TDA7020T

      The TDA702OT integrated circuit is for FM portable radios, stereo as well as mono, where a minimum periphery is important in terms of small dimensions and low cost. The lC has a FLL (Frequency Locked Loop) system with an intermediate frequency of 76 kHz. The selectivity of TDA7020T is obtained by active'RC filters. The only function to be tuned is the resonant circuit of the oscillator. lnterstatiownoise as well as noise from receiving weak signals is reduced by a correlation mute system. Special precautions have been taken to meet local oscillator radiation requirements. Because of the low intermediate frequency, law pass filtering of the MPX signal is required to avoid noise when receiving stereo. 50 l<Hz roll-off compensation, needed because of the low pass characteristic of the FLL, is performed by the integrated LF amplifier. For mono application this amplifier TDA7020T can be used to directly drive an earphone. The field-strength detector enables field-strength dependent channel separation control.
      The TDA7020T includes the following functions: RF input stage , Loop amplifier, Mixer , Internal reference circuit, Local oscillator, LF amplifier TDA7020T for: mono earphone amplifier or MPX filter, IF amplifier/limiter, Frequency detector, Mute circuit, field-strength dependent channel separation control facility. Supply voltage range (pin 4) Vp=1,8 to 6, Supply current at Vp = 3 (lp)=typ. 6,3 mA, RF input frequency range(frf)=1,5 to 110 MHz, Sensitivity for -3 dB limiting voltage) (source impedance: 75 9; mute disabled)(EMF)=typ. 3 V, Signal handling voltage(source impedance: 75) (EMF)=typ. 200 mV, AF output voltage(Vo)=typ. 90 mV.