CMOS SyncFIFO
TM
256 x 18, 512 x 18, 1,024 x 18,
2,048 x 18, and 4,096 x 18
IDT72205LB, IDT72215LB,
IDT72225LB, IDT72235LB,
IDT72245LB
FEATURES:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
256 x 18-bit organization array (IDT72205LB)
512 x 18-bit organization array (IDT72215LB)
1,024 x 18-bit organization array (IDT72225LB)
2,048 x 18-bit organization array (IDT72235LB)
4,096 x 18-bit organization array (IDT72245LB)
10 ns read/write cycle time
Empy and Full flags signal FIFO status
Easy expandable in depth and width
Asynchronous or coincident read and write clocks
Programmable Almost-Empty and Almost-Full flags with
default settings
Half-Full flag capability
Dual-Port zero fall-through time architecture
Output enable puts output data bus in high-impedence state
High-performance submicron CMOS technology
Available in a 64-lead thin quad flatpack (TQFP/STQFP)
and plastic leaded chip carrier (PLCC)
Industrial temperature range (–40°C to +85°C) is available
°
°
Green parts available, see ordering information
DESCRIPTION:
The IDT72205LB/72215LB/72225LB/72235LB/72245LB are very high
speed, low-power First-In, First-Out (FIFO) memories with clocked read and
write controls. These FIFOs are applicable for a wide variety of data buffering
needs, such as optical disk controllers, Local Area Networks (LANs), and
interprocessor communication.
These FIFOs have 18-bit input and output ports. The input port is controlled
by a free-running clock (WCLK), and an input enable pin (WEN). Data is read
into the synchronous FIFO on every clock when
WEN
is asserted. The output
port is controlled by another clock pin (RCLK) and another enable pin (REN).
The read clock can be tied to the write clock for single clock operation or the
two clocks can run asynchronous of one another for dual-clock operation. An
Output Enable pin (OE) is provided on the read port for three-state control of
the output.
The synchronous FIFOs have two fixed flags, Empty (EF) and Full (FF),
and two programmable flags, Almost-Empty (PAE) and Almost-Full (PAF). The
offset loading of the programmable flags is controlled by a simple state machine,
and is initiated by asserting the Load pin (LD). A Half-Full flag (HF) is available
when the FIFO is used in a single device configuration.
These devices are depth expandable using a Daisy-Chain technique. The
XI
and
XO
pins are used to expand the FIFOs. In depth expansion configu-
ration, First Load (FL) is grounded on the first device and set to HIGH for all
other devices in the Daisy Chain.
The IDT72205LB/72215LB/72225LB/72235LB/72245LB is fabricated
using IDT’s high-speed submicron CMOS technology.
FUNCTIONAL BLOCK DIAGRAM
WCLK
D0-D17
INPUT REGISTER
OFFSET REGISTER
WRITE CONTROL
LOGIC
WRITE POINTER
•
•
RAM ARRAY
256 x 18, 512 x 18
1,024 x 18, 2,048 x 18
4,096 x 18
•
•
FLAG
LOGIC
/(
READ POINTER
READ CONTROL
LOGIC
)
(
)/
EXPANSION LOGIC
OUTPUT REGISTER
RESET LOGIC
Q0-Q17
RCLK
2766 drw 01
IDT and the IDT logo are registered trademarks of Integrated Device Technology, Inc. SyncFIFO is a trademark of Integrated Device Technology, Inc.
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
1
OCTOBER 2008
DSC-2766/2
©2008
Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice.
IDT72205LB/72215LB/72225LB/72235LB/72245LB CMOS SyncFIFO
TM
256 x 18, 512 x 18, 1,024 x 18, 2,048 x 18 and 4,096 x 18
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
PIN CONFIGURATIONS
D
15
D
16
D
17
GND
RCLK
V
CC
GND
V
CC
Q
17
Q
16
GND
Q
15
V
CC
Q
14
Q
13
GND
Q
12
Q
11
V
CC
Q
10
Q
9
GND
Q
8
Q
7
V
CC
Q
6
Q
5
GND
Q
4
D
14
D
13
D
12
D
11
D
10
D
9
V
CC
D
8
GND
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
9 8 7 6 5 4 3 2
68 67 66 65 64 63 62 61
10
60
1
11
59
12
58
13
57
14
56
15
55
16
54
17
53
18
52
19
51
20
50
49
21
48
22
47
23
46
24
45
25
44
26
27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43
WCLK
Q
0
Q
1
GND
Q
2
Q
3
V
CC
2766 drw 02
V
CC
PLCC (J68-1, order code: J)
TOP VIEW
D
16
D
17
GND
RCLK
V
CC
GND
/
PIN 1
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
WCLK
Q
0
Q
1
GND
Q
2
Q
3
V
CC
/
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
D
15
D
14
D
13
D
12
D
11
D
10
D
9
D
8
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
Q
17
Q
16
GND
Q
15
V
CC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
Q
14
Q
13
GND
Q
12
Q
11
V
CC
Q
10
Q
9
GND
Q
8
Q
7
Q
6
Q
5
GND
Q
4
V
CC
2766 drw 03
TQFP (PN64-1, order code: PF)
STQFP (PP64-1, order code: TF)
TOP VIEW
2
OCTOBER 22, 2008
IDT72205LB/72215LB/72225LB/72235LB/72245LB CMOS SyncFIFO
TM
256 x 18, 512 x 18, 1,024 x 18, 2,048 x 18 and 4,096 x 18
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
PIN DESCRIPTION
Symbol
D0–D17
RS
WCLK
WEN
Name
Data Inputs
Reset
Write Clock
Write Enable
I/O
I
I
I
I
Data inputs for a 18-bit bus.
When
RS
is set LOW, internal read and write pointers are set to the first location of the RAM array,
FF
and
PAF
go HIGH, and
PAE
and
EF
go LOW. A reset is required before an initial WRITE after power-up.
When
WEN
is LOW, data is written into the FIFO on a LOW-to-HIGH transition of WCLK, if the FIFO is not full.
When
WEN
is LOW and LD is HIGH, data is written into the FIFO on every LOW-to-HIGH transition of
WCLK. When
WEN
is HIGH, the FIFO holds the previous data. Data will not be written into the FIFO if the
FF
is LOW.
When
REN
is LOW, data is read from the FIFO on a LOW-to-HIGH transition of RCLK, if the FIFO is not empty.
When
REN
is LOW, and
LD
is HIGH, data is read from the FIFO on every LOW-to-HIGH transition of RCLK.
When
REN
is HIGH, the output register holds the previous data. Data will not be read from the FIFO if the
EF
is LOW.
When
OE
is LOW, the data output bus is active. If
OE
is HIGH, the output data bus will be in a high-impedance
state.
When
LD
is LOW, data on the inputs D0–D11 is written to the offset and depth registers on the LOW-to-HIGH
transition of the WCLK, when
WEN
is LOW. When
LD
is LOW, data on the outputs Q0–Q11 is read from the
offset and depth registers on the LOW-to-HIGH transition of the RCLK, when
REN
is LOW.
In the single device or width expansion configuration,
FL
is grounded. In the depth expansion configuration,
FL
is grounded on the first device (first load device) and set to HIGH for all other devices in the Daisy Chain.
In the single device or width expansion configuration,
WXI
is grounded. In the depth expansion configuration,
WXI
is connected to
WXO
(Write Expansion Out) of the previous device.
In the single device or width expansion configuration,
RXI
is grounded. In the depth expansion configuration,
RXI
is connected to
RXO
(Read Expansion Out) of the previous device.
When
FF
is LOW, the FIFO is full and further data writes into the input are inhibited. When
FF
is HIGH, the FIFO
is not full.
FF
is synchronized to WCLK.
When
EF
is LOW, the FIFO is empty and further data reads from the output are inhibited. When
EF
is HIGH, the
FIFO is not empty.
EF
is synchronized to RCLK.
When
PAE
is LOW, the FIFO is almost empty based on the offset programmed into the FIFO. The default
offset at reset is 31 from empty for IDT72205LB, 63 from empty for IDT72215LB, and 127 from empty for
IDT72225LB/72235LB/72245LB.
When
PAF
is LOW, the FIFO is almost-full based on the offset programmed into the FIFO. The default offset at
reset is 31 from full for IDT72205, 63 from full for IDT72215LB, and 127 from full for IDT72225LB/72235LB/
72245LB.
In the single device or width expansion configuration, the device is more than half full when
HF
is LOW. In the
depth expansion configuration, a pulse is sent from
WXO
to
WXI
of the next device when the last location in the
FIFO is written.
In the depth expansion configuration, a pulse is sent from
RXO
to
RXI
of the next device when the last
location in the FIFO is read.
Data outputs for an 18-bit bus.
+5V power supply pins.
Eight ground pins for the PLCC and seven gound pins for the TQFP/STQFP.
Description
RCLK
REN
Read Clock
Read Enable
I
I
OE
LD
Output Enable
Load
I
I
FL
WXI
RXI
FF
EF
PAE
First Load
Write Expansion
Read Expansion
Full Flag
Empty Flag
Programmable
Almost-Empty Flag
Programmable
Almost-Full Flag
Write Expansion
Out/Half-Full Flag
Read Expansion
Out
Data Outputs
Power
Ground
I
I
I
O
O
O
PAF
O
WXO/HF
O
RXO
Q0–Q17
V
CC
GND
O
O
3
OCTOBER 22, 2008
IDT72205LB/72215LB/72225LB/72235LB/72245LB CMOS SyncFIFO
TM
256 x 18, 512 x 18, 1,024 x 18, 2,048 x 18 and 4,096 x 18
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
ABSOLUTE MAXIMUM RATINGS
Symbol
V
TERM
T
STG
I
OUT
Rating
Terminal Voltage
with respect to GND
Storage
Temperature
DC Output Current
Commercial
–0.5 to +7.0
–55 to +125
–50 to +50
Unit
V
°C
mA
RECOMMENDED DC OPERATING
CONDITIONS
Symbol
V
CC
GND
V
IH
V
IL
(1)
T
A
T
A
Parameter
Supply Voltage
Commercial/Industrial
Supply Voltage
Input High Voltage
Commercial/Industrial
Input Low Voltage
Commercial/Industrial
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
°C
°C
NOTES:
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.
NOTE:
1. 1.5V undershoots are allowed for 10ns once per cycle.
DC ELECTRICAL CHARACTERISTICS
(Commercial: V
CC
= 5V ± 10%, T
A
= 0
°
C to +70
°
C; Industrial: V
CC
= 5V
±
10%V, TA = -40°C to +85°C)
IDT72205LB
IDT72215LB
IDT72225LB
IDT72235LB
IDT72245LB
Commercial and Industrial
(1)
t
CLK
= 10, 15, 25 ns
Typ.
—
—
—
—
—
—
Symbol
I
LI
(2)
I
LO
(3)
V
OH
V
OL
I
CC1
(4,5,6)
I
CC2
(4,7)
Parameter
Input Leakage Current (any input)
Output Leakage Current
Output Logic “1” Voltage, I
OH
= –2 mA
Output Logic “0” Voltage, I
OL
= 8 mA
Active Power Supply Current
Standby Current
Min.
–1
–10
2.4
—
—
—
Max.
1
10
—
0.4
60
5
Unit
µA
µA
V
V
mA
mA
NOTES:
1. Industrial Temperature Range Product for the 15ns and the 25ns speed grades are available as a standard device.
2. Measurements with 0.4
≤
V
IN
≤
V
CC
.
3.
OE
≥
V
IH,
0.4
≤
V
OUT
≤
V
CC
.
4. Tested with outputs disabled (I
OUT
= 0).
5. RCLK and WCLK toggle at 20 MHZ and data inputs switch at 10 MHz.
6. For the IDT72205/72215/72225 the typical I
CC1
= 1.81 + 1.12*f
S
+ 0.02*C
L
*f
S
(in mA);
for the IDT72235/72245 the typical I
CC1
= 2.85 + 1.30*f
S
+ 0.02*C
L
*f
S
(in mA)
These equations are valid under the following conditions:
V
CC
= 5V, T
A
= 25
°
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, except RCLK and WCLK, which toggle at 20 MHz.
CAPACITANCE
(T
A
= +25
°
C, f = 1.0MHz)
Symbol
C
IN
(2)
C
OUT
(1,2)
Parameter
(1)
Input
Capacitance
Output
Capacitance
Conditions
V
IN
= 0V
V
OUT
= 0V
Max.
10
10
Unit
pF
pF
NOTES:
1. With output deselected, (OE
≥
V
IH
).
2. Characterized values, not currently tested.
4
OCTOBER 22, 2008
IDT72205LB/72215LB/72225LB/72235LB/72245LB CMOS SyncFIFO
TM
256 x 18, 512 x 18, 1,024 x 18, 2,048 x 18 and 4,096 x 18
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
AC ELECTRICAL CHARACTERISTICS
(Commercial: VCC = 5V ± 10%, TA = 0°C to +70°C; Industrial: VCC = 5V ± 10%, TA = -40°C to +85°C)
Commercial
IDT72205LB10
IDT72215LB10
IDT72225LB10
IDT72235LB10
IDT72245LB10
Symbol
f
S
t
A
t
CLK
t
CLKH
t
CLKL
t
DS
t
DH
t
ENS
t
ENH
t
RS
t
RSS
t
RSR
t
RSF
t
OLZ
t
OE
t
OHZ
t
WFF
t
REF
t
PAF
t
PAE
t
HF
t
XO
t
XI
t
XIS
t
SKEW1
t
SKEW2(2)
Parameter
Clock Cycle Frequency
Data Access Time
Clock Cycle Time
Clock HIGH Time
Clock LOW Time
Data Set-up Time
Data Hold Time
Enable Set-up Time
Enable Hold Time
Reset Pulse Width
(2)
Reset Set-up Time
Reset Recovery Time
Reset to Flag and Output Time
Output Enable to Output in Low-Z
(3)
Output Enable to Output Valid
Output Enable to Output in High-Z
(3)
Write Clock to Full Flag
Read Clock to Empty Flag
Clock to Asynchronous Programmable Almost-Full Flag
Clock to Programmable Almost-Empty Flag
Clock to Half-Full Flag
Clock to Expansion Out
Expansion In Pulse Width
Expansion In Set-Up Time
Skew time between Read Clock & Write Clock forFull Flag
Skew time between Read Clock & Write Clock for
Empty Flag
Min.
—
2
10
4.5
4.5
3
0
3
0
10
8
8
—
0
3
3
—
—
—
—
—
—
3
3.5
5
5
Max.
100
6.5
—
—
—
—
—
—
—
—
—
—
15
—
6
6
6.5
6.5
17
17
17
6.5
—
—
—
—
Commercial & Industrial
(1)
IDT72205LB15
IDT72215LB15
IDT72225LB15
IDT72235LB15
IDT72245LB15
Min.
—
2
15
6
6
4
1
4
1
15
10
10
—
0
3
3
—
—
—
—
—
—
6.5
5
6
6
Max.
66.7
10
—
—
—
—
—
—
—
—
—
—
20
—
8
8
10
10
24
24
24
10
—
—
—
—
IDT72205LB25
IDT72215LB25
IDT72225LB25
IDT72235LB25
IDT72245LB25
Min.
—
2
25
10
10
6
1
6
1
25
15
15
—
0
3
3
—
—
—
—
—
—
10
10
10
10
Max.
40
15
—
—
—
—
—
—
—
—
—
—
25
—
12
12
15
15
26
26
26
15
—
—
—
—
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
NOTES:
1. Industrial temperature range product for the 15ns and the 25ns speed grades are available as a standard device. All other speed grades are available by special order.
2. Pulse widths less than minimum values are not allowed.
3. Values guaranteed by design, not currently tested.
5V
1.1K
D.U.T.
AC TEST CONDITIONS
Input Pulse Levels
Input Rise/Fall Times
Input Timing Reference Levels
Output Reference Levels
Output Load
GND to 3.0V
3ns
1.5V
1.5V
See Figure 1
680Ω
30pF*
2766 drw 04
Figure 1. Output Load
* Includes jig and scope capacitances.
5
OCTOBER 22, 2008
嵌入式系统
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