SL5067DPAS GEC [General Electric Company], SL5067DPAS Datasheet - Page 4

• Manufacturer Part Number: SL5067DPAS
• Description: MULTI - STANDARD VIDEO MODULATOR
• Manufacturer: GEC [General Electric Company]

SL5067
VIDEO
(see Fig.9). This capacitor provides both clamping and black
level hold. The internal peak white AGC can cope with an input
signal of between 0.5 and 1.5 volts peak to peak.The full 9.5
dB AGC range is handled within a 600mV span on this storage
capacitor.
amplitude and video polarity, see Fig. 3. Since the video input
is internally AGC’d, varying the carrier amplitude will also
adjust the video modulation index, see Fig. 4.
an 80% modulation index, pin 3 should be set to 1.1Volts (see
Fig. 4). This voltage corresponds to an unmodulated RF
output level of 82dB
AUDIO
6.5MHz to cover all sound standards. The centre frequency is
determined by the Sound IF Tank LC connected between pins
15 and 16.
The centre frequency is given by.
The video signal is applied to pin 4 via a coupling capacitor,
Pin 3 (MOD INDEX) is used to control both RF carrier
For example, for a negative modulation (PAL or NTSC) with
The sound IF oscillator can operate from 4.5MHz to
The Q factor of the TANK is given by.
f
Q
0
+
+
1770
2
2
p
p
f
1
0
L
LC
+
m
80dB
V, see Fig. 3.
1770
m
V
77
87
85
83
81
79
2
0.0
p
f
0
C
Fig. 4. Picture carrier, unmodulated RF output level
1.0
1.4
VOLTAGE SET ON PIN 3
2.0
2.45
The Q factor of the coil must be high, e.g. >20
choice of temperature coefficients for C
MODULATED RF OUTPUT
open collectors which should be externally connected to V
via 75
decoupling of the supply to these outputs.
connection to a balun or impedance matching transformer.
coupling, thus giving improved RF performance.
capacitor. The maximum input level is 1 volts peak to peak.
(FMAMSEL). The DC value on this pin controls the level of the
sound subcarrier. The crossover point between FM and AM
sound occurs at
voltage, the modulator is set to FM sound; above it to AM.
Graphs for AM and FM sound subcarrier output levels are
shown in Figs. 6 and 7.
modulated carrier is fed into the Audio input. Further details of
this are mentioned at the end of the datasheet in the paragraph
marked ‘‘Positive Modulation”
Good temperature stability can be achieved by the correct
The Audio signal should be coupled into pin 17 via a 470nF
Selection of AM or FM sound is made via pin 18
If AM sound is required, it is recommended that a
The modulated RF outputs from pin 1 and pin 2 consist of
Both outputs are suitable for driving either 75
This has the added benefit of minimising common mode
3.0
W
resistors. Great care must be taken with the
½
4.0
V
CC
(measured at pin 18). Below this
5.0
sound
and L
W
line, or for
sound
.
CC