![](http://datasheet.mmic.net.cn/370000/GS9010A_datasheet_16694373/GS9010A_4.png)
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PAL/NTSC THRESHOLD ADJUST
To adjust the P/N threshold using a potentiometer, monitor the
OUT voltage at pin 2 of the GS9010A. Start with a composite
NTSC source, and record the voltage at pin 2 as V
NTSC
. Now
connect a PAL source to the input and record the voltage at pin
2 as V
PAL
. Adjust the reference voltage, V
REF
at pin 16 to a value
approximately halfway between V
PAL
and V
NTSC
, i.e. V
REF
=
(V
NTSC
+ V
PAL
)/2. The P/N threshold will now be set.
Gating of the HSYNC input is available on the SWF pin. This
gating is used with the GS9010A to improve immunity to
missing TRS detection during power-up or in noisy system
applications.
Capacitor values for the GS9010A should be used as indicated
in Figure 3. These capacitors have been optimised to
produce correct system operation.
GS9010 REPLACEMENT NOTE:
To ensure proper operation of the GS9010A, the resistor
network connected between the GS9010A OUT (pin 2) and
GS9005A R
VCO3
(pin 17), and the value of FVCAP (pin 9) must
be as per this data sheet (Figure 3). Replacing a GS9010 with
a GS9010A will require modification to these component
values.
RE-TIMED DATA
RECOVERED CLOCK
RVCO
1k2
1k2
100nF
120
THRESHOLD
ADJUST
SERIAL
DATA IN
2
1
13
8
HSYNC
V
REF
C
INT
20k
SWF
+
-
OSCILLATOR
COMPOSITE /
COMPONENT
DETECTOR
PAL/NTSC
÷
4
5
14
LOOP
FILTER
6
16
+5V
MODULUS
CONTROL
/2
CARRIER
DETECT
GS9005A/GS9015A
GS9000B/GS9000S
GS9010A
SERIAL
DIGITAL
PLL
DIGITAL
VIDEO
DECODER
+
-
18k
25k
All resistors in ohms, all capacitors in microfarads unless otherwise stated.
Fig. 1 Automatic Tuning Sub System Block Diagram