Texas Instruments’ TPA3125D2N – Audio Amplifier Design

MicroCrystal RV-8803 – A Really Accurate RTC June 17, 2019- RTC chips traditionally were the domain of Maxim and NXP. Switzerland-based MicroCrystal recently made quite a buzz with its RV-8803, which offers simple integration, an I2C interface and extreme accuracy. Let us start out by looking at a system overview. Figure one shows how this I2C RTC is made up internally – interested observers note […]
Analog Devices’ LTM2887 – If a Digital Bus Needs Galvanic Isolation June 15, 2019- In theory, digital buses are intended to connect things to one another. Sadly, one sometimes wants but a logical connection – in many cases, galvanic isolation helps out. Should you ever feel like isolating very fast buses, definitely give the LTM2887 a chance. From a technical point of view, Linear Technologies attempt at entering the […]
AVAGO APDS-9008 or APDS-9005-020 – Keeping an Eye on Ambient Light June 14, 2019- Recent times saw quite a bit of interest for part numbers such as the APDS-9008 or APDS-9005-020 – they are a very interesting type of ambient light sensor. One of the oldest questions in regards to light sensors involves their spectral sensitivity. If a part is to output but one voltage level, the conversion between […]
STMicroelectronics’ LIS2DH12 – Low Power Motion Sensing June 12, 2019- Apple’s iPhone introduced gyroscopic sensors to a wider range – before that, accelerometers were not commonly found in consumer hardware. STM sells excellent parts which, however, get little media attention – time to take a look at the LIS2DH12. Integrating the part into your circuit as an MPU6500 alternative or MPU9500 alternative is not difficult. […]
Panasonic AMG8833 – FLIR for cheap June 7, 2019- FLIR made infrared thermal sensors cool – sadly, their parts are all but cheap (and suffer from export control problems). Panasonic’s Grid-EYE family is a low-resolution alternative which comes at significantly lower cost. From a technical point of view, Panasonic’s image sensor could not be simpler. We are looking at an 8×8 sensor with an […]
DipTronics DTS-62R-V – Small Switch, Very Big (and Very Cheap) June 5, 2019- When yours truly was but a lowly cadet, various US manufacturers produced (pricey but quite reliable) switches. Chinese vendors recently started to catch up – seeing the DTS-62R-V top our customer interest list shows that the run stage of the crawl-walk-run cycle is reached. DipTronics has been around the Asian switch market for ages, exhibiting […]

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.