CMOS DUAL ASYNCHRONOUS FIFO
DUAL 256 x 9, DUAL 512 x 9,
DUAL 1,024 x 9, DUAL 2,048 x 9,
DUAL 4,096 x 9, DUAL 8,192 x 9
FEATURES:
•
•
•
•
•
•
•
The 7280 is equivalent to two 7200 256 x 9 FIFOs
The 7281 is equivalent to two 7201 512 x 9 FIFOs
The 7282 is equivalent to two 7202 1,024 x 9 FIFOs
The 7283 is equivalent to two 7203 2,048 x 9 FIFOs
The 7284 is equivalent to two 7204 4,096 x 9 FIFOs
The 7285 is equivalent to two 7205 8,192 x 9 FIFOs
Low power consumption
— Active: 685 mW (max.)
— Power-down: 83 mW (max.)
Ultra high speed—12 ns access time
Asynchronous and simultaneous read and write
Offers optimal combination of data capacity, small foot print
and functional flexibility
Ideal for bi-directional, width expansion, depth expansion, bus-
matching, and data sorting applications
Status Flags: Empty, Half-Full, Full
Auto-retransmit capability
High-performance CMOS technology
Space-saving TSSOP
Industrial temperature range (–40
o
C to +85
o
C) is available
IDT7280
IDT7281
IDT7282
IDT7283
IDT7284
IDT7285
DESCRIPTION:
The IDT7280/7281/7282/7283/7284/7285 are dual-FIFO memories that
load and empty data on a first-in/first-out basis. These devices are functional
and compatible to two 7200/7201/7202/7203/7204/7205 FIFOs in a single
package with all associated control, data, and flag lines assigned to separate
pins. The devices use Full and Empty flags to prevent data overflow and
underflow and expansion logic to allow for unlimited expansion capability in both
word size and depth.
The reads and writes are internally sequential through the use of ring
pointers, with no address information required to load and unload data.
Data is toggled in and out of the devices through the use of the Write (W)
and Read (R) pins.
The devices utilize a 9-bit wide data array to allow for control and parity
bits at the user’s option. This feature is especially useful in data commu-
nications applications where it is necessary to use a parity bit for transmis-
sion/reception error checking. It also features a Retransmit (RT) capability
that allows for reset of the read pointer to its initial position when
RT
is
pulsed LOW to allow for retransmission from the beginning of data. A Half-Full
Flag is available in the single device mode and width expansion modes.
These FIFOs are fabricated using IDT’s high-speed CMOS technology.
They are designed for those applications requiring asynchronous and
simultaneous read/writes in multiprocessing and rate buffer applications.
•
•
•
•
•
•
•
•
•
FUNCTIONAL BLOCK DIAGRAM
DATA INPUTS
(DA
0
-DA
8
)
WA
WRITE
CONTROL
WRITE
POINTER
THREE-
STATE
BUFFERS
RAM
ARRAY A
256 x 9
512 x 9
1,024 x 9
2,048 x 9
4,096 x 9
8,192 x 9
RSA
WB
WRITE
CONTROL
WRITE
POINTER
DATA INPUTS
(DB
0
-DB
8
)
RAM
ARRAY B
256 x 9
512 x 9
1,024 x 9
2,048 x 9
4,096 x 9
8,192 x 9
THREE-
STATE
BUFFERS
RSB
READ
POINTER
READ
POINTER
RA
READ
CONTROL
FLAG
LOGIC
EXPANSION
LOGIC
RESET
LOGIC
READ
CONTROL
FLAG
LOGIC
EXPANSION
LOGIC
RESET
LOGIC
XIA
XOA/HFA
FFA
EFA
DATA
OUTPUTS
(QA
0
-QA
8
)
FLA/RTA
RB
XIB
XOB/HFB
FFB
EFB
DATA
OUTPUTS
(QB
0
-QB
8
)
FLB/RTB
3208 drw 01
DECEMBER 1998
1
©
1998
Integrated Device Technology, Inc.
DSC-3208/3
IDT7280/81/82
IDT
PIN CONFIGURATION
FFA
QA
0
QA
1
QA
2
QA
3
QA
8
GND
RA
QA
4
QA
5
QA
6
QA
7
XOA/HFA
EFA
FFB
QB
0
QB
1
QB
2
QB
3
QB
8
GND
RB
QB
4
QB
5
QB
6
QB
7
XOB/HFB
EFB
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
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
XIA
DA
0
DA
1
DA
2
DA
3
DA
8
WA
V
CC
DA
4
DA
5
DA
6
DA
7
FLA/RTA
RSA
XIB
DB
0
DB
1
DB
2
DB
3
DB
8
WB
V
CC
DB
4
DB
5
DB
6
DB
7
FLB/RTB
RSB
3208 drw 02
ABSOLUTE MAXIMUM RATINGS
Symbol
V
TERM
T
STG
I
OUT
Rating
Terminal Voltage with
Respect to GND
Storage Temperature
DC Output Current
Com'l & Ind'l
–0.5 to +7.0
–55 to +125
–50 to +50
Unit
V
C
mA
o
NOTE:
3208 tbl 01
1. Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause
permanent damage to the device. This is a stress rating only and functional operation
of the device at these or any other conditions above those indicated in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect reliability.
RECOMMENDED DC OPERATING
CONDITIONS
Symbol
V
CC
GND
V
IH
(1)
V
IL
(2)
T
A
T
A
Parameter
Supply Voltage
Supply Voltage
Input High Voltage
Input Low Voltage
Operating Temperature
Commercial
Operating Temperature
Industrial
Min.
4.5
0
2.0
—
0
–40
Typ.
5.0
0
—
—
—
—
Max.
5.5
0
—
0.8
70
85
Unit
V
V
V
V
o
C
C
o
TSSOP (SO56-2, order code: PA)
TOP VIEW
NOTES:
1. For
RT/RS/XI
input, V
IH
= 2.6V (commercial).
2. 1.5V undershoots are allowed for 10ns once per cycle.
3208 tbl 03
DC ELECTRICAL CHARACTERISTICS
(Commercial: V
CC
= 5V ± 10%, T
A
= 0
o
C to +70
o
C; Industrial: V
CC
= 5V ± 10%, T
A
= –40
o
C to +85
o
C)
IDT7280L
IDT7281L
IDT7282L
Com'l & Ind'l
(1)
t
A
= 12, 15, 20 ns
Min.
Max.
–1
1
–10
10
2.4
—
—
0.4
—
125
(6)
—
15
IDT7283L
IDT7284L
IDT7285lL
Com'l & Ind'l
(1)
t
A
= 12, 15, 20 ns
Min.
Max.
–1
—
–10
10
2.4
—
—
0.4
—
150
—
15
Symbol
I
LI(2)
I
LO(3)
V
OH
V
OL
I
CC1(4,5)
I
CC2(4,7)
Parameter
Input Leakage Current (Any Input)
Output Leakage Current
Output Logic “1” Voltage
I
OH
= –2mA
Output Logic “0” Voltage
I
OL
= 8mA
Active Power Supply Current (both FIFOs)
Standby Current (R=W=RS=FL/RT=V
IH
)
Unit
µA
µA
V
V
mA
mA
NOTES:
1. Industrial temperature range product for the 20ns speed grade is available as a standard
device. All other speed grades are available by special order.
2. Measurements with 0.4
≤
V
IN
≤
V
CC
.
3.
R
≥
V
IH
, 0.4
≤
V
OUT
≤
V
CC
.
4. Tested with outputs open (I
OUT
= 0).
5. Tested at f = 20 MHz.
6. Typical I
CC1
= 2*[15 + 2*f
S
+ 0.02*C
L
*f
S
] (in mA) with V
CC
= 5V, T
A
= 25
o
C, f
S
= WCLK
frequency = RCLK frequency (in MHz, using TTL levels), data switching at f
S
/2,
C
L
= capacitive load (in pF).
7. All Inputs = V
CC
- 0.2V or GND + 0.2V.
AC TEST CONDITIONS
Input Pulse Levels
Input Rise/Fall Times
Input Timing Reference Levels
Output Reference Levels
Output Load
5V
TO
OUTPUT
PIN
1.1K
30pF*
3208 drw 03
or equivalent circuit
GND to 3.0V
5ns
1.5V
1.5V
See Figure 1
3208 tbl 08
CAPACITANCE
(T
A
= +25
o
C, f = 1.0 MHz)
Symbol
C
IN
C
OUT
Parameter
Input Capacitance
Output Capacitance
Condition
V
IN
= 0V
V
OUT
= 0V
Max.
8
8
Unit
pF
pF
2679 tbl 02
680Ω
NOTE:
1. Characterized values, not currently tested.
Figure 1. Output Load
* Includes scope and jig capacitances.
2
IDT7280/81/82
IDT
AC ELECTRICAL CHARACTERISTICS
(1)
(Commercial: V
CC
= 5V ± 10%, T
A
= 0
o
C to +70
o
C; Industrial: V
CC
= 5V ± 10%, T
A
= –40
o
C to +85
o
C)
Commercial
7280L12
7281L12
7282L12
7283L12
7284L12
7285L12
Symbol
t
S
t
RC
t
A
t
RR
t
RPW
t
RLZ
t
WLZ
t
DV
t
RHZ
t
WC
t
WPW
t
WR
t
DS
t
DH
t
RSC
t
RS
t
RSS
t
RSR
t
RTC
t
RT
t
RTS
t
RTR
t
EFL
t
HFH,FFH
t
RTF
t
REF
t
RFF
t
RPE
t
WEF
t
WFF
t
WHF
t
RHF
t
WPF
t
XOL
t
XOH
t
XI
t
XIR
t
XIS
Shift Frequency
Read Cycle Time
Access Time
Read Recovery Time
Read Pulse Width
(3)
Read Pulse Low to Data Bus at Low Z
Write Pulse High to Data Bus at Low Z
Data Valid from Read Pulse High
Read Pulse High to Data Bus at High Z
(4)
Write Cycle Time
Write Pulse Width
Data Set-up Time
Data Hold Time
Reset Cycle Time
Reset Pulse Width
(3)
(3)
(4)
(4,5)
7280L15
7281L15
7282L15
7283L15
7284L15
7285L15
Max.
50
—
12
—
—
—
—
—
12
—
—
—
—
—
—
—
—
—
—
—
—
—
12
17
20
12
14
—
12
14
17
17
—
12
12
—
—
—
Min.
—
25
—
10
15
3
5
5
—
25
15
10
11
0
25
15
15
10
25
15
15
10
—
—
—
—
—
15
—
—
—
—
15
—
—
15
10
10
Max.
40
—
15
—
—
—
—
—
15
—
—
—
—
—
—
—
—
—
—
—
—
—
25
25
25
15
15
—
15
15
25
25
—
15
15
—
—
—
Parameter
Min.
—
20
—
8
12
3
5
5
—
20
12
8
9
0
20
12
12
8
20
12
12
8
—
—
—
—
—
12
—
—
—
—
12
—
—
12
8
8
Com'l & Ind'l
(2)
7280L20
7281L20
7282L20
7283L20
7284L20
7285L20
Min.
Max.
—
33.3
30
—
10
20
3
5
5
—
30
20
10
12
0
30
20
20
10
30
20
20
10
—
—
—
—
—
20
—
—
—
—
20
—
—
20
10
10
—
20
—
—
—
—
—
15
—
—
—
—
—
—
—
—
—
—
—
—
—
30
30
30
20
20
—
20
20
30
30
—
20
20
—
—
—
Unit
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
3208 tbl 06
Write Recovery Time
Reset Set-up Time
(4)
Reset Recovery Time
Retransmit Cycle Time
Retransmit Pulse Width
(3)
(4)
Retransmit Set-up Time
Retransmit Recovery Time
Reset to Empty Flag Low
Reset to Half-Full and Full Flag High
Retransmit Low to Flags Valid
Read Low to Empty Flag Low
Read High to Full Flag High
Read Pulse Width after
EF
High
Write High to Empty Flag High
Write Low to Full Flag Low
Write Low to Half-Full Flag Low
Read High to Half-Full Flag High
Write Pulse Width after
FF
High
Read/Write to
XO
Low
Read/Write to
XO
High
XI
Pulse Width
(3)
XI
Recovery Time
XI
Set-up Time
NOTES:
1. Timings referenced as in AC Test Conditions.
2. Industrial temperature range is available by special order for speed grades faster than 20ns.
3. Pulse widths less than minimum value are not allowed.
4. Values guaranteed by design, not currently tested.
5. Only applies to read data flow-through mode.
3
IDT7280/81/82
IDT
Device Mode, this pin acts as the retransmit input. The Single Device Mode is
initiated by grounding the Expansion In (XI).
These devices can be made to retransmit data when the Retransmit
Enable control (RT) input is pulsed LOW. A retransmit operation will set the
internal read pointer to the first location and will not affect the write pointer.
Read Enable (R) and Write Enable (W) must be in the HIGH state during
retransmit. This feature is useful when less than 256/512/1,024/2,048/4,096/
8,192 writes are performed between resets. The retransmit feature is not
compatible with the Depth Expansion Mode and will affect the Half-Full Flag
(HF), depending on the relative locations of the read and write pointers.
XI
EXPANSION IN (XI
XI)
This input is a dual-purpose pin. Expansion In (XI) is grounded to
indicate an operation in the single device mode. Expansion In (XI) is
connected to Expansion Out (XO) of the previous device in the Depth
Expansion or Daisy Chain Mode.
SIGNAL DESCRIPTIONS
INPUTS:
DATA IN (D
0
– D
8
)
Data inputs for 9-bit wide data.
RS
RESET (RS
RS)
Reset is accomplished whenever the Reset (RS) input is taken to a LOW
state. During reset, both internal read and write pointers are set to the first
location. A reset is required after power up before a write operation can take
place.
Both the Read Enable (R) and Write Enable (W) inputs must be
R
W
in the HIGH state during the window shown in Figure 2, (i.e., t
RSS
before the rising edge of
RS
and should not change until t
RSR
after
RS)
the rising edge of
RS
Half-Full Flag (HF will be reset to HIGH after
RS.
HF)
HF
Reset (RS
RS).
RS
WRITE ENABLE (W)
W
A write cycle is initiated on the falling edge of this input if the Full Flag
(FF) is not set. Data set-up and hold times must be adhered to with respect
to the rising edge of the Write Enable (W). Data is stored in the RAM array
sequentially and independently of any on-going read operation.
After half of the memory is filled and at the falling edge of the next write
operation, the Half-Full Flag (HF) will be set to LOW and will remain set until the
difference between the write pointer and read pointer is less than or equal to
one half of the total memory of the device. The Half-Full Flag (HF) is then reset
by the rising edge of the read operation.
To prevent data overflow, the Full Flag (FF) will go LOW, inhibiting further
write operations. Upon the completion of a valid read operation, the Full Flag
(FF) will go HIGH after t
RFF
, allowing a valid write to begin. When the FIFO
is full, the internal write pointer is blocked from
W,
so external changes in
W
will not affect the FIFO when it is full.
READ ENABLE (R)
R
A read cycle is initiated on the falling edge of the Read Enable (R)
provided the Empty Flag (EF) is not set. The data is accessed on a First-In/First-
Out basis, independent of any ongoing write operations. After Read Enable (R)
goes HIGH, the Data Outputs (Q
0
– Q
8
) will return to a high impedance condition
until the next Read operation. When all data has been read from the FIFO, the
Empty Flag (EF) will go LOW, allowing the “final” read cycle but inhibiting further
read operations with the data outputs remaining in a high impedance state.
Once a valid write operation has been accomplished, the Empty Flag (EF) will
go HIGH after t
WEF
and a valid Read can then begin. When the FIFO is empty,
the internal read pointer is blocked from
R
so external changes in
R
will not affect
the FIFO when it is empty.
FIRST LOAD/RETRANSMIT (FL
RT
FL/RT
FL RT)
This is a dual-purpose input. In the Depth Expansion Mode, this pin is
grounded to indicate that it is the first loaded (see Operating Modes). In the Single
CONTROLS:
FULL FLAG (FF
FF)
FF
The Full Flag (FF) will go LOW, inhibiting further write operation, when the
write pointer is one location less than the read pointer, indicating that the
device is full. If the read pointer is not moved after Reset (RS), the Full-Flag
(FF) will go LOW after 256 writes for IDT7280, 512 writes for the IDT7281,
1,024 writes for the IDT7282, 2,048 writes for the IDT7283, 4,096 writes for
the IDT7284 and 8,192 writes for the IDT7285.
EF
EMPTY FLAG (EF
EF)
The Empty Flag (EF) will go LOW, inhibiting further read operations, when
the read pointer is equal to the write pointer, indicating that the device is
empty.
EXPANSION OUT/HALF-FULL FLAG (XO
HF
XO/HF
XO HF)
This is a dual-purpose output. In the single device mode, when Expan-
sion In (XI) is grounded, this output acts as an indication of a half-full
memory.
After half of the memory is filled and at the falling edge of the next write
operation, the Half-Full Flag (HF) will be set LOW and will remain set until the
difference between the write pointer and read pointer is less than or equal
to one half of the total memory of the device. The Half-Full Flag (HF) is then
reset by using rising edge of the read operation.
In the Depth Expansion Mode, Expansion In (XI) is connected to
Expansion Out (XO) of the previous device. This output acts as a signal to
the next device in the Daisy Chain by providing a pulse to the next device
when the previous device reaches the last location of memory.
DATA OUTPUTS (Q
0
– Q
8
)
Data outputs for 9-bit wide data. This data is in a high impedance
condition whenever Read (R) is in a HIGH state.
OUTPUTS:
4
Analog electronics
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