TA2022AFNG Ver la hoja de datos (PDF) - Toshiba
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Fabricante
TA2022AFNG Datasheet PDF : 18 Pages
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5. MPX IN
This IC can attenuate only FM stereo main signal level. Because
MPX input for main signal (pin(20)) is independent of that for
pilot signal (pin(21), this terminal is shared with AM input).
Internal circuit of MPX in terminal (pin(20)) is shown in fig.2. FM
stereo main signal level can be attenuated by connecting an
external resistor RX. Because FM stereo main signal level is
attenuated by internal resistor (14kΩ and10kΩ) and resistor
RX. And it is applied to an emitter of transistor Q.
6. AM tweets
It is necessary to connect the capacitor Ct (about 330pF)
between VCC terminal (pin(6)) and DET OUT (pin(22)), in case that
AM tweets occurs by pattern layout. (Fig.3)
This Ct can also functions as phase compensation of MPX stage.
7. AM AGC
It is necessary to connect a capacitor C (about 68pF) between
VCC terminal (pin(8)) and AM IF IN terminal (pin(6)), in case that
AGC circuit doesn't operate normally. Because second harmonic
of local oscillator is applied AM IF terminal (pin(6)) by pettern
layout.
In case that capacitor (C = 68pF) is connected, AM stop pulse
sensitivity is delayed about 1dB.
Output DC voltage of AGC terminal (pin(8)) is V8 = 0.1V (typ.,
AM mode, at no signal).
8. Stereo indicator / AM IF output (for AM stereo)
• The terminal of pin(13) is built in stereo indicator function and
modulated AM IF signal output. In AM mode, RIF (3kΩ or
less) should be connected between VCC and pin(13) , or pin(13)
should connected to VCC directly. (Fig.5) In case that
RIF >3kΩ or pin (13) is opened, this IC doesn't operate
normally in AM mode. Because transistor Q2 is saturated.
TA2022AFNG
Fig.2 Internal circuit of MPX
in terminal
Fig.3 Countermeasures for AM
tweets
8
2006-04-11
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