LF2242 查看數據表（PDF） - LOGIC Devices
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LF2242 Datasheet PDF : 8 Pages
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DEVICES INCORPORATED
LF2242
12/16-bit Half-Band Interpolating/
Decimating Digital Filter
FIGURE 2. INPUT AND OUTPUT FORMATS
Two’s Complement Input Format
11 10 9 8
–20 2–1 2–2 2–3
(Sign)
3210
2–8 2–9 2–10 2–11
Two’s Complement Output Format (TCO = 1, Non-interpolate)
15 14 13 12
–20 2–1 2–2 2–3
(Sign)
3210
2–12 2–13 2–14 2–15
Two’s Complement Output Format (TCO = 1, Interpolate)
15 14 13 12
–21 20 2–1 2–2
(Sign)
3210
2–11 2–12 2–13 2–14
Inverted Offset Binary Output Format (TCO = 0, Non-interpolate)
15 14 13 12
20 2–1 2–2 2–3
(Sign)
3210
2–12 2–13 2–14 2–15
Inverted Offset Binary Output Format (TCO = 0, Interpolate)
15 14 13 12
21 20 2–1 2–2
(Sign)
3210
2–11 2–12 2–13 2–14
RND2-0 — Rounding Control
The rounding control inputs set the posi-
tion of the effective LSB of the output data
by adding a rounding bit to the internal
bit position that is one below that speci-
fied by RND2-0. All bits below the effec-
tive LSB position are subsequently ze-
roed (Table 2).
TCO — Two’s Complement Format
Control
The TCO input determines the format of
the output data. When TCO is HIGH, the
output data is presented in two’s comple-
ment format. When TCO is LOW, the
data is in inverted offset binary format
(all output bits are inverted except the
MSB — the MSB is unchanged).
OE — Output Enable
When the OE signal is LOW, the current
data in the output register is available on
the SO15-0 pins. When OE is HIGH, the
outputs are in a high-impedance state.
TABLE 2. ROUNDING FORMAT
RND2-0 SO15 SO14 SO13 SO12 • • •
SO8 SO7 SO6 SO5 SO4 SO3 SO2 SO1 SO0
000
X
X
X
X
•••
X
X
X
X
X
X
X
X
R
001
X
X
X
X
•••
X
X
X
X
X
X
X
R
0
010
X
X
X
X
•••
X
X
X
X
X
X
R
0
0
011
X
X
X
X
•••
X
X
X
X
X
R
0
0
0
100
X
X
X
X
•••
X
X
X
X
R
0
0
0
0
101
X
X
X
X
•••
X
X
X
R
0
0
0
0
0
110
X
X
X
X
•••
X
X
R
0
0
0
0
0
0
111
X
X
X
X
•••
X
R
0
0
0
0
0
0
0
'R' indicates the half-LSB rounded bit (effective LSB position)
Video Imaging Products
3
08/16/2000–LDS.2242-K
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