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 1/5 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. 3/5 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. 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