TCL SERVICE MANUAL - Tecnicosaurios

More documents

Recommendations

Info

STV8172A Application Hints 4 Application Hints The yoke can be coupled either in AC or DC. 4.1 DC-coupled Application When DC coupled (see Figure 4), the display vertical position can be adjusted with input bias. On the other hand, 2 supply sources (V S and -V EE ) are required. A Stand-by state will be reached by switching OFF the positive supply alone. In this state, where both inputs are the same voltage as pin 2 or higher, the output will sink negligible current from the deviation coil. Figure 4: DC-coupled Application 470µF 0.1µF C F (47 to 100µF) +Vs Output Voltage Vref Power Amplifier Vertical Position Adjustment 7 + 1 - V R3 M V m -V EE 6 4 3 2 Flyback Generator Thermal Safety 5 1.5 0.22µF Output Current Rd(*) I p Yoke Ly 470µF 0.1µF R2 R1 (*) recommended: Ly Ly ------------- < R d < ------------- 50s 20s 4.1.1 Application Hints For calculations, treat the IC as an op-amp, where the feedback loop maintains V 1 = V 7 . STMicroelectronics Confidential 5/14
Application Hints STV8172A 4.1.1.1 Centering Display will be centered (null mean current in yoke) when voltage on pin 7 is (R 1 is negligible): V M + V m R 2 V 7 = ------------------------ --------------------- 2 R 2 + R 3 4.1.1.2 Peak Current V M – V m R 2 I P = ---------------------------- ------------------ 2 R xR 1 3 Example: for V m =2V, V M = 5 V and I P =1A Choose R 1 in the1 range, for instance R 1 =1 From equation of peak current: R 2 ------- R 3 = 2 I P R 1 ---------------------------- = V M – V m 2 -- 3 Then choose R 2 or R 3 . For instance, if R 2 = 10 k, then R 3 = 15 k Finally, the bias voltage on pin 7 should be: 4.1.2 Ripple Rejection V M + V m 1 V 7 = ------------------------ ----------------- = 2 R 3 1 + ------- R 2 When both ramp signal and bias are provided by the same driver IC, you can gain natural rejection of any ripple caused by a voltage drop in the ground (see Figure 5), if you manage to apply the same fraction of ripple voltage to both booster inputs. For that purpose, arrange an intermediate point in the bias resistor bridge, such that (R 8 / R 7 ) = (R 3 / R 2 ), and connect the bias filtering capacitor between the intermediate point and the local driver ground. Of course, R 7 should be connected to the booster reference point, which is the ground side of R 1 . 7 --- 2 Figure 5: Ripple Rejection 1 ------- = 1.4V 2.5 Reference Voltage 6 Power Amplifier 3 2 Flyback Generator 7 + R 9 R 8 R 7 5 1 - Thermal Safety Rd Yoke Ly 4 Ramp Signal R 3 R 2 R 1 Driver Ground Source of Ripple 6/14 STMicroelectronics Confidential
Page 1 and 2:
TCL SERVICE MANUAL NX56LA 1、 Caut
Page 3 and 4: IMPORTANT SAFETY INSTRUCTIONS CAUTI
Page 5 and 6: OPERATION OF YOUR SET 18. This tele
Page 7 and 8: TTE Corporation R&D Center (Shen’
Page 9 and 10: TTE Corporation R D Center (Shen’
Page 11 and 12: TTE Corporation R D Center (Shen’
Page 13 and 14: TCL-THOMSON Electronics R&D Center
Page 25 and 26: Chapter II Block Diagram of NX56 Ju
Page 27 and 28: RF Section Tuner Tu101 receive the
Page 29 and 30: (Fig3. Block Diagram of IC201.) Hor
Page 31: Audio Power Amplifying Section Powe
Page 40 and 41: UOC-TOP-64 N1 series Versatile sign
Page 42 and 43: NXP Semiconductors UOC-TOP-64 N1 se
Page 50 and 51: ® STV8172A Vertical Deflection Boo
Page 52 and 53: STV8172A Electrical Characteristics
Page 56 and 57: STV8172A Application Hints 4.2 AC-C
show all

TCL SERVICE MANUAL - Tecnicosaurios

Create successful ePaper yourself

Delete template?

Save as template?