GTV1000 AN98051 TDA884X P83C053 TDA8351/56 PR31602 TDA8380A TDA8846/47

The GTV1000 Global TV Receiver AN98051 QuvyvÃTr vpqp The GTV1000 Global TV Receiver Application Note AN98051 Abstract The

APPLICATION NOTE The GTV1000 GTV1000 Global TV Receiver AN98051 AN98051 QuvyvÃTr vpqp The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 Abstract The GTV1000 GTV1000 receiver has been designed around the TDA884X TDA884X TV signal processor. The large signal part is suited for 90° picture tubes and build on one board with the small signal part. The board design is such that it can easily be adapted for use in the following markets: USA, South America, Europe and most of the Far East countries. The board can be fitted with different external AV connectors and sound modules. When a video processor with YUV interface is used, it is possible to insert feature modules. The GTV1000 GTV1000 was designed as a demonstration receiver and has been tested on picture, sound and EMC performance, but has not been released for production. Purchase of Philips I2C components conveys a license under the Philips I2C patent to use the components in the I2C system, provided the system conforms to the I2C specifications defined by Philips. " Philips Electronics N.V. 1999 All rights are reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. No liability will be accepted by the publisher for any consequence of its use. Publication thereof does not convey nor imply any license under patent- or other industrial or intellectual property rights. 2 QuvyvÃTr vpqp The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 APPLICATION NOTE The GTV1000 GTV1000 Global TV Receiver AN98051 AN98051 Author(s) Ton Hummelink Ton Smits Philips Semiconductors Systems Laboratory Eindhoven, The Netherlands Keywords TDA884X TDA884X Low-end TV receiver for 90 ° picture tube Global concept PAL/SECAM/NTSC external CVBS, Y/C and RGB inputs Number of pages: 76 Date: 27-01-1999 3 QuvyvÃTr vpqp The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 Summary This application note describes the GTV1000 GTV1000 global demonstration colour TV receiver, which is based on a TDA884X TDA884X "one chip" TV processor. The global concept allows the board to be adapted to the TV standards in different countries all over the world by adding or changing components and connecting or disconnecting solder jumpers. The micro controller socket is suited for use of non-text micro controllers as well as types with integrated text and types with integrated close caption. The board contains the small signal part, control and all the large signal circuitry to drive a 90° picture tube. On the board connectors are available to insert the different types of external input signal connectors needed in the different areas. The basic board is equipped with mono FM sound, but two connectors are available to add AM sound or different stereo options corresponding to the desired area of use. In case of stereo, a stereo power amplifier can be added on the main board. In case a video processor type with YUV interface is used, a YUV connector can be mounted where picture improvement options can be inserted. On the board leaded components are used. 4 QuvyvÃTrvpqp The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 TABLE OF CONTENTS 1. INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2. SMALL SIGNAL. . . . . . . . . . . . . . . . . . . . . 2.1 TV processor TDA884X TDA884X. . . . . . . . . . . . . . 2.2 Functional description of the small signal part. . 2.2.1 Tuner and IF circuit. . . . . . . . . . 2.2.2 Intercarrier sound and sound options. 2.2.3 CVBS path. . . . . . . . . . . . . . . 2.2.4 RGB input/switch. . . . . . . . . . . 2.2.5 Colour decoder. . . . . . . . . . . . 2.2.6 YUV interface. . . . . . . . . . . . . 2.2.7 RGB outputs & CRT board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 . 11 . 15 . 16 . 18 . 21 . 23 . 24 . 26 . 26 3. MICRO CONTROLLER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Universal micro controller interface description. . . . . . . . . . . . . 3.2 VST-Tuning voltage control output (Micro-controller pin1 application). 3.3 Service connector and Factory mode. . . . . . . . . . . . . . . . . . 3.4 Standby command line "On_Off". . . . . . . . . . . . . . . . . . . . 3.5 OSD outputs FBL, R, G and B. . . . . . . . . . . . . . . . . . . . . 3.6 I2C-bus control input/outputs SDA, SCL, SDA1 and SCL1. . . . . . . 3.7 Reset and supply-voltage-guard circuit. . . . . . . . . . . . . . . . . 3.8 Micro hardware environment configuration. . . . . . . . . . . . . . . 3.8.1 Stereo-playback hardware configuration. . . . . . . . . . 3.8.2 P83C053 P83C053 (MTV) Micro controller configuration. . . . . . . 3.8.3 P83Cx66 Micro controller configuration. . . . . . . . . . . 3.8.4 P83Cx70 Micro controller configuration. . . . . . . . . . . 3.8.5 SAA549x (ETT) Micro controller configuration. . . . . . . 3.9 Software package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 . 27 .28 . 29 . 29 . 29 . 29 . 30 . 31 . 31 . 32 . 33 . 34 . 35 . 35 4. LARGE SIGNAL. . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Power supply. . . . . . . . . . . . . . . . . . . . . . . . 4.1.1 Circuit description of power supply. . . . . . . 4.2 Horizontal deflection. . . . . . . . . . . . . . . . . . . . 4.2.1 Low voltage horizontal deflection driver circuit. 4.2.2 Horizontal flyback feedback circuit. . . . . . . 4.2.3 Horizontal deflection corrections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 . 37 . 38 . 42 . 42 . 44 . 45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . #!" Tprpv ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃ#$ #!"" 4.3 4.4 G vrhv Ãprpv ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃ#$ #!"! 9 h vpÃuvhyuhrÃprpv ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃ#% TDA8351/56 TDA8351/56 vertical deflection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Beam current information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 5. LAY-OUT & EMC RECOMMENDATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 5.1 Lay-out. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 5.2 EMC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 6. ALIGNMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 6.1 Front end IF-PLL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 6.2 Tuner AGC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 5 QuvyvÃTr vpqp The GTV1000 GTV1000 Global TV Receiver 6.3 6.4 6.5 6.6 Vertical geometry. . . . . . . . Horizontal geometry. . . . . . . Video amplifiers. . . . . . . . . Luminance-Chrominance delay. . . . . . . . . . . . . . . . . Application Note AN98051 AN98051 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50 .51 .51 .51 7. MODIFICATIONS WITH RESPECT TO PRINTED CIRCUIT PR31602 PR31602. . . . . . . . . . . . . . . . . . .51 8. REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54 APPENDIX 1 Main diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56 APPENDIX 2 GTV pin-compatibility of Philips TV micro controllers . . . . . . . . . . . . . . . . . . .57 APPENDIX 3 Control diagramdiagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58 APPENDIX 4 Tuner diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59 APPENDIX 5 Peri interface cinch diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60 APPENDIX 6 Peri interface Scart diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61 APPENDIX 7 Audio amplifier diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62 APPENDIX 8 AM Audio diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63 APPENDIX 9 NICAM Audio diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64 APPENDIX 10 BTSC Audio diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65 APPENDIX 11 RGB output and CRT panel diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66 APPENDIX 12 Vertical Deflection diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67 APPENDIX 13 Power Supply diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68 APPENDIX 14 Horizontal Deflection diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69 APPENDIX 15 EMC test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70 APPENDIX 16 "Bill Of Materials" of Project: PR31602 PR31602 Last Update: 1999/02/04 . . . . . . . . . . . . .71 APPENDIX 17 Component layout for the NTSC-Only configuration. . . . . . . . . . . . . . . . . . . . .76 APPENDIX 18 Component layout for the South America configuration. . . . . . . . . . . . . . . . . . .76 APPENDIX 19 Component layout for the Pal Multi Sandard VST configuration. . . . . . . . . . . . . .76 6 QuvyvÃTrvpqp The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 LIST OF FIGURES Fig.1 Fig.2 Fig.3 Fig.4 Fig.5 Fig.6 Fig.7 Fig.8 Fig.9 Fig.10 Fig.11 Fig.12 Fig.13 Fig.14 Fig.15 Fig.16 Fig.17 Fig.18 Fig.19 Fig.20 Fig.21 Fig.22 Fig.23 Fig.24 Fig.25 Fig.26 Fig.27 Fig.28 Fig.29 Fig.30 Fig.31 Fig.32 Fig.33 The GTV1000 GTV1000 board. . . . . . . . . . . . . . . . . . . . . . . . Internal Block diagram of the TDA884X TDA884X . . . . . . . . . . . . . . Global design structure . . . . . . . . . . . . . . . . . . . . . . Band switching with VST. . . . . . . . . . . . . . . . . . . . . . AGC circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sound switching. . . . . . . . . . . . . . . . . . . . . . . . . . . NICAM sound switching. . . . . . . . . . . . . . . . . . . . . . . CVBS, Y/C switching. . . . . . . . . . . . . . . . . . . . . . . . RGB input and switch. . . . . . . . . . . . . . . . . . . . . . . . Colour decoder application. . . . . . . . . . . . . . . . . . . . . YUV interface . . . . . . . . . . . . . . . . . . . . . . . . . . . VST tuning curve linearisation for UHF band . . . . . . . . . . . Reset and Voltage guard circuit. . . . . . . . . . . . . . . . . . . Reset signal during start-up. . . . . . . . . . . . . . . . . . . . . Reset signal during a power dip. . . . . . . . . . . . . . . . . . . P83C053 P83C053 (MTV) Micro controller configuration. . . . . . . . . . . P83Cx66 Micro controller configuration. . . . . . . . . . . . . . . P83Cx70 Micro controller configuration. . . . . . . . . . . . . . . SAA549x (ETT) Micro controller configuration. . . . . . . . . . . Block Diagram of the power supply. . . . . . . . . . . . . . . . . Horizontal drive circuit . . . . . . . . . . . . . . . . . . . . . . . L910 primary signal shapes. . . . . . . . . . . . . . . . . . . . . L910 secondary signal shapes. . . . . . . . . . . . . . . . . . . Flyback adapter circuit . . . . . . . . . . . . . . . . . . . . . . . S-corrected horizontal deflection current. . . . . . . . . . . . . . Horizontal phase shift reduction circuit. . . . . . . . . . . . . . . Block diagram of the vertical output stageTDA8351/56 . . . . . . Average Beam current circuit . . . . . . . . . . . . . . . . . . . Black current feed-back. . . . . . . . . . . . . . . . . . . . . . . Modified Reset and Voltage guard circuit. . . . . . . . . . . . . . Write protection circuit non volatile memory. . . . . . . . . . . . GTV pin-compatibility of Philips TV micro controllers . . . . . . . Radiated immunity of GTV1000 GTV1000 receiver measured on SECAM-L. 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 . 14 . 15 . 16 . 17 . 19 . 21 . 22 . 24 . 25 . 26 .28 . 30 . 31 . 31 . 32 . 33 . 34 . 35 . 37 . 42 . 43 . 43 . 44 . 45 . 46 . 47 . 48 . 52 . 53 . 54 . 57 . 70 QuvyvÃTr vpqp The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 LIST OF TABLES TABLE 1 TABLE 2 TABLE 3 TABLE 4 TABLE 5 TABLE 6 TABLE 7 TABLE 8 Features of the different types . . . . . . . . . . Pinning of the TDA884X TDA884X S-DIL 56 . . . . . . . . Overview TV-system and associated SAW-filter . Supported PHILIPS micro controllers. . . . . . . Micro controller versus software package. . . . . pinning of the TDA8380A TDA8380A . . . . . . . . . . . . 5V / 3.3V micro resistor values. . . . . . . . . . 5V / 3.3V stand-by resistor values . . . . . . . . 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 .13 .18 .27 .36 .38 .41 .42 QuvyvÃTrvpqp The GTV1000 GTV1000 Global TV Receiver 1. Application Note AN98051 AN98051 INTRODUCTION. This application note describes the GTV1000 GTV1000 global demonstration colour TV receiver, which was designed to demonstrate the TDA884X TDA884X video processor and the different micro controllers that are available for low-end applications. The GTV1000 GTV1000 is a low-end 90 ° TV receiver based on the TDA884X TDA884X "one chip" I2C bus controlled TV processor. The TDA884X TDA884X contains all small signal circuitry for a colour TV receiver. The board can be adapted to handle the following TV standards: 1. 2. 3. 4. NTSC-M (TDA8846/47 TDA8846/47). PAL-M/N, NTSC-M (TDA8841/43 TDA8841/43). PAL-only (TDA8840 TDA8840). PAL, SECAM (TDA8842/44 TDA8842/44). In configuration 2), the set can also handle PAL 4.43 via the external input if a 4.43 MHz crystal is added. If an NTSC-M crystal is added in configuration 3) and 4), the external input can handle NTSC signals here. The small signal part, control and large signal circuitry are build on one board. The board can be equipped with a VST (UV1315 UV1315) or a PLL (UV1316 UV1316, UV1336 UV1336) tuner. Via solder jumper, connection for both symmetrical and asymmetrical tuners can be made. The basic board contains intercarrier FM mono sound and a single audio amplifier (TDA7056B TDA7056B). It is possible to switch between two sound bandpasses to select one of two sound standards. Two connectors (sound-1 and sound-2) are available to extend the system with AM sound or different stereo options, as explained in chapter 2.2.2. In case of stereo, a double audio amplifier (TDA7075AQ TDA7075AQ) can be added on the main board. In two other connectors (peri-1 and peri-2) different boards containing external input connectors can be inserted, to obtain the correct configuration for each country. A discrete RGB switch can be mounted on the main board when a full scart application is wanted, to switch between RGB from the scart connector and OSD RGB information (see chapter 2.2.4). To offer the possibility to decode all colour standards and create multi standard applications, it is possible to insert 1, 2, 3 or 4 crystals on the board (PAL 4.43/SECAM 43/SECAM, NTSC-M, PAL-M and PAL-N). When a video processor with YUV interface is used, it is possible to insert a connector on the main board (YUV) where picture improvement options can be inserted. The circuitry around the micro controller was designed in such way that it is possible to insert different micro's. The correct configuration can be set by solder jumpers. For non-text countries the 83C054 83C054 (MTV) can be used, while for countries with teletext the SAA529X SAA529X (ETT) with integrated teletext can be inserted. A third option is the P83C770 P83C770 which has integrated close caption. On the board a service connector is present, where a PC with I2C bus interface can be connected. In this case the service pin of this connector has to be grounded, to stop the micro controller. A separate local keyboard is delivered with the main board and can be connected to the local keyboard connector. 9 QuvyvÃTr vpqp The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 BUT11A BUT11A BU2506DF BU2506DF TDA8380A TDA8380A DEFLECTION n n n n n n n n P902 Ã ' Ã & Ã % Ã $ G G v v r r Ã # G G v v r r Ã " Ã ! Ã Ã CRT SUPP n n n n n n Ã $ $ W W Avyh Ã y v Ã! Ã# 6qht Ã$ p Ã% DEGAUSS n n Avytq Ã" r !W '$W P701 Ã Ã Ã q t Ã ! Ã Ã Ã " Ã q t Ã ! Ã Ã " Ã Ã q t Ã ! Ã Ã " Ã n n n n n n P601 nnn P602 P604 MONO/SUB L-OUT R-OUT Ã P901 MAINS n n TDA7056B TDA7056B Ã Ã TDA7075AQ TDA7075AQ Ã Ã SOUND-2 n n n n n n n n n n n n P900 Ã Ghv Ã! Shv Ã" Ã# Ã$ Bq Sv Ã Ã% Gv G Ã Sv S (Ã G Hv@ 'Ã S Bq &Ã Ã& Ã' ( KEYBOARD n n n n n n n n n RGB n n n n n Wi Bq # G@9I $ F@` % F@` & F@`! ' F@`" ( %Ã Pss Ã n n n n n n n n n n n n P204 MICRO CONTROLLER 7f Ã# % Arhr & Thqp ' T96 ( T8G ÃT8G `rq PCF85116 PCF85116 #ÃT96 $ÃTrvpr %ÃT8G &ÃT96 ' 9FG HG Ã `v & Ã Bq % Ã 8v $ Ã 'W 'W # Ã Bq 8W7T " Ã DA 6! ! Ã ! DABI9 6 P600 7 7 W W n n n n n P800 VERT " Th! HA@ Ã `r ! !Ã Bq 8W7Tr Ã !ÃBq "ÃWi DpA@ %Wfh 8W7TAr Ã TDA884X TDA884X 'W 6 6 p W W ( Ã( S`rq Th Ã' 7`rq $ $W Ã& Bq # Ã% " Ã" 7`r Ã$ ! ! PERI-1 n n n n n n n n n n n n Ã Ã! P500 SERVICE n n n n n n n SOUND-1 n n n n n n n n n n n n S`r Ã P401 P700 YUV "Ã !Ã S Bf Ã$ 7 B Sf Ã# #Ã Bq Ã" $Ã Aiy P603 Diyhpx Ã! Bq T96 ! SAW " !Ã T8G Sp$I ! Bq PERI-2 n n n n n n n n n n n n Gv # $ TDA8351/56 TDA8351/56 P203 Fig.1 The GTV1000 GTV1000 board. 10 TUNER VST or PLL Ã P400 QuvyvÃTrvpqp The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 For the vertical deflection a DC coupled amplifier (TDA8356 TDA8356) is used. The line deflection was designed to drive a 90° picture tube. The line transformer supplies the voltages to drive the picture tube: EHT, Vfocus, Vg2, filament supply and the video amplifier supply. The board also contains the mains filter, the degaussing circuit and the switched mode power supply, which delivers the supply voltages for the line deflection, vertical deflection, audio part, video processing and control part. 2. SMALL SIGNAL. 2.1 TV processor TDA884X TDA884X. The heart of the total system is formed by the "One Chip" TV processor TDA884X TDA884X. This chapter gives a short description of this IC family. More detailed information concerning the internal circuitry can be found in report ref.[3] Report no: AN98002 AN98002. Common features of the family: · · · · · · · · · · · · · · · · · · · · Vision IF circuit with alignment-free PLL demodulator Alignment-free multi-standard FM sound demodulator (4.5 to 6.5 MHz) Audio switch Flexible source selection with internal and external CVBS input, Y(CVBS)/C input and selected CVBS out, suited for comb filter use Integrated chroma trap (auto calibrated) Integrated chroma band pass (auto calibrated) with switchable centre frequency Integrated luminance delay line Asymmetrical peaking in luminance channel with defeatable coring function Black stretching Blue stretch circuit which offsets near white colours to blue Integrated RGB processor with "continuous cathode calibration" and white point adjustment Linear RGB inputs with fast blanking input Possibility to insert "blue mute" when no signal is present Dynamic skin tone ("flesh") correction for NTSC signals Horizontal synchronisation with two control loops and alignment-free horizontal oscillator Slow start and stop of the horizontal drive pulses Vertical divider circuit Vertical driver stage optimized for DC-coupled output stages I2C bus control Low power dissipation The table below shows the various S-DIL types, which can be inserted in the GTV1000 GTV1000 board. For the mid-end types (TDA8843/44/47 TDA8843/44/47) a YUV interface has been added on the board, however the EW drive is not used in GTV1000 GTV1000, because the deflection is designed for raster correction free deflection units. 11 QuvyvÃTr vpqp The GTV1000 GTV1000 Global TV Receiver TABLE 1 Features of the different types IC version (TDA) 8840 8841 Application Note AN98051 AN98051 8842 8846 8846A 8843 8844 8847 Automatic volume levelling X X X X X Positive / Negative modulation N N N/P N N N/P N/P N X X X X X X X X X X X NTSC decoding PAL decoding (integrated delay-line) X SECAM decoding (integrated SECAM decoder) X Colour matrix PAL / NTSC (Japan) X X X X X X X X Horizontal geometry (E-W output) X X X Linear zoom function X X X 50/60 50/60 60 Colour matrix USA / Japan X YUV interface Vertical frequency X1 X 50/60 50/60 50/60 60 60 X 1. In the TDA8846A TDA8846A version the delay line is present. For NTSC-system it acts like a cross colour reduction as a comb-filter does for PAL. On the next pages, the pinning of the TDA884X TDA884X as well as the internal block diagram can be found. The internal block diagram shows the most extended version of the series. The notes at this block diagram correspond to the remarks of the pinning table. 12 QuvyvÃTrvpqp The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 TABLE 2 Pinning of the TDA884X TDA884X S-DIL 56 Pin 1 21 3 4 5 6 7 8 9 10 11 12 13 14 15 163 17 18 19 20 21 22 23 24 25 26 275 286 Function Intercarrier sound-IFIN InExternal audioIN Not connected Not connected IF-PLL loop filter IF-VideoOUT (2VPP) SCL I2C-bus SDA I2C-bus Bandgap decoupling Input CS-VHS Input YS-VHS (or CVBS3EXT) Main +8V supply CVBS1 (internal CVBS) (1VPP) Ground AudioOUT SECAM PLL decoupling CVBS2 (external CVBS) (1VPP) Black currentIN BOUT GOUT R OUT Beam current limiter/V-guardIN R IN GIN BIN Fast Blank RGBIN YIN YOUT Pin 56 55 54 53 52 51 50 49 48 47 46 452 44 43 42 41 40 39 38 37 36 354 34 33 32 31 30 29 Function Sound demodulator decoupling De-emphasis & Int. audioOUT Tuner AGCOUT AGC decoupling Vertical current reference Vertical sawtooth capacitor EHT/over-voltage protectionIN IFIN IFIN Vertical I-driveAOUT Vertical I-driveBOUT AVL cap. or East-West driveOUT Ground j 1-loop filter j 2-loop filter H-flybackIN & SandcastleOUT HOUT Decoupling digital supply CVBS-switchOUT +8V supply Colour PLL filter Xtal 4.43/3.58 MHz Xtal 3.58 MHz Chroma ReferenceOUT R-YIN B-YIN R-YOUT B-YOUT 1. Positive modulation automatically selects pin2 for sound input (external AM demodulator). 2. 3. 4. 5. 6. TDA8840/41/42/46 TDA8840/41/42/46(A) have AVL instead of East-West drive, AVL capacitor at pin 45. Pin 16 (SECAM PLL) only used in TDA8842/44 TDA8842/44. In NTSC only versions TDA8846 TDA8846(A)/47 pin 35 (Xtal 4.43) is not connected. TDA8840/41/42 TDA8840/41/42 have no YIN, pin 28 is not connected, pin 27 becomes Yout. TDA8840/41/42 TDA8840/41/42 pin 28 is not connected. 13 QuvyvÃTr vpqp EW_DRIVE2) The GTV1000 GTV1000 Global TV Receiver @ W D S 9 W U P S Q U C @ #$ #% $ ` S U @ # T6I986TUG T6I986TUG@ Q P P G Ã q ! # AG`768F #! 'W 'W @ W D S 9 W #& $ U V P Ã S P Ã $! ! G P S U I P 8 Ã ` S U @ H P @ B 7 B S U T S U I TDA 884X CPSÃ9SDW@ U V P B U V P S G 6 8 D U S @ W X @ H P @ B Application Note AN98051 AN98051 ( I D B I D 7 I B 6 I G D 7 F !# !" !$ !% S U T Ã F 8 6 G 7 U V Q U V P Ã S U T Ã @ V G 7 7 B S G P S U I H P Ã 8 ` U B 6 T Y D S U 6 U V Q I D H Ã Ã 7 7 B B S S Y D S U 6 S V I U D T U !& U I D U Ã I D F T ` 6 G @ 9 Ã S @ T D G D 7 6 U T U I @ S S V 8 "! 7` S` ' X F 8 6 G 7 " YIN 5) B I D F 6 6 @ H Q Ã V G @ I D G ` 6 G @ 9 9 I 6 7 @ T 6 7 B I D S P 8 Ã %/$&. !' @ U U I D D C 7 W 9 S 6 I H V D 6 B S @ W 7 !! U T CT B@ D SI S @ 9 D W D 9 Ã S V 8 U V P 7 YOUT 6) 8VSS@IU !( 7` " S` "& ! "( ( Ã P 8 W # G P S U I P 8 S P U 6 S 6 Q @ T 8 I ` T @ S ## "# 8 I ` T Ã Q P P G Ã Ã S P U 6 S 6 Q @ T U S @ W B I D I V U S @ U G D A See note 4) "$ 8 T U I Ã Ã G 6 Q #" H 6 8 @ T S @ 9 P 8 @ 9 "% "" 8uhÃSrs % T8G ' T V 7 8 ! D & S @ W D @ 8 I 6 S U 8 6 9 y 8 3 2 7 U D 7 Ã % Ã # U D 7 ' $# 6B8 8 ` T 7 W 8 Q 6 S U C 8 U D 8TWCT 8W7T"`TWCT X T C 8 U D T 7 W 8 C U D X T "' & 8W7TÃPVU 8W7T!ÃDI " X T 8W7T ÃDI G $" UVI@S U D 7 Ã # Ã SECAM PLL 3) Decoupling @ V C T T 6 Q S P A Ã 8 B 6 S @ I V U Ã Ã A D S @ D A D G Q P @ 9 D W @ @ U 9 D V W H @ V H P @ H 6 D W @ U V H 9 I V 9 I V P T T Q H A G G Q H @ U 6 Ã V @ S H Ã Q 9 P H @ 9 9 I V P T Q 6 S U % C # " I P D U 6 S 7 H D 6 G 6 A 8 D Ã W S @ D A D G Q #' I D A D P H @ G G Q #( U D U I @ 9 D 8 A 6 & ) $ Ã C 8 U D U I @ 9 D Ã P @ 9 D W 9 I T $$ $ I D A D @ H V ! $ # Ã v Ã G W 6 W Ã Ã X G T P Ã IN1) T96 9 I 6 7 @ S $ 2 , '7 88 $2 A v t!ÃÃD rhy Ã7ypxÃqvhthÃsÃurÃU96 ''#Y 14 X T S @ U D H D G G W $% 9 I V P T 9 T I T 6 6 7 Q QuvyvÃTrvpqp The GTV1000 GTV1000 Global TV Receiver 2.2 Application Note AN98051 AN98051 Functional description of the small signal part. To simplify the design process of the GTV receivers, a common basic structure was selected. This structure can be found in the figure below. 7XQHU & $XGLR & 7 Z % & 5*% K $ 3HUL & & 9HUWLFDO 0DLQ & & % % & & % % & % % 7 $ % & % $ % % $ @ ] + 0 > yvrh # UvtÃbWyd " QXH # Drth Fig.12 VST tuning curve linearisation for UHF band After linearisation, a VST system has a more constant step size, but still a variation of a factor four. If a `step' is calculated (worst case) to give 1 MHz frequency increment, the less steep areas will render a fourfold smaller step, so four times slower too. After each value change, the tuning PWM DAC needs 128 x 42.66us = 5.5ms to produce the new pulse pattern. When the non-linear integration filter has T=5, each tuning step must be followed by a delay of 30 . 50ms. 28 The GTV1000 GTV1000 Global TV Receiver 3.3 Application Note AN98051 AN98051 Service connector and Factory mode. The Service connector P203 (see chapter 'The GTV1000 GTV1000 board." on page 10), gives access to the two (split) I2C-busses plus the possibility to inactivate the micro controller (service and factory mode). The Service Line is connected to an interrupt pin of the micro controller. This makes it possible in future software packages to implement some kind of protocol e.g. to a factory computer. When contact "Service" of the service connector is short-circuited to ground during 250ms, the software shows a service menu. The configuration and geometry parameters can now be modified, using a standard remote control or the local keyboard. In service mode, the video processor protections are disabled to avoid RGBOUT blanking. This is easier during repair actions. When the short circuit lasts longer than 500ms, the software enters the Factory mode. It stops the continuous update via the I2C-bus and OSD is suppressed. Now a factory production computer can read or write into the EEPROM. When a command from remote control or local keyboard is received, all devices are updated and the processor releases the I2C-bus again. In this way the non-I2C-bus controlled outputs of the micro can still be controlled. When the service contact is released the software resets the set automaticly. APPENDIX 3 shows that the signal "Service" is also used as an EEPROM write protect line. Dependent on the applied type EEPROM, a certain area can not be written, while "Service" is high. This gives extra protection against accidental over writing e.g. alignment data. If the micro controller wishes to write data to the protected area, it will temporarily pull down the Service-line. 3.4 Standby command line "On_Off". Open drain output/input, used to switch the power supply between standby mode and normal operation. When the pin is externally pulled low, this is interpreted as a command to go into standby mode. With this, a local standby key can be implemented. · Output low = Power supply in standby mode · Output high, input high (> 3.5 Volt) = Power supply on · Output high but input pulled low (1.0 . 1.5 Volt) = Power still on, but local command to go to standby 3.5 OSD outputs FBL, R, G and B. These outputs have a push-pull outputs for fast OSD transitions. Pin FBL is used as a fast blanking signal and connected to the fast-blanking input of the RGB-switch (see chapter 'RGB input/switch." on page 23). A low output indicates absence of OSD and a high output represents a colour or blanking active. Synchronization input signals Hsync and Vsync are derived from the deflection part to get a stable OSD picture on the television screen. The polarity of these signals is active high. 3.6 I2C-bus control input/outputs SDA, SCL, SDA1 and SCL1. These pins are respectively the data and the clock wires of 2 (split-bus) single-master bidirectional I2Cbusses. When the I2C-bus appears to be blocked the stand-by LED will start blinking. If the bus remains blocked for a longer time (e.g. 5 minutes) the TV-set will go into standby. SDA1 and SCL1 are only connected to the EEPROM and the TDA884x, to avoid problems with I2Cbus slave devices blocking the bus e.g. when a power supply voltage fails. With this split-bus system it 29 The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 is now possible to derive supply voltages from the line output transformer (LOT). Further a split-bus construction decreases the chance of data corruption in the EEPROM. 3.7 Reset and supply-voltage-guard circuit. This demo receiver has a sophisticated reset and supply voltage guard circuit, which triggers the micro controller reset and EEPROM power supply. Most micro-controllers have a internal power-supply guard which will generate an internal reset once the supply-voltage drops below a threshold level. During this reset the outputs do have a defined output condition (most of the time floating). However when the supply falls further, even the internal circuits of the micro stops functioning. This may lead to unpredictable bouncing of the outputs. Because the I2C-bus is controlled by such outputs, a burst of pulses can appear on the clock and data-lines. This can lead to un-wanted write actions, because some EEPROMs keeps on functioning at very low supply voltages. Once the supply-voltage starts to fall, an external reset is generated before the internal reset becomes active (even if the supply has a falling glitch the external reset will get a defined duration). At the same time the EEPROM supply voltage is switches-off. +Vstb C2011 C2011 R2048 R2048 10k R2045 R2045 TR203 TR203 BC558 BC558 10uF 50V 10k R2046 R2046 100 Z201 3.6V R2051 R2051 TR204 TR204 BC558 BC558 TR205 TR205 10k BC548 BC548 R2054 R2054 Reset micro R2049 R2049 1k 22k TR206 TR206 BC548 BC548 +Supply EEPROM Fig.13 Reset and Voltage guard circuit. The circuit description refers to the previous picture. Advantages of this circuit are the: · well defined reset duration after reaching a well defined supply voltage. · guaranteed reset pulse even after a short supply voltage dip. · power control of the EEPROM. 30 The GTV1000 GTV1000 Global TV Receiver Reset micro Supply EEPROM +5V stand-by Time base: 100mSec/Div. Trigger CH3. Application Note AN98051 AN98051 The reset input of the micro controller is active high. During start-up of the supply voltage Vstb, TR203 TR203 is switched off and consequently TR204 TR204 starts conducting. This forces the reset input to follow Vstb. This status remains, until Vstb reaches the threshold level of 4.2V (UZ201 UZ201 + Ube TR203 TR203). Starting from this level, TR203 TR203 starts conducting and TR204 TR204 switches-off. Now C2011 C2011 will be charged via the pull down resister1 inside the micro controller and resistor R2054 R2054. This guarantees a sufficient reset pulse duration, after reaching the valid supply voltage. Fig.14 Reset signal during start-up. Reset micro Supply EEPROM +5V stand-by Time base: 100mSec/Div. Trigger CH3. If the supply voltage falls below the threshold voltage, TR203 TR203 switches off immediately and TR204 TR204 switches on. This discharges C2011 C2011 and activates the external reset of the micro controller. Even for short supply voltage drops (below threshold level), a well defined external reset is guaranteed. The EEPROM supply voltage is also controlled by the reset pulse to protect the EEPROM data during power up, shut down and/or supply glitches. This prevents uncontrolled write actions as a result of bouncing of the I2C data and clock lines. Fig.15 Reset signal during a power dip. 3.8 Micro hardware environment configuration. In this subsection the hardware aspects for the micro environment configuration are give. For each of the supported micros, a detail of the copper (bottom-side underneath the micro) has been included on wich the jumpers to close are marked. Besides setting of the jumpers, it is necessary the change some components in some of the configurations. The critical one are marked on the copper layout details. The bill of material (BOMs) gives the complete information about the micro related components such as not assembled components around the 42-pins micros (MTV and P83Cx66). 3.8.1 Stereo-playback hardware configuration. For the sound-options the sound-processor/mono option is shown. The stereo play-back function is discussed here because it is micro independent. Fig.16 shows the location of the jumpers and resistors involved. Close jumper J201 and open J202. Now assemble resistors R2019 R2019, R2025 R2025 and R2030 R2030. 1. The value of the internal pull-down resister is micro controller type dependent. This resistor is 8K inside the P83Cx70 and 550K for the ETT micro processor. 31 The GTV1000 GTV1000 Global TV Receiver 3.8.2 Application Note AN98051 AN98051 P83C053 P83C053 (MTV) Micro controller configuration. J212 R2030 R2030 J204 R2019 R2019 R2018 R2018 J210 J209 J208 C201 J207 J206 J211 J213 L201 C201 J205 J201 J200 J203 J202 Fig.16 P83C053 P83C053 (MTV) Micro controller configuration. The MTV needs additional components for the OSD-oscillator. L201 = 22microH and capacitors C2014 C2014 and C2015 C2015 are 22pF. 32 The GTV1000 GTV1000 Global TV Receiver 3.8.3 Application Note AN98051 AN98051 P83Cx66 Micro controller configuration. J212 J207 J210 J209 J206 J211 J213 J208 J204 J205 J201 J200 J203 J202 Fig.17 P83Cx66 Micro controller configuration. The RGB-outputs of this micro are push-pull current sources which can deliver 8mA. This maximum current can be controlled by software to align brightness of the OSD. By means of a resistor (0.82K) to ground (instead of C2019 C2019, C2020 C2020 and C2021 C2021) the R, G and B output current is converted into a voltage which is fed to the RGB switch. The OSD brightness can be set by changing this resistor. The higher the value the higher the OSD brightness. 33 The GTV1000 GTV1000 Global TV Receiver 3.8.4 Application Note AN98051 AN98051 P83Cx70 Micro controller configuration. J212 J207 J208 J204 J201 J210 J209 J206 J211 J213 J205 J200 J203 J202 Fig.18 P83Cx70 Micro controller configuration. The RGB-outputs of this micro are push-pull current sources which can deliver 6mA. This maximum current can be controlled by software to align brightness of the OSD. By means of a resistor (1K) to ground (instead of C2019 C2019, C2020 C2020 and C2021 C2021) the R, G and B output current is converted into a voltage which is fed to the RGB switch. The OSD brightness can be set by changing this resistor. The higher the value the higher the OSD brightness. 34 The GTV1000 GTV1000 Global TV Receiver 3.8.5 Application Note AN98051 AN98051 SAA549x (ETT) Micro controller configuration. J212 J207 J208 J204 J201 J210 J209 J206 J211 J213 J205 J200 J203 J202 Fig.19 SAA549x (ETT) Micro controller configuration. 3.9 Software package. As said, the GTV1000 GTV1000 can be controlled by four different types of micro-controllers. For these devices we have different demonstration software packages. For detailed user information about these packages we refer to the user manual. The following table illustrates the micro / software package and user manual reference number. 35 The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 TABLE 5 Micro controller versus software package. Micro controller type Software package User manual reference. P83C053 P83C053 P83Cx66 / P87Cx66 P83Cx70 SAA529x / SAA549x CTV271 CTV271 / CTV272 CTV272. ETV/UM 97012.0 / ETV/UM 97011.3 (see [13]) and (see [14]) . CTV828 CTV828 ETV/UM 98013.1 (see [15]) CTV832 CTV832 CTV832S/ CTV832S/ CTV832R CTV832R (see [16]) 36 The GTV1000 GTV1000 Global TV Receiver 4. Application Note AN98051 AN98051 LARGE SIGNAL. 4.1 Power supply. The power supply is a mains insulated flyback converter supporting the full mains range. The supply is built around the TDA8380A TDA8380A Switch Mode Power Supply controller. It operates at a fixed frequency of 28.8 KHz and in a discontinuous current mode. The output voltages are controlled by duty-cycle modulation of the primary current. The mains insulation is provided by a SMPS transformer for power transfer and an opto-coupler for the feedback from the secondary side. The feedback information guarantees good stable output voltages. ThqiÃpy Hhv Hhv 3V3 5V 16V 15V 45V 115V Srpvsvr Trpqh Srpvsvr Thqi @ 8yyr D8 hyvsvr PÃ8yr Fig.20 Block Diagram of the power supply. The principle of a flyback converter is simple, see Fig.20. However we have to deal with non-ideal components. These make the realisation more complex. The TDA8380A TDA8380A SMPS controller IC supports several control and protection functions to handle the complexity more easily. The mains voltage is rectified and supplied to the SMPS transformer. The primary current is controlled via the power switching transistor. Modulation of the on/off time (duty cycle) controls the output voltages of the SMPS transformer. The 115V supply voltage (line deflection supply voltage) is used as feedback information. Via an error amplifier and opto-coupler the control signal is fed-back to the TDA8380A TDA8380A at the primary side of the supply. During start-up, the controller is supplied by the rectified mains via a series resistor. Once operational, the controller gets its supply from the auxiliary winding of the SMPS transformer. 37 The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 Via the stand-by control line the 15V can be switched on and off. If switched into stand-by, the supply reduces its output voltages to 60% of their nominal value. The TDA8380A TDA8380A is available in a 16-DIL 16-DIL package and incorporates the following features: · Internal stabilized supply voltage · High and low supply-voltage protection · External programmable reference currents · Operating frequency 10 to 100KHz · Access to pulse-width modulator to facilitate use of an alternative external error amplifier · Fail-safe control loop · Duty factor fold back · Slow-start or soft-start option. · Direct-drive output stage · First level cycle by cycle over-current protection · Second trip over-current protection · Protection against power transistor short-circuit · Demagnetization sensing The following table shows the pinning of the TDA8380A TDA8380A. TABLE 6 pinning of the TDA8380A TDA8380A Pin: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 4.1.1 Function Positive drive output. Supply voltage of drive output stage. Demagnetization sense input. Minimum Vcc threshold setting. Supply voltage Vcc. Reference current setting. Feedback input. Output error amplifier. Not used in this application. Pulse width modulator input. Oscillator capacitor. Synchronisation input. Not used in this application. Maximum duty factor (Dmax) setting combined with slow start time programming. Input current protection. Ground. Emitter of output sink transistor. Collector of sink output. Circuit description of power supply. Diodes D903 . D906 rectifies the mains voltage which feeds buffer capacitor C9010 C9010 via a series resistor. This resistor reduces the inrush current during switch on. The diodes are shunted by four capacitors to smooth their switch-off behaviour to reduce mains interference. To supply the SMPS controller during start-up series resistor R9008 R9008 charges C9016 C9016. Once reaching the fixed threshold level of 17V, the TDA8380A TDA8380A starts-up the supply. Capacitor C9016 C9016 delivers the 38 The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 supply for the controller and transistor base-current, until the auxiliary winding voltage is sufficient to take over the SMPS supply. The following two criterion are considered to dimension C9016 C9016: · Its minimum value must avoid under-voltage lock-out. Before taking over, the voltage at C9016 C9016 will fall, so the value of C9016 C9016 must be sufficient to bridge the period during start-up. This means, once the controller supply voltage falls below the minimum operating voltage of 8.4V, the controller switches off again. Operation below 8.4V is not allowed because the base-drive to the power transistor BUT11A BUT11A cannot be adequately defined. · Its maximum value depends on the maximum allowed start-up time. To start the SMPS, the UC9016 UC9016 must exceed 17V. The charge current depends on the mains supply voltage and the value of resistor R9008 R9008. So the maximum start-up time is found at the lowest mains supply voltage. Decreasing R9008 R9008 will improve start-up time, but decreases the efficiency as well. Beside the controller part, also the primary winding of the SMPS transformer is connected to the rectified mains (+VB). The other side of the winding is attached to power switching transistor TR901 TR901. Parallel to this winding a dV/dt limiting network R9002 R9002, R9005 R9005, C9005 C9005 and D900 is connected to protect the power transistor. The maximum dV/dt value for this transistor is 1000V/uS. Resistor R9002 R9002 has two functions: · to discharge C9005 C9005 prior to each flyback. · to damp the transformer ringing which follows each fly-back. This damping must be sufficient to suppress the recurrence of positive pulses at the demagnetization input to the IC during the next oscillator cycle. To control the output power of the SMPS, the primary current through the transformer is switched. The needed base drive of the bipolar power transistor consist of two separated drives: · a forward drive to switch on the transistor. The forward base-current can be adjusted by resistance R9022 R9022 and R9019 R9019. This construction is used to reduce power dissipation in the forward drive transistor of the SMPS controller. For the used transistor the typical base current is 0.5A for the duration of the duty-cycle. The nominal take-over supply voltage is close to 20V. So the nominal base-current is about 20/30 = 0.67A. · a reverse drive to switch off the transistor. To ensure minimum transistor dissipation, a negative going base current is needed. This requires a negative supply voltage (with respect to the transistor's emitter). Capacitor C9022 C9022 acts like such a voltage source. It will be charged by the positive base current and zener diode D910 limits the voltage to 5V1. Inductor L906 limits the dIbase/ dt ensuring a nominal storage time of about 1uS. R9024 R9024 avoids switching of the transistor during the dead time of the clock cycle. During this time both forward and reverse outputs are floating. R9025 R9025 damps ringing of inductor L906 and D912 protects the SMPS controller output transistor against electromotive force (EMF) generated by L906. To control the line deflection supply voltage with 1% accuracy, the secondary +115V output voltage delivers feedback information. This information will be processed in a differential amplifier formed by TR902 TR902 and TR903 TR903. The base of TR902 TR902 is connected to the reference voltage UD916 UD916 (5V6) and R9043 R9043. Via this resistor, beam-current related information is added to compensate the horizontal picture width modulation caused by the average beam-current (See chapter 4.4, page 49). This width gets larger at higher beam-currents. To compensate for this, the horizontal deflection voltage will decrease as function of the beam-current. 39 The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 Via the base of TR903 TR903, the divided +115V output voltage is added to the differential amplifier. The divider is formed by resistors R9034 R9034, R9037 R9037, R9040 R9040, R9045 R9045 and R9041 R9041. Via R9045 R9045 the output voltage can be adjusted. During normal operation transistor TR904 TR904 is conducting and the base level is calculated from: {(R9040 R9040+R9045 R9045)//R9041 //R9041} / [R9034 R9034+R9037 R9037+{(R9040 R9040+R9045 R9045)//R9041 //R9041}] * +115V. The result is [4 / {68+3,9+4}] * 115V = 6V. The added diode D914 prevents the +8V to fall once the +115V output is unloaded. In this situation, the output capacitor will integrate the voltage over-shoot at the transformer output caused by transformer ringing. This ringing should lead to 10 to 15% higher output voltages, however the feedback loop corrects this. This correction results to 10 to 15% less output voltage at the loaded low voltage outputs. This will happen during stand-by operation of the TV chassis. Once the +16V falls below +12V, the feedback information will be adjusted to track with this +12V. This take-over voltage is calculated by: {(R9040 R9040+R9045 R9045)//R9041 //R9041}+R9037 R9037 / [R9034 R9034+R9037 R9037+{(R9040 R9040+R9045 R9045)//R9041 //R9041}] * 115V. To reduce the stand-by power consumption, TR904 TR904, R9041 R9041 and capacitor C9035 C9035 were added to the feedback input of the differential amplifier. During stand-by, resistor R9041 R9041 is de-coupled from the +115V feedback divider. Now the feedback voltage becomes: (R9040 R9040+R9045 R9045) / [R9034 R9034+R9037 R9037+R9040 R9040+R9045 R9045] * 115V = 9V. The differential amplifier corrects this so that the outputs will drop by about 40%. Only D914 can overrule this output voltage reduction. To improve the start-up coming from the stand-by mode, capacitor C9035 C9035 has been added to guarantee a smooth transition. The input LED of the opto coupler is controlled by TR903 TR903. The collector of TR903 TR903 is connected to the cathode while the anode is supplied by a stabilized 8V2 supply voltage. Increase of the +115V output gives more LED-current. As a result the opto coupler's output transistor starts to conduct more, causing a reduction of the input voltage at the duty-cycle control pin. Now the controller starts to reduce the duty-cycle of the primary supply current. The following part describes the application topics to realize the SMPS protections: · Slow-start: The slow-start time is programmed via capacitor C9029 C9029. It controls the speed of the duty-cycle buildup, preventing current and/or demagnetization protection during start-up. This guarantees a smooth start-up behaviour. The value of this capacitor is a trade off between two situations: -The minimal value for this capacitor can be found by checking the current and/or demagnetisation protection signals at the minimum and maximum mains supply input voltages. -The maximum value for this slow-start capacitor is related to the buffer capacitor at the controllers power supply (C9016 C9016). Increasing the slow-start time also increases the TDA8380A TDA8380A power supply take-over time. To guarantee no under-voltage lockout, C9016 C9016 must increase accordingly. · Maximal Duty cycle: To avoid the continuous current mode operation of the SMPS a maximum duty cycle can be programmed via resistor R9027 R9027. The maximum duty-cycle is programmed to be 60%. · Current protection: The current protection can be programmed by resistors R9028 R9028, R9029 R9029, R9030 R9030, R9033 R9033 and R9032 R9032. Resistors R9028 R9028 . R9030 R9030 are sensing the emitter current of power transistor TR901 TR901. Because the emitter of this transistor is directly connected to the reference ground of the SMPS controller, the base-emitter voltage is independent of the voltage drop over these sense resistors. Resistor R9032 R9032 and R9033 R9033 define a DC-offset voltage at the current protection I/O pin (with respect 40 The GTV1000 GTV1000 Global TV Receiver Application Note AN98051 AN98051 to the reference ground). The emitter current of TR901 TR901 flows through current sensing resistors R9028 R9028 . R9030 R9030. The positive side is connected to the reference ground, while the negative side is connected to pin13 via resistor R9033 R9033. If the emitter current increases this causes the voltage level at pin13 to drop. Once reduced to 200mV, the cycle by cycle current protection is activated. At 0V, the supply will be switched-off immediately and will re-start via the slow-start procedure. The maximum primary current depends on the maximum current specification of the used SMPS transformer (3Amp) and not on the used power transistor BUT11A BUT11A. For this chassis the current is limited at 2.5A. Resistor R9032 R9032 is added to realize a current fold back due to over-loading one of the SMPS outputs. If a cycle by cycle over-current protection is present, this will result in a lower output and auxiliary voltages. Reduction of the auxiliary voltage reduces the DC-voltage at the current protection pin and herewith the maximal allowed current. · Over-voltage protection The outputs of the SMPS are protected against an over-voltage condition. This can be the result of a defect feedback circuit. Via resistors divider R9014 R9014 and R9020 R9020 the over voltage protection pin (pin7) is connected to the auxiliary winding, in order to monitor the output voltages of the transformer. Once the voltage at input pin7 exceeds 3.2V, the controller switches off and re-starts via the slow-start procedure. During nominal operation this voltage is R9020 R9020 / (R9020 R9020+R9014 R9014) * 20V = 15/106 * 20 = 2.8V. · Demagnetization protection Via resistor R9015 R9015 and R9018 R9018 the un-rectified auxiliary winding voltage is used to monitor the stored magnetic energy in the SMPS transformer. This must prevent cumulation of magnetic energy inside the transformer. Before starting the next SMPS cycle, the remaining energy must be zero preventing saturation of the SMPS transformer. A saturated transformer results in a very high primary current which can damage the power switching transistor. A voltage above 0.6V at the demagnetization input will prevent the power transistor from switching. At the auxiliary winding the switching level is calculated from: R9018/ R9018/(R9015 R9015+R9018 R9018)xVaux