USB Sound Card

USB Sound Card with PCM2702 and NS8002

This compact USB sound card converts digital audio from a computer into analog output using the PCM2702 USB audio interface and drives small speakers with the NS8002 audio amplifier IC. It is ideal for desktop audio or portable USB-powered audio projects.

Power Supply

Powered directly from the USB 5V line.
Includes a 3.3V voltage regulator to supply the PCM2702 IC.
The NS8002 amplifier is powered from the USB 5V line to deliver up to 2.4 W output.

Circuit Operation

PCM2702: Converts USB digital audio into analog signals (DAC functionality).
NS8002: Amplifies the analog audio signal to drive small speakers.
Volume and signal filtering can be implemented at the output for better audio quality.
The circuit is fully USB-powered, requiring no external power supply.

Key Features

USB-powered audio interface
PCM2702 DAC for high-quality digital-to-analog conversion
NS8002 amplifier delivering up to 2.4 W into 4 Ω speakers
Compact design suitable for desktop or portable audio
No external power supply required — plug-and-play operation

Construction Notes

Use decoupling capacitors near both the PCM2702 and NS8002 ICs for stable operation.
Keep signal paths short and shielded to reduce noise from the USB supply.
Ensure proper heatsinking or PCB copper area for the NS8002 IC to handle full output power.
Optionally, include a small volume potentiometer at the amplifier output for adjustable sound levels.