AXT Systems

PA-1 68W Class-AB Power Amp
PA-1 Module
This handy little power amplifier module uses the LM3886 device, whcih is capable of up to 68W into 4 ohms with an appropriate power supply.

This device can be powered from +/-10V up to +/-42V. An unregulated supply consisting of a transformer, bridge rectifier and large reservoir capacitors can be used to provide the DC power rails. A module such as the PSU-13 can also be used for some applications.

The module was used with a +/-20V rail in the mono balance check monitor project, driving a 4 ohm speaker.
The PA-1 requires a heatsink, and the design is such that it can be bolted directly to one with simple mounting for the module. The size of the heatsink will depend on the application and can be calculated using the data sheet for the LM3886 and the thermal resistance of the heatsink.

On-board fuses are present to provide protection due to catastophic failure. The LM3886 has significant protective circuitry contained in it, including short circuit and thermal protection.