LA4440 single chip BTL 20W power amplifier

LA4440 is a single-chip dual-channel amplifier integrated block. It uses the characteristics of its built-in dual-channel symmetrical amplifier circuit to form a BT circuit through simple external connections. Subjective listening evaluation shows that the sound quality is better than that of TDA2003BTL, and the output power is sufficient. See the circuit diagram.

The basic circuit is still OTL, so it also has the problem of the optimal load impedance value.

The electrical parameters are: Vcc=12V, RL---4 ohms, Po=20W. Since the single-row lead pin is more suitable for scaffolding welding, the precautions are the same as above. The functions of each pin are: ① negative feedback; ② input 1; ③ pre-amplifier ground; ④ noise reduction; ⑤ filtering; ⑥ input 2; ⑦ negative feedback 2; ⑧, ⒁ power amplifier ground; ⑨ bootstrap 2; ⑩ output 2; ⑾ power supply positive Vcc; ⑿ output 1; ⒀ bootstrap 1.

It grounds the input of the second power amplifier, and connects the negative feedback of the first power amplifier and the negative feedback of the second power amplifier by voltage division under AC state. Then, alternating signals with equal amplitude and opposite phase will be output at pins ⑿ and ⑩, thereby obtaining double audio power by superimposing positive and negative half cycles on the load RL.