TA8122AN, TA8122AF single-chip radio integrated circuit diagram

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TA8122AN/AF is a large-scale radio receiver integrated circuit introduced by Toshiba Corporation, which is widely used in various audio radio circuits. For example, car audio and home audio.

1. Features

The TA8122AN/AF integrated circuit includes amplitude modulation mixing, local oscillator, neutral, and gun wave circuits: frequency modulation, high frequency mixing, local oscillator, neutral, center frequency, frequency discrimination, stereo decoding, etc. The auxiliary circuit has a tuning display drive circuit. The stereo indication drive circuit, the AM-M switch electronic switch and other circuits, the internal circuit block diagram is shown in Figure 1.

Figure 1 Block diagram of the circuit inside the TA8122AN/AF integrated circuit

2. Pin function and data

The TA8122AN/AF integrated circuit is available in two package styles with different suffixes. Among them: TA8122AN adopts 24-pin small dual in-line (DIP) package form, the pin pitch is l/2 of standard DIP; TA8122叮 adopts 24-pin surface package form. However, the pin functions and order of the two are basically the same and can be used interchangeably.

The pin functions and data of the TA8122AN/AF integrated circuit are listed in Table 1.

Table 1 Pin functions and data of TA8122AN/AF integrated circuit

3. Main electrical parameters

The power consumption of the TA8122AN/AF integrated circuit is quite low, only about 6mA in the AM state, and only about 8mA in the FM state: the operating voltage range is wide, and it can work normally and stably in 1.7-7V. The typical operating voltage is 3V. The two No. 5 batteries can work stably: the receiving sensitivities of the AM and FM bands are about 1 mV/m and 2OμV/m, respectively.

4. Typical application circuit

A typical application circuit consisting of a TA8122AN/AF integrated circuit is shown in Figure 1. This is a basic circuit: many radios, walkmans, car audio and other radio circuits are similar to this circuit.

5. Signal flow

(1) AM band. The wireless signal enters the IC internal mixing circuit from the TA8122AN/AF(24) pin, and the mixed signal is output from the 4-pin→T-selection→BC1 further frequency selection→TA8122AN/AF7 in-pin IF amplification circuit amplification, detection, audio pre- Zoom in, output from the (19) pin → C7 → TA8122 (18) pin after conversion by the MWFM electronic switch, and output from the (13) and (14) pins respectively after processing. Since the AM has no pilot signal, only two identical signals are output from the (13) and (14) pins.

(2) FM band. The FM signal received by the wireless is added to the TA8122AN/AF1 pin via C26. The intermediate frequency signal obtained after high-level mixing and mixing is output from the 3 pin. After being selected by BC2, it enters the 8 pin, and is also inserted in the middle. After the audio pre-amplification and AM/FM electronic switch are switched, the left and right channel signals obtained from the (19) pin output → C7 → TA8122AN/AF (18) are decoded by stereo decoding from (13), (14). Foot output.

Tip: The radio is silent. The voltage on the feet of the TA8122AN/AF(6), (22), and (23) should be checked. If the voltage is normal, check if C7 is invalid or open circuit.

AM radio is silent. The TA8122AN/AF4 pin can be touched by the interference method. If there is no sound, the circuit components between the TA8122AN/AF7 pin and the 9 pin are abnormal. If the 4 pin is silent, the component between the 4 pin and the 7 pin is abnormal; the touch (24) is silent. , check the AM oscillation and mixing circuit; if the sound is normal, it is a problem of the wireless input circuit.

FM radio is silent. The cause of the fault can be found by detecting the FM IF signal of the TA8122AN/AF8 pin, the local oscillating signal on the (21) pin, and the waveform of the high frequency amplified signal on the (23) pin.

Figure 1 Typical application circuit of TA8122AN/AF integrated circuit