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TMC22x5yA
PRODUCT SPECIFICATION
52
REV. 1.0.0 2/4/03
For PAL comb filters the
LYE
,
LME
, and
LPE
errors signals
are always selected by default. In this way the error signals
into the XLUT always represent the comb filter being imple-
mented. The resolution of the error signals selected is con-
trolled by the XIP[1:0] register bits as shown in Table 6:
XLUT Input Selection. The position of these error signals on
the XLUT input address X[7:0] is also shown.
The selected comb fail signals are translated by the user-
programmed configuration within the 256*5 XLUT into the
mix signal (K) which controls the 30 levels of cross-fade
between the weighted comb filter and the band split filters.
The 1 to 31 mix signal is modified on the input to the cross-
fade to produce a 0 to 32 control signal, as shown in Table 7.
The special function assigned to K = 0 is programmed into
the XSF[1:0] register bits, as shown in Table 8.
Table 8. XLUT Special Function Definitions
The “Flat with notch” selection passes the
FLAT
input
through onto the luminance channel and selects the notch
filter, centered at 0.25 of the normalized clock frequency.
This mode is therefore only useful with inputs at 4*Fsc or in
cases when a notch at 0.25 of the normalized clock
frequency is adequate for application.
The XLUT output, is fed through a bypassable low-pass
filter KLPF to avoid switching between comb and simple
decoders on a pixel by pixel basis. When the special function
is selected (K = 0) the input to the KLPF is held and the filter
is automatically bypassed. The output of the XLUT can be
externally monitored by reading XOP[4:0] in register 4Bh.
Table 6. XLUT Input Selection
XIP[1:0]
00
Function
2 bits of phase error (X[7:6]), 3 bits of
chroma (X[5:3]) and luma magnitude error
(X[3:0]).
4 bits of chroma (X[7:4]) and luma
magnitude error (X[3:0]).
3 bits of phase error (X[7:5]), 3 bits of
chroma magnitude error (X[4:2]), and 2
bits of luma magnitude error (X[1:0]).
4 bits of phase error (X[7:4]) and chroma
magnitude error (X[3:0]).
01
10
11
Table 7. XLUT Output Function.
XLUT
OUTPUT
0
K
Special function (e.g. luma comb and HPF
on chroma)
0 - 100% Bandsplit
2
3
:
1
2
3
:
16
:
29
30
31
16 - 50% Bandsplit, 50% Comb
:
29
30
32 - 100% Comb
KIP
1-0
XLUT special function selection
Y
comb
simple
fl
at with notch
fl
at with notch
C
00
01
10
11
simple
comb
simple
comb
Table 7. XLUT Output Function.
(cont.)
XLUT
OUTPUT
K
Figure 20. XLUT Input Selection
XLUT
XLUT
Input
Select
Filter
2:1
MUX
65-22x5y-61
K[4:0]
XFEN
XIP[1:0]
X[7:0]
YERR
PERR
MERR