TA8127N single-chip radio integrated circuit diagram

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TA8127N/F is an AM/FM stereo radio monolithic integrated circuit introduced by Toshiba Corporation. It is widely used in various audio system receiving circuits, such as car audio, walkman, radio, home audio and so on.

1. Features

The TA8127N/F integrated circuit contains all the small signal processing circuits required for AM/FM filter segment radio reception. These include: AM mixing, local oscillator, neutral, detection, AGC circuits: FM4 high-amplifier, FM mixing, local oscillator, mid-range, frequency discrimination and stereo decoding circuits; auxiliary circuits with tuning display driver, stereo indicator driver, AM/FM switch, etc. The block diagram of the circuit is shown in Figure 1.

2. Main electrical parameters

The operating power supply voltage range of the TA8127N/F integrated circuit, Vcc=1.8-8V; the power consumption is also very small. Under the condition of 3V working voltage, the FM state is less than 60mW, and the AM state is less than 40mw.

3. Pin function and data

The TA8127N/F integrated circuit is available in two packages with different suffix letters. Among them: TA8127N uses 24-pin dual in-line package: low TA8127F uses double-row flat package, the volume is smaller than the former, but the order of the two pins and the function of the same gold, can be replaced.

Figure 1 Block diagram of the internal circuit of the TA8127N/F integrated circuit

The pin functions and data of the TA8127N/F integrated circuit are listed in Table 1.

Table 1 Pin functions and data of TA8127N/F integrated circuit

(1) AM band signal flow

The signal received by the L1 magnetic antenna → TA8127N/F (24) pin, after mixing, output from 4 feet → T2 → BC1 → TA8127N / 7 foot once in the AM in the IC, detection, audio preamplification → AM / FM switch from ( 19) The foot output is output from the (10) and (14) pins after being processed by C10→TA8127(18). Since the AM signal is mono, the outputs of (13) and (14) are only two. The same mono signal of the road.

(2) FM band signal flow

The signal selected by the 87-108MHz band-pass filter BPF is inserted into the TA8127N/F1 pin. After high-level mixing and mixing, it is output from the 3-pin→T1→R5→BC2→TA8127N/F(18) pin. In the FM, the FM, the audio pre-amplification → AM/FM electronic switch is converted from the (19) pin output, and the C10→TA8127(18) pin is stereo-demodulated and output from the (13) and (14) pins respectively. Left and right channel stereo signals.

Tip: FM radio has no sound. First measure the voltage on the TA8127N/F8 and (19) pins to determine if the FM amplifier circuit is normal. If the voltage is normal, consider whether BC2 is invalid. If there is no BC2 exchange at a time, a 6.8-27pF capacitor can be used and connected to the BC2 input and output terminals.

Measure the voltage on the TA8127N/F(12) pin to determine if the discriminator circuit is normal.

Measure the voltage on the TA8127N/F(21) pin to determine if the FM oscillator is activated.

Measure the voltage on the TA8127N/F(23) pin to determine if the FM high-amplifier circuit is normal.

AM radio is silent. Measure the voltage of the TA8127N/F(5), (7), and (19) feet to determine whether the elbow-aligned amplifier circuit is working properly.

Measure the voltage on the TA8127N/F(20) pin to determine the operation of the AM amplitude modulated local oscillator circuit. If the measured voltage is not equal to the normal value of the IC, it indicates that there is a problem with the amplitude modulation local oscillator circuit.

The AM band still receives FM band programs. This type of fault is only found on the AM/FM band conversion circuit. It is important to check whether the S1 switch contacts are good. Normally, in the AM band, the voltage of the TA8127N/F(16) pin is 3V, and in the AM band, the voltage of the (16) pin is about 2.2V, which can be detected by detecting the voltage at the key point of the TA8127N/F(16) pin. It is judged whether the AM/FM electronic conversion circuit in S1 and 1C is working normally.

The replacement or rewind data of the wearing parts in the typical application circuit is listed in Table 2 for reference.

Table 2 Appropriate application circuit of TA8127N/F integrated circuit replaces or rewinds data