The amplifier shown shown is based on the MAX9715 integrated circuit from Maxim (www.maxim-ic.com) providing an output power of up to 2.8 W with supply voltages in the range of 4.5 to 5.5 V with a load of 4 ohms. The circuit operates in Class d which guarantees an efficiency that reaches 87%. The distortion is low, only 0.06% at 1 kHz. For this amplifier it is possible to program the gain at +10.5 dB or +9.0 dB and the PSRR is 71 dB at 1 kHz. In addition, the integrated circuit used has short-circuit protection and thermal protection. The housing is the 16-pin QFN-EP. Among the applications suggested by Maxim we have LCD projectors, portable sound, multimedia stations and notebooks. In the figure below we have the MAX9715 housing. Given the high performance of the circuit, there is no need to install it in a heat sink.
