TEA2029 STMICROELECTRONICS [STMicroelectronics], TEA2029 Datasheet - Page 28

• Manufacturer Part Number: TEA2029
• Description: APPLICATION NOTE
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

TEA2028 - TEA2029 APPLICATION NOTE
Figure 54
V.6.2.1 - 60Hz STANDARD SWITCHING
The NTSC standard requires a vertical picture
scanning frequencyof 60Hz, i.e. a saw-tooth period
of 16.66ms.
In order to obtain an identical deflection amplitude
whatever the standard (50 or 60Hz), the saw-tooth
amplitude for both periods must be the same.
60Hz standard recognition is performed automat-
ically by the frame logic block, which will issue a
signal to drive a current generator ” I
current will be summed with the external charge
current and will increase the saw-tooth slope, so as
to yield same saw-tooth amplitude to that set in
50Hz standard. This current is centered around
14 A and is a fraction of I
Employing the recommended component values
for network connected to Pin 5, this current will
result in identical amplitude in both standards.
Figure 56 : Block Diagram
28/46
V
5
1.26V
(
V
I
60
4.4V
REF
64 s
V
Frame Sync.
C
Frame Blanking
Extracted
3
)
5
T
FRI Inhibition
60
( 1)
I
DIGITAL SYNC.
DIRECT SYNC.
50
C
VCR
OR
5
20ms (50Hz)
T
50
MISCELLANEOUS
REF
FUNCTIONS
I
60
Recognition
Sync.
(Mute)
applied to Pin 14.
Video
H/2 (32 s)
I
FREE-RUNNING
50
FREQUENCY
&
PULSES
60
50
VCR
Sync. Window
Q1
&
60
1.2
”. This
BINARY DIVIDERS
t
GENERATOR
64 s
f
WINDOW
I
60Hz
50
SYNC
Sync.
1
2 s
&
&
I
therefore I
V.6.3 - Functions of frame logic block
This section is fully implemented by I
It is clocked by an accurate ”H/2” clock running at
half line period (32 s). The required periods and
time intervals are obtained by counting the clock
pulses.
For the sake of clarity, timing signals so obtained
are labeled by the line number corresponding to
video signal.
The time corresponding to ”x” scanned lines with
respect to the beginning of frame saw-tooth (RE-
SET) is therefore :
Figure 55
f
Reset
50
50Hz
Q10
2-bit Register
R
E
Reset
5
3-bit Register
(50Hz)
32.768ms
DISCHARGE
FLIP-FLOP
(60Hz)
2.7M
SYNC.
RESET
(Counter)
H/2
FRAME
SAWTOOTH
(Pin 3)
200V
60
= 14 A
t
x
= 64 s (x - 1) + 32 s
48 s (VCR)
74 A
64 s or
L625
32 s
I
60
L1
50/60Hz
Identification
88 A
Control
Sawtooth Generator
Capacitor Discharge
I
60
L1
tx
L2
2
L logic gates.
LX
L2