IDT72275 IDT [Integrated Device Technology], IDT72275 Datasheet - Page 8

• Manufacturer Part Number: IDT72275
• Manufacturer: IDT [Integrated Device Technology]

IDT72275/72285 SUPERSYNC FIFO™
32,768 x 18, 65,536 x 18
PROGRAMMING FLAG OFFSETS
The IDT72275/72285 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
pin. During Master Reset, the state of the
whether serial or parallel flag offset programming is enabled.
A HIGH on
offset values and in addition, sets a default
of 3FFH (a threshold 1,023 words from the empty boundary),
and a default
words from the full boundary). A LOW on
Reset selects parallel loading of offset values, and in addition,
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.
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
TABLE I –– STATUS FLAGS FOR IDT STANDARD MODE
Full and Empty Flag offset values are user programmable.
Number of
Words in
FIFO
Number of
Words in
FIFO
LD
(
1)
PAF
during Master Reset selects serial loading of
offset value of 3FFH (a threshold 1,023
16,386 to (32,769-(m+1))
16,385 to (32,768-(m+1))
(32,768-m)
(32,769-m)
(n+1) to 16,384
(n+2) to 16,385
72275
1 to n
72275
32,768
1 to n+1
32,769
0
(2)
0
to 32,768
LD
to 32,767
(1)
LD
(1)
input determines
PAE
during Master
offset value
(2)
LD
(Load)
32,770 to (65,537-(m+1))
32,769 to (65,536-(m+1))
(65,536-m)
(65,537-m)
(n+2) to 32,769
(n+1) to 32,768
sets a default
from the empty boundary), and a default
07FH (a threshold 127 words from the full boundary). See
Figure 3, Offset Register Location and Default Values .
possible to read the current offset values. It is only possible to
read offset values via parallel read.
quence , summarizes the control pins and sequence for both
serial and parallel programming modes. For a more detailed
description, see discussion that follows.
grammed) any time after Master Reset, regardless of whether
serial or parallel programming has been selected.
72285
1 to n+1
In addition to loading offset values into the FIFO, it also
Figure 4, Programmable Flag Offset Programming Se-
The offset registers may be programmed (and repro-
72285
65,537
1 to n
65,536
0
0
(2)
to 65,536
to 65,535
(1)
(1)
PAE
(2)
offset value of 07FH (a threshold 127 words
H
H
H
H
H
L
L
L
L
L
H
L
COMMERCIAL TEMPERATURE RANGE
H
H
H
H
H
H
H
H
L
L
L
L
H
H
H
L
L
L
H
H
H
L
L
L
PAF
H
H
H
H
L
L
H
H
H
H
L
L
4674 drw 05
offset value of
H
H
H
H
H
H
L
L
L
L
L
L
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