HiFi headphone amplifier circuit
LM4880 is HiFi dual audio amplifier IC from National Semiconductors. This IC is specifically designed to produce high quality audio output with a minimum number of external components.LM4880 is capable of delivering 250mW per channel into an 8 ohm load. The IC has 0.1% THD and has a supply voltage range of 2.7 to 5V DC.
In the circuit shown below, resistors R1 and R2 are feedback resistors.C4 and C5 are input DC decoupling capacitors. Capacitor C3 provides power supply filtering and thereby reduces noise. The amplifier automatically shut downs when a logic high is given to the shutdown pin (pin 5). Capacitor C6 does the job of half supply filtering.
- Assemble the circuit on a good quality PCB.
- The circuit can be powered from anything between 2.7 to 5V DC.
- A logic high at pin % will drive the amplifier to shut down mode.
- To a 32 ohm headphone the amplifier will deliver 85mW at 0.1% THD.