
TMC22x5yA
PRODUCT SPECIFICATION
4
General Description
The TMC22x5yA digital decoder can be used as a universal 
input to digital video processing systems by decoding digital 
composite video and transcoding digital component inputs 
into a common data format.
The digital comb filter decoder implements one of sixteen 
comb filter architectures to produce luminance and color dif-
ference component signals which are virtually free of the 
cross-color and cross-luminance artifacts associated with 
simple bandsplit filter decoders.
Table 1. TMC22x5yA Decoder Family
Because the cost/performance tradeoff varies among applica-
tions, the TMC22x5yA decoder has been developed as a 
family of six parts. They are all assembled in the same 
package, and fit the same footprint. The register maps are 
identical. 
Figure 1. Logic Symbol
The devices come in 8- and 10-bit resolution versions (see 
Figure 2 for data alignment between 8- and 10-bit versions). 
Within each resolution version there are three models, offer-
ing three-line adaptive comb filtering, two-line adaptive 
comb filtering, and simple decoding. The TMC22153A 
10-bit three-line comb filter can be programmed to emulate 
any of the other parts. All prototyping can be performed with 
this version to evaluate performance tradeoffs, and lower-
cost versions are easily substituted in production.
Input Processor
The digitized video and clocks provided to the decoder can 
be either locked to the line frequency or the subcarrier fre-
quency of the digitized waveform, providing broadcast qual-
ity decoding from the NTSC square pixel rate of 12.27 MHz 
to the PAL four times subcarrier pixel rate of 17.73 MHz.
Figure 2. Pixel Data Format
Inputs containing embedded GRS (Fairchild Video Input 
Processors), TRS words (D1 multiplexed component sig-
nals), and TRS-ID words (deserialized D2 signals) can be 
used to lock the internal horizontal and vertical state 
machines to the embedded information. If this information is 
not provided, external horizontal and vertical syncs are 
required for all line-locked input formats, and are optional 
for NTSC inputs locked to four times the subcarrier (4*Fsc). 
A simple sync separator is provided for digitized inputs 
locked to the subcarrier frequency: the internal sync separa-
tor locks to the mid point of syncs during the vertical field 
group, then flywheels during the active portion of the field. 
For this reason, the DHSYNC and DVSYNC operations are 
not guaranteed in subcarrier mode.
Adaptive Comb Filter
The line based adaptive comb filter in the TMC22x5yA adds 
or subtracts the high frequency data from three adjacent field 
lines to produce the average of the high frequency luminance 
by canceling the chrominance signals, which in flat fields of 
color are 180 degrees apart. Unfortunately flat fields of color 
are rare and, when vertical transitions in the picture occur, 
the output of the comb filter contains a mixture of both high 
frequency luminance and chrominance, at which time the 
comb fails. To avoid the comb filter artifacts that occur when 
this happens, three sets of error signals are sent to a user-pro-
grammable lookup table, allowing the output of the comb fil-
ter to be mixed with the output of an internal bandsplit 
decoder. 
To produce these comb fail error signals, the video on each 
of the inputs to the comb filter is passed through a simple 
bandsplit decoder. The low-frequency portion of the signal is 
TMC2215yA
3
2
TMC2205yA
3
2
Function
1
1
10-bit Data
8-bit Data
D1 Interface
Line-Locked Mode
f
SC
-Locked Mode
Genlock Mode
NTSC Frame Comb
NTSC/PAL Field Comb
3-Line Comb
2-Line Comb
Line Grab
Pixel Grab
65-22x5yA-02
VIDEOA
9-0
VIDEOB
9-0
BUFFER
LDV
HSYNC
VSYNC
MASTER
TMC22x5yA
Multistandard
Digital
Video
Decoder
CLOCK
CS
R/W
D
7-0
A
1-0
G/Y
9-0
B/C
B9-0
R/C
R9-0
FID
2-0
AVOUT
DHSYNC
DVSYNC
SER
SET
RESET
SA
2-0
SDA
SCL
MSB
VA
9
VB
9
G/Y
9
B/C
B9
R/C
R9
LSB
VA
0
VB
0
G/Y
0
B/C
B0
R/C
R0
VA
8
VB
8
G/Y
8
B/C
B 8
R/C
R8
···
VA
2
VB
2
G/Y
2
B/C
B2
R/C
R2
VA
1
VB
1
G/Y
1
B/C
B1
R/C
R1
10 bit
VA
9
VB
9
G/Y
9
B/C
B9
R/C
R9
VA
8
VB
8
G/Y
8
B/C
B 8
R/C
R8
···
VA
2
VB
2
G/Y
2
B/C
B2
R/C
R2
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
8 bit