mc13077p Freescale Semiconductor, Inc, mc13077p Datasheet - Page 8

• Manufacturer Part Number: mc13077p
• Description: Mc13077 Advanced Pal/ntsc Encoder
• Manufacturer: Freescale Semiconductor, Inc

Chroma Band Limiting and Luma Delay
been modulated, the two components are internally summed
and applied to an output buffer that will drive the external
bandpass circuitry before entering the chip again at Pin 20.
The sum of the color difference modulators produces an
output that is high in harmonic content. For this reason, and
to reduce the possibility of cross color, a chroma bandpass
transformer is used to band–limit the chroma. Suggested
bandpass filters and specifications for NTSC and PAL are
shown in Figure 6a and 6b. For each of
Characteristics of TOKO Bandpass Filter
(H286BAIS – 6276DAD)
Frequency (MHz)
8
Once the color difference and burst flag envelopes have
10
20
30
40
50
60
f sc /256
0
0
f sc
3.58
2.0
2.8
4.3
6.2
Attenuation
Response of the TOKO Bandpass Filter
1.0
Figure 6a. Group Delay and Magnitude
Intended for NTSC Applications
2.0
17
TOKO H286BAlS–6276DAD
NTSC Bandpass Filter
1.0 k
3.0
Ins. Loss 3.5 (max)
Attenuation (dB)
FREQUENCY (MHz)
NTSC: (3.58 MHz) (63.56 µs) = 227.5 counts
1
6
8.0 (min)
3.0
3.0
3
4
15 (min)
4.0
Figure 5. Relationship Showing the Counts of a 3.58 MHz Clock
3.0
3.0
versus a 4.43 MHz Clock at the End of a Horizontal Period
5.0
4.7 nF
1.0 k
Group Delay
20
6.0
Group Delay (µs)
7.0
0.290
these filters,
0.12
0.25
0.24
0.05
8.0
0.030
MC13077
9.0
0.4
0.2
256
approximately 300 ns of group delay is experienced by the
filtered chroma. There is also an internal delay on the order of
100 ns due to internal filtering that must be considered. Thus
a 400 ns luma delay line is used to equalize the timing of the
luma and the chroma. Suitable 400 ns delay lines are the
T O K O
DL122401D–1533. The delay of the luma channel is inserted
between Pins 10 and 6. Pin 10 is the buffered output of the
luma from the RGB matrix. This output is capable of driving
the external passive delay line with no external gain or
buffering required.
10
20
30
40
50
60
Characteristics of TOKO Bandpass Filter
(H286BAIS – 4963DAD)
0
Frequency (MHz)
0
PAL: (4.43 MHz) (64 µs) = 283.75 counts
Response of the TOKO Bandpass Filter
2.50
3.73
4.43
5.13
6.50
1.0
Figure 6b. Group Delay and Magnitude
H 3 2 1 L N P – 1 4 3 6 P B A B
Attenuation
Intended for PAL Applications
2.0
17
MOTOROLA ANALOG IC DEVICE DATA
TOKO H286BAIS–4963DAD
1.0 k
3.0
FREQUENCY (MHz)
Ins Loss 2.0 (max)
PAL Bandpass Filter
Attenuation (dB)
4.0
1
6
3.0
3.0
10 (min)
12 (min)
3
4
5.0
3.0
3.0
4.7 nF
1.0 k
6.0
20
Group Delay
a n d
7.0
Group Delay (µs)
0.295
512
8.0
0.075
t h e
0.24
0.24
0.05
0.035
9.0
T D K
0.4
0.2