The Microphone AMP Board features a microphone connected to a power amplifier LM4864 designed for use in low-voltage consumer applications. The gain is internally set to 20 in order to keep external part count low, but the addition of a potentiometer and capacitor between pins 1 and 8 will increase the gain up to 200.
IC/Module: LM4864 Audio Power Amplifier with Shutdown Mode
LM4864 is a 725mW audio power amplifier for a 5V power supply. Designed specifically to work on a low supply voltage with high quality output power, LM4864 requires a minimal amount of external components. This module does not require output coupling capacitors, bootstrap capacitors, or snubber circuits, making it fit for use in low-power portable applications.
Bridge Amplifier Design
The bridge amplifier design features some benefits over the single-ended configuration. It provides differential drive to the load, and thus doubles output swing for a specified supply voltage. It can provide four times the output power as compared to a single-ended amplifier. Another advantage is that it eliminates the need for an output coupling capacitor required in a single supply, single-ended amplifier configuration.