The sound chip is generally divided into 4 kinds of audio output modes: current DAC audio output mode, dual channel PWM direct type audio output mode, voltage type DAC audio output mode and CLASS A/B type output mode. The following nine chip electronics respectively introduce the advantages and disadvantages of four audio output modes of the sound module, respectively.
1. Current mode DAC audio output mode. The sound module is simpler than the external circuit and can be connected directly to the transistor for voice amplification. Because the triode is a current type device if a three-stage tube is connected to a shunt resistor and a three pole tube, the audio is output. If the amplifier is connected, only one shunt resistance and a coupling capacitor are needed.
The disadvantage is: if the external transistor is output, there is a DC component in the loudspeaker, which causes the horn power to be too large, the no-load current is too large, and the horn is burned. And the audio output efficiency is low. If the shunt resistance value is not selected properly, the output sound quality will be worse.
2. Sound module PWM direct push audio output mode. The main advantage of this audio output mode is that no external components can be directly connected to the horn to output audio, and no distortion can be generated.
The disadvantages are obvious, and the output power is limited. If you want to have a larger output power, the power amplifier circuit will be more complex and the sound quality will also be lost. Another thing is to produce a high-frequency current in the loudspeaker when the sound is released, resulting in an increase in power.
3. Voltage type DAC audio output mode. This voice IC is usually applied to an external power amplifier. Transistors can also be amplified, but the circuit is relatively complex. And the triode class A magnify the highest efficiency is less than 50%, so it is generally used for an external power amplifier.
The external power amplifier circuit is similar to the sound module of the current mode DAC audio output mode. The advantage of voice output of this type of audio output is that the output is better than the other IC.
4. Class A/B class audio output. The advantage of the voice IC is that the sound quality is relatively good, and the relative efficiency is relatively high, generally over 75%. If the external audio amplifier is relatively simple, it is similar to the sound module of DAC audio output mode.
The disadvantage is that the circuit is relatively complex, and the cost is relatively high. In fact, this kind of audio output mode can be said to be an audio output mode, which is mainly voltage type DAC plus a class A/B audio amplifier. Because this kind of audio output is processed by an analog circuit, there is no high-frequency harmonic current.