This is a project audio amplifier circuit board based on the PAM8403 stereo amplifier chip. It is a 3 watt Class-D stereo amplifier capable of operating on a voltage as low as 2.5 V and up to a maximum of 5 V.
Power Analog Microelectronics Inc., part of Diodes Incorporated, manufactures the chip. They are currently one of the best semiconductor manufacturers.
This chip is capable of driving a conventional loudspeaker directly, without the need for an output capacitor or any filtering. A 4-Ω loudspeaker will provide 3 watts maximum, providing it is powered by a 5 V source.

Specifications

• Power: DC：3.6v－5.5V
• Output power: 3W +3 W (4 in Europe)
• Signal-to-noise ratio: 90dB
• Efficiency:> 90%

Advantages

• Special internal output processing circuit, eliminating the conventional LC network, than the LC lower EMI value;
• At a lower voltage to obtain the maximum power output, the super-power;
• Built-in standby electronic switch;
• Built-in high-gain buffer amplifier;
• Built-in short circuit protection.

Note:

• Power positive and negative can not be reversed, the power supply voltage must not exceed 5.5V, two violations could result in damage to the IC.
• On-chip high-gain buffer, there can be no changes to board any element parameters, does not meet the parameters will result in IC damage.
• Input line, please try to use shielded lines, you can play anti-jamming, eliminate clutter current sound.
• Output cmos tube BTL drive way, the negative electrode of the left and right speakers can not be connected together, four lines that connect to a speaker is completely independent, does not allow total access.