IDT72141L35P Просмотр технического описания (PDF) - Integrated Device Technology
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IDT72141L35P Datasheet PDF : 13 Pages
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IDT72131, IDT72141
CMOS PARALLEL-TO-SERIAL FIFO 2048 x 9 & 4096 x 9
COMMERCIAL TEMPERATURE RANGES
PIN DESCRIPTIONS
Symbol
Name
I/O
D0–D8 Inputs
I
RS
Reset
I
W
Write
I
SOCP Serial Output
I
Clock
NR
Next Read
I
FL/RT First Load/
I
Retransmit
XI
Expansion In
I
SOX
Serial Output
I
Expansion
SO
Serial Output
O
FF
Full Flag
O
EF
Empty Flag
O
AEF
Almost-Empty/
O
Almost-Full Flag
XO/HF Expansion Out/
O
Half-Full Flag
Q4, Q6, Data Set
O
Q7 and
Q8
VCC
Power Supply
GND
Ground
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. W must be HIGH and SOCP must be LOW during RS cycle.
A write cycle is initiated on the falling edge of WRITE 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 WRITE. Data is stored
in the RAM array sequentially and independently of any ongoing read operation.
A serial bit read cycle is initiated on the rising edge of SOCP if the Empty Flag (EF) is not set. In
both Depth and Serial Word Width Expansion modes, all of the SOCP pins are tied together.
To program the Serial Out data word width , connect NR with one of the Data Set pins (Q4, Q6,
Q7 and Q8). For example, NR - Q7 programs for a 8-bit Serial Out word width.
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. W must be high and SOCP must be low before setting FL/RT LOW. Retransmit
is not compatible with depth expansion. In the depth expansion configuration, FL/RT grounded
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.
In the Serial Output Expansion mode, the SOX pin of the least significant device is tied HIGH.
The SOX pin of all other devices is connected to the Q8 pin of the previous device. Data is then
clocked out least significant bit first. For single device operation, SOX is tied HIGH.
Serial data is output on the Serial Output (SO) pin. Data is clocked out Least Significant Bit first.
In the Serial Width Expansion mode the SO pins are tied together and each SO pin is tristated
at the end of the byte.
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. See the description on page 6 for more details.
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.
The appropriate Data Set pin (Q4, Q6, Q7 and Q8) is connected to NR to program the Serial Out
data word width. For example: Q6 - NR programs a 7-bit word width, Q8 - NR programs a 9-bit
word width, etc.
Single Power Supply of 5V.
Single ground at 0V.
2751 tbl 01
STATUS FLAGS
Number of Words in FIFO
IDT72131
IDT72141
0
0
1-255
1-511
256-1024
512-2048
1025-1792
2049-3584
1793-2047
3585-4095
2048
4096
FF AEF
H
L
H
L
H
H
H
H
H
L
L
L
HF EF
H
L
H
H
H
H
L
H
L
H
L
H
2751 tbl 02
5.34
2
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