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2001 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice.
DSC-3269/2
AUGUST 2001
CMOS BUS-MATCHING SyncFIFO
TM
256 x 36, 512 x 36, 1,024 x 36
IDT723623
IDT723633
IDT723643
COMMERCIAL TEMPERATURE RANGE
IDT, the IDT logo are registered trademarks of Integrated Device Technology, Inc. SyncFIFO is a trademark of Integrated Device Technology, Inc.
.EATURES:




Memory storage capacity:
IDT723623
256 x 36
IDT723633
512 x 36
IDT723643
1,024 x 36




Clocked FIFO buffering data from Port A to Port B




Clock frequencies up to 83 MHz (8 ns access time)




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
three default offsets (8, 16 and 64)




Serial or parallel programming of partial flags




Port B bus sizing of 36 bits (long word), 18 bits (word) and 9 bits
(byte)




Big- or Little-Endian format for word and byte bus sizes




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)




Industrial temperature range (40


C to +85


C) is available
DESCRIPTION:
The IDT723623/723633/723643 are monolithic, high-speed, low-power,
CMOS unidirectional Synchronous (clocked) FIFO memories which support
clock frequencies up to 83 MHz and have read access times as fast as 8 ns.
.UNCTIONAL BLOCK DIAGRAM
Mail 1
Register
Programmable Flag
Offset Registers
Status Flag
Logic
EF
/OR
AE
36
FF
/IR
AF
36
Timing
Mode
FWFT
A
0
-A
35
SPM
FS0/SD
FS1/
SEN
B
0
-B
35
Write
Pointer
Read
Pointer
Mail 2
Register
MBF2
CLKB
CSB
W
/RB
ENB
MBB
BE
BM
SIZE
Port-B
Control
Logic
10
3269 drw01
Input
Register
RAM ARRAY
256 x 36
512 x 36
1,024 x 36
CLKA
CSA
W/
R
A
ENA
MBA
Port-A
Control
Logic
FIFO1
Mail1,
Mail2,
Reset
Logic
RS1
MBF1
36
36
Bus-
Matching
Output
Register
PRS
36
36
RS2
2
COMMERCIAL TEMPERATURE RANGE
IDT723623/723633/723643 BUS-MATCHING SyncFIFOTM
256 x 36, 512 x 36, 1,024 x 36
PIN CON.IGURATION
TQFP (PK128-1, order code: PF)
TOP VIEW
W/
R
A
CLKB
3269 drw02
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
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
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
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
102
101
128
127
126
125
124
123
122
121
120
119
118
117
116
115
114
113
112
111
110
109
108
107
106
105
Vcc
Vcc
B35
B34
B33
B32
GND
GND
B31
B30
B29
B28
B27
B26
Vcc
B25
B24
BM
GND
B23
B22
B21
B20
B19
B18
GND
B17
B16
Vcc
B15
B14
B13
B12
GND
B11
B10
CSA
FF
/IR
NC
PRS
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
A9
A8
A7
A
6
G
N
D
A
5
A4
A3
SPM
Vcc
A2
A1
A0
GND
B0
B1
B2
B3
B
4
B
5
GND
B
6
Vcc
B7
B8
B
9
104
103
INDEX
SIZE
DESCRIPTION (CONTINUED)
The 256/512/1,024 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.
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 synchro-
nous control.
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 three possible default flag offset settings, 8, 16 or 64.
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
3
COMMERCIAL TEMPERATURE RANGE
IDT723623/723633/723643 BUS-MATCHING SyncFIFOTM
256 x 36, 512 x 36, 1,024 x 36
is useful since it permits flushing of the FIFO memory without changing any
configuration settings.
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 neces-
sitate 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
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 program-
mable Almost-Full flag (
AF). AE indicates when a selected number of words
remain in the FIFO memory achieve a predetermined "almost-empty state".
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. The Serial Programming Mode
pin (
SPM) makes this selection. Three default offset settings are also provided.
The
AE threshold can be set at 8, 16 or 64 locations from the empty boundary
and the
AF threshold can be set at 8, 16 or 64 locations from the full boundary.
All these choices are made using the FS0 and FS1 inputs during Reset.
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 (I
CC
) is at a minimum. Initiating any operation (by activating control
inputs) will immediately take the device out of the Power Down state.
The IDT723623/723633/723643 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.
4
COMMERCIAL TEMPERATURE RANGE
IDT723623/723633/723643 BUS-MATCHING SyncFIFOTM
256 x 36, 512 x 36, 1,024 x 36
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
O
Programmable Almost-Empty flag synchronized to CLKB. It is LOW when the number of words in the FIFO
Flag (Port B)
is less than or equal to the value in the Almost-Empty B offset register, X.
AF
Almost-Full
O
Programmable Almost-Full flag synchronized to CLKA. It is LOW when the number of empty locations in the
Flag (Port A)
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/
I
This is a dual purpose pin. During Master Reset, a HIGH on BE will select Big-Endian operation. In this case,
First Word
depending on the bus size, the most significant byte or word written to Port A is read from Port B first. A
Fall Through
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.
BM
(1)
Bus-Match
I
A HIGH on this pin enables either byte or word bus width on Port B, depending on the state of SIZE. A
Select (Port B)
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.
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
I
CSA must be LOW to enable to LOW-to-HIGH transition of CLKA to read or write on Port A. The A0-A35
Select
outputs are in the high-impedance state when
CSA is HIGH.
CSB
Port B Chip
I
CSB must be LOW to enable a LOW-to-HIGH transition of CLKB to read or write on Port B. The B0-B35
Select
outputs are in the high-impedance state when
CSB is HIGH.
EF/OR
Empty/Output
O
This is a dual function pin. In the IDT Standard mode, the
EF function is selected. EF indicates whether or
Ready Flag
not the FIFO memory is empty. In the FWFT mode, the OR function is selected. OR indicates the presence of valid
(Port B)
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
O
This is a dual function pin. In the IDT Standard mode, the
FF function is selected. FF indicates whether or
Ready Flag
not the FIFO memory is full. In the FWFT mode, the IR function is selected. IR indicates whether or not there
(Port A)
is space available for writing to the FIFO memory.
FF/IR is synchronized to the LOW-to-HIGH transition of
CLKA.
FS1/
SEN
Flag Offset
I
FS1/SEN and FS0/SD are dual-purpose inputs used for flag offset register programming. During Reset,
Select 1/
FS1/
SEN and FS0/SD, together with SPM, select the flag offset programming method. Three offset register
Serial Enable,
programming methods are available: automatically load one of three preset values (8, 16, or 64), parallel
load from Port A, and serial load.
FS0/SD
Flag Offset
I
When serial load is selected for flag offset register programming, FS1/
SEN is used as an enable synchronous
Select 0/
to the LOW-to-HIGH transition of CLKA. When FS1/
SEN is LOW, a rising edge on CLKA load the bit present
Serial Data
on FS0/SD into the X and Y registers. The number of bit writes required to program the offset registers is 16
for the IDT723623, 18 for the IDT723633, and 20 for the IDT723643. The first bit write stores the Y-register
MSB and the last bit write stores the X-register LSB.
MBA
Port A Mailbox
I
A HIGH level on MBA chooses a mailbox register for a Port A read or write operation.
Select
MBB
Port B Mailbox
I
A HIGH level on MBB chooses a mailbox register for a Port B read or write operation. When the B0-B35
Select
outputs are active, a HIGH level on MBB selects data from the mail1 register for output and a LOW level
selects FIFO data for output.
MBF1
Mail1 Register
O
MBF1 is set LOW by a LOW-to-HIGH transition of CLKA that writes data to the mail1 register. Writes to
Flag
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 following either a Reset (RS1) or Partial
Reset (
PRS).
5
COMMERCIAL TEMPERATURE RANGE
IDT723623/723633/723643 BUS-MATCHING SyncFIFOTM
256 x 36, 512 x 36, 1,024 x 36
Symbol
Name
I/O
Description
MBF2
Mail2 Register
O
MBF2 is set LOW by a LOW-to-HIGH transition of CLKB that writes data to the mail2 register. Writes to the mail2
Flag
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 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 three 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-to-HIGH transitions of CLKB must occur while
RS1 is LOW.
PRS
Partial Reset
I
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.
SIZE
(1)
Bus Size Select
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
(Port B)
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.
SPM
(1)
Serial Program-
I
A LOW on this pin selects serial programming of partial flag offsets. A HIGH on this pin selects parallel
ming Mode
programming or default offsets (8, 16, or 64).
W/
RA
Port A Write/
I
A HIGH selects a write operation and a LOW selects a read operation on Port A for a LOW-to-HIGH transition
Read Select
of CLKA. The A0-A35 outputs are in the HIGH impedance state when W/
RA is HIGH.
W/RB
Port B Write/
I
A LOW selects a write operation and a HIGH selects a read operation on Port B for a LOW-to-HIGH transition
Read Select
of CLKB. The B0-B35 outputs are in the HIGH impedance state when
W/RB is LOW.
PIN DESCRIPTIONS (CONTINUED)
NOTE:
1. BM, SIZE and
SPM are not TTL compatible. These inputs should be tied to V
CC
or GND.