SL5067 GEC | Alldatasheet
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Technical content
D.S. 3802 1.3 SL5067 MULTI – STANDARD VIDEO MODULATOR The SL5067 is a video up converter, capable of operating at frequencies up to 900MHz. It is compatible with both PAL and NTSC, accepting baseband video and sound inputs and modulating up to any desired VHF or UHF channel. Modulated UHF outputs consist of open collectors driving external 75 load resistors for line matching requirements. Prescaler outputs are also provided enabling the use of a synthesiser to control oscillator frequency. The SL5067 operates from a 5V supply.
FEATURES
Symmetrical RF Oscillator Operating to 900MHz Symmetrical RF drive to a frequency synthesiser Video Signal Input Clamp Video Peak White Level Detection and Automatic Gain Control Control of Video Modulation Index Direct Drive into 75, via Symmetrical open Collector Outputs ESD Protection Picture Carrier to Sound Carrier Ratio Adjustment Low External Component Count ESD Precautions must be observed
APPLICATIONS
In Home Rebroadcast System (LPTV) MOD OUTPUT 2 MOD OUTPUT 1 MOD INDEX VIDEO INPUT AGC HOLD GND PRESCALER OUTPUT 1 PRESCALER OUTPUT 2 LO INPUT 1 LO OUTPUT 1 GND VCC FM/AM SELECT AUDIO INPUT SOUND OSC 1 SOUND OSC 2 GND LO INPUT 2 LO OUTPUT 2 LO VCC GND VCC FM/AM SELECT AUDIO INPUT SOUND OSC 1 SOUND OSC 2 GND LO INPUT 2 LO OUTPUT 2 LO VCC MOD OUTPUT 2 MOD OUTPUT 1 MOD INDEX VIDEO INPUT AGC HOLD GND PRESCALER OUTPUT 1 PRESCALER OUTPUT 2 LO INPUT 1 LO OUTPUT 1 SL5067 SL5067 DP20 MP20 Fig. 1 Pin connections – top view
ORDERING INFORMATION
SL5067/KG/MPEF (Tape and Reel)
Fig. 2 SL5067 block diagram
ELECTRICAL CHARACTERISTICS
Tamb= –10°C to 80°C, VCC=4.5V to 5.5V. These characteristics are guaranteed over the following conditions (unless otherwise stated). They apply within the specified ambient temperature and supply voltage ranges. Characteristics Pin Value Units Conditions Characteristics Pin Min Typ Max Units Conditions Supply Voltage 11, 19 4.5 5.5 V Supply Current 11, 19 mA VCC=5V LO Prescaler Output Level 7, 8 mV RMS Single ended into 50 LO Prescaler Output Impedance 7, 8 LO drift with temp from switch on 10, 12 kHz See note 1 LO variation with supply 10, 12 330 kHz See note 1, VCC = 4.5 to 5.5 V RF carrier output level 1,2 dBV unmodulated into 50 Video Input 0.5 1.0 1.5 Vp–p Video mod index 1, 2 See note 2 Video Signal/Noise Ratio 1, 2 dB Weighted PAL 200kHz – 5.5MHz Sound Subcarrier temperature drift from switch on 15, 16 kHz See note1 Sound drift with supply 15, 16 2.5 kHz VCC = 4.5 to 5.5V Audio Input Impedance k Audio Input Voltage reference V Audio Input Level 0.88 Vp–p Measured at pin 17 FM THD 1, 2 Q = 9, f = 35kHz AM THD 1.2 Input level 880mV p–p Picture/Sound Carrier Ratio (FM) 1, 2 dB R = 0, See note 3
ELECTRICAL CHARACTERISTICS (cont.) Tamb= –10°C to 80°C, VCC=4.5V to 5.5V. These characteristics are guaranteed over the following conditions (unless otherwise stated). They apply within the specified ambient temperature and supply voltage ranges. Characteristics Conditions Units Value Pin Characteristics Conditions Units Max Typ Min Pin Sound Oscillator FM Deviation 1, 2 250 kHz/V C = 120pF, L = 5.6H (QL = 9) NOTES Including external components effects May be increased by use of external resistor, see Fig. 3 May be adjusted by use of external resistor dependent on video content, see Fig. 4 The above measurements assume nominal 80% modulation depth on vision and sound carriers ABSOLUTE MAXIMUM RATINGS All voltages are referred to VEE=0V Parameter Pin Value Units Conditions Parameter Pin Min Max Units Conditions Supply Voltage 11, 19 –0.3 V Modulation index –0.3 VCC+0.3 V Video input –0.3 VCC+0.3 V Audio input –0.3 VCC+0.3 V FM/AM select –0.3 VCC+0.3 V Storage temperature –55 +125 DP20 thermal resistance, chip–to–ambient °C/W DP20 thermal resistance, chip–to–case °C/W MP20 thermal resistance, chip to ambient °C/W MP20 thermal resistance, chip–to–case °C/W Power consumption at 5.5V 300 mW Fig. 3 Frequency spectrum above the Video picture carrier (QTANK = 9) –16dB –13dB –65dB –70dB –70dB –47dB 84dBV Power levels shown are relative to picture carrier fp typically fp fp+(fs–fc) 1.57MHz fc 4.43MHz fs 6MHz 2xfc 8.86MHz 2xfs 12MHz 3xfs 18MHz
The video signal is applied to pin 4 via a coupling capacitor, (see Fig.9). This capacitor provides both clamping and black level hold. The internal peak white AGC can cope with an input signal of between 0.5 and 1.5 volts peak to peak.The full 9.5 dB AGC range is handled within a 600mV span on this storage capacitor. Pin 3 (MOD INDEX) is used to control both RF carrier amplitude and video polarity, see Fig. 3. Since the video input is internally AGC’d, varying the carrier amplitude will also adjust the video modulation index, see Fig. 4. For example, for a negative modulation (PAL or NTSC) with an 80% modulation index, pin 3 should be set to 1.1Volts (see Fig. 4). This voltage corresponds to an unmodulated RF output level of 82dBV, see Fig. 3. AUDIO The sound IF oscillator can operate from 4.5MHz to 6.5MHz to cover all sound standards. The centre frequency is determined by the Sound IF Tank LC connected between pins 15 and 16. The centre frequency is given by. 2 LC The Q factor of the TANK is given by. Q 1770 2f0L 1770 2f0C The Q factor of the coil must be high, e.g. >20 Good temperature stability can be achieved by the correct choice of temperature coefficients for Csound and Lsound. The Audio signal should be coupled into pin 17 via a 470nF capacitor. The maximum input level is 1 volts peak to peak. Selection of AM or FM sound is made via pin 18 (FMAMSEL). The DC value on this pin controls the level of the sound subcarrier. The crossover point between FM and AM sound occurs at VCC (measured at pin 18). Below this voltage, the modulator is set to FM sound; above it to AM. Graphs for AM and FM sound subcarrier output levels are shown in Figs. 6 and 7. If AM sound is required, it is recommended that a modulated carrier is fed into the Audio input. Further details of this are mentioned at the end of the datasheet in the paragraph marked ‘‘Positive Modulation” MODULATED RF OUTPUT The modulated RF outputs from pin 1 and pin 2 consist of open collectors which should be externally connected to VCC via 75 resistors. Great care must be taken with the decoupling of the supply to these outputs. Both outputs are suitable for driving either 75 line, or for connection to a balun or impedance matching transformer. This has the added benefit of minimising common mode coupling, thus giving improved RF performance. 0.0 1.0 2.0 3.0 4.0 5.0 80dBV 1.4 2.45 VOLTAGE SET ON PIN 3 Fig. 4. Picture carrier, unmodulated RF output level
80.0 60.0 40.0 20.0 0.00 0.0 1.0 2.0 3.0 4.0 5.0 80% NEGATIVE Fig. 5. Modulation index as a function of pin 3 voltage 1.1 2.2 96% POSITIVE PIN 3 VOLTAGE MOD INDEX % (VIDEO) NEGATIVE Fig. 6 FM sound carrier amplitude dBV. 0.0 1.0 2.0 3.0 1.66V RF O/P LEVEL dBV INTO 50 ref to ground PIN18 VOLTAGE PIN 18 Fig. 7 AM sound carrier amplitude dBV unmodulated 4.0 3.0 2.0 AUDIO OUTPUT LEVEL dBV INTO 50 PIN18 VOLTAGE MODULATION POSITIVE MODULATION
5.6H (6MHz) FM/AM SEL AUDIO I/P SOUND TANK SL5067 330n 470nF VIDEO INPUT SL5067 VIDEO MODULATION INDEX SET VIDEO INPUT AGC HOLD Fig. 9 Video input Fig. 8. Typical FM sound section VCC 120 120 5mA SL5067 1.2p 1.2p 1.5p 1.5p 47K 47K 40nH BB405 BB405 TUNING VOLTAGE Fig. 10 RF oscillator Fig. 11 Modulated outputs 4mA SL5067 NOTE:– both coils 24SWG VCC 1.2p 1.2p 1.5p 1.5p 100n 100pF 2 turns 3mm ∅ turns 3mm ∅ 100p 5p6 BB405 22K 22K 10K 10n VTUNE Fig. 12 UHF application
1.2p 1.5p +30V 22K 2N3904 10n 10K 22K BB405 100p 5p6 2 turns 6mm ∅ turn 6mm ∅ 100nF 100pF 1.2p 1.5p VCC LAUDIO CAUDIO 5.6 120p 220p AUDIO INPUT 220K SL5067 Fig.14 typical application showing video modulator with synthesised oscillator 470n VCC 100nF 1nF 1nF RV1 VCC 2 VCC RV2 NOTES:– RV2 adjusts the picture carrier to sound carrier ratio RV1 adjusts the modulation index In applications the potentiometers should be replaced by 1% fixed resistors connected between VCC G and ND The values chosen must reproduce the correct bias voltages on the relevant input pins 22K 480 100 120 140 160 180 200 220 240 260 280 120 160 200 240 280 320 380 400 440 Q=16 Q=2 Q=8 OUTPUT LEVEL (dBV) UNTERMI- NATED FM DEVIATION (kHz/V) PICTURE CARRIER SOUND SUBCARRIER DEVIATION 3rd HARMONIC SOUND TANK CAPACITANCE Fig. 13 Sound oscillator harmonics v. tank capacitance (fSOUND=6.0MHz)
The key to good modulator performance is to ensure good and compact circuit layout with adequate grounding of all supplies. Earth loops must be avoided or kept as small as possible since RF coupling either through the air, or through the ground plane itself is the single most important factor in degrading modulator performance. Double sided board with a groundplane should be used, and all sensitive pins must be properly decoupled as close to the device as practicable. Oscillator design and layout The oscillator should be kept as small as possible to minimise parasitics. It is recommended that the circuit diagram shown in these application notes is used if the entire UHF band is to be covered. For lower frequencies or for applications requiring less tuning range, component values can be adjusted. Surface mount components should be used throughout the circuit and particular care must be taken with placement as the two coils should be as close to the oscillator pins as possible.( See Figs. 16 and 17) For applications at low VHF frequencies, it is suggested that the values of the coupling capacitors on pins 9, 10, 11 and 12 are increased, 2.2pF capacitors (or greater) may be used for frequencies up to 500MHz but it must be remembered that the larger the coupling capacitor used, the smaller the tuning range will be, as the varactor diode capacitance will form a lower percentage of the total tuning capacitance of the loop. For fixed frequencies (or small tuning ranges) up to 100MHz, 15pF or 18pF capacitors may be used. Varactor tuning of the SL5067 should not be attempted unless the application either uses a synthesiser, or a temperature compensating network is used. The capacitance of most varactor diodes changes greatly with temperature, and this must be compensated for if the modulator is to remain on tune to the correct channel. For applications requiring tuning over only a few channels, an air variable capacitor plus appropriate temperature compensation may be used. Modulated outputs Care must be taken with the routing of the modulated outputs and also with the mod index pin, pin3. It is suggested that pin 1 is used, and that the unused modulated output on pin 2 is terminated in a way which looks as physically and electrically similar to the used output on pin 1. Experiments have shown that a RF coupling problem can exist between pins 2 and 3. This manifests itself at frequencies over 600MHz in applications where pin 3 is not taken directly to ground. Good decoupling of pin 3 (with 10pF and 10nF) will help to reduce these effects. The modulated outputs must be routed away from the oscillator tank as there is danger of the local oscillator signal coupling directly into the modulated outputs. This will produce distortions in the modulated signal giving bad performance in such characteristics as differential phase and gain. For VHF and other applications below 500MHz RF coupling is not such a problem, however similar care should still be taken with layout in order to maximise device performance. Use of a balun It is possible to further improve device performance with the use of a balun to remove the effects of common mode coupling. Although using a balun will add to component cost, it may be the only way to achieve acceptable performance at higher frequencies where common mode noise has made it impossible to achieve a low enough minimum power signal to give the necessary dynamic range in the output signal. A low cost balun wound on a ferrite bead former should be sufficient to provide adequate performance in the majority of applications. Sound tank circuit Care must also be taken with the layout of the sound tank, in order to minimise harmonics,and reduce coupling between the audio and video parts of the circuit. The sound tank must be situated as close to the device pins as possible. If this is not done, RF may couple into the sound tank, via the tracks connecting the sound oscillator to the inductor and capacitor. In practice, it is easiest to mount the sound tank capacitor close to, or directly on pin 15 and 16, with the inductor slightly further away. This appears to give the best linearity. In some cases where some coupling and/or distortion problems are occurring, the addition of small 2p2 capacitors from either side of the tank circuit to ground may improve both FM deviation and linearity. For optimum performance (in the FM case) the sound tank should be selected to give a Q of around 10. The circuits shown in the datasheet give a value of approximately 9, and are the suggested normalised values to be used. Lower values of Q will give greater FM deviation per volt input (kHz/Volt), but also increase the level of the 3rd harmonic of the sound subcarrier. This is shown in Fig. 10. The Q of the inductor chosen should be at least 2.5 times the Q of the tank circuit itself. It is not recommended that a Q of over 16 is used, as the amplitude of the sound subcarrier fundamental will start to decrease once a Q of approx 12 has been reached. Thus if a Q of 20 were used in order to give good harmonic performance, there would be an unacceptable trade off in terms of picture carrier to sound subcarrier ratio, which would be approx 20dB. MISCELLANEOUS POINTS Board layout and decoupling Good decoupling techniques must be used throughout with the use of surface mount components wherever possible. For best performance, all supplies and sensitive pins should be decoupled as close to the device as possible, with a combination of capacitors, say 100pF and 10nF to ground. The use of double sided board with a groundplane is strongly advised. This should be of particular help in the reduction of oscillator coupling. Mod index pin As already stated, great care must be taken with the mod index pin, pin 3. This should be decoupled with chip components as close to the pin as possible. Ideally the mod index should be defined with a DC voltage, thus requiring the use of two external resistors, see Figs 4 and 5. It is also possible to define mod index through the use of a single resistor connected to ground or VCC depending on whether negative or positive modulation is required. Synthesiser drive It is suggested that any synthesiser (if used) is driven differentially. This is done by taking both of the prescaler outputs (pin 7 and 8) to the synthesiser via 1nF or 10nF capacitors. FM/AM select The voltage on the FM/AM select pin should be defined by two external resistors between vcc and ground, see Figs 6 and 7. The application diagram Fig. 14 shows a potentiometer, RV2 which is used to define the voltage on this pin in the demo board in practice it is suggested that in low total resistance value (5V or less) is used between VCC and GND since this will ensure a constant voltage on pin 18 irrespective of any small internal resistance variations between devices, thus ensuring a constant PC/SC ratio. It should be noted that the sound subcarrier level is referenced to the AGC sidebands rather
than the picture carrier itself. Thus if the picture carrier level is reduced by using a resistor on pin 3 (mod index set), the level of the sound subcarrier will not change. This should be remembered when setting up a modulator to give the desired modulation index and vision/sound carrier ratio. POSITIVE MODULATION Several references are made in the text to positive video modulation and AM sound. Whilst it is possible to switch the device into these modes, it should be noted that the SL5067 will not perform to full SECAM specifications. Use of AM sound may produce sound–in–vision interference at higher modulation depths. It should be possible, however to AC couple in modulated audio. If this is attempted, the sound tank circuit on pins 15 and 16 would not be required. The modulated audio signal should be fed into the Audio input pin (pin 17) via a 470nF capacitor. The FM/AM select pin can be used as a gain control pin, but will not switch the device between FM and AM modes.
+5V +30V 47nF 22K 220nF 4MHz 18pF 22K 2N3904 NC NC NC NC NC NC NC NOTES: SDA SCL +5V 10nF 22K 10K 10nF 1nF 75R 75R 75R 10nF 10nF 75R 339nF 470nF 10nF 10nF 1p2 1p5
2 TURNS
NOTE BOTH INDUCTORS ARE 6mm DIA
1 TURN
FM–AM SOUND SELECT PRE–EMPHASIS 220K 220pF AUDIO I/P +5V Fig. 16 Video modular test board circuit diagram RV1 adjusts the modulation index RV2 adjusts the picture carrier to sound carrier ratio RV3 adjusts the AM modulation path In applications the potentiometers should be replaced by 1% fixed resistors connected between Vcc and Gnd. The values chosen must reproduce the correct bias voltages on the relevent input pins. For AM sound applications the pre–emphasis cpmponents are bypassed, the I/P being connected to pin 17 via 470nF. For FM sound applications the pre=emphasis components are switched in and RV3 is switched out. 5u6H RV1 MOD INDEX S P S L NC FM AM
Fig. 17
Dimensions are shown thus: mm (in). For further package information please contact your local Customer Service Centre SEATING 7.11 (0.280) MAX 0.23/0.41 PLANE 2.54 (0.100) NOM 0.38/0.61 (0.015/0.024) 0.51 (0.020) MIN (0.045/0.065) 27.94/1.100 MAX 1.14/1.65 5.08 (0.200) MAX 3.05 (0.120) MIN (0.009/0.016) 7.62 (0.300) NOM
20 LEAD PLASTIC DIL DP20
0.36/0.48 12.60/13.00 0.74(0.029) 7.70/7.80 1.27 (0.050) NOM 0.41/1.27 0.10/0.30 2.36/2.64 10.00/10.64 0.25/0.51 0.23/0.33 PIN 1 IDENTIFICATION (0.496/0.512) AT 4 PLACES 0.291/0.299) (0.093/0.104) (0.014/0.019) (0.004/0.012) PIN SPACING (0.394/0.419)
20 LEAD MINIATURE PLASTIC MP20
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