IDT72V2101_14 Datasheet, PDF (8/27 Pages) Integrated Device Technology – 3.3 VOLT HIGH DENSITY CMOS SUPERSYNC FIFO

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO^TM 262,144 x 9, 524,288 x 9
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
PROGRAMMING FLAG OFFSETS
Full and Empty Flag offset values are user programmable. The IDT72V2101/
72V2111 has internal registers for these offsets. Default settings are stated in the
footnotes of Table 1 and Table 2. Offset values can be programmed into the FIFO
in one of two ways; serial or parallel loading method. The selection of the loading
method is done using the LD (Load) pin. During Master Reset, the state of the
LD input determines whether serial or parallel flag offset programming is
enabled. A HIGH on LD during Master Reset selects serial loading of offset
values and in addition, sets a default PAE offset value of 3FFH (a threshold 1,023
words from the empty boundary), and a default PAF offset value of 3FFH (a
threshold 1,023 words from the full boundary). A LOW on LD during Master
Reset selects parallel loading of offset values, and in addition, sets a default PAE
offset value of 07FH (a threshold 127 words from the empty boundary), and
a default PAF offset value of 07FH (a threshold 127 words from the full
boundary). See Figure 3, Offset Register Location and Default Values.
In addition to loading offset values into the FIFO, it also possible to read the
current offset values. It is only possible to read offset values via parallel read.
Figure 4, Programmable Flag Offset Programming Sequence, summa-
rizes the control pins and sequence for both serial and parallel programming
modes. For a more detailed description, see discussion that follows.
The offset registers may be programmed (and reprogrammed) any time
after Master Reset, regardless of whether serial or parallel programming
has been selected.
TABLE I ⎯ STATUS FLAGS FOR IDT STANDARD MODE
IDT72V2101
IDT72V2111
FF PAF HF PAE EF
0
0
H HH L
L
Number of
Words in
FIFO
1 to n ⁽¹⁾
(n+1) to 131,072
131,073 to (262,144-(m+1))
(262,144-m) ⁽²⁾ to 262,143
262,144
1 to n ⁽¹⁾
H HH L H
(n+1) to 262,144
H HH H H
262,145 to (524,288-(m+1))
H
HL
H
H
(524,288-m) ⁽²⁾ to 524,287
H LL H H
524,288
L LL H H
NOTES:
1. n = Empty Offset, Default Values: n = 127 when parallel offset loading is selected or n = 1,023 when serial offset loading is selected.
2. m = Full Offset, Default Values: m = 127 when parallel offset loading is selected or m = 1,023 when serial offset loading is selected.
TABLE II ⎯ STATUS FLAGS FOR FWFT MODE
IDT72V2101
IDT72V2111
IR PAF HF PAE OR
Number of
Words in
FIFO
0
0
L HH LH
1 to n+1⁽¹⁾
1 to n+1⁽¹⁾
L HH L L
(n+2) to 131,073
(n+2) to 262,145
L HH H L
131,074 to (262,145-(m+1)) ⁽²⁾ 262,146 to (524,289-(m+1)) ⁽²⁾
L
HL
H
L
(262,145-m) _{to 262,144}
(524,289-m) _{to 524,288}
LLL HL
262,145
524,289
HL L H L
NOTES:
1. n = Empty Offset, Default Values: n = 127 when parallel offset loading is selected or n = 1,023 when serial offset loading is selected.
2. m = Full Offset, Default Values: m = 127 when parallel offset loading is selected or m = 1,023 when serial offset loading is selected.
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