Audio amplifier design is an interesting and annoying task - while some made a fortune writing books on the topic, in many cases, any amplifier is good enough. Normally, parts such as the PAM8302 get used. In practice, one often needs more power - in this case, Texas Instruments TPA3125D2N is the part to call on.

While the part comes in an easy to handle DIP package, do not let the packaging fool you. Texas Instruments uses a modern class D amplifier, and can supply either 10 or 20 watts into an eight ohm speakers when supplied with 24 V of direct current.

However, due to the high efficiency of the part, no heatsink is needed when approaching the extremely high values. From a technical point of view, the TPA3125D2N is relatively simple. Driving a speaker, in principle, is done with the following application example.

Driving a speaker with the TPA3125D2N is pretty simple

Sadly, working with low input voltages is not a strength of the part. The lowest supply voltage Texas Instruments specifies in the data sheet is 10V - the figure shows how the output power varies across the various input voltages.

Output power depends on input voltage

Another interesting aspect involves circuitry intended to eliminate the popping sound found when connecting or disconnecting power or speakers. This is highly valuable, as it reduces potential risk of damage to the audio system.

Finally, let's also recommend a look at the data sheet found by Clicking Here – it contains interesting additional information on power supply problems and similar issues encountered when dealing with class D amplifyers.

Author: Tam Hanna
Published: March 12, 2021