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The GTV1000 Global TV Receiver

AN98051

APPLICATION NOTE
The GTV1000 Global TV Receiver
AN98051
The GTV1000 Global TV Receiver
Application Note AN98051
Abstract
The GTV1000 receiver has been designed around the 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 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
The GTV1000 Global TV Receiver
Application Note AN98051
APPLICATION NOTE
The GTV1000 Global TV Receiver
AN98051
Author(s) Ton Hummelink Ton Smits Philips Semiconductors Systems Laboratory Eindhoven, The Netherlands
Keywords 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
The GTV1000 Global TV Receiver
Application Note AN98051
Summary
This application note describes the GTV1000 global demonstration colour TV receiver, which is based on a 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.
The GTV1000 Global TV Receiver
TABLE OF CONTENTS
Application Note AN98051
The GTV1000 Global TV Receiver
Application Note AN98051
Vertical geometry. . . . . . . . Horizontal geometry. . . . . . . Video amplifiers. . . . . . . . . Luminance-Chrominance delay.
APPENDIX 1 APPENDIX 2 APPENDIX 3 APPENDIX 4 APPENDIX 5 APPENDIX 6 APPENDIX 7 APPENDIX 8 APPENDIX 9
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
The GTV1000 Global TV Receiver
LIST OF FIGURES
Application Note AN98051
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 board. . . . . . . . . . . . . . . . . . . . . . . . Internal Block diagram of the 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 (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 receiver measured on SECAM-L.
The GTV1000 Global TV Receiver
Application Note 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 S-DIL 56 . . . . . . . . Overview TV-system and associated SAW-filter . Supported PHILIPS micro controllers. . . . . . . Micro controller versus software package. . . . . pinning of the TDA8380A . . . . . . . . . . . . 5V / 3.3V micro resistor values. . . . . . . . . . 5V / 3.3V stand-by resistor values . . . . . . . .
The GTV1000 Global TV Receiver
1. INTRODUCTION.
Application Note AN98051
This application note describes the GTV1000 global demonstration colour TV receiver, which was designed to demonstrate the TDA884X video processor and the different micro controllers that are available for low-end applications. The GTV1000 is a low-end 90 ° TV receiver based on the TDA884X "one chip" I2C bus controlled TV processor. The 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). PAL-M / N, NTSC-M (TDA8841 / 43). PAL-only (TDA8840). PAL, SECAM (TDA8842 / 44).
The GTV1000 Global TV Receiver
Application Note AN98051
BU2506DF
TDA8380A
BUT11A
DEFLECTION n n n n n n n n P902
DEGAUSS n n
n n n n n n P601 nnn P602 P604 MONO / SUB L-OUT R-OUT
TDA7056B TDA7075AQ
MAINS n n
Bq Aiy
Diyhpx Bq Sf Bf 7f
MICRO CONTROLLER
PCF85116
TDA884X
8W7TAr
Bq 8W7Tr Th
TDA8351 / 56
TUNER VST or PLL
Fig.1 The GTV1000 board.
The GTV1000 Global TV Receiver
For the vertical deflection a DC coupled amplifier (TDA8356) is used.
Application Note AN98051
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.
SMALL SIGNAL. TV processor TDA884X.
The heart of the total system is formed by the "One Chip" TV processor 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. 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 board. For the mid-end types (TDA8843 / 44 / 47) a YUV interface has been added on the board, however the EW drive is not used in GTV1000, because the deflection is designed for raster correction free deflection units.
The GTV1000 Global TV Receiver
Application Note AN98051
TABLE 1 Features of the different types IC version (TDA) 8840 Automatic volume levelling Positive / Negative modulation NTSC decoding PAL decoding (integrated delay-line) SECAM decoding (integrated SECAM decoder) Colour matrix PAL / NTSC (Japan) Colour matrix USA / Japan YUV interface Horizontal geometry (E-W output) Linear zoom function Vertical frequency 50 / 60 X X N
1. In the 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 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.
The GTV1000 Global TV Receiver
TABLE 2 Pinning of the TDA884X S-DIL 56
Application Note AN98051
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
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
1. Positive modulation automatically selects pin2 for sound input (external AM demodulator).
2. 3. 4. 5. 6. 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. In NTSC only versions TDA8846(A) / 47 pin 35 (Xtal 4.43) is not connected. TDA8840 / 41 / 42 have no YIN, pin 28 is not connected, pin 27 becomes Yout. TDA8840 / 41 / 42 pin 28 is not connected.
The GTV1000 Global TV Receiver
Application Note AN98051
YIN 5)
TDA 884X
8VSS@IU
YOUT 6)
See note 4)
SECAM PLL 3) Decoupling
UVI@S 6B8
The GTV1000 Global TV Receiver
2.2 Functional description of the small signal part.
Application Note AN98051
To simplify the design process of the GTV receivers, a common basic structure was selected. This structure can be found in the figure below.
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9HUWLFDO
&RQWURO
Fig.3 Global design structure
The structure is also found in the appendixes: Schematics.
The GTV1000 Global TV Receiver
Application Note AN98051
To obtain flexibility in the GTV1000, the grey blocks are designed as add-on boards. In this way it is possible to add YUV features, the correct external connector combination for each area and different stereo systems. The sound block also contains the audio amplifiers, which are mounted on the main board and not on the add-on board, because they need a heatsink.
Tuner and IF circuit.
The GTV1000 design is made in such way, that a UV1316 / 1336 (PLL) or UV1315 (VST) can be used In case a PLL tuner is used, the following measures have to be taken: · · · · · · · · · Jumper J300 has to be short circuit to select the right tuner address. Jumpers J301 and J302have to be opened to disconnect the bandswitch lines. Resistors R3004 and 3007 have to be inserted to connect the I2C bus. Resistor R3002 has to be removed to disconnect the VST tuning voltage.
When a VST tuner is used, the following measures have to be taken: Jumper J300 has to be opened. Jumpers J301 and J302 have to be closed to connect the bandswitch lines. Resistor R3004 and R3007 have to be removed to disconnect the I2C bus. Resistor R3015 has to be removed to disconnect the 33V. Resistor R3002 has to be present, to feed the tuning voltage to the tuner.
The three bandswitch signals are decoded from two micro controller outputs Sw0 and Sw1. The circuit and truth table can be found in the figure below.
US" pq pq pq pq
Fig.4 Band switching with VST.
The GTV1000 Global TV Receiver
Application Note AN98051
The AGC output of the TDA884X is an open collector. The maximum and minimum voltage at the tuner pin is determined by three external resistors, as can be found in the figure below. Resistor R2 and R3 determine the maximum AGC voltage, which is 4V for the UV13XX tuner series. The minimum voltage is determined by R1 and R2 and the saturation voltage of the AGC output of the TDA884X (0.3V). This minimum voltage is important, because most tuners have a fold-back in the lower part of the AGC characteristic (1.1V for UV13XX). The correct resistor values for GTV1000 are indicated in the figure below.
TUNER
TDA884X
SAWFilter
Fig.5 AGC circuit Note: Resistor R3 to ground is missing in the lay-out of the GTV1000. Please solder a resistor in the PCB in order to prevent that the tuner is driven outside the specification. The performance of the receiver remains the same.
For positive modulation a diode with parallel resistor can be inserted. This circuit takes care of a fast response when the gain has to be reduced, while the charge time of the capacitor at the tuner side is larger, to assure a constant AGC level over one field. The two IF outputs of the tuner are connected directly to the SAW filter. If an asymmetrical tuner is used, one IF pin can be connected to ground via jumper J303, near the tuner, to keep the connection between the tuner and SAW filter as symmetrical as possible. For the same reason the SAW filter ground is connected to the ground of the IF part of the TDA884X. The two IF lines are also connected to the sound option connector, for AM demodulation in case an AM add-on board is inserted. Because the GTV1000 is an economy concept, only 5 pins in line SAW filters can be inserted. The following table shows the different SAW filters which can be used for different areas.
The GTV1000 Global TV Receiver
Application Note AN98051
Intercarrier sound and sound options.
From the video demodulator output of the TDA884X (pin6) the signal is connected to two emitter followers. The first one (TR103) drives the sound-bandpasses, while the second one (TR105) feeds the CVBS signal to the sound traps. This configuration has been selected to reduce the breakthrough from the sound to the video path. For the same reason it is important to keep the sound and video path separated in the lay-out. The GTV1000 is designed to select between two sound systems. One of the two sound band-passes is selected by the DKL1 signal, coming from the micro controller. Via two transistors (TR101, TR102) one of the diodes D100 or D101 is conducting the sound carrier to the SIF input (pin1). In series with this pin a small inductor (L101) is connected to reduce high frequency pick-up by the pin. The demodulated sound is present on pin 55, where the de emphasis capacitor is connected. The sound signal on this pin has no volume control and can be used to feed the front-end sound to the SCART connector. An amplifier is added here to avoid loading the pin and to create a gain of 2 to 3 dB, which is needed to bring the signal level to SCART specification. The connection to the SCART panel is running via the sound option connectors, to offer the possibility to switch also AM sound to the SCART output, in case this is needed (see Fig.6) .
The GTV1000 Global TV Receiver
Application Note AN98051
Cin Yin
Mono out Front-end MoutFE
Fig.6 Sound switching.
The GTV1000 Global TV Receiver
Application Note AN98051
The GTV1000 Global TV Receiver
Application Note AN98051
Cin Yin
Mono out Front-End MoutFE
Fig.7 NICAM sound switching.
The fourth stereo option that can be inserted is BTSC stereo sound. The add-on board is designed for the TDA9852 / 9855. The drive signal for the sound processor is coming from the fixed level audio output of the TDA884X. The correct input level can be set in the audio processor. These sound processors have only one external stereo sound input, so here a switch is needed to select more than one external input sources. The front-end sound out is not present here, because the IC has no fixed level sound output. The reason is that in NTSC countries the sound out is not used for low and mid-end sets. The left and right output is fed directly to the TDA7075AQ audio amplifier. The TDA 9855 has extra features with respect to the TDA9852. These are tone control and a sub woofer output. This sub woofer signal can be fed to the mono amplifier (TDA7056B). If the feature is used, jumper J600 on the main board has to be changed. More information about the TDA9855 can be found in ref.10 and ref.12 report no: AN95047 and AN94004.
CVBS path.
On the demodulator output an emitter follower (TR105) is connected, to drive the sound traps. The collector of this transistor has a separate decoupling. The follower, the decoupling and the traps should be connected to one ground track, to avoid disturbance of other circuit parts by the large currents in the
The GTV1000 Global TV Receiver
Application Note AN98051
ground pins of the traps. This first follower is build with a PNP transistor. The reason for this choice is that two other followers are connected behind this first one. If all followers would be NPN types, the DC voltage drop towards the SCART connector would be too much. The traps that are used are of course depending upon the systems that have to be received. In the USA and south america versions only a 4.5 MHz trap is inserted. In the PAL / SECAM versions the triple trap is used. This device traps three frequencies: 5.5, 5.74 and 6.5 MHz. Space for an extra trap of 6.0 MHz is also present. Behind the traps again an emitter follower is connected, to supply low impedance drive to the CVBS input of the TDA884X for proper clamping. At the SCART output an other emitter follower is present. This one is needed to avoid high currents in the lead from the trap circuit to the SCART connector. These high currents can easily course cross-talk from external to internal CVBS. The high currents are normally caused by the capacitive load of a SCART cable. It is also important to keep the tracks of internal and external CVBS separated.
Note: The crosstalk performance of this GTV1000 board can be improved, by adding a ground track between these CVBS tracks.
8W7T Y
US6Q 8W7Tv
8W7Tv
Cin Yin
8W7Tr
UYU88 vp
T86SU
Fig.8 CVBS, Y / C switching.
Different external input configurations can be inserted in the two PERI connectors. This set-up has been selected to keep the board flexible for all TV markets. The different options are: · Single cinch audio / video in + S-VHS in (mono). · Double cinch audio / video in + S-VHS in (mono / stereo). · Full SCART connector + cinch audio / video in + S-VHS in (mono / stereo). At all the incoming and outgoing lines of the external connectors spark gaps and filters are connected close to the connector, to protect the internal circuit. The first option offers a simple direct connection to the inputs of the TDA884X. The second board contains two CVBS inputs, where the second CVBS input is combined with the Y input of the S-VHS connector. The TDA884X offers the possibility to change the Y input into CVBS
The GTV1000 Global TV Receiver
Application Note AN98051
input. This board can be used for stereo applications. The sound inputs of the second CVBS and SVHS inputs are combined. To switch between the two sound inputs, CMOS switch HEF4052 is used. The third option is a full scart connection containing stereo audio in / out, CVBS in / out, RGB+FBlank in and AV status in. The second CVBS input is again combined with the S-VHS input, as well as the sound input. The S-VHS connector contains a switch, witch can be used to generate a status signal. Again HEF4052 switch is used for switching between the two sound inputs. The CVBS, Y / C inputs contain a terminating resistor of 75, a spark gap and a filter. The lines are connected via a clamp capacitor directly to the corresponding inputs of the TDA884X. The RGB input is described in the next chapter.
RGB input / switch.
The GTV1000 Global TV Receiver
Application Note AN98051
T86 SU
W Wrs Csyihpx
Fig.9 RGB input and switch.
When OSD information is present, the RGB information coming from the SCART-input has to be suppressed. In this case the OSD information coming from the micro via an emitter follower is divided down to the correct level using two resistors. To obtain a proper OSD performance the switching transistor has to be fast. In the GTV1000 a PH2369 is used. The fast blank signal coming from the SCART connector is only active when AV1 is selected. In this case the sync signal for the TDA884X is coming from the CVBS input on the same SCART connector. The fast blank signal coming from the SCART-connector is coupled to the one coming from the micro via an OR function.
Colour decoder.
The colour decoding (NTSC, PAL, SECAM) as well as the base band delay line are fully integrated into the TDA884X. On the outside just the crystals and the colour PLL loop filter have to be connected. Information concerning the application around these pins can be found in ref.3 report no: AN98002 page109. In the GTV1000 concept the crystal switching has been designed in such a way, that it is possible to connect 1, 2, 3 or 4 crystals.
The GTV1000 Global TV Receiver
Application Note AN98051
Q6G7 B
US 7A#(#
Fig.10 Colour decoder application.
· In case one 4.43 MHz crystal is used (PAL 4.4, SECAM), it is connected to pin 35 (X100). · For one crystal 3.58 MHz applications (NTSC-M or PAL-M or PAL-N), the crystal is connected to pin 34, by closing jumper J102. · Two crystal applications, either a combination of 4.43 and 3.58 MHz or two 3.58 MHz crystals can be made by simply connecting one crystal to pin 34 and the other to pin 35 (J102 closed). · When 3 crystals have to be connected, which can be the case for 3 system reception in South America, the NTCS-M crystal is connected to pin 34, while either the PAL-M or PAL-N crystal can be switched to pin 35, using the line SW0 (J100, J102 and J103 closed). · The most extended situation is the 4 crystal application, which is sometimes used in South America, to decode PAL 4.43 MHz besides the three existing systems. In this case the 4.43 MHz crystal is connected to pin 35, while the three 3.58 crystals are switched to pin 34, using the switching lines SW0 and SW1 (J101 closed). The TDA884X contains a chroma reference output, which supplies the selected chroma frequency to the outside. This signal can be used as a reference for a comb filter. In GTV1000 this comb filter option is not included in the board. For information about the comb filter application see ref.6 Report no: AN98092.
The GTV1000 Global TV Receiver
Application Note AN98051
YUV interface.
S@UVSI
Fig.11 YUV interface
RGB outputs & CRT board.
The RGB outputs of the TDA884X are connected to the CRT board via three small series resistors. The cable from the small signal board to the CRT-board also contains the ground connection of the video amplifier. This ground has to be connected to the ground guard ring around the TDA 884X, as indicated in ref.5 report no: AN98097. The TDA884X contains a continuous cathode calibration circuit, which adapts the DC level and the gain of each of the RGB channels every frame. On the RGB outputs every field reference pulses are generated and the current running in the cathodes of the picture tube are fed back to the black current input of the TDA884X. The RGB outputs are regulated to a DC level and a gain, so one field a current of 8mA is flowing into the black current pin and the next field 20mA. The reference pulses producing the 8 and 20mA are not coupled to odd and even field. The black current feed-back line is the most sensitive part of the loop. For this reason some precautions have to be taken to avoid instability. The first one is to keep the ground line on the board and in the cable to the CRT board between the RGB lines and the Black current feed-back line. The second one is to apply some filtering on the black current feed-back signal. In the GTV1000 a capacitor (330pF) is connected to the black current feed-back line on the main board, just before the series resistor (10k) connecting the line to pin 18 of the TDA884X. On the CRT board a TDA6107 triple video amplifier with black current output is used. This device has a fixed gain of 52. To reduce the gain to approximately 45 three series resistors have been added at the RGB inputs. The gain of 45 is needed to obtain the proper drive for the 90° picture tube (Philips A51EAL155X01). If a higher bandwidth is needed, e.g. when picture enhancement features are used, the TDA6107 can be replaced by a TDA6108. The outputs of the video amplifiers are connected to the picture tube via special flash-proof resistors. All tube electrodes, not connected to ground, contain a spark-gap connected to the aqua-dag ground. The focus spark-gap is integrated in the tube socket connector. The aqua-dag ground is connected to
The GTV1000 Global TV Receiver
Application Note AN98051
the ground of the line transformer. This configuration has been selected to keep flash-over-currents in a loop as small as possible. More information about the RGB outputs and black current loop can be found in ref.3 report no: AN98002 page119. Additional information about the video amplifier can be found in ref.4 report no: AN96072.
MICRO CONTROLLER.
TABLE 4 Supported PHILIPS micro controllers. Type number Description Software Package CTV271 / CTV272.
P83C053 P83Cx66 / P87Cx66 P83Cx70 SAA529x / SAA549x
Micro controller for Television and Video (MTV). Single chip 8 bit micro controller for TV. Micro controller for NTSC TV with OSD and Close Caption Micro controller for TV with OSD and One Page Economy Teletext.
CTV828. CTV832.
By means of jumpers and some component changes, this receiver can be configured for one of the listed micro controllers. The different configurations are explained in this sub-section.
Universal micro controller interface description.
To simplify a TV hardware platform which can demonstrate all PHILIPS Micro Controller types, an universal pin definition is defined. In a global TV chassis, this pinning can be used to minimize hardware modifications necessary to configure the set for different market segments. For example the: · ETT in Europe to support Teletext. · P83Cx70 for the American market to support Close Caption. · MTV for the low-end sets without teletext. In this sub-section the functional description of the micro controller input and output lines (I / O-lines) is given. Although the functionality of the pins are discussed in the software manuals of the used software
The GTV1000 Global TV Receiver
Application Note AN98051
packages the VST-tuning voltage output pin1, Service / Factory input pin35 / 45, Stand-by input pin13 / 21 and Reset input pin33 / 43 are discussed in detail.
VST-Tuning voltage control output (Micro-controller pin1 application).
Fig.12 VST tuning curve linearisation for UHF band
The GTV1000 Global TV Receiver
3.3 Service connector and Factory mode.
Application Note AN98051
OSD outputs FBL, R, G and B.
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
The GTV1000 Global TV Receiver
Application Note 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.
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 R2048 10k TR203 BC558 R2051 TR204 BC558 10k R2054 Reset micro 22k TR206 BC548 R2045 10k R2046 100 Z201 3.6V TR205 BC548 R2049 1k
C2011 10uF 50V
+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.
The GTV1000 Global TV Receiver
Application Note AN98051
Reset micro
Supply EEPROM
+5V stand-by
Time base: 100mSec / Div. Trigger CH3.
The reset input of the micro controller is active high. During start-up of the supply voltage Vstb, TR203 is switched off and consequently TR204 starts conducting. This forces the reset input to follow Vstb. This status remains, until Vstb reaches the threshold level of 4.2V (UZ201 + Ube TR203). Starting from this level, TR203 starts conducting and TR204 switches-off. Now C2011 will be charged via the pull down resister1 inside the micro controller and resistor 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
If the supply voltage falls below the threshold voltage, TR203 switches off immediately and TR204 switches on. This discharges 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.
+5V stand-by
Time base: 100mSec / Div. Trigger CH3.
Fig.15 Reset signal during a power dip.
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).
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, R2025 and R2030.
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.
The GTV1000 Global TV Receiver
Application Note AN98051
P83C053 (MTV) Micro controller configuration.
J212 J213 J211
L201 C201
J204 R2030 R2019 R2018 J201 J200
J203 J202
Fig.16 P83C053 (MTV) Micro controller configuration.
The GTV1000 Global TV Receiver
3.8.3 P83Cx66 Micro controller configuration.
Application Note AN98051
J212 J213 J211
J204 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, C2020 and 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.
The GTV1000 Global TV Receiver
Application Note AN98051
P83Cx70 Micro controller configuration.
J212 J213 J211
J204 J201
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, C2020 and 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.
The GTV1000 Global TV Receiver
3.8.5 SAA549x (ETT) Micro controller configuration.
Application Note AN98051
J212 J213 J211
J204 J201
J203 J202
Fig.19 SAA549x (ETT) Micro controller configuration.
Software package.
As said, the 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.
The GTV1000 Global TV Receiver
Application Note AN98051
TABLE 5 Micro controller versus software package. Micro controller type Software package User manual reference.
P83C053 P83Cx66 / P87Cx66 P83Cx70 SAA529x / SAA549x
CTV271 / CTV272. CTV828 CTV832
ETV / UM 97012.0 / ETV / UM 97011.3 (see 13) and (see 14) .
ETV / UM 98013.1 (see 15) CTV832S / CTV832R (see 16)
The GTV1000 Global TV Receiver
4. 4.1 LARGE SIGNAL. Power supply.
Application Note AN98051
The power supply is a mains insulated flyback converter supporting the full mains range. The supply is built around the 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.
Hhv Srpvsvr Trpqh Srpvsvr
3V3 5V 16V 15V 45V 115V
8yyr D8
@ hyvsvr
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 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 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.
The GTV1000 Global TV Receiver
Application Note AN98051
Pin: 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 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 charges C9016. Once reaching the fixed threshold level of 17V, the TDA8380A starts-up the supply. Capacitor C9016 delivers the
The GTV1000 Global TV Receiver
Application Note AN98051
The GTV1000 Global TV Receiver
Application Note AN98051
The GTV1000 Global TV Receiver
Application Note AN98051
TABLE 7 5V / 3.3V micro resistor values R9017 R9023 Output voltage 2K4 1K 3K3 3K 5V 3.3V
The GTV1000 Global TV Receiver
Application Note AN98051
· 5V / 3.3V stand-by, used to supply the micro controller. This supply is programmable by resistor divider R9004 and R9006. See the next table for the proper values.
TABLE 8 5V / 3.3V stand-by resistor values R9004 R9006 Output voltage 2K4 1K 3K3 3K 5V 3.3V
Although this name suggests to be the only stand-by supply, both 5V / 3.3V supplies remain powered during stand-by operation. This because most micro controllers must be powered at all its supply pins (Vdd core, Vdd peripheral and Vdd analog). Transistor TR900 switches the power supply between normal and stand-by operation. The base current is controlled via a transistor, which is controlled by the on / off-output-pin of the micro controller. Removal of the micro controller results in a normal operation of the power supply. This makes it possible to control the chassis via a personal computer, without extra handling to switch-on the supply.
Horizontal deflection. Low voltage horizontal deflection driver circuit.
+8V +15V
R9053 100 L910 C9041 470nF R9055 1k 3 2 BU2506DF+BEAD TR906 R9052 1.8k C9040 470nF R9054 10
HORDRIVE
The horizontal driver stage requires a 16V supply voltage. The horizontal drive current is extremely low, because of Field Effect Transistor TR907. The horizontal drive is AC coupled via C9044, which prevents excessive power dissipation during stand-by operation. The selected BU2506DF horizontal output transistor features a: ·a current gain of 5.5x. ·build in efficiency diode (Iforward max.: 3.0A). ·build in resistor between base and emitter of 60. ·isolated package. Fig.22 shows the signal relationship between the horizontal drive, horizontal flyback, gate source voltage of TR907 and the primary
C9044 10uF 16V TR907 BST70A C9045 33nF
D921 1N4148
R9057 18k
Fig.21 Horizontal drive circuit
current of L910.
The GTV1000 Global TV Receiver
. Legend:
Application Note AN98051
· ch1: HORDRIVE. · ch2: UCollector of TR906. · ch3: Ugs of TR906. · ch4: Idrain of transistor TR907. Scale: 200mA / Div. Once the Hordrive signal is high (CH1), TR907 starts conducting. This results in a rising current at the primary side of transformer L910 (CH4). Now, energy is stored into the core, because the baseemitter diode of TR906 prevents a current to flow at the secondary side.
Resistor R9053 determines the stored energy thus the base-current for TR906. Increasing the resistance value, reduces the base-current. The maximum base-current is set to 600mA, which is sufficient to drive a peak-collector current of about 3A. The average deflection current through the collector of TR906 is about 2.5A. After a high to low transition of the Hordrive-signal, TR907 will switch-off and a flyback pulse at the secondary side of L910 turns-on transistor TR906. Fig.23 shows the signal shapes at the secondary side of the driver transformer. Legend: · · · ·
Fig.23 L910 secondary signal shapes.
Fig.22 L910 primary signal shapes.
ch1: HORDRIVE. ch2: UCollector of TR906. ch3: Ube of TR906. ch4: Ibase of transistor TR906. Scale: 1A / Div.
The GTV1000 Global TV Receiver
Application Note AN98051
Horizontal flyback feedback circuit.
R9046 100
C9036 1uF C9037 100pF D917 BAT85 C9038 330pF
To control the phi-2 phase locked loop circuit, the video processor needs an input signal called Hflyback. This signal is generated by the circuit shown in (see Fig.24) . It supports two different threshold levels: 1. 30V for the rising edge. This level can be selected more or less by R9047, R9049 and capacitor C9037.
2. 400V for the falling edge. The hysteresis between rising and falling edge levels can be tuned by C9037,
TR905 BC548C
R9047 220k R9050 10k R9049 47k D918 1N4148
R9048 220k
Hflyback
Fig.24 Flyback adapter circuit
The GTV1000 Global TV Receiver
4.2.3 4.2.3.1 Horizontal deflection corrections. Linearity correction.
Application Note AN98051
The horizontal linearity correcting device L909 consists of a coil, wounded on a ferroxcube rod with a magnet. Because of the magnet, the core material is close to saturation if the current flows in one direction. This results in a low inductance of the coil. Once the current flows in the other direction, the electro magnetic field will compensate for the magnet, resulting in a high inductance. This corrects for the resistance of the deflection coil.
When a line-scan starts, the linearity corrector consumes energy in its permanent magnet until this is saturated. The rest of the line scan the (saturated) linearity corrector has a low impedance. In the last part of a line-scan, the Ohmic resistance of the H-deflection coils consumes deflection energy. When the linearity coil is well balanced to the deflection yoke, it improves the linearity of the horizontal scan. L909 is connected in series with capacitor C9042 and the horizontal winding of the deflection yoke. The effectivety of this component is deflection yoke dependent, so the correction must be checked for different picture-tube types. If the horizontal linearity is not good, exchange L909 for a more suitable value. Be sure the current direction through the coil is correct.
S-correction.
To correct the horizontal linearity between centre and the left- and righthand edges of the screen, the supply for the horizontal deflection is not taken directly from +VB but from a charged capacitor C9042. When the deflection saw-tooth current flows through this capacitor, its voltage will be modulated with a parabola. This in return causes an "S" shaped modulation of the deflection current. The required amount of S-correction depends on the picture tube type.
During the scan period the capacitor is used to realize a S shaped horizontal deflection current (see Fig.25) The required S-correction is picture tube type dependent. Decreasing the capacitance of C9042 increases the correction.
Defl. Current
T-axis
Fig.25 S-corrected horizontal deflection current
The GTV1000 Global TV Receiver
Application Note AN98051
Dynamic horizontal-phase correction.
HOR Defl
To reduce the voltage drop across C9042, capacitor C9043, resistor R9051 and diode D919 are added. C9043 is charged during the fly-back period via R9051. After UC9042 drops below the U C9043 - UD919, it will be re-charged by C9043. This reduces the horizontal phase shift drastically.
Fig.26 Horizontal phase shift reduction circuit.
TDA8351 / 56 vertical deflection.
The TDA8356 is a 9 pins vertical deflection circuit (2 App) for DC-coupled 90° deflection systems with frame frequencies from 50 up to 120 Hz. Two supply voltages are required, one supply voltage for the scan and a second supply for the flyback. For deflection systems that need 3 App, the compatible TDA8351 can be used.
The GTV1000 Global TV Receiver
Application Note AN98051
)HHGEDFN
Fig.27 Block diagram of the vertical output stageTDA8351 / 56
The GTV1000 Global TV Receiver
Application Note AN98051
R1033 1k D102 D103 1N4148
Vsync
R1039 2.7k 1N4148 TR107 BC558
Emitter follower TR107 is added because the total load of the vertical guard input, Beam-current interface and micro controller Vsync input can not be driven by the TDA8356 guard output. This buffered vertical guard signal is used for:
The GTV1000 Global TV Receiver
Application Note AN98051
because the falling switching threshold of the vertical sync. input of some micro controllers is about 0.9V. D103 prevents the influence of UC1032 at this low level. To minimize vertical related disturbances in the ground and supply tracks of the receiver, resistor R8004 and de-couple capacitor C8004 are added near the IC. Also the Fly-back supply voltage at input pin 6 is de-coupled by resistor R8005 and capacitor C8002. Its maximum aloud capacitance is 22uF to limit excessive peak loads in the IC. Instead of connecting C8002 directly to the IC ground, it is decoupled towards the operating voltage at pin 3. This reduces the internal voltage differences during switching-off the set. Because the load at the 16V supply is higher compared to the 45V supply load, the 16V will drop fast. By de-coupling the 45V to the 16V, it will drop accordingly. This result in less internal stress in the IC.
Beam current information.
The GTV1000 Global TV Receiver
Application Note AN98051
LAY-OUT & EMC RECOMMENDATIONS. Lay-out.
All remarks concerning the lay-out of parts of the receiver have been integrated in the chapter describing the specific circuit part. A special report has been created, describing the TDA884X board design step by step. The information can be found in ref.5 EMC guidelines for TDA88XX applications, report no: AN98097.
Report AN98097 ref.5 also describes all design rules, to obtain optimal EMC performance of the board. The performance of the GTV1000 receiver has been measured with different input signals. In APPENDIX 15 the EMC performance can be found when receiving a SECAM L signal, because this is the most critical situation.
ALIGNMENTS.
The presence of all components in the required configuration Correct setting of all solder jumpers Good connections of all cables, especially the high voltages to the CRT panel and picture tube Connection of picture tube Aqua-dag grounding to CRT panel
Before the receiver is switched on, please check the following:
Front end IF-PLL.
This only for N1 version of the TDA8844. Apply a 38.9MHz IF-signal, modulated with a PAL test pattern to the IF output of the tuner (at pin 11 of tuner). Force the system in PAL mode. Enter the service menu and select item "IF". Adjust the value until the AFC indication toggles between 01 and 02. The N2 version has an alignment free IF coil inside.
Tuner AGC.
Apply an RF signal between 10mV and 50mV to the tuner. Tune to this signal. For an asymmetrical tuner, adjust "AGC" for 1Vp-p at the input of the SAW filter. For an symmetrical tuner, adjust for 0.5VPP.
Vertical geometry.
The GTV1000 Global TV Receiver
Application Note AN98051
Horizontal geometry.
Apply a picture with a cross-hedge pattern to Scart input AV1 and selects this input. Adjust the picture height "VA", vertical shift "VSH" and vertical S-correction "SC". Adjust the horizontal phase "HSH" and picture width "EW" (full scan width). Adjust the horizontal linearity with the linearity corrector coil on the power & deflection board. Adjust the parabola width "PW" and the corner parabola correction "CP" for perfect straight vertical lines. · Adjust the trapezium correction "TC".
Video amplifiers.
Luminance-Chrominance delay.
The TDA884x has an adjustable luminance delay "DLY" to correct for delay in the SAW filter. This can be used to equalise the luminance delay for each colour system, so that the transitions in grey match the colour transitions. (Suggestion: In a multi-standard receiver, the embedded software can store this alignment for each colour system separately). · Set contrast, brightness, colour saturation and peaking to normal values. · Select a colour test circle pattern via the front-end (tuner) and adjust the luminance delay DLY.
MODIFICATIONS WITH RESPECT TO PRINTED CIRCUIT PR31602.
The GTV1000 Global TV Receiver
Application Note AN98051
· The CVBSout track from the demodulator output to the SCART and the track conducting CVBSext from the external input to the TDA884X are directly next to each other on the GTV1000 board. This situation should be avoided, because this can cause cross-talk between internal and external CVBS. See also Chapter 2.2.3 on page 21. · A small modification was introduced to improve the stability of the black current feed-back loop. There was a series resistor present of 1k from the current output of the video amplifiers to the black current input of the TDA884X. The resistor is increased to 10k. Also a small capacitor C of 330pF is added between the "guard-ring" ground and black current signal comming from the video amplifier side, see Fig.29 . This modification reduces the bandwidth the black current feed-back loop. This is no problem, because the the reference pulses on the RGB outputs is present during the scan period of one line, while the feed-back current is measured on approximately 2 / 3 of the line. ·
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