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Taming the LM3886 Chip Amplifier
NOTE: I consider this page to be a live document. I.e., I will update it when I have new thoughts or findings on the topic. Last update was: September 20th, 2019.
The National Semiconductor (now Texas Instruments) LM3886 chip amp is a pretty nice little chip. With headline specs touting nearly 70 W of output power at 0.03 % THD and the ability to source over 11 A, what's not to like? Well, as with any high-performance IC, it takes some engineering to get the circuit to live up to the data sheet specs. In particular with power op-amps, such as LM3886, the PCB layout or point-to-point wiring routes make a significant difference in the circuit performance. Judging by the chatter on the DIY Audio Chip Amps Forum, the main challenges for designers appear to be stability, bypassing, grounding, layout, and thermal design. My intent with these pages is to explore some of the common pitfalls and provide a design guide to a successful LM3886 design.
Section 1: Stability > 2: Supply Decoupling > 3: Grounding > 4: Output Power > 5: Thermal Design > 6: Power Supply Design > 7: Rectification & Snubbers
Practice what you preach
The LM3886 Done Right shown below is a simple, beginner-friendly amplifier based on the LM3886. The circuit and PCB layout were designed using the theory and principles outlined in these pages as well as quite a bit of information which has yet to make it into these pages. If you find the information in these pages valuable, please consider purchasing my circuit boards. You can find more information on the LM3886DR and buy your boards by following this link: LM3886 Done Right.
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