TDA4950
TV EAST/WEST CORRECTION CIRCUIT
October 1998
1
2
3
4
8
7
6
5
KEYSTONE CORRECTION INPUT
FRAME SAWTOOTH CURRENT INPUT
CURRENT REFERENCE
GND
NON-INVERTING INPUT 100
A CURRENT SINK
PARABOLA OUTPUT INVERTING INPUT
OUTPUT
+V
S
495
0-
01
.
E
P
S
PIN CONNECTIONS
POWERDIP8 (Th = 0.4mm)
(Plastic Package)
ORDER CODE : TDA4950
.
LOW DISSIPATION
.
SQUARE GENERATOR FOR PARABOLIC
CURRENT
.
EXTERNAL KEYSTONE ADJUSTMENT (sym-
metry of the parabola)
.
INPUT FOR DYNAMIC FIELD CORRECTION
(beam current change)
.
STATIC PICTURE WIDTH ADJUSTMENT
.
PULSE-WIDTH MODULATOR
.
FINAL STAGE D-CLASS WITH ENERGY RE-
DELIVERY
.
PARASITIC PARABOLA SUPPRESSION,
DURING FLYBACK TIME OF THE VERTICAL
SAWTOOTH
DESCRIPTION
The TDA4950 is a monolithic integrated circuit in a
8 pin minidip plastic package designed for use in
the east-west pin-cushion correction by driving a
diode modulator in TV and monitor applications.
1/5
4
5
6
7
8
Q15
Q16
Q14
Q18
Q17
R2
R4
D1
Q13
R5
OUTPUT
Q12
R6
R7
Q21
Q19
Q20
R8
R3
OP2
COMPARATOR AND OUTPUT STAGE
Q4
Q13
Q2
Q1
CURRENT LIMITER
R5
Q5
OP1
Q6
Q7
Q8
Q9
Q10
Q11
R9
R10
R11
R12
R13
2
1
OP3
D2
D3
Z1
Q22
3
FULL-WAVE RECTIFIER
PARABOLA NETWORK
CURRENT REFERENCE
GND
+V
S
I
IN
V
S
- 6 V
BE
V
S
- 3 V
BE
I
REF
V
REF
TDA4950
49
50
-
0
2
.
E
P
S
BLOCK DIAGRAM
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
V
S
Supply Voltage
35
V
I
S
Supply Current
500
mA
P
tot
Power Dissipation at T
amb
= 70
C
800
mW
T
stg
, T
j
Storage and Junction Temperature
25, +150
C
49
50
-
0
1
.
T
B
L
THERMAL DATA
Symbol
Parameter
Value
Unit
R
th (j-a)
Thermal Resistance Junction-ambient
Max.
100
C/W
R
th (j-c)
Thermal Resistance Junction-pin (4)
Max.
70
C/W
49
50
-
0
2.
T
B
L
ELECTRICAL CHARACTERISTICS (T
amb
= 25
o
C, V
S
= 26 V, V
fr
= 0, S1 and S2 in "a" position,
refer to test circuit unless otherwise specified)
Symbol
Parameter
Test Conditions
Min.
Typ.
Max.
Unit
V
S
Supply Voltage
17
24
30
V
I
S
Supply Current
4.5
7
mA
V
ref
Internal Reference Voltage
7.6
8.0
8.8
V
I
ref
Internal Reference Current
V
ref
/R3
0.73
mA
V
7(A)
Pin 7 Output Voltage
I
fr
= 0
A, see Figure 2
15.3
16.0
16.7
V
V
7(B)
Pin 7 Output Voltage
I
fr
= 30
A, see Figure 2
15
V
49
50
-
0
3
.
T
B
L
TDA4950
2/5
ELECTRICAL CHARACTERISTICS (T
amb
= 25
o
C, V
S
= 26 V, V
fr
= 0, S1 and S2 in "a" position,
refer to test circuit unless otherwise specified) (continued)
Symbol
Parameter
Test Conditions
Min.
Typ.
Max.
Unit
K1
Parabola Coefficient
K
1
=
V
7A
-
V
7B
V
7A
-
V
7C
, see Figure 2
0.28
K
2
Parabola Coefficient
K
2
=
V
7A
-
V
7C
V
7A
-
V
7D
, see Figure 2
0.71
V
7
(*)
V
7
= V
7E
V
7F
, see Figure 2
40
40
mV
I
8
Current Source
S1
b
100
A
V
SATL
Saturation Voltage
Io = 400 mA Sink
S2
b
1
2
V
V
SATH
Saturation Voltage
Io = 100 mA Source
S2
c S1
b
0.8
1.5
V
V
F
Forward Voltage
I
o
= 400 mA
S2
d S1
b
1.2
1.7
V
I
fr
Frame Sawtooth Current
V
fr
= 6.6 V
PP
66
A
49
50-
04
.
T
B
L
7
R7
R6
10k
10k
R2
R8
20k
a
b
S1
R3
11k
10k
R1
S2
a
b
c
d
TDA4950
V
S
V
F
V
SATH
I
O
V
SATL
I
F
-I
O
I
FR
V
REF
V
FR
6
5
8
4
3
1
2
4
9
5
0
-0
3
.
EPS
Figure 1 : Test CIrcuit
-60
0
15
30
36
60
V
7F
V
7A
V
7B
V
7C
V
7D
V
7E
V
7
(V)
I
FR
(
A)
4
9
5
0
-0
4
.
EPS
Figure 2 : Parabola Characteristics
CIRCUIT OPERATION
(see the shematic diagram)
A differential amplifier OP1 is driven by a vertical
frequency sawtooth current of
33
A which is
produced via an external resistor from the sawtooth
voltage. The non-inverting input of this amplifier is
connected with a reference voltage corresponding
to the DC level of the sawtooth voltage. This DC
voltage should be adjustable for the keystone cor-
rection. The rectified output current of this amplifier
drives the parabola network which provides a para-
bolic output current. This output current produces
the corresponding voltage due to the voltage drop
across the external resistor at pin 7.
If the input is overmodulated (> 40
A) the internal
current is limited to 40
A. This limitation can be
used for suppressing the parasitic parabolic current
generated during the flyback time of the frame
sawtooth.
A comparator OP2 is driven by the parabolic cur-
rent. The second input of the comparator is con-
nected with a horizontal frequency sawtooth
voltage the DC level of which can be changed by
the external circuitry for the adjustment of the pic-
ture width.
The horizontal frequency pulse-width modulated
output signal drives the final stage. It consists of a
class D push-pull output amplifier that drives, via
an external inductor, the diode modulator.
TDA4950
3/5
LM
5
TDA4950
R5
RT3
1k
Hfly
from L.T.
Keystone
Adj.
Line Transformer
(L.T.)
Pin 1
Voltage
H. Width
Pin-cushion
adjustment
L1
10mH
R3
RT2
4.7k
47k
7
2
1
3
4
8
6
C1
47nF
R4
18k
V
S
C2
100nF
D1
1N4148
C3
4.7nF
R2
12k
RT1
100k
R1 =
V
FRAME
66
A
PP
V
FRAME
49
50
-
0
5
.
E
P
S
Figure 3 : Application Circuit with Keystone Correction
HFLY
TO LM
GND
TDA4950
D1
C3
C1
R4
R3
L1
C2
RT2
RT1
R2
R1
R5
RT3
V
FRAME
V
S
4
9
5
0
-0
6
.
EPS
Figure 4 : P.C. Board and Component Layout of the Circuit of Figure 3 (1:1 scale)
TDA4950
4/5
P
M
-
D
I
P
8
.
EP
S
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC POWERDIP
Dimensions
Millimeters
Inches
Min.
Typ.
Max.
Min.
Typ.
Max.
A
3.3
0.130
a1
0.7
0.020
B
1.39
1.65
0.055
0.065
B1
0.91
1.04
0.036
0.041
b
0.5
0.020
b1
0.38
0.5
0.015
0.020
D
9.8
0.386
E
8.8
0.346
e
2.54
0.100
e3
7.62
0.300
e4
7.62
0.300
F
7.1
0.280
I
4.8
0.189
L
3.3
0.130
Z
0.44
1.6
0.017
0.063
D
I
P8
PW
.
T
BL
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consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from
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without express written approval of STMicroelectronics.
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1998 STMicroelectronics - All Rights Reserved
Purchase of I
2
C Components of STMicroelectronics, conveys a license under the Philips I
2
C Patent.
Rights to use these components in a I
2
C system, is granted provided that the system conforms to
the I
2
C Standard Specifications as defined by Philips.
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TDA4950
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