LA7577 Sanyo Semiconductor Corporation, LA7577 Datasheet
LA7577
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LA7577 Summary of contents
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... Ordering number: EN 4037C Overview The LA7577N is a high tone quality and high picture qual- ity, video IF and sound IF IC. It employs split processing of the video IF signal and sound IF signal using SAW fil- ters and a PLL detector. Further, the PLL detector incorpo- rates a buzz canceler for Nyquist buzz interference suppression to achieve high tone quality ...
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... Differential phase Maximum AFT voltage Minimum AFT voltage White-noise threshold voltage White-noise clamp voltage Black-noise threshold voltage Black-noise clamp voltage AFT detector sensitivity VIF-stage input resistance VIF-stage input capacitance APC pull-in range (U) APC pull-in range (L) VCO maximum variation range LA7577N Symbol Conditions ...
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... Minimum AFT voltage White-noise threshold voltage White-noise clamp voltage Black-noise threshold voltage Black-noise clamp voltage AFT detector sensitivity [SIF] FM detector output voltage [Mute, Defeat] AFT defeat start voltage AV mute threshold FM mute threshold AFT defeat voltage LA7577N Symbol Conditions 10mVrms SIF1 i V max +2 ...
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... Sample Application Circuit (Japan) LA7577N No. 4037—4/16 ...
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... Leave pin 22 open When the AFT circuit is not used • Tie pins 11 and 12 to GND • Leave pin 14 open When the RF AGC circuit is not used • Connect a 0.01 F capacitor between pin 4 and GND • Leave pin 10 open LA7577N No. 4037—5/16 ...
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... LA7577N Interface Circuit LA7577N No. 4037—6/16 ...
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... In this case, the RF signal is converted signal by the Nyquist slope of the SAW filter. Since the sidebands in the vicinity of the LA7577N The PLL detector is shown in Figure 1. The automatic phase control (APC) circuit multiplies the IF signal by the VCO output signal, which is phase shifted sup- press the AM component. The APC output is passed through a low-pass fi ...
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... This phase distortion is the cause of audio buzz, or Nyquist buzz, because the VCO synchronizes to the com- posite vector. A Nyquist buzz cancelation circuit is incor- porated into the LA7577N to reduce the level of this noise as shown in Figure 3. A typical signal with Nyquist buzz is shown in Figure 4 together with the compensating signal generated by the Nyquist-slope canceler and the resultant signal ...
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... AGC and 2nd AGC, respectively, as shown in Figure 8. The IF AGC audio component of the input signal to the video IF stage is first removed by an audio trap. Figure 8. IF AGC circuits LA7577N Typical AGC filter time constants Single time Pin Component ...
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... DC SAW fil- ter is used, an inductor should also be connected as shown in Figure 14. This matches the SAW filter output capaci- tance to the LA7577N input capacitance and increases the sensitivity. The inductor typically would be 0.62 H (for Japan), 1.0 H (for the USA) or 1.3 H (for PAL countries). ...
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... AFT tank. The AFT can be defeated by connecting pin 11 to ground through resistor R1, which should be 20k or lower. Figure 17. AFT tank characteristics LA7577N AFT Output (Pin 14) An external bleeder resistor is required to generate the AFT voltage. The AFT loop time constant is formed by external resistor R3 and capacitor C2, as shown in Figure 19 ...
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... VCO tank susceptibility to external effects can be reduced by using either chip capacitors or capacitors integrated with the tank coil. Figure 21. VCO tank LA7577N Composite Video Output (Pin 17) The 4.5MHz composite video output circuit is shown in Figure 22. A resistor should be connected between this emitter-follower output and ground to ensure adequate output drive capability ...
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... Figure 25. The bleeder resistor should be chosen to avoid excessive gain and extreme video sync tip voltages. Figure 25. Voltage amplifier configuration LA7577N Figure 24. Equalization amplifier External bleeder resistor selection If the equalization amplifier is configured for non-unity ...
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... The input impedance of the amplifier, shown in Figure 29, is approximately 1k . Any interference on pin 24, a video signal for example, can cause audio buzz or heterodyning. Good circuit board layout is essential. Examples of both good and poor layout are shown in Figure 30. LA7577N Figure 29. SIF stage input circuit Figure 30. PCB layout examples No. 4037—14/16 ...
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... Sanyo SAW Filters Two types of surface acoustic wave (SAW) filter built on different piezoelectric substrates can be used with the LA7577N—Lithium Tantalate and Lithium Niobate. Lithium Tantalate (LiTaO ) SAW filters 3 LiTaO SAW filters have a low temperature coefficient of 3 18ppm/ C and good stability, but have high insertion loss ...
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... This catalog provides information as of June, 1997. Specifications and information herein are subject to change without notice. LA7577N Japan USA ...