TDA9103 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'TDA9103' PDF : 27 Pages View PDF
TDA9103
PARABOLA GENERATION FOR EAST-WEST
CORRECTION (see Figure 21)
Starting from the vertical ramp a parabola is gen-
erated for E/W correction.
The core of the parabola generator is an analog
multiplier which generates a current in the form :
I = k (VRAMP - VMID)2
Where VRAMP is the vertical ramp, typically com-
prised between 2 and 5V, VMID is a DC voltage with
a nominal value of 3.5V, but adjustable in the range
3.2V → 3.8V in order to generate a dissymmetric
parabola if required (keystone adjustment).
The current is converted into voltage through a
variable gain transresistance amplifier. The gain,
controlled by the voltage on Pin 37 (E/W-AMP) can
be adjusted in the ratio 3/1.
The parabola is available on Pin 36 by the way of
an emitter follower which has to be biased by an
external resistor (10kΩ). It must be AC coupled with
external circuitry.
The typical parabola amplitude (AC), with the DC
Figure 21 : Parabola Generation Principle
control voltages V37 and V38 set to 4V, is 2V.
It is important to note that the parasitic parabola
during the discharge of the vertical oscillator ca-
pacitor is suppressed.
VERTICAL PART (see Figure 22)
The vertical part generates a fixed amplitude ramp
which can be affected by a S correction shape.
Then, the amplitude of this ramp is adjusted to drive
an external power stage.
The internal reference voltage used for the vertical
part is available between Pin 26 and Pin 24. It can
be used as voltage reference for any DC adjusment
to keep a high accuracy to each adjustment. Its
typical value is :
V26 = VREF = 8V.
The charge of the external capacitor on Pin 27
(VCAP) generates a fixed amplitude ramp between
the internal voltages, VL (VL = VREF/4) and VH
(VH = 5/8 ⋅ VREF).
Analog.
Multiplier
+
I
Vertical Ramp
or
38
E/W-CENT
36
37
E/W-AMP
Figure 22 : Vertical Part Block Diagram
V-SYNC 34
SYNCHRO
Charge Current
R
19R
VREF
Disch. 27
OSCIL
Osc
Cap
Transconductance
Amplifier
VREF
25
Sampling
Cap
Parabola
Generator
38
KEYST
36 EW-OUT
37
EW-AMP
29 S-CENTER
28 S-AMP
S Correction
30 VERT-OUT
31
VERT-AMP
17/27
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