BA1404 FM emission chip internal schematic block diagram and application circuit diagram ----- Ba1404

Keywords: ba1404, frequency modulation circuit diagram BA1404 FM emission chip internal principle block diagram and application circuit diagram BA1404 is a stereo FM emission integrated circuit, which can also be applied to remote control circuitry. BA1404 is the US RoHM product, high integration, less peripheral components, reliable work. The power supply voltage is widely adapted, and it can still work normally when it is as low as 1.5V. Figure 1 BA1404 internal circuit principle block diagram Figure 2 BA1404 application circuit BA1404 Application Notes: (1) In order to make the frequency characteristics of the frequency modulation are consistent with the frequency characteristics of the FM broadcast receiver, the left and right channel lifts are required to pass a pre-load circuit of 50 μs, such as the figure. Show. When used for radio remote transmitting circuits, the left and right input terminals can be merged, and the capacitance is connected to the signal input with a 0.1 ~ 1μF capacitor. (2) 12 ~ 14 foot external R, C components, is to ensure that the output signal of the stereo modulator is combined into a composite signal, and the phase characteristics of the two are consistent, and the channel separation is not deteriorated, in general, no change . If you need to change, it should be determined after the actual test. (3) When stereo modulation, the frequency limit of the modulated signal is 19 kHz, and if the input signal is associated with a pulse syndrome, in order to prevent the deterioration of the beacon and channel separation, the low pass filter should be subjected to the input end. (4) 16 ~ 17 feet are used to regulate balanced pins, even what is not even linked, and satisfactory separation can be obtained. In the usual use, a 50 kΩ potentiometer is always connected, and the separation is further improved by adjusting the DC balance. (5) 11 The DC output voltage of the foot is fixed to VDD ~ 0.7V by the internal circuit. (6) 38kHz crystal is not easy to find, can be used instead of work between 5, 6 of the circuit, but the three-dimensional effect will not be obvious.

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