2
COMMERCIAL TEMPERATURE RANGE
IDT72125 PARALLEL-TO-SERIAL CMOS FIFO
1,024 x 16
PIN CONFIGURATION
PIN DESCRIPTIONS
PLASTIC THIN DIP (P28, order code: TP)
SOIC (SO28, order code: SO)
TOP VIEW
5
6
7
8
9
10
11
12
13
HF
D
2
D
3
D
4
GND
1
2
3
4
14
28
27
26
25
24
23
22
21
RSOX/AEF
FL/DIR
Vcc
SO
SOCP
20
19
18
17
16
15
D
1
D
0
W
D
13
D
14
D
15
D
12
FF
EF
RSIX
D
5
D
6
D
7
D
9
D
10
D
11
D
8
RS
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Symbol Name I/O Description
D0–D15 Inputs I Data inputs for 16-bit wide data.
RS Reset I When RS is set low, internal READ and WRITE pointers are set to the first location of the RAM array.
FF and HF go HIGH. EF and AEF go LOW. A reset is required before an initial WRITE after power-up.
W must be high during the RS cycle. Also the First Load pin (FL) is programmed only during Reset.
W Write I 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.
SOCP Serial Output Clock I 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.
FL/DIR First Load/Direction I This is a dual purpose input used in the width and depth expansion configurations. The First Load (FL)
function is programmed only during Reset (RS) and a LOW on FL indicates the first device to be loaded
with a byte of data. All other devices should be programmed HIGH. The Direction (DIR) pin controls shift
direction after Reset and tells the device whether to read out the Least Significant or Most Significant bit first.
RSIX Read Serial In I In the single device configuration, RSIX is set HIGH. In depth expansion or daisy chain expansion, RSIX
Expansion is connected to RSOX (expansion out) of the previous device.
SO Serial Output O Serial data is output on the Serial Output (SO) pin. Data is clocked out LSB or MSB depending on the
Direction pin programming. During Expansion the SO pins are tied together.
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.
HF Half-Full Flag O When HF is LOW, the device is more than half-full. When HF is HIGH, the device is empty to half-full.
RSOX/AEF Read Serial O This is a dual purpose output. In the single device configuration (RSIX HIGH), this is an AEF output pin.
Out Expansion When AEF is LOW, the device is empty-to-(1/8 full -1) or (7/8 full +1)-to-full. When AEF is HIGH, the device
Almost-Empty, is 1/8-full up to 7/8-full. In the Expansion configuration (RSOX connected to RSIX of the next device) a
Almost-Full Flag pulse is sent from RSOX to RSIX to coordinate the width, depth or daisy chain expansion.
VCC Power Supply Single power supply of 5V.
GND Ground Single ground of 0V.
