IDT IDT72041 Cmos asynchronous fifo with retransmit 1k x 9, 2k x 9, 4k x 9 Datasheet

CMOS ASYNCHRONOUS FIFO WITH
RETRANSMIT
1K x 9, 2K x 9, 4K x 9
IDT72021
IDT72031
IDT72041
Integrated Device Technology, Inc.
FEATURES:
DESCRIPTION:
• First-In/First-Out Dual-Port memory
• Bit organization
– IDT72021—1K x 9
– IDT72031—2K x 9
– IDT72041—4K x 9
• Ultra high speed
– IDT72021—25ns access time
– IDT72031—35ns access time
– IDT72041—35ns access time
• Easily expandable in word depth and/or width
• Asynchronous and simultaneous read and write
• Functionally equivalent to IDT7202/03/04 with Output
Enable (OE) and Almost Empty/Almost Full Flag (AEF)
• Four status flags: Full, Empty, Half-Full (single device
mode), and Almost Empty/Almost Full (7/8 empty or 7/8
full in single device mode)
• Output Enable controls the data output port
• Auto-retransmit capability
• Available in 32-pin DIP and PLCC
• Military product compliant to MIL-STD-883, Class B
• Industrial temperature range (-40oC to +85oC) is avail
able, tested to military electrical specifications
IDT72021/031/041s are high-speed, low-power, dual-port
memory devices commonly known as FIFOs (First-In/FirstOut). Data can be written into and read from the memory at
independent rates. The order of information stored and extracted does not change, but the rate of data entering the FIFO
might be different than the rate leaving the FIFO. Unlike a
Static RAM, no address information is required because the
read and write pointers advance sequentially. The IDT72021/
031/041s can perform asynchronous and simultaneous read
and write operations. There are four status flags, (HF, FF, EF,
AEF) to monitor data overflow and underflow. Output Enable
(OE) is provided to control the flow of data through the output
port. Additional key features are Write (W), Read (R), Retransmit (RT), First Load (FL), Expansion In (XI) and Expansion Out
(XO). The IDT72021/031/041s are designed for those applications requiring data control flags and Output Enable (OE) in
multiprocessing and rate buffer applications.
The IDT72021/031/041s are fabricated using IDT’s CMOS
technology. Military grade product is manufactured in compliance with the latest version of MIL-STD-883, Class B, for high
reliability systems.
FUNCTIONAL BLOCK DIAGRAM
W
DATA INPUT
(D0–D8)
1
2
WRITE
CONTROL
RAM
ARRAY
1024 x 9
2048 x 9
4096 x 9
WRITE
POINTER
READ
POINTER
1024/
2048/
4096
OE
THREESTATE
BUFFERS
R
RESET
LOGIC
RS
FL/RT
DATA OUTPUTS
(Q0–Q8)
READ
CONTROL
EF
FF
FLAG
LOGIC
AEF
XI
EXPANSION
LOGIC
XO/HF
2677 drw 01
The IDT logo is a registered trademark of Integrated Device Technology, Inc.
FAST is a trademark of National Semiconductor Co.
MILITARY AND COMMERCIAL TEMPERATURE RANGES
1996 Integrated Device Technology, Inc.
For latest information contact IDT's web site at www.idt.com or fax-on-demand at 408-492-8391.
5.09
DECEMBER 1996
DSC-2677/7
1
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
4 3 2
D5
VCC
D4
VCC
D3
D8
INDEX
W
PIN CONFIGURATIONS
32 31 30
1
D2
D1
5
6
29
28
D0
Q0
Q1
7
8
9
10
11
12
27
26
25
24
23
22
Q7
Q2
13
21
Q6
XI
AEF
FF
J32-1
D6
D7
FL/RT
RS
OE
EF
XO/HF
R
Q4
Q5
GND
Q3
Q8
GND
14 15 16 17 18 19 20
MILITARY AND COMMERCIAL TEMPERATURE RANGES
VCC
1
32
VCC
W
2
31
D4
D8
3
30
D5
D3
4
29
D6
D2
5
28
D7
D1
6
27
D0
7
26
XI
AEF
FF
8
9
24
10
23
FL/RT
RS
OE
EF
XO/HF
D32-1
25
Q0
11
22
Q7
Q1
12
21
Q6
Q2
13
20
Q5
Q3
14
19
Q4
Q8
15
18
R
GND
16
17
GND
2677 drw 03
2677 drw 02
PLCC TOP VIEW
DIP TOP VIEW
PIN DESCRIPTIONS
Symbol
Name
I/O
Description
D0–D8
Inputs
I
RS
Reset
I
W
Write
I
When WRITE is LOW, data can be written into the RAM array sequentially, independent of
READ. In order for WRITE to be active, FF must be HIGH. When the FIFO is full (FF-LOW),
the internal WRITE operation is blocked.
R
Read
I
FL/RT
When READ is LOW, data can be read from the RAM array sequentially, independent of
WRITE. In order for READ to be active, EF must be HIGH. When the FIFO is empty (EF-LOW),
the internal READ operation is blocked. The three-state output buffer is controlled by the read
signal and the external output control (OE).
First Load/
I
Retransmit
Data inputs for 9-bit wide data.
When RS is set LOW, internal READ and WRITE pointers are set to the first location of the RAM
array. HF and FF go HIGH, and AEF and EF go LOW. A reset is required before an initial WRITE
after power-up. R and W must be HIGH during RS cycle.
This is a dual-purpose input. In the single device configuration (XI grounded), activating
retransmit (FL/RT-LOW) will set the internal READ pointer to the first location. There is no effect
on the WRITE pointer. R and W must be HIGH before setting FL/RT LOW. Retransmit is not
compatible with depth expansion. In the depth expansion configuration, FL/RT-LOW indicates
the first activated device.
XI
Expansion In
I
OE
Output Enable
I
FF
Full Flag
O
When FF goes LOW, the device is full and further WRITE operations are inhibited. When FF
is HIGH, the device is not full.
EF
Empty Flag
O
When EF goes LOW, the device is empty and further READ operations are inhibited. When EF
is HIGH, the device is not empty.
Almost-Empty/
Almost-Full Flag
Expansion Out/
Half-Full Flag
O
When AEF is LOW, the device is empty to 1/8 full or 7/8 to completely full. When AEF is HIGH,
the device is greater than 1/8 full, but less than 7/8 full.
AEF
XO/HF
Q0–Q8
In the single device configuration, XI is grounded. In depth expansion or daisy chain expansion,
XI is connected to XO (expansion out) of the previous device.
When OE is set HIGH, the data flow through the three-state output buffer is inhibited regardless
of an active READ operation. A read operation does increment the read pointer in this situation.
When OE is set LOW, Q0-Q8 are still in a HIGH impedance condition if no READ occurs. For
a complete READ operation with data appearing on Q0-Q8, both R and OE should be asserted
LOW.
Outputs
O
O
This is a dual purpose output. In the single device configuration (XI grounded), the device is
more than half full when HF is LOW. In the depth expansion configuration (XO connected to
XI of the next device), a pulse is sent from XO to XI when the last location in the RAM array is
filled.
Data outputs for 9-bit wide data.
2677 tbl 01
5.09
2
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
STATUS FLAG
MILITARY AND COMMERCIAL TEMPERATURE RANGES
CAPACITANCE (TA = +25°C, f = 1.0 MHz)
Number of Words in FIFO
FF AEF HF
EF
0
H
L
H
L
1-255
1-511
H
L
H
H
128-512
256-1024
512-2048
H
H
H
H
1K
2K
4K
0
0
1-127
513-896
1025-1792
2049-3584
H
H
L
H
897-1023
1793-2047
3585-4095
H
L
L
H
1024
2048
4096
L
L
L
H
Symbol
CIN
COUT
Parameter(1)
Input Capacitance
Output Capacitance
Condition
VIN = 0V
VOUT = 0V
Max.
10
10
NOTE:
1. These parameters are sampled and not 100% tested.
Unit
pF
pF
2677 tbl 03
RECOMMENDED DC
OPERATING CONDITIONS
2677 tbl l 02
Min.
Typ.
Max.
Unit
VCCM
Symbol
Military Supply
Voltage
4.5
5.0
5.5
V
VCCC
Commercial
Supply Voltage
4.5
5.0
5.5
V
GND
Supply Voltage
0
0
0
V
VIH
Input High Voltage
Commercial
2.0
—
—
V
VIH
Input High Voltage
Military
2.2
—
—
V
VIL(1)
Input Low Voltage
Commercial and
Military
—
—
0.8
V
(1)
ABSOLUTE MAXIMUM RATINGS
Symbol
Rating
VTERM Terminal Voltage
with Respect
to GND
TA
Operating
Temperature
TBIAS
Temperature
Under Bias
TSTG
Storage
Temperature
IOUT
DC Output
Current
Com’l.
Mil.
Unit
–0.5 to +7.0 –0.5 to +7.0 V
–55 to +125
°C
–55 to +125 –65 to +135
°C
–55 to +125 –65 to +155
°C
0 to +70
50
50
mA
Parameter
NOTE:
1. 1.5V undershoots are allowed for 10ns once per cycle.
2677 tbl 05
NOTE:
2677 tbl 04
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 reliabilty.
5.09
3
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
MILITARY AND COMMERCIAL TEMPERATURE RANGES
DC ELECTRICAL CHARACTERISTICS — IDT72021
(Commercial: VCC = 5.0V±10%, TA = 0°C to +70°C; Military: VCC = 5V±10%, TA = –55°C to +125°C)
IDT72021
Commercial
tA =25,35ns
Symbol
IDT72021
Commercial
tA =50ns
IDT72021
Military
tA =50ns
Min.
Typ.
Max.
Min.
Typ.
Max.
Min.
Typ.
Max.
Min.
Input Leakage Current
(Any Input)
–1
—
1
–10
—
10
–1
—
1
–10
—
10
µA
ILO(2)
Output Leakage Current
–10
—
10
–10
—
10
–10
—
10
–10
—
10
µA
VOH
Output Logic “1” Voltage
IOH = –2mA
2.4
—
—
2.4
—
—
2.4
—
—
2.4
—
—
V
VOL
Output Logic “0” Voltage
IOL = 8mA
—
—
0.4
—
—
0.4
—
—
0.4
—
—
0.4
V
ICC1(3,4)
Active Power Supply
Current
Standby Current
(R = W = RS = FL/RT = VIH)
—
—
120
—
—
140
—
50
80
—
70
100
mA
—
—
12
—
—
20
—
5
8
—
8
15
mA
Power Down Current
(All Input = VCC – 0.2V)
—
—
500
—
—
900
—
—
500
—
—
900
µA
ILI(1)
ICC2(3)
ICC3(3)
Parameter
IDT72021
Military
tA =30,40ns
Typ. Max.
Unit
2677 tbl 06
DC ELECTRICAL CHARACTERISTICS — IDT72031, IDT72041
(Commercial: VCC = 5.0V±10%, TA = 0°C to +70°C; Military: VCC = 5V±10%, TA = –55°C to +125°C)
IDT72031
IDT72041
Commercial
tA =35,50ns
Symbol
Min.
Typ.
Input Leakage Current (Any Input)
–1
Output Leakage Current
–10
VOH
Output Logic “1” Voltage IOUT = –2mA
VOL
ICC1(3,5)
ICC2(3)
ICC3(3)
ILI(1)
ILO(2)
Parameter
IDT72031
IDT72041
Military
tA =40,50ns
Max.
Min.
—
1
–10
—
10
µA
—
10
–10
—
10
µA
2.4
—
—
2.4
—
—
V
Output Logic “0” Voltage IOUT = 8mA
—
—
0.4
—
—
0.4
V
Active Power Supply Current
—
75
120
—
100
150
mA
Standby Current (R = W = RS = FL/RT = VIH)
—
8
12
—
12
25
mA
Power Down Current (All Input = VCC – 0.2V)
—
—
2
—
—
4
mA
NOTES:
1. Measurements with 0.4 ≤ VIN ≤ VCC.
2. R ≥ VIH, 0.4 ≤ VOUT ≤ VCC.
3. ICC measurements are made with OE = HIGH.
4. Tested at f = 20MHz.
5. Tested at f = 15.3 MHz.
Typ. Max. Unit
2677 tbl 07
5.09
4
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
MILITARY AND COMMERCIAL TEMPERATURE RANGES
AC ELECTRICAL CHARACTERISTICS — IDT72021(1)
(Commercial: VCC = 5.0V±10%, TA = 0°C to +70°C; Military: VCC = 5V±10%, TA = –55°C to +125°C)
Symbol
Parameter
Com’l
Mil.
Com’l
Mil.
Com’l & Mil.
72021L25
72021L30
72021L35
72021L40
72021L50
Min.
Max.
Min.
Max.
Min.
Max.
fS
Shift Frequency
Min. Max.
—
28.5
—
25
—
22.2
—
20
Min. Max. Unit
—
15
MHz
tRC
R Cycle Time
35
—
40
—
45
—
50
—
65
—
ns
tA
Access Time
—
25
—
30
—
35
—
40
—
50
ns
10
—
10
—
10
—
10
—
15
—
ns
25
—
30
—
35
—
40
—
50
—
ns
5
—
5
—
5
—
5
—
10
—
ns
5
—
5
—
5
—
5
—
5
—
ns
5
—
5
—
5
—
5
—
5
—
ns
tWR
R Recovery Time
R Pulse Width(2)
R Pulse LOW to Data Bus at Low-Z(3)
W Pulse HIGH to Data Bus at Low-Z(3,4)
Data Valid from R Pulse HIGH
R Pulse HIGH to Data Bus at High-Z(3)
W Cycle Time
W Pulse Width(2)
W Recovery Time
10
—
10
—
10
—
10
—
15
—
ns
tDS
Data Set-up Time
15
—
18
—
18
—
20
—
30
—
ns
tDH
Data Hold Time
0
—
0
—
0
—
0
—
5
—
ns
tRR
tRPW
tRLZ
tWLZ
tDV
tRHZ
tWC
tWPW
tRSC
tRS
tRSS
tRSR
tRTC
tRT
tRTR
tRSF1
tRSF2
tREF
tRFF
tRPE
tWEF
tWFF
tWHF
tRHF
tWPF
tRF
tWF
tOEHZ
tOELZ
tAOE
RS Cycle Time
RS Pulse Width(2)
RS Set-up Time
RS Recovery Time
RT Cycle Time
RT Pulse Width(2)
RT Recovery Time
RS to EF and AEF LOW
RS to HF and FF HIGH
R LOW to EF LOW
R HIGH to FF HIGH
R Pulse Width After EF HIGH
W HIGH to EF HIGH
W LOW to EF LOW
W LOW to HF LOW
R HIGH to HF HIGH
W Pulse Width after FF HIGH
R HIGH to Transitioning AEF
W LOW to Transitioning AEF
OE HIGH to High-Z (Disable)(3)
OE LOW to Low-Z (Enable)(3)
OE LOW Data Valid (Q0–Q8)
—
18
—
20
—
20
—
25
—
30
ns
35
—
40
—
45
—
50
—
65
—
ns
25
—
30
—
35
—
40
—
50
—
ns
35
—
40
—
45
—
50
—
65
—
ns
25
—
30
—
35
—
40
—
50
—
ns
25
—
30
—
35
—
40
—
50
—
ns
10
—
10
—
10
—
10
—
15
—
ns
35
—
40
—
45
—
50
—
65
—
ns
25
—
30
—
35
—
40
—
50
—
ns
10
—
10
—
10
—
10
—
15
—
ns
—
35
—
40
—
45
—
50
—
65
ns
—
35
—
40
—
45
—
50
—
65
ns
—
25
—
30
—
30
—
35
—
45
ns
—
25
—
30
—
30
—
35
—
45
ns
25
—
30
—
35
—
40
—
50
—
ns
—
25
—
30
—
30
—
35
—
45
ns
—
25
—
30
—
30
—
35
—
45
ns
—
35
—
40
—
45
—
50
—
65
ns
—
35
—
40
—
45
—
50
—
65
ns
25
—
30
—
35
—
40
—
50
—
ns
—
35
—
40
—
45
—
50
—
65
ns
—
35
—
40
—
45
—
50
—
65
ns
0
12
0
15
0
17
0
20
0
25
ns
0
12
0
15
0
17
0
20
0
25
ns
—
15
—
18
—
20
—
25
—
30
ns
NOTES:
1. Timings referenced as in AC Test Conditions.
2. Pulse widths less than minimum value are not allowed.
3. Values guaranteed by design, not currently tested.
4. Only applies to read data flow-through mode.
2677 tbl 08
5.09
5
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
MILITARY AND COMMERCIAL TEMPERATURE RANGES
AC ELECTRICAL CHARACTERISTICS — IDT72031, IDT72041(1)
(Commercial: VCC = 5.0V±10%, TA = 0°C to +70°C; Military: VCC = 5V±10%, TA = –55°C to +125°C)
Com'l
72031L35
72041L35
Symbol
Parameter
Mil.
Com'l and Mil.
72031L40
72041L40
72031L50
72041L50
Min.
Max.
Min.
Max.
Min.
Max.
Unit
fS
Shift Frequency
—
22.2
—
20
—
15
MHz
tRC
R Cycle Time
45
—
50
—
65
—
ns
tA
Access Time
—
35
—
40
—
50
ns
10
—
10
—
15
—
ns
35
—
40
—
50
—
ns
5
—
5
—
10
—
ns
5
—
5
—
5
—
ns
5
—
5
—
5
—
ns
tWR
R Recovery Time
R Pulse Width(2)
R Pulse LOW to Data Bus at Low-Z(3)
W Pulse HIGH to Data Bus at Low-Z(3,4)
Data Valid from R Pulse HIGH
R Pulse HIGH to Data Bus at High-Z(3)
W Cycle Time
W Pulse Width(2)
W Recovery Time
10
—
10
—
15
—
ns
tDS
Data Set-up Time
18
—
20
—
30
—
ns
tDH
Data Hold Time
0
—
0
—
5
—
ns
tRR
tRPW
tRLZ
tWLZ
tDV
tRHZ
tWC
tWPW
tRSC
tRS
tRSS
tRSR
tRTC
tRT
tRTR
tRSF1
tRSF2
tREF
tRFF
tRPE
tWEF
tWFF
tWHF
tRHF
tWPF
tRF
tWF
tOEHZ
tOELZ
tAOE
RS Cycle Time
RS Pulse Width(2)
RS Set-up Time
RS Recovery Time
RT Cycle Time
RT Pulse Width(2)
RT Recovery Time
RS to EF and AEF LOW
RS to HF and FF HIGH
R LOW to EF LOW
R HIGH to FF HIGH
R Pulse Width After EF HIGH
W HIGH to EF HIGH
W LOW to EF LOW
W LOW to HF LOW
R HIGH to HF HIGH
W Pulse Width after FF HIGH
R HIGH to Transitioning AEF
W LOW to Transitioning AEF
OE HIGH to High-Z (Disable)(3)
OE LOW to Low-Z (Enable)(3)
OE LOW Data Valid (Q0–Q8)
NOTES:
1. Timings referenced as in AC Test Conditions.
2. Pulse widths less than minimum value are not allowed.
3. Values guaranteed by design, not currently tested.
4. Only applies to read data flow-through mode.
—
20
—
25
—
30
ns
45
—
50
—
65
—
ns
35
—
40
—
50
—
ns
45
—
50
—
65
—
ns
35
—
40
—
50
—
ns
35
—
40
—
50
—
ns
10
—
10
—
15
—
ns
45
—
50
—
65
—
ns
35
—
40
—
50
—
ns
10
—
10
—
15
—
ns
—
45
—
50
—
65
ns
—
45
—
50
—
65
ns
—
30
—
35
—
45
ns
—
30
—
35
—
45
ns
35
—
40
—
50
—
ns
—
30
—
35
—
45
ns
—
30
—
35
—
45
ns
—
45
—
50
—
65
ns
—
45
—
50
—
65
ns
35
—
40
—
50
—
ns
—
45
—
50
—
65
ns
—
45
—
50
—
65
ns
0
17
0
20
0
25
ns
0
17
0
20
0
25
ns
—
20
—
25
—
30
ns
2677 tbl 09
5.09
6
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
MILITARY AND COMMERCIAL TEMPERATURE RANGES
5V
AC TEST CONDITIONS
Input Pulse Levels
Input Rise/Fall Times
Input Timing Reference Levels
Output Reference Levels
Output Load
GND to 3.0V
5ns
1.5V
1.5V
See Figure 1
1.1K
TO
OUTPUT
PIN
30pF*
680Ω
2677 tbl 10
2677 drw 04
or equivalent circuit
Figure 1. Output Load
* Includes scope and jig capacitances.
t RSC
t RS
RS
t RSR
t RSS
W
t RSS
R
t RSF1
AEF, EF
t RSF2
HF, FF
2677 drw 05
Figure 2. Reset
NOTES:
1. EF, FF, HF, and AEF may change status during Reset, but flags will be valid at tRSC.
2. W and R = VIH around the rising edge of RS.
t RC
t RPW
t RR
tA
tA
R
t RLZ
t DV
Q 0 –Q 8
t RHZ
DATA OUT VALID
DATA OUT VALID
t WC
t WPW
t WR
W
t DS
D 0 –D 8
t DH
DATA IN VALID
DATA IN VALID
2677 drw 06
Figure 3. Asynchronous Write and Read Operation
NOTE:
1. Assume OE is asserted LOW.
5.09
7
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
LAST WRITE
IGNORED
WRITE
FIRST READ
MILITARY AND COMMERCIAL TEMPERATURE RANGES
ADDITIONAL
READS
FIRST
WRITE
R
W
t WFF
t RFF
FF
2677 drw 07
Figure 4. Full Flag From Last Write to First Read
LAST READ
IGNORED
READ
FIRST WRITE
ADDITIONAL
WRITES
FIRST
READ
W
R
t REF
t WEF
EF
tA
(1)
DATA OUT
VALID
VALID
2677 drw 08
Figure 5. Empty Flag From Last Read to First Write
NOTE:
1. Assume OE is asserted LOW.
tRTC
tRT
RT
t RTR
W,R
AEF, HF, EF, FF
FLAG VALID
2677 drw 09
Figure 6. Retransmit
5.09
8
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
MILITARY AND COMMERCIAL TEMPERATURE RANGES
W
t WEF
EF
t RPE
R
2677 drw 10
Figure 7. Empty Flag Timing
Figure 9. Almost-Empty/Almost-Full Flag and Half-Full Timings
R
t RFF
FF
t WPF
W
2677 drw 11
Figure 8. Full Flag Timing
W
R
t RHF
t WHF
HALF–FULL
HALF–FULL (1/2)
(1/2)
HF
HALF–FULL + 1
t RF
t WF
(7/8 FULL)
AEF
AEF
(7/8 FULL)
ALMOST–FULL (7/8 FULL + 1)
ALMOST–EMPTY
(1/8 FULL–1)
(1/8 FULL)
ALMOST–EMPTY (1/8 FULL–1)
2677 drw 12
Figure 9. Almost-Empty/Almost-Full Flag and Half-Full Timings
tRC
tRR
R
TERMINATE READ CYCLE
tA
OE
tRLZ
Q0-8
SECOND READ BY
CONTROLLING OE
tAOE
tOELZ
tOEHZ
DATA 1
DATA 1
tDV
HIGH IMPEDANCE
2677 drw 13
Figure 10. Output Enable and Read Operation Timings
5.09
9
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
MILITARY AND COMMERCIAL TEMPERATURE RANGES
WRITE TO
LAST PHYSICAL
LOCATION
READ FROM
LAST PHYSICAL
LOCATION
W
R
t XOH
t XOL
t XOL
t XOH
XO
2677 drw 14
Figure 11. Expansion Out
t
t XIR
XI
XI
t
W
XIS
WRITE TO
FIRST PHYSICAL
LOCATION
t XIS
R
READ FROM
FIRST PHYSICAL
LOCATION
2677 drw 15
Figure 12. Expansion In
OPERATING CONFIGURATIONS
SINGLE DEVICE CONFIGURATION
The IDT72021/031/041 is in the Single Device
Configuration when the Expansion In (XI) control input is
grounded (see Figure 13).
(HALF–FULL FLAG) HF
AEF
WRITE (W)
READ (R)
9
DATA IN (D)
FULL FLAG (FF)
9
IDT
72021/031/041
RESET (RS)
DATA OUT (Q)
EMPTY FLAG (EF)
RETRANSMIT (RT)
OUTPUT ENABLE (OE)
EXPANSION IN (XI)
2677 drw 16
Figure 13. Block Diagram of Single 1K/2K/4K x 9 FIFO
5.09
10
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
WIDTH EXPANSION CONFIGURATION
Word width may be increased simply by connecting the
corresponding input control signals of multiple devices. Status flags (EF, FF, HF, and AEF) can be detected from any one
AEF
18
MILITARY AND COMMERCIAL TEMPERATURE RANGES
device. Figure 14 demonstrates an 18-bit word width by using
two IDT72021/031/041 devices. Any word width can be attained by adding additional IDT72021/031/041s.
HF
AEF
9
HF
9
DATA IN (D)
OUTPUT ENABLE (OE)
WRITE (W)
FULL FLAG (FF)
IDT
72021/031/041
READ (R)
IDT
72021/031/041
EMPTY FLAG (EF)
RESET (RS)
9
RETRANSMIT (RT)
9
XI
XI
18
DATA OUT (Q)
2677 drw 17
Figure 14. Block Diagram of 1K/2K/4K x 18 FIFO Memory Used in Width Expansion Configuration
NOTE:
1. Flag detection is accomplished by monitoring the FF, EF, HF and AEF signals on either (any) device used in the width expansion configuration. Do
not connect any output signals together.
DEPTH EXPANSION (DAISY CHAIN) MODE
The IDT72021/031/041 can easily be adapted to applications when the requirements are for greater than 1K/2K/4K
words. Figure 15 demonstrates Depth Expansion using three
IDT72021/031/041s. Any depth can be attained by adding
additional devices. The IDT72021/031/041 operates in the
Depth Expansion configuration when the following conditions
are met:
1. The first device must be designed by grounding the First
Load (FL) control input.
2. All other devices must have FL in the HIGH state.
3. The Expansion Out (XO) pin of each device must be tied
to the Expansion In (XI) pin of the next device. See
Figure 15.
4. External logic is needed to generate a composite Full
Flag (FF) and Empty Flag (EF). This requires the ORing
of all EFs and ORing of all FFs (i.e. all must be set to
generate the correct composite FF or EF). See
Figure 15.
5. The Retransmit (RT) function and Half-Full Flag (HF) are
not available in the Depth Expansion Mode. For additional information refer to Tech Note 9: “Cascading
FIFOs or FIFO Modules”.
COMPOUND EXPANSION MODE
The two expansion techniques described above can be
applied together in a straight forward manner to achieve large
FIFO arrays (see Figure 16).
BIDIRECTIONAL MODE
Applications which require data buffering between two
systems (each system capable of Read and Write operations)
can be achieved by pairing IDT72021/031/041s as shown in
Figure 17. Care must be taken to assure that the appropriate
flag is monitored by each system (i.e., FF is monitored on the
device where W is used; EF is monitored on the device where
R is used). Both Depth Expansion and Width Expansion may
be used in this mode.
DATA FLOW-THROUGH MODES
Two types of flow-through modes are permitted: a read
flow-through and write flow-through mode. For the read flowthrough mode (Figure 18), the FIFO permits the reading of a
single word after writing one word of data into an empty FIFO.
The data is enabled on the bus in (tWEF + tA) ns after the rising
edge of W, called the first write edge. It remains on the bus until
the R line is raised from LOW-to-HIGH, after which the bus
would go into a three-state mode after tRHZ ns. The EF line
would have a pulse showing temporary deassertion and then
would be asserted. In the interval of time that R was LOW,
more words can be written to the FIFO (the subsequent writes
after the first write edge will be deassert the Empty Flag);
however, the same word (written on the first write edge),
presented to the output bus as the read pointer, would not be
incremented when R was LOW. On toggling R, the other
words that are written to the FIFO will appear on the output bus
as in the read cycle timings.
5.09
11
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
In the write flow-through mode (Figure 18), the FIFO
permits the writing of a single word of data immediately after
reading one word of data from a full FIFO. The R line causes
the FF to be deasserted but the W line, being LOW causes it
to be asserted again in anticipation of a new data word. On the
rising edge of W, the new word is loaded in the FIFO. The W
MILITARY AND COMMERCIAL TEMPERATURE RANGES
line must be toggled when FF is not asserted to write new data
in the FIFO and to increment the write pointer.
For additional information refer to Tech Note 8: “Operating
FIFOs on Full and Empty Boundary Conditions” and Tech
Note 6: “Designing with FIFOs”.
TRUTH TABLES
TABLE I—RESET AND RETRANSMIT
Single Device Configuration/Width Expansion Mode
RT
XI
0
1
X
0
0
0
Internal Status
Read Pointer
Write Pointer
Location Zero
Location Zero
Location Zero
Unchanged
1
1
0
Increment(1)
RS
Mode
Reset
Retransmit
Read/Write
Inputs
Increment(1)
Outputs
EF
FF
HF
AEF
0
X
1
X
1
X
0
X
X
X
X
X
NOTE:
1. Pointer will increment if flag is HIGH.
2677 tbl 11
TABLE II—RESET AND FIRST LOAD TRUTH TABLE
Depth Expansion/Compound Expansion Mode
Mode
Reset First Device
Reset All Other Devices
Read/Write
RS
Inputs
FL
XI
0
0
0
1
(1)
(1)
1
X
(1)
Internal Status
Read Pointer
Write Pointer
Location Zero
Location Zero
Location Zero
Location Zero
X
EF
X
Outputs
FF
0
0
1
1
X
X
NOTE:
2677 tbl 12
1. XI is connected to XO of previous device. See Figure 15. RS = Reset Input FL/RT = First Load/Retransmit, EF = Empty Flag Output, FF = Flag Full Output,
XI = Expansion Input, HF = Half-Full Flag Output, AEF = Almost Empty/Almost Full Flag.
XO
R
W
FF
D
9
9
IDT
72021/
031/041
EF
9
Q
FL
VCC
EF
EMPTY
XI
XO
FF
FULL
IDT
72021/
031/041
9
FL
XI
XO
FF
9
EF
IDT
72021/
031/041
RS
FL
XI
2677 drw 18
Figure 15. Block Diagram of 3K/6K/12K x 9 FIFO Memory (Depth Expansion)
NOTE:
1. IDT only guarantees depth expansion with identical IDT part numbers and speed.
5.09
12
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
MILITARY AND COMMERCIAL TEMPERATURE RANGES
•••
IDT72021/
031/041
DEPTH
EXPANSION
BLOCK
R, W, RS
IDT72021/
031/041
DEPTH
EXPANSION
BLOCK
D 0 –D N
•••
Q 0 –Q N
IDT72021/
031/041
DEPTH
EXPANSION
BLOCK
•••
2677 drw 19
Figure 16. Compound FIFO Expansion
NOTES:
1. For depth expansion block see section od Depth Expansion and Figure 15.
2. For Flag detection see section on Width Expansion and Figure 14.
WA
FFA
IDT
IDT
72021/
7201A
031/041
DA 0-8
RB
EF B
HFB
Q B 0-8
AEF
SYSTEM A
SYSTEM B
Q A 0-8
RA
HFA
EF A
D B 0-8
IDT
72021/
031/041
WB
FF B
2677 drw 20
AEF
Figure 17. Bidirectional FIFO Mode
DATA IN
W
t RPE
R
EF
t REF
t WEF
t WLZ
DATA OUT
(1)
tA
DATA OUT VALID
2677 drw 21
Figure 18. Read Data Flow-Through Mode
NOTE:
1. Assume OE is asserted LOW.
5.09
13
IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
MILITARY AND COMMERCIAL TEMPERATURE RANGES
R
t WPF
W
t RFF
FF
t WFF
DATA IN
DATA IN VALID
tA
DATA OUT
t DH
t DS
(1)
DATA OUT VALID
2677 drw 22
Figure 19. Write Data Flow-Through Mode
NOTE:
1. Assume OE is asserted LOW.
ORDERING INFORMATION
IDT XXXXX
Device Type
X
X
X
X
Power
Speed
Package
Process/
Temperature
Range
Blank
Commercial (0°C to+70°C)
B
Military (–55°C to+125°C)
Compliant to MIL-STD-883, Class B
D
J
CERDIP
Plastic Leaded Chip Carrier
25
30
35
40
50
72021–Com’l. Only
72021–Mil. Only
72021/031/041–Com’l. Only
72021/031/041–Mil. Only
72021/031/041–Com'l & Mil.
L
Low Power
72021
72031
72041
1024 x 9-Bit FIFO
2048 x 9-Bit FIFO
4096 x 9-Bit FIFO
Access Time (tA)
Speed in Nanoseconds
2677 drw 23
5.09
14
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