
MC44002 MC44007
28
MOTOROLA ANALOG IC DEVICE DATA
PIN FUNCTION DESCRIPTION (continued)
Pin
Description
Equivalent Internal Circuit
32
33
Gnd
VCC
To Pin 1
MC44140
400
14.3 MHz
17.7 MHz
22 p
22 p
120 p
32
33
20
μ
A
Crystals (Respectively 14.3 MHz and 17.7 MHz)
Drive for externally fitted crystal clock reference for PAL, SECAM or
NTSC. Four times Fsc is used. If the NTSC system is not going to be
received, the 14.3 MHz crystal may be omitted. The crystal is parallel
driven from a single pin and it requires a series load capacitance of
appropriate value (usually 20 to 30 pF). Only crystals intended for
VCO use should be fitted. The reference frequency is divided down in
a capacitor chain to provide about 50 mV of clock reference for the
MC44140.
Positions for Pins 32 and 33 are selected by software.
34
35
5.0 V Supply (35) and Ground (34)
Supply line, nominally 5.0 V, requiring about 120 mA. The actual
voltage should be in the range of 4.75 to 5.25 V for usable results. It is
recommended to decouple the supply line using a small ceramic
capacitor mounted close to the supply and ground pins.
36
37
VCC
Gnd
1.0
μ
100 n
To MC44140
B–Y and R–Y Outputs
Demodulated color difference outputs. These signals are ac coupled
to the MC44140 for correction and delay with PAL and SECAM
respectively. Signal level of about 1.4 Vpp may be expected on B–Y
output when using a standard 75% color bars input video signal.
38
VCC
Gnd
0.047
3.0 k
Identification
External filter used by R–Y identification circuit. The filter normally
consists of a single capacitor whose value is a compromise between
rapid identification and noise rejection. Experience has shown that
0.047
μ
F is a suitable value.
39
VCC
Gnd
0.047
50 k
50 k
Oscillator Loop Filter
External time constant for chroma PLL. The crystal reference
oscillator is phase locked to the incoming burst in PAL and NTSC. A
low value ceramic capacitor, for good noise immunity, is normally
placed in parallel with a much longer RC time constant. The PLL
pull–in range is reduced when the time constant on the pin is made
bigger, allowing this function to be optimized by the user.