MC13077 Motorola, MC13077 Datasheet - Page 9

• Manufacturer Part Number: MC13077
• Description: ADVANCED PAL/NTSC ENCODER
• Manufacturer: Motorola

Chroma Encoding
performed by two double–balanced mixers that are driven
from quadrature signals provided by an internal ring counter.
The quadrature signals are derived from a ring counter that is
driven by the 4x oscillator, and which makes highly accurate
quadrature angles possible.
is provided to both B–Y and R–Y components equally, then
the R–Y envelope phase is switched positive and negative
from line–to–line to provide the PAL alternating burst phase
characteristic. An internal flip–flop that provides the internal
f H /2 switching is enabled by opening the connection at
Pin 19. If enabled, the pin will exhibit the internally generated
half line frequency squarewave. If it is desired to reverse the
sense of the PAL swinging burst, it can be done at this pin by
pulling Pin 19 low when the squarewave is high. The
component envelopes with the proper PAL burst phase are
then modulated to produce the composite chroma.
difference component is provided a negative burst flag. This
envelope when modulated results in the characteristic –180
phase difference between the color burst and the subcarrier
for the B–Y component. Pin 19 should be grounded for NTSC
operation to disable the PAL flip–flop.
the versatility of the MC13077.
MOTOROLA ANALOG IC DEVICE DATA
Modulation of the color difference components is
If PAL encoding is selected, negative burst flag envelope
If the MC13077 is encoding to NTSC, only the B–Y color
Figures 8 through 13 are application examples showing
Figure 8. Standard Encoder Application with RGB Inputs and Phase–Locked Subcarrier
+5.0 V
1.1 k
1.0 F
20
1
4.7 n
19
2
Bandpass
Chroma
75
APPLICATIONS INFORMATION
18
3
75
17
MC13077
4
1.0
75
k
16
5
MC13077
10 n
10 n
Video Outputs
with the composite luma information for the Composite Video
output. The composite chroma and composite luma
components are also kept separate and buffered for the
chroma S–Video and luma S–Video outputs. The video
outputs are provided with low impedance emitter–follower
stages and, therefore, require an external 75
determining series resistor (see Figure 7). The outputs are
designed to drive a 75
series resistor.
(sync tip–to–peak chroma) for 100% saturated video at the
75
white) at the 75
provide 885 mVpp at the 75
After being filtered, the composite chroma is recombined
The Composite Video output will provide 1.23 Vpp of video
15
6
10 n
1.2 k
load. Luma S–Video will be 1.0 Vpp (sync tip–to–peak
1.0 k
7
MC13077
14
Figure 7. Composite S–Luma and
14.32/
1.0
17.73
20 p
Luma Delay
S–Chroma Video Outputs
13
load and the Chroma S–Video output will
8
1.0
75
12
9
1.0 n
1.0
load through the external 75
load.
11
10
Zo = 75
1.2 k
75
impedance
9