3.3 VOLT CMOS TRIPLE BUS SyncFIFO
TM
WITH BUS-MATCHING
2,048 x 36 x 2
4,096 x 36 x 2
8,192 x 36 x 2
IDT72V3656
IDT72V3666
IDT72V3676
•
•
•
•
•
•
•
FEATURES
•
•
•
•
•
•
Memory storage capacity:
IDT72V3656 – 2,048 x 36 x 2
IDT72V3666 – 4,096 x 36 x 2
IDT72V3676 – 8,192 x 36 x 2
Clock frequencies up to 100 MHz (6.5ns access time)
Two independent FIFOs buffer data between one bidirectional
36-bit port and two unidirectional 18-bit ports (Port C receives
and Port B transmits)
18-bit (word) and 9-bit (byte) bus sizing of 18 bits (word) on
Ports B and C
Select IDT Standard timing (using
EFA
,
EFB
,
FFA
, and
FFC
flag
functions) or First Word Fall Through Timing (using ORA, ORB,
IRA, and IRC 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
Big- or Little-Endian format for word and byte bus sizes
Loopback mode on Port A
Retransmit Capability
Master Reset clears data and configures FIFO, Partial Reset
clears data but retains configuration settings
Mailbox bypass registers for each FIFO
Free-running CLKA, CLKB and CLKC may be asynchronous or
coincident (simultaneous reading and writing of data on a single
clock edge is permitted)
Auto power down minimizes power dissipation
Available in a space-saving 128-pin Thin Quad Flatpack (TQFP)
Pin and functionally compatible versions of the 5V parts,
IDT723656/723666/723676
Pin compatible to the lower density parts, IDT72V3626/3636/3646
Industrial temperature range (–40°C to +85°C) is available
°
°
FUNCTIONAL BLOCK DIAGRAM
MBF1
CLKA
CSA
W/RA
ENA
MBA
LOOP
MRS1
PRS1
Mail 1
Register
Output Bus-
Matching
Output
Register
Input
Register
Port-A
Control
Logic
18
B
0
-B
17
36
RAM ARRAY
2,048 x 36
4,096 x 36
8,192 x 36
36
FIFO1,
Mail1
Reset
Logic
36
Port-B
Control
Logic
Write
Pointer
Read
Pointer
CLKB
RENB
CSB
MBB
SIZEB
FFA/IRA
AFA
FS2
FS0/SD
FS1/SEN
A
0
-A
35
EFA/ORA
AEA
FIFO1
Status Flag
Logic
Common
Port
Control
Logic
(B and C)
EFB/ORB
AEB
Programmable Flag
Offset Registers
13
FIFO2
Timing
Mode
BE
Status Flag
Logic
Read
Pointer
Write
Pointer
FIFO2,
Mail2
Reset
Logic
Input Bus-
Matching
Input
Register
18
FWFT
FFC/IRC
AFC
MRS2
PRS2
36
RT1
RTM
RT2
Output
Register
FIFO1 and
FIFO2
Retransmit
Logic
36
RAM ARRAY
2,048 x 36
4,096 x 36
8,192 x 36
Mail 2
Register
36
C
0
-C
17
CLKC
WENC
MBC
SIZEC
4665 drw01
Port-C
Control
Logic
MBF2
IDT and the IDT logo are registered trademarks of Integrated Device Technology, Inc. The SyncFIFO is a trademark of Integrated Device Technology, Inc.
COMMERCIAL TEMPERATURE RANGE
1
2003
Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice.
NOVEMBER 2003
DSC-4665/3
IDT72V3656/72V3666/72V3676 3.3V CMOS TRIPLE BUS SyncFIFO
TM
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
DESCRIPTION
The IDT72V3656/72V3666/72V3676 are pin and functionally compatible
versions of the IDT723626/723636/723646, designed to run off a 3.3V supply
for exceptionally low-power consumption. These devices are a monolithic,
high-speed, low-power, CMOS Triple Bus synchronous (clocked) FIFO
memory which supports clock frequencies up to 100 MHz and has read access
times as fast as 6.5ns. Two independent 2,048/4,096/8,192 x 36 dual-port
SRAM FIFOs on board each chip buffer data between a bidirectional 36-bit bus
(Port A) and two unidirectional 18-bit buses (Port B transmits data, Port C
receives data.) FIFO data can be read out of Port B and written into Port C using
either 18-bit or 9-bit formats with a choice of Big- or Little-Endian configurations.
These devices are a synchronous (clocked) FIFO, meaning each port
employs a synchronous interface. All data transfers through a port are gated
to the LOW-to-HIGH transition of a port clock by enable signals. The clocks for
PIN CONFIGURATION
CSA
FFA/IRA
EFA/ORA
PRS1/RT1
V
CC
AFA
AEA
MBF2
MBA
MRS1
FS0/SD
CLKC
GND
FS1/SEN
MRS2
MBB
MBF1
V
CC
AEB
AFC
EFB/ORB
FFC/IRC
GND
CSB
WENC
RENB
INDEX
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
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
128
127
126
125
124
123
122
121
120
119
118
117
116
115
114
113
112
111
110
109
108
107
106
105
104
103
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
CLKB
PRS2/RT2
LOOP
C17
C16
C15
C14
RTM
MBC
C13
C12
C11
C10
C9
C8
V
CC
C7
C6
SIZEB
GND
C5
C4
C3
C2
C1
C0
GND
B17
B16
SIZEC
V
CC
B15
B14
B13
B12
GND
B11
B10
A9
A8
A7
A6
GND
A5
A4
A3
FS2
V
CC
A2
A1
A0
GND
B0
B1
B2
B3
B4
B5
GND
B6
V
CC
B7
B8
B9
4665 drw02
TQFP (PK128-1, order code: PF)
TOP VIEW
2
IDT72V3656/72V3666/72V3676 3.3V CMOS TRIPLE BUS SyncFIFO
TM
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
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 FIFOs via two mailbox
registers. The mailbox registers' width matches the selected bus width of ports
B and C. 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: Master Reset and Partial
Reset. Master Reset initializes the read and write pointers to the first location
of the memory array and selects serial flag programming, parallel flag program-
ming, or one of five possible default flag offset settings, 8, 16, 64, 256 or 1,024.
Each FIFO has its own, independent Master Reset pin,
MRS1
and
MRS2.
Partial Reset also sets the read and write pointers to the first location of the
memory. Unlike Master 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. Each FIFO has its own, independent Partial Reset pin,
PRS1
and
PRS2.
Note that the Retransmit Mode, RTM pin must be LOW at
the point a partial reset is performed.
Both FIFO's have Retramsmit capability, when a Retransmit is performed
on a respective FIFO only the read pointer is reset to the first memory location.
A Retransmit is performed by using the Retransmit Mode, RTM pin in conjunction
with the Retransmit pins
RT1
or
RT2,
for each respective FIFO. Note that the
two Retransmit pins
RT1
and
RT2
are muxed with the Partial Reset pins.
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 Master
Reset determines the mode in use.
Each FIFO has a combined Empty/Output Ready Flag (EFA/ORA and
EFB/ORB)
and a combined Full/Input Ready Flag (FFA/IRA and
FFC/
IRC). 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.
Each FIFO has a programmable Almost-Empty flag (AEA and
AEB)
and
a programmable Almost-Full flag (AFA and
AFC). AEA
and
AEB
indicate when
a selected number of words remain in the FIFO memory.
AFA
and
AFC
indicate
when the FIFO contains more than a selected number of words.
FFA/IRA, FFC/IRC, AFA
and
AFC
are two-stage synchronized to the
Port Clock that writes data into its array.
EFA/ORA, EFB/ORB, AEA,
and
AEB
are two-stage synchronized to the Port Clock that reads data from its array.
Programmable offsets for
AEA, AEB, AFA, AFC
are loaded in parallel using
Port A or in serial via the SD input. Five default offset settings are also provided.
The
AEA
and
AEB
threshold can be set at 8, 16, 64, 256, and 1,024 locations
from the empty boundary and the
AFA
and
AFC
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 Master Reset.
Interspersed Parity can also 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.
A Loopback function is provided on Port A. When the Loop feature is
selected via the
LOOP
pin, the data output from FIFO2 will be directed to the
data input of FIFO1. If Loop is selected and Port A is set-up for write operation
via W/RA pin, then data output from FIFO2 will be written to FIFO1, but will not
be placed on the output Port A (A0-A35). If Port A is set-up for read operation
via W/RA then data output from FIFO2 will be written into FIFO1 and placed onto
Port A (A0-A35). The Loop will continue to happen provided that FIFO1 is not
full and FIFO2 is not empty. If during a Loop sequence FIFO1 becomes full then
any data that continues to be read out from FIFO2 will only be placed on the
Port A (A0-A35) lines, provided that Port A is set-up for read operation. If during
a Loop sequence the FIFO2 becomes empty, then the last word from FIFO2
will continue to be clocked into FIFO1 until FIFO1 becomes full or until the Loop
function is stopped. The Loop feature can be useful when performing system
debugging and remote loopbacks.
Two or more FIFOs may be used in parallel to create wider data paths.
Such a width expansion requires no additional, external components. Further-
more, two IDT72V3656/72V3666/72V3676 FIFOs can be combined with
unidirectional FIFOs capable of First Word Fall Through timing (i.e. the
SuperSync FIFO family) to form a depth expansion.
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 IDT72V3656/72V3666/72V3676 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
IDT72V3656/72V3666/72V3676 3.3V CMOS TRIPLE BUS SyncFIFO
TM
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
A0-A35
AEA
AEB
AFA
AFC
B0-B17
BE/FWFT
Name
Port A Data
Port A Almost-
Empty Flag
Port B Almost-
Empty Flag
Port A Almost-
Full Flag
Port C Almost-
Full Flag
Port B Data
Big-Endian/
First Word Fall
Through Select
I/O
I/O
O
O
O
O
O
I
36-bit bidirectional data port for side A.
Programmable Almost-Empty flag synchronized to CLKA. It is LOW when the number of words in FIFO2
is less than or equal to the value in the Almost-Empty A Offset register, X2.
Programmable Almost-Empty flag synchronized to CLKB. It is LOW when the number of words in FIFO1
is less than or equal to the value in the Almost-Empty B Offset register, X1.
Programmable Almost-Full flag synchronized to CLKA. It is LOW when the number of empty locations
in FIFO1 is less than or equal to the value in the Almost-Full A Offset register, Y1.
Programmable Almost-Full flag synchronized to CLKC. It is LOW when the number of empty locations
in FIFO2 is less than or equal to the value in the Almost-Full C Offset register, Y2.
18-bit output data port for side B.
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 on Port A is read from
Port B first (A-to-B data flow) or is written to Port C first (C-to-A data flow). A LOW on BE will select
Little-Endian operation. In this case, the
least
significant byte or word on Port A is read from Port B first
(A-to-B data flow) or is written to Port C first (C-to-A data flow).
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.
C0-C17
CLKA
Port C Data
Port A Clock
I
I
18-bit input data port for side C.
CLKA is a continuous clock that synchronizes all data transfers through Port A and can be
asynchronous or coincident to CLKB.
FFA/IRA, EFA/ORA, AFA,
and
AEA
are all synchronized to
the LOW-to-HIGH transition of CLKA.
CLKB is a continuous clock that synchronizes all data transfers through Port B and can be asynchronous
or coincident to CLKA.
EFB/ORB
and
AEB
are synchronized to the LOW-to-HIGH transition of CLKB.
CLKC is a continuous clock that synchronizes all data transfers through Port C and can be asynchronous
or coincident to CLKA.
FFC/IRC
and
AFC
are synchronized to the LOW-to-HIGH transition of CLKC.
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
must be LOW to enable a LOW-to-HIGH transition of CLKB to read data on Port B. The B0-B17
outputs are in the high-impedance state when
CSB
is HIGH.
This is a dual function pin. In the IDT Standard mode, the
EFA
function is selected.
EFA
indicates
whether or not the FIFO2 memory is empty. In the FWFT mode, the ORA function is selected. ORA
indicates the presence of valid data on the A0-A35 outputs, available for reading.
EFA/ORA
is
synchronized to the LOW-to-HIGH transition of CLKA.
This is a dual function pin. In the IDT Standard mode, the
EFB
function is selected.
EFB
indicates
whether or not the FIFO1 memory is empty. In the FWFT mode, the ORB function is selected. ORB
indicates the presence of valid data on the B0-B17 outputs, available for reading.
EFB/ORB
is synchronized
to the LOW-to-HIGH transition of CLKB.
ENA must be HIGH to enable a LOW-to-HIGH transition of CLKA to read or write data on Port A.
This is a dual function pin. In the IDT Standard mode, the
FFA
function is selected.
FFA
indicates
whether or not the FIFO1 memory is full. In the FWFT mode, the IRA function is selected. IRA
indicates whether or not there is space available for writing to the FIFO1 memory.
FFA/IRA
is
synchronized to the LOW-to-HIGH transition of CLKA.
This is a dual function pin. In the IDT Standard mode, the
FFC
function is selected.
FFC
indicates
whether or not the FIFO2 memory is full. In the FWFT mode, the IRC function is selected. IRC
indicates whether or not there is space available for writing to the FIFO2 memory.
FFC/IRC
is
synchronized to the LOW-to-HIGH transition of CLKC.
Description
CLKB
CLKC
CSA
CSB
EFA/ORA
Port B Clock
Port C Clock
Port A Chip
Select
Port B Chip
Select
Port A Empty/
Output Ready
Flag
Port B Empty/
Output Ready Flag
I
I
I
I
O
EFB/ORB
O
ENA
FFA/IRA
Port A Enable
Port A Full/
Input Ready Flag
I
O
FFC/IRC
Port C Full/
Input Ready Flag
O
4
IDT72V3656/72V3666/72V3676 3.3V CMOS TRIPLE BUS SyncFIFO
TM
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
FS0/SD
Name
I/O
Description
Flag Offset Select 0/ I FS1/SEN and FS0/SD are dual-purpose inputs used for flag Offset register programming. During Master Reset,
Serial Data
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),
Flag Offset Select 1/ I parallel load from Port A, and serial load.
Serial Enable
When serial load is selected for flag Offset register programming, FS1/SEN is used as an enable synchronous to
Flag Offset Select 2 I 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 44 for the
72V3656, 48 for the 72V3666, and 52 for the 72V3676. The first bit write stores the Y-register (Y1) MSB and the
last bit write stores the X-register (X2) LSB.
Loopback Select
I This pin selects the loopback feature for Port A. During Loopback data from FIFO2 will be directed to the input of
FIFO1. to initiate a Loop the
LOOP
pin must be held LOW and the ENA pin must be HIGH.
Port A Mailbox
Select
Port B Mailbox
Select
Port C Mailbox
Select
Mail1 Register
Flag
Mail2 Register
Flag
Master Reset
I
A HIGH level on MBA chooses a mailbox register for a Port A read or write operation. When the A0-A35
outputs are active, a HIGH level on MBA selects data from the mail2 register for output and a LOW level selects
FIFO2 output-register data for output.
A HIGH level on MBB chooses a mailbox register for a Port B read operation. When the B0-B17 outputs are
active, a HIGH level on MBB selects data from the mail1 register for output and a LOW level selects FIFO1 output
register data for output.
FS1/SEN
FS2
(1)
LOOP
MBA
MBB
I
MBC
MBF1
A HIGH level on MBC chooses the mail2 register for a Port C write operation. This pin must be HIGH during
Master Reset.
O
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 following either a Master or Partial Reset of FIFO1.
O
MBF2
is set LOW by a LOW-to-HIGH transition of CLKC 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 set HIGH following either a Master or Partial Reset of FIFO2.
I A LOW on this pin initializes the FIFO1 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
MRS1
selects the programming method (serial or
parallel) and one of five programmable flag default offsets for FIFO1 and FIFO2. It also configures ports B and
C for bus size and endian arrangement. Four LOW-to-HIGH transitions of CLKA and four LOW-to-HIGH
transitions of CLKB must occur while
MRS1
is LOW.
I A LOW on this pin initializes the FIFO2 read and write pointers to the first location of memory and sets the Port A
output register to all zeroes. A LOW-to-HIGH transition on
MRS2,
toggled simultaneously with
MRS1,
selects
the programming method (serial or parallel) and one of the five flag default offsets for FIFO2. Four LOW-to-HIGH
transitions of CLKA and four LOW-to-HIGH transitions of CLKC must occur while
MRS2
is LOW.
I This pin is muxed for both Partial Reset and Retransmit operations, it is used in conjunction with the RTM pin. If RTM
is in a LOW condition, a LOW on this pin performs a Partial Reset on FIFO1 and initializes the FIFO1 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, a LOW on this pin performs a Retransmit and initializes the FIFO1 read pointer only to
the first memory location.
I This pin is muxed for both Partial Reset and Retransmit operations, it is used in conjunction with the RTM pin. If RTM
is in a LOW condition, a LOW on this pin performs a Partial Reset on FIFO2 and initializes the FIFO2 read and write
selected bus size, endian arrangement, programming method (serial or parallel), and programmable flag settings are
all retained. If RTM is HIGH, a LOW on this pin performs a Retransmit and initializes the FIFO2 read pointer only to
the first memory location.
RENB must be HIGH to enable a LOW-to-HIGH transition of CLKB to read data on Port B.
This pin is used in conjunction with the
RT1
and
RT2
pins. When RTM is HIGH a Retransmit is performed on FIFO1
or FIFO2 respectively.
I
MBF2
MRS1
MRS2
Master Reset
PRS1/
RT1
Partial Reset/
Retransmit FIFO1
PRS2/
RT2
Partial Reset/
Retransmit FIFO2
RENB
RTM
Port B Read Enable I
Retransmit Mode
I
5
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