STMICROELECTRONICS TDA4950

TDA4950
TV EAST/WEST CORRECTION CIRCUIT
..
.
.
..
.
.
LOW DISSIPATION
SQUARE GENERATOR FOR PARABOLIC
CURRENT
EXTERNAL KEYSTONE ADJUSTMENT (symmetry of the parabola)
INPUT FOR DYNAMIC FIELD CORRECTION
(beam current change)
STATIC PICTURE WIDTH ADJUSTMENT
PULSE-WIDTH MODULATOR
FINAL STAGE D-CLASS WITH ENERGY REDELIVERY
PARASITIC PARABOLA SUPPRESSION,
DURING FLYBACK TIME OF THE VERTICAL
SAWTOOTH
POWERDIP8 (Th = 0.4mm)
(Plastic Package)
ORDER CODE : TDA4950
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.
PIN CONNECTIONS
1
8
NON-INVERTING INPUT 100µA CURRENT SINK
FRAME SAWTOOTH CURRENT INPUT
2
7
PARABOLA OUTPUT INVERTING INPUT
CURRENT REFERENCE
3
6
+VS
GND
4
5
OUTPUT
4950-01.EPS
KEYSTONE CORRECTION INPUT
October 1998
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TDA4950
BLOCK DIAGRAM
8
7
TDA4950
CURRENT LIMITER
COMPARATOR AND OUTPUT STAGE
Q14
6
+VS
5
OUTPUT
4
GND
Q15
Q16
Q1
Q13
VS - 3 VBE
VREF
Q4
Q2
R2
Q13
Q17
D1
Q18
R5
R4
R3
OP2
R6
Q12
Q19
R5
Q20
R7
Q21
OP1
1
R8
Q5
2
IIN
VS - 6 VBE
IREF
OP3
Q11
Q6
Q22
D2
Q10
D3
Q8
Q9
Z1
R9
R10
R11
R12
R13
CURRENT REFERENCE
PARABOLA NETWORK
FULL-WAVE RECTIFIER
4950-02.EPS
Q7
3
Symbol
VS
IS
Ptot
Tstg, Tj
Parameter
Supply Voltage
Supply Current
Power Dissipation at Tamb = 70 °C
Storage and Junction Temperature
Value
35
500
800
– 25, +150
Unit
V
mA
mW
°C
Value
100
70
Unit
°C/W
°C/W
4950-01.TBL
ABSOLUTE MAXIMUM RATINGS
Symbol
Rth (j-a)
Rth (j-c)
Parameter
Thermal Resistance Junction-ambient
Thermal Resistance Junction-pin (4)
Max.
Max.
4950-02.TBL
THERMAL DATA
Symbol
VS
IS
Vref
– Iref
V7(A)
V7(B)
2/5
Parameter
Supply Voltage
Supply Current
Internal Reference Voltage
Internal Reference Current
Pin 7 Output Voltage
Pin 7 Output Voltage
Test Conditions
Min.
17
7.6
Vref/R3
Ifr = 0 µA, see Figure 2
Ifr = 30 µA, see Figure 2
15.3
Typ.
24
4.5
8.0
0.73
16.0
15
Max.
30
7
8.8
16.7
Unit
V
mA
V
mA
V
V
4950-03.TBL
ELECTRICAL CHARACTERISTICS (Tamb = 25oC, VS = 26 V, Vfr = 0, S1 and S2 in "a" position,
refer to test circuit unless otherwise specified)
TDA4950
ELECTRICAL CHARACTERISTICS (Tamb = 25oC, VS = 26 V, Vfr = 0, S1 and S2 in "a" position,
refer to test circuit unless otherwise specified) (continued)
Parameter
Parabola Coefficient
K2
Parabola Coefficient
∆V7 (*)
I8
VSATL
VSATH
VF
Ifr
Test Conditions
V7A − V7B
, see Figure 2
K1 =
V7A − V7C
V7A − V7C
, see Figure 2
K2 =
V7A − V7D
∆V7 = V7E – V7F, see Figure 2
S1 → b
Io = 400 mA Sink
S2 → b
Io = 100 mA Source S2 → c S1 → b
Io = 400 mA
S2 → d S1 → b
Vfr = 6.6 VPP
Current Source
Saturation Voltage
Saturation Voltage
Forward Voltage
Frame Sawtooth Current
Min.
Typ.
0.28
Max.
Unit
40
mV
µA
V
V
V
µA
0.71
– 40
100
1
0.8
1.2
66
2
1.5
1.7
4950-04.TBL
Symbol
K1
Figure 1 : Test CIrcuit
VS
R7
R6
10kΩ
IFR
10kΩ
7
VF
6
VSATH
a
2
R2
VFR
S2
TDA4950
1
b
5
c
R1
d
3
10kΩ
R3
11kΩ
IO
4
VREF
8
IF
-IO
VSATL
4950-03.EPS
R8
20kΩ
b
a
S1
Figure 2 : Parabola Characteristics
V7 (V)
V7A
V7B
V7C
V7E
V7F
-60
0
15
36
30
60
IFR (µA)
CIRCUIT OPERATION
(see the shematic diagram)
A differential amplifier OP1 is driven by a vertical
frequency sawtooth current of ± 33µA 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
4950-04.EPS
V7D
to the DC level of the sawtooth voltage. This DC
voltage should be adjustable for the keystone correction. The rectified output current of this amplifier
drives the parabola network which provides a parabolic 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 (> 40µA) the internal
current is limited to 40µA. 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 current. The second input of the comparator is connected with a horizontal frequency sawtooth
voltage the DC level of which can be changed by
the external circuitry for the adjustment of the picture 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.
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TDA4950
Figure 3 : Application Circuit with Keystone Correction
Line Transformer
(L.T.)
L1
10mH
LM
Pin-cushion
adjustment
R3
RT2
4.7kΩ
R4
18kΩ
7
C1
47nF
2
TDA4950
6
VS
C2
100nF
1
3
4
RT1
8
C3
4.7nF
R2
12kΩ
Keystone 100kΩ
Adj.
D1
1N4148
1kΩ
Hfly
from L.T.
H. Width
R5
RT3
4950-05.EPS
VFRAME
Pin 1
Voltage
47kΩ
5
VFRAME
R1 =
66µAPP
Figure 4 : P.C. Board and Component Layout of the Circuit of Figure 3 (1:1 scale)
RT3
D1
R5
C3
R1
VFRAME
RT1
TDA4950
HFLY
R4
C2
VS
RT2
GND
4/5
L1
R2
R3
4950-06.EPS
TO LM
C1
TDA4950
PM-DIP8.EPS
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC POWERDIP
A
a1
B
B1
b
b1
D
E
e
e3
e4
F
I
L
Z
Min.
Millimeters
Typ.
3.3
0.7
1.39
0.91
Max.
Min.
1.65
1.04
0.020
0.055
0.036
0.5
0.38
Inches
Typ.
0.130
0.065
0.041
0.020
0.5
9.8
0.015
8.8
2.54
7.62
7.62
0.020
0.386
0.346
0.100
0.300
0.300
7.1
4.8
0.280
0.189
3.3
0.44
Max.
DIP8PW.TBL
Dimensions
0.130
1.6
0.017
0.063
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the
consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from
its use. No licence is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications
mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information
previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems
without express written approval of STMicroelectronics.
The ST logo is a registered trademark of STMicroelectronics
© 1998 STMicroelectronics - All Rights Reserved
Purchase of I2C Components of STMicroelectronics, conveys a license under the Philips I2C Patent.
Rights to use these components in a I2C system, is granted provided that the system conforms to
the I2C Standard Specifications as defined by Philips.
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