TEA2029 STMICROELECTRONICS [STMicroelectronics], TEA2029 Datasheet - Page 16

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

TEA2028 - TEA2029 APPLICATION NOTE
It is therefore deduced that the system can follow
all input phase variations without producing any
static error.
In practice, there will be a slight error due to the
input bias current ”I
f
phase comparator which will generate a phase
error of :
- long time constant :
- short time constant :
These two errors cause a horizontal picture dis-
placement. On a large screen of 54cm wide, this
will be : 64 - 12 = 52 s, which for both modes
corresponds to a shift of :
It is obvious that such displacement can be fully
neglected.
Response to a Frequency Step
- The input phase is :
- The accuracy is :
In this case, the phase error depends on both, the
magnitude of the frequency step and the static gain
ABR.
In general,
taken into consideration.
- In normal mode : A
16/46
O
p
= 3.4 10
which as a function of (p) is :
lim
where R = 500k at f(o)
= 500kHz. This DC current is delivered by a
0
= ABR =
f
t
LONG
LINE
= AB’R
f
t
IN
= 5.5kHz/ s, R = 500k
=
=
-3
A
f
f
rd or 35ns in t
OUT
LONG
which is the open-loop static gain, is
I
2
LONG
t
2
T
B
H
2
(B’ in kHz/V)
f
= 0.55
52
B
p 0
lim
LONG
” of VCO, which is 0.55 A at
= A 2
IN
SHORT
p
(t) =
SHORT
= 0.16 mA/rd
10
0.16
ABf
3
B’ R
520 = 0.24mm
=
IN
o
t
(p) =
A
SHORT
I
ABR
B
p
2
= 12ns
- In VCR mode : A
Note : The capture range is specified within
Numerical Example
Let’s suppose that in VCR mode there is a fre-
quency variation of
variation of 0.1/16.5, i.e.
wide screen, will produce a horizontal shift of
It is obvious that an excellent image stability is thus
obtained.
V.3.6.2 - Dynamic study
The loop response in transient mode is quite im-
portant. It determines the overall system stability
and the phase recovery time, which are imposed
by the external filter ”f(p)”.
The close-loop transfer function is equivalent to a
second order system. These time constants are in
practice displayed on screen by a bar delivered by
a special pattern generator representing the phase
errors.
The following optimizedresults were obtained from
filter f(p) connected to Pin 22.
Filter component values are :
R1 = 4.7k , C1 = 2.2 F, C = 10nF
A. LONG TIME CONSTANT
- At t of 4 s
B. SHORT TIME CONSTANT
- At t = 4 s
- n = 5 lines
One should notice fast phase recovery, naturally
followed by bounced oscillations due to the char-
acteristics of a second order device.
As given in application diagram section 6, an other
alternative would be to use the following compo-
nent values : R1 = 3.9k , C1 = 4.7 F, C = 15nF.
LINE
System oscillations are perfectly damped. Image
stability with a noisy video signal is very satisfac-
tory.
500Hz with respect to 15625Hz.
=
f
t
= 16.5kHz/ s
0.06mm !
N = 5 lines, i.e.
N=18 lines, i.e.
SHORT
100Hz, this will yield a phase
= 0.47 mA/rd
6ns which, on a 54cm
SHORT
LONG
= 0.32ms
= 1.15ms.