
C
B35  B27
B26  B18
B17  B9
B26  B18
B17  B9
Figure 2. Bus sizing
15
3rd: Read from FIFO
B8  B0
A
(e) BYTE SIZE  LITTLE-ENDIAN
2nd: Read from FIFO
B8  B0
B
B35  B27
1st: Read from FIFO
4th: Read from FIFO
5610 drw 04
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
CLKA
1
2
CLKB
tRSTS
tRSTH
RS1, RS2
tBEH
tBES
BE/FWFT
tFWS
BE
tFSH
tFSS
FS2,
FS1,FS0
FWFT
0,1
tWFF
tWFF
FF/IR
tREF(2)
EF/OR
tRSF
AE
tRSF
AF
tRSF
MBF1,
MBF2
RTM
LOW
5610 drw05
NOTES:
1. PRS must be HIGH during Reset.
2. If BE/FWFT is HIGH, then EF/OR will go LOW one CLKB cycle earlier than in this case where BE/FWFT is LOW.
Figure 3. Reset and Loading X and Y with a Preset Value of Eight (IDT Standard and FWFT Modes)
CLKA
CLKB
tRSTS
tRSTH
PRS
tWFF
tWFF
FF/IR
tREF (2)
EF/OR
tRSF
AE
tRSF
AF
tRSF
MBF1,
MBF2
RTM
LOW
5610 drw 06
NOTES:
1. RS1 must be HIGH during Partial Reset.
2. If BE/FWFT is HIGH, then EF/OR will go LOW one CLKB cycle earlier than in this case where BE/FWFT is LOW.
Figure 4. Partial Reset (IDT Standard and FWFT Modes)
16
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
CLKA
2
1
4
COMMERCIAL TEMPERATURE RANGE
RS1
tFSS
tFSH
FS2
tFSS
FS1,FS0
tFSH
0,0
tWFF
FF/IR
tENS2
tENH
ENA
tDH
tDS
A0-A35
AE Offset
(X)
AF Offset
(Y)
First Word to FIFO1
5610 drw 07
NOTE:
1. CSA = LOW, W/RA = HIGH, MBA = LOW.
Figure 5. Parallel Programming of the Almost-Full Flag and Almost-Empty Flag Offset Values after Reset
(IDT Standard and FWFT Modes)
CLKA
4
RS1
tFSS
tFSH
FS2
tWFF
FF/IR
tFSS
tSPH
tSENS
tSENH
tSENS
tSENH
tSDS
tSDH
tSDS
tSDH
FS1/SEN
FS0/SD(2)
AF Offset
(Y) MSB
AE Offset
(X) LSB
NOTES:
1. It is not necessary to program offset register bits on consecutive clock cycles. FIFO write attempts are ignored until FF/IR is set HIGH.
2. Programmable offsets are written serially to the SD input in the order AF offset (Y) and AE offset (X).
Figure 6. Serial Programming of the Almost-Full Flag and Almost-Empty Flag Offset Values after Reset
(IDT Standard and FWFT Modes)
17
5610 drw 08
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
tCLKH
tCLK
COMMERCIAL TEMPERATURE RANGE
tCLKL
CLKA
FF/IRA HIGH
tENS1
tENH
CSA
tENS1
tENH
tENS2
tENH
tENS2
tENH
W/RA
MBA
tENS2
tENH
tENS2
tENH
ENA
tDS
tDH
W1 (1)
A0-A35
No Operation
W2 (1)
5610 drw09
NOTE:
1. Written to FIFO.
Figure 7. Port A Write Cycle Timing for FIFO (IDT Standard and FWFT Modes)
tCLK
tCLKH
tCLKL
CLKB
EF/OR
HIGH
CSB
W/RB
MBB
tENS2
tENS2
tENH
tENH
tENH
tENS2
ENB
tMDV
tA
tEN
B0-B35
tMDV
OR
tDIS
tA
W1 (1)
(FWFT Mode)
tDIS
W2 (1)
tA
tEN
B0-B35
W1(1)
Previous Data
(Standard Mode)
No Operation
tA
W2
(1)
W3
(1)
5610 drw10
NOTE:
1. Data read from the FIFO
DATA SIZE TABLE FOR FIFO LONG-WORD READS
SIZE MODE(1)
DATA WRITTEN TO FIFO
(SELECT AT RESET)
DATA READ FROM FIFO
BM
SIZE
BE
A35-A27
A26-A18
A17-A9
A8-A0
B35-B27
B26-B18
B17-B9
B8-B0
L
X
X
A
B
C
D
A
B
C
D
NOTE:
1. BE is selected at Reset: BM and SIZE must be static throughout device operation.
Figure 8. Port B Long-Word Read Cycle (IDT Standard and FWFT Modes)
18
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
CLKB
FF/OR
HIGH
CSB
W/RB
MBB
tENS2
tENH
ENB
tMDV
B0-B17
tEN
(Standard Mode)
OR
tMDV
tEN
B0-B17
Read 1
tDIS
Read 2
Read 1
tDIS
Read 2
tA
tA
(FWFT Mode)
No Operation
tA
tA
Previous Data
Read 3
5610 drw11
NOTE:
1. Unused word B18-B35 are indeterminate.
DATA SIZE TABLE FOR WORD READS
SIZE MODE (1)
DATA WRITTEN TO FIFO 1
READ
NO.
BM
SIZE
BE
A35-A27
A26-A18
A17-A9
A8-A0
H
L
H
A
B
C
D
H
L
L
A
B
C
D
B17-B9
B8-B0
1
A
B
2
C
D
1
C
D
2
A
B
NOTE:
1. BE is selected at Reset: BM and SIZE must be static throughout device operation.
Figure 9. Port B Word Read Cycle Timing (IDT Standard and FWFT Modes)
19
DATA READ FROM FIFO
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
CLKB
EF/OR HIGH
CSB
W/RB
MBB
tENS2
tENH
ENB
No Operation
tMDV
tA
B0-B8
tA
tA
tA
tA
Read 1
Read 2
Read 3
Read 4
Previous Data
OR
tEN
B0-B8
tMDV
(FWFT Mode)
tA
Read 2
tEN
(Standard Mode)
tA
tA
Read 1
tDIS
Read 4
Read 3
tDIS
Read 5
5610 drw12
NOTE:
1. Unused bytes B9-B17, B18-B26, and B27-B35 are indeterminate.
DATA SIZE TABLE FOR BYTE READS
SIZE MODE(1)
BM
H
H
SIZE
H
H
DATA WRITTEN TO FIFO
BE
H
L
A35-A27
A
A
A26-A18
B
B
A17-A9
C
C
DATA READ
FROM FIFO
B8-B0
1
A
2
B
3
C
4
D
1
D
2
C
3
B
4
A
A8-A0
D
D
NOTE:
1. BE is selected at Reset: BM and SIZE must be static throughout device operation.
Figure 10. Port B Byte Read Cycle Timing (IDT Standard and FWFT Modes)
20
READ
NO.
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
tCLK
tCLKH
tCLKL
CLKA
CSA
W/RA
LOW
HIGH
tENS2
tENH
tENS2
tENH
MBA
ENA
IR
HIGH
tDS
A0-A35
tDH
W1
tSKEW1
CLKB
(1)
tCLKH
1
tCLK
tCLKL
2
3
tREF
OR
tREF
FIFO Empty
CSB
LOW
W/RB
MBB
HIGH
LOW
tENS2
tENH
ENB
tA
B0-B35
Old Data in FIFO Output Register
W1
5610 drw13
NOTES:
1. tSKEW1 is the minimum time between a rising CLKA edge and a rising CLKB edge for OR to transition HIGH and to clock the next word to the FIFO 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 OR HIGH and load of the first word to the output register may
occur one CLKB cycle later than shown.
2. If Port B size is word or byte, OR is set LOW by the last word or byte read from the FIFO, respectively.
Figure 11. OR Flag Timing and First Data Word Fall Through when FIFO is Empty (FWFT Mode)
21
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
tCLK
tCLKH tCLKL
CLKA
CSA
W/RA
LOW
HIGH tENS2
tENH
tENS2
tENH
MBA
ENA
FF
HIGH
tDS
A0-A35
tDH
W1
(1)
tSKEW1
CLKB
tCLK
tCLKH tCLKL
1
2
tREF
EF
tREF
FIFO Empty
CSB
LOW
W/RB
MBB
HIGH
LOW
tENS2
tENH
ENB
tA
B0-B35
W1
5610 drw14
NOTES:
1. tSKEW1 is the minimum time between a rising CLKA edge and a rising CLKB edge for EF 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 the transition of EF HIGH may occur one CLKB cycle later than shown.
2. If Port B size is word or byte, EF is set LOW by the last word or byte read from the FIFO, respectively.
Figure 12. EF Flag Timing and First Data Read when FIFO is Empty (IDT Standard Mode)
22
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
tCLK
tCLKH
tCLKL
CLKB
CSB
LOW
W/RB
MBB
HIGH
LOW
tENS2
tENH
ENB
OR
HIGH
tA
B0-B35
Next Word From FIFO
Previous Word in FIFO Output Register
(1)
tSKEW1
CLKA
tCLKH
1
tCLK
tCLKL
2
tWFF
tWFF
IR
FIFO Full
CSA
LOW
W/RA
HIGH
tENS2
tENH
tENS2
tENH
MBA
ENA
tDS
tDH
A0-A35
To FIFO
5610 drw15
NOTES:
1. tSKEW1 is the minimum time between a rising CLKB edge and a rising CLKA edge for IR 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 IR may transition HIGH one CLKA cycle later than shown.
2. If Port B size is word or byte, tSKEW1 is referenced to the rising CLKB edge that reads the last word or byte write of the long word, respectively.
Figure 13. IR Flag Timing and First Available Write when FIFO is Full (FWFT Mode)
23
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
tCLKH
tCLK
COMMERCIAL TEMPERATURE RANGE
tCLKL
CLKB
CSB LOW
W/RB HIGH
MBB LOW
tENS2
tENH
ENB
EF
B0-B35
HIGH
tA
Previous Word in FIFO Output Register
Next Word From FIFO
tSKEW1(1)
tCLKH
CLKA
tCLK
tCLKL
1
2
t WFF
t WFF
FF FIFO Full
CSA LOW
W/RA
HIGH
tENH
tENS2
MBA
tENS2
tENH
ENA
tDS
tDH
A0-A35
To FIFO
5610 drw16
NOTES:
1. tSKEW1 is the minimum time between a rising CLKB edge and a rising CLKA edge for FF 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 FF may transition HIGH one CLKA cycle later than shown.
2. If Port B size is word or byte, tSKEW1 is referenced from the rising CLKB edge that reads the last word or byte of the long word, respectively.
Figure 14. FF Flag Timing and First Available Write when FIFO is Full (IDT Standard Mode)
CLKA
tENS2
tENH
ENA
tSKEW2
CLKB
(1)
1
2
tPAE
tPAE
AE
X Words in FIFO
(X+1) Words in FIFO
tENS2
tENH
ENB
5610 drw17
NOTES:
1. tSKEW2 is the minimum time between a rising CLKA edge and a rising CLKB edge for AE 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 AE may transition HIGH one CLKB cycle later than shown.
2. FIFO Write (CSA = LOW, W/RA = LOW, MBA = LOW), FIFO read (CSB = LOW, W/RB = HIGH, MBB = LOW). Data in the FIFO output register has been read from the FIFO.
3. If Port B size is word or byte, AE is set LOW by the last word or byte read from the FIFO, respectively.
Figure 15. Timing for AE when the FIFO is Almost-Empty (IDT Standard and FWFT Modes).
24
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
CLKA
1
tENH
tENS2
tSKEW2
2
(1)
ENA
tPAF
AF
tPAF
(D-Y) Words in FIFO
[D-(Y+1)] Words in FIFO
CLKB
tENH
tENS2
ENB
5610 drw18
NOTES:
1. tSKEW2 is the minimum time between a rising CLKA edge and a rising CLKB edge for AF 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 AF may transition HIGH one CLKA cycle later than shown.
2. FIFO Write (CSA = LOW, W/RA = HIGH, MBA = LOW), FIFO read (CSB = LOW, W/RB = HIGH, MBB = LOW). Data in the FIFO output register has been read from the FIFO.
3. D = Maximum FIFO Depth = 2,048 for the IDT723653, 4,096 for the IDT723663, 8,192 for the IDT723673.
4. If Port B size is word or byte, tSKEW2 is referenced from the rising CLKB edge that reads the last word or byte of the long word, respectively.
Figure 16. Timing for AF when the FIFO is Almost-Full (IDT Standard and FWFT Modes).
CLKA
tENS1
tENH
tENS1
tENH
tENS2
tENH
tENS2
tENH
CSA
W/RA
MBA
ENA
tDS
W1
A0-A35
tDH
CLKB
tPMF
tPMF
MBF1
CSB
W/RB
MBB
tENS2
tENH
ENB
tEN
B0-B35
tMDV
tDIS
tPMR
FIFO Output Register
W1 (Remains valid in Mail1 Register after read)
5610 drw19
NOTE:
1. If Port B is configured for word size, data can be written to the Mail1 Register using A0-A17 (A18-A35 are don't care inputs). In this first case B0-B17 will have valid data (B18B35 will be indeterminate). If Port B is configured for byte size, data can be written to the Mail1 Register using A0-A8
(A9-A35 are don't care inputs). In this second case, B0-B8 will have valid data (B9-B35 will be indeterminate).
Figure 17. Timing for Mail1 Register and MBF1 Flag (IDT Standard and FWFT Modes)
25
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
CLKB
tENS1
CSB
COMMERCIAL TEMPERATURE RANGE
tENH
tENS1
tENH
tENS2
tENH
tENS2
tENH
W/RB
MBB
ENB
tDS
W1
B0-B35
tDH
CLKA
tPMF
tPMF
MBF2
CSA
W/RA
MBA
tENS2
tENH
ENA
tEN
A0-A35
tMDV
FIFO Output Register
tPMR
tDIS
W1 (Remains valid in Mail2 Register after read)
5610 drw20
NOTE:
1. If Port B is configured for word size, data can be written to the Mail2 Register using B0-B17 (B18-B35 are don't care inputs). In this first case A0-A17 will have valid data (A18A35 will be indeterminate). If Port B is configured for byte size, data can be written to the Mail2 Register using B0-B8 (B9-B35 are don't care inputs). In this second case, A0-A8
will have valid data (A9-A35 will be indeterminate).
Figure 18. Timing for Mail2 Register and MBF2 Flag (IDT Standard and FWFT Modes)
26
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
CLKA
1
CLKB
2
4
3
2
1
COMMERCIAL TEMPERATURE RANGE
3
4
tENS2
tENH
ENB
tRSTH
tRSTS
RT
tRTMS
tRTMH
RTM
(2)
(2)
tREF
tREF
EF
tA
B0-Bn
Wx
W1
5610 drw21
NOTES:
1. CSB = LOW; W/RB is HIGH
2. Retransmit setup is complete after EF returns HIGH, only then can a read operation begin.
3. W1 = first word written to the FIFO after Master Reset.
4. No more than D-2 may be written to the FIFO between Reset (Master or Partial) and Retransmit setup. Therefore, FF will be LOW throughout the Retransmit setup procedure.
D = 2,048, 4,096 and 8,192 for the IDT723653, IDT723663 and IDT723673 respectively.
Figure 19. Retransmit Timing (IDT Standard Mode)
CLKA
1
CLKB
ENB
RT
2
1
4
3
2
3
4
LOW
tRSTS
tRSTH
tRTMS
tRTMH
RTM
(2)
(2)
tREF
tREF
OR
tA
B0-Bn
Wx
W1
5610 drw22
NOTES:
1. CSB = LOW; W/RB is HIGH
2. Retransmit setup is complete after OR returns HIGH, only then can a read operation begin.
3. W1 = first word written to the FIFO after Master Reset.
4. No more than D-2 may be written to the FIFO between Reset (Master or Partial) and Retransmit setup. Therefore, IR will be LOW throughout the Retransmit setup procedure.
D = 2,048, 4,096 and 8,192 for the IDT723653, IDT723663 and IDT723673 respectively.
Figure 20. Retransmit Timing (FWFT Mode)
27
IDT723653/723663/723673 CMOS SyncFIFOTM WITH BUS-MATCHING
2,048 x 36 x 2, 4,096 x 36 x 2 and 8,192 x 36 x 2
COMMERCIAL TEMPERATURE RANGE
TRANSFER CLOCK
WRITE
READ
WRITE CLOCK (CLKA)
CHIP SELECT (CSA)
VCC
CLKA
CLKB
EF/OR
ENA
ENB
FF/IR
CSB
CSA
MBB
MBA
READ CLOCK (CLKB)
CHIP SELECT (CSB)
EMPTY FLAG/
OUTPUT READY (EF/OR)
WRITE SELECT (W/RA)
WRITE ENABLE (ENA)
ALMOST-FULL FLAG (AF)
A0-A35
IDT
723653
723663
723673
n
READ ENABLE (ENB)
READ SELECT (W/RB)
IDT
723653
723663
723673
VCC
ALMOST-EMPTY FLAG (AE)
DATA IN (Dn)
B0-B35
FULL FLAG/
INPUT READY (FF/IR)
A0-A35
n
Qn
W/RB
MBA
n
B0-B35
DATA OUT (Qn)
Dn
VCC
VCC
W/RA
MBB
5610 drw23
NOTES:
1. Mailbox feature is not supported in depth expansion applications. (MBA + MBB tie to GND)
2. Transfer clock should be set either to the Write Port Clock (CLKA) or the Read Port Clock (CLKB), whichever is faster.
3. The amount of time it takes for EF/OR of the last FIFO in the chain to go HIGH (i.e. valid data to appear on the last FIFO’s outputs) after a word has been written to the first FIFO is the
sum of the delays for each individual FIFO: (N - 1)*(4*transfer clock) + 3*TRCLK, where N is the number of FIFOs in the expansion and TRCLK is the CLKB period.
4. The amount of time it takes for FF/IR of the first FIFO in the chain to go HIGH after a word has been read from the last FIFO is the sum of the delays for each individual FIFO:
(N - 1)*(3*transfer clock) + 2*TWCLK, where N is the number of FIFOs in the expansion and TWCLK is the CLKA period.
Figure 21. Block Diagram of 256 x 36, 512 x 36, 1,024 x 36 Synchronous FIFO Memory with
Programmable Flags used in Depth Expansion Configuration
PARAMETER MEASUREMENT INFORMATION
5.0 V
1.1KΩ
From Output
Under Test
30 pF
(1)
680Ω
PROPAGATION DELAY
LOAD CIRCUIT
3V
Timing
Input
3V
1.5 V
High-Level
Input
GND
tS
3V
1.5 V
1.5 V
GND
tW
Low-Level
Input
GND
VOLTAGE WAVEFORMS
SETUP AND HOLD TIMES
1.5 V
1.5 V
GND
VOLTAGE WAVEFORMS
PULSE DURATIONS
3V
Output
Enable
1.5 V
tPLZ
1.5 V
GND
tPZL
≈3V
1.5 V
Low-Level
Output
VOH
1.5 V
tPHZ
Input
VOL
tPZH
High-Level
Output
1.5 V
th
3V
Data,
Enable
Input
1.5 V
3V
1.5 V
1.5 V
tPD
tPD
GND
VOH
In-Phase
Output
1.5 V
1.5 V
≈ OV
VOLTAGE WAVEFORMS
ENABLE AND DISABLE TIMES
VOLTAGE WAVEFORMS
PROPAGATION DELAY TIMES
NOTE:
1. Includes probe and jig capacitance.
Figure 22. Load Circuit and Voltage Waveforms.
28
VOL
5610 drw24
ORDERING INFORMATION
IDT
XXXXXX
Device Type
X
Power
XX
Speed
X
Package
X
Process/
Temperature
Range
BLANK
Commercial (0°C to +70°C)
PF
Thin Quad Flat Pack (TQFP, PK128-1)
12
15
Commercial Only
L
Low Power
723653
723663
723673
2,048 x 36  SyncFIFO with Bus-Matching
4,096 x 36  SyncFIFO with Bus-Matching
8,192 x 36  SyncFIFO with Bus-Matching
Clock Cycle Time (tCLK)
Speed in Nanoseconds
5610 drw25
NOTE:
1. Industrial temperature range is available by special order.
DATASHEET DOCUMENT HISTORY
12/20/2000
03/21/2001
08/01/2001
11/03/2003
pgs.
pgs.
pgs.
pg.
12 and 28.
6 and 7.
6, 8, 9 and 29.
1.
CORPORATE HEADQUARTERS
2975 Stender Way
Santa Clara, CA 95054
for SALES:
800-345-7015 or 408-727-6116
fax: 408-492-8674
www.idt.com
29
for TECH SUPPORT:
408-330-1753
e-mail: [email protected]