IDT72041 データシートの表示（PDF） - Integrated Device Technology
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IDT72041 Datasheet PDF : 14 Pages
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IDT72021, IDT72031, IDT72041
CMOS ASYNCHRONOUS FIFO WITH RETRANSMIT 1K x 9, 2K x 9, 4K x 9
MILITARY AND COMMERCIAL TEMPERATURE RANGES
PIN CONFIGURATIONS
INDEX
4 3 2 1 32 31 30
D2
5
29
D6
D1
6
D0
7
XI 8
AEF 9
FF
10
Q0
11
J32-1
28
D7
27
FL/RT
26
RS
25
OE
24
EF
23
XO/HF
Q1
12
22
Q7
Q2
13
21
Q6
14 15 16 17 18 19 20
PLCC TOP VIEW
2677 drw 03
VCC 1
W2
D8 3
D3 4
D2 5
D1 6
D0 7
XI 8
AEF 9
FF 10
Q0 11
Q1 12
Q2 13
Q3 14
Q8 15
GND 16
32
31
30
29
28
27
26
D32-1 25
24
23
22
21
20
19
18
17
DIP TOP VIEW
VCC
D4
D5
D6
D7
FL/RT
RS
OE
EF
XO/HF
Q7
Q6
Q5
Q4
R
GND
2677 drw 02
PIN DESCRIPTIONS
Symbol Name
I/O
D0–D8
Inputs
I
RS
Reset
I
W
Write
I
R
Read
I
FL/RT
XI
OE
First Load/
I
Retransmit
Expansion In
I
Output Enable I
FF
EF
AEF
XO/HF
Full Flag
O
Empty Flag
O
Almost-Empty/ O
Almost-Full Flag
Expansion Out/ O
Half-Full Flag
Q0–Q8
Outputs
O
Description
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.
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.
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).
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.
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.
When FF goes LOW, the device is full and further WRITE operations are inhibited. When FF
is HIGH, the device is not full.
When EF goes LOW, the device is empty and further READ operations are inhibited. When EF
is HIGH, the device is not empty.
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.
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
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