SGS Thomson Microelectronics TDA4950 Datasheet

TV EAST/WEST CORRECTION CIRCUIT

.

LOW DISSIPATION

.

SQUARE GENERATOR FOR PARABOLIC
CURRENT

.

EXTERNA L KEYSTONE AD JUST MENT (sym ­metry of the parabola)

.

INPUT FOR DYNAMIC FIELD CORRECTION
(beam current change)

.

ST ATIC P ICTURE WI DTH A DJ USTM ENT

.

PULSE-WIDTH MODULATOR

.

FINAL STAGE D-C LASS WITH EN ERGY RE­DELIVERY

.

PARASITIC PARABOLA SUPPRESSION,
DURIN G FLYBACK TIME OF TH E VERTICAL
SAWTOOTH

POWERDIP8

(Plastic Package)

TDA4950

(Th = 0.4mm)

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

KEYSTONE CORRECTION INPUT

FRAME SAWTOOTH CURRENT INPUT

CURRENT REFERENCE

GND

1
2
3
4

ORDER CODE :

8

NON-INVERTING INPUT 100

7

PARABOLA OUTPUT INVERTING INPUT
+V

6
5

S

OUTPUT

TDA4950

µ

A CURRENT SINK

October 1998

4950-01.EPS

1/5

TDA4950

BLOCK DIAGRAM

TDA4950

1

2

I

IN

VS - 3 V

Q7

CURRENT LIMITER

BE

OP1

VS - 6 V

BE

Q1

Q2

R5

Q5

Q6

Q8 Q9

Q4Q13

Q10

7

R9

8

COMPARATOR AND OUTPUT STAGE

V

OP2

Q11

R10 R11 R12 R13

+V

6

S

Q14

Q13

REF

R5

R6

Q12

R7

R2

Q21

D2
D3

Z1

Q15

Q16

Q20

Q22

D1

5

OUTPUT

I

REF

4

GND

Q18Q17

R3

R4

Q19

R8

OP3

FULL-WAVE RECTIFIER

PARABOLA NETWORK

CURRENT REFERENCE

3

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

I

S

P

tot

, TjStorage and Junction Temperature – 25, +150

T

stg

Supply Voltage 35 V

S

Supply Current 500 mA
Power Dissipation at T

= 70 °C 800 mW

amb

THERMAL DATA

Symbol Parameter Value Unit

R

th (j-a)

R

th (j-c)

ELECTRICAL CHARACTERISTICS

Thermal Resistance Junction-ambient Max. 100
Thermal Resistance Junction-pin (4) Max. 70

= 25oC, VS = 26 V, V

(T

amb

= 0, S1 and S2 in "a" position,

fr

refer to test circuit unless otherwise specified)

Symbol Parameter Test Conditions Min. Typ. Max. Unit

– I
V
V

V

I

S

V

ref

7(A)
7(B)

Supply Voltage 17 24 30 V

S

Supply Current 4.5 7 mA
Internal Reference Voltage 7.6 8.0 8.8 V
Internal Reference Current V

ref

/R3 0.73 mA

ref

Pin 7 Output Voltage Ifr = 0 µA, see Figure 2 15.3 16.0 16.7 V
Pin 7 Output Voltage Ifr = 30 µA, see Figure 2 15 V

°

°

C/W

°

C/W

4950-02.EPS

C

4950-01.TBL

4950-02.TBL

4950-03.TBL

2/5

TDA4950

ELECTRICAL CHARACTERISTICS

= 25oC, VS = 26 V, V

(T

amb

= 0, S1 and S2 in "a" position,

fr

refer to test circuit unless otherwise specified) (continued)

Symbol Parameter Test Conditions Min. Typ. Max. Unit

K1 Parabola Coefficient

K

∆

V

7

I

8

V

SATL

V

SATH

V

I

fr

Figure 1 :

Parabola Coefficient

2

(*)

Current Source S1 → b 100
Saturation Voltage Io = 400 mA Sink S2 → b12V
Saturation Voltage Io = 100 mA Source S2 → cS1 → b 0.8 1.5 V
Forward Voltage Io = 400 mA S2 → dS1 → b 1.2 1.7 V

F

Frame Sawtooth Current Vfr = 6.6 V

Test CIrcuit

V

FR

10k

R1

11k

V

− V

7A

V7A − V
V

− V

7A

V7A − V

PP

7

TDA4950

7B

, see Figure 2

7C
7C

, see Figure 2

7D

V

S

6

84

R8
20k

V

F

5

Ω

V

SATH

a

S2

I

F

b
c

d

-I

O

=

K

1

=

K

2

∆

V7 = V7E – V7F, see Figure 2 – 40 40 mV

R7 R6

10kΩ 10kΩ

I

FR

2

R2

1

Ω

R3

Ω

3

V

REF

V

I

O

SATL

0.28

0.71

66

µ

A

µ

A

4950-04.TBL

Figure 2 :

V

7E

Parabola Characteristics

V7 (V)

V

7A

V

-60 0 15 30

7B

V

7C

V

7D

V

7F

36

60

I

(µA)

FR

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

b

a

S1

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 paras itic parabolic current
generated during the flyback time of the frame
sawtooth.
A comparator OP2 is driven by the parabolic cur-

4950-04.EPS

rent. 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.

4950-03.EPS

3/5

TDA4950

Figure 3 :

Pin 1
Voltage

Application Circuit with Keystone Correction

Line Transformer

V

FRAME

R1 =

66µA

PP

V

FRAME

2

1

(L.T.)

LM

L1
10mH

R3 RT2

4.7k

5

TDA4950

Pin-cushion

adjustment

Ω

47k

Ω

7

R4
18k

6

C2

C1
47nF

Ω

V

S

100nF

Figure 4 :

3 4 8

C3

4.7nF

Keystone

RT1

100k

R2
12k

Ω

Ω

Adj.

Hfly
from L.T.

R5 RT3

P.C. Board and Component Layout of the Circuit of Figure 3 (1:1 scale)

HFLY

V

FRAME

GND

TO LM

RT3

R5

R1

TDA4950

RT1

V

S

R2

C2

RT2

L1

D1

C3

C1

R4

R3

D1
1N4148

1k

Ω

H. Width

4950-05.EPS

4/5

4950-06.EPS

TDA4950

PACKAGE MECHANICAL DATA

8 PINS - PLASTIC POWERDIP

Dimensions

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

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© 1998 STMicroelectronics - All Rights Reserved

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5/5

PM-DIP8.EPS

DIP8PW.TBL