Even if they are internally connected, they should both be connected unless otherwise specified. A possible reasons for two pins could be current sharing. Or it could have to do with the temperature distribution in the package. If there was no reason, the designer would have saved the work and the additional connection.akis said:You have connected both Vcc+ pins on the chip, is that needed? I am gemnuinly curious because I have not bothered to connect one on mine, I could not fit in a thick trace so I thought why bother.
Could be. The coil will inductively couple its signals into neighboring traces and components and vice versa.Razor_x said:Is this going to affect the sound
In theory, yes. In practice you might not notice the difference.Razor_x said:Will different lengths of power rails affect working of amplifier? How would you solve this on my PCB?
Have a look at National's reference designs for LM1876, 4765, 4766 (homepage) or 4780 (datasheet). You could copy the way it is done there. You will find that the 100 nF decoupling capacitors are very near to the IC's power supply pins, and that the supply capacitors are physically located in a certain pattern. The bigger the capacity, the further away from the IC they are.
Look also, how the grounding is done there and how the designer tried to avoid running certain traces in parallel and how traces cross each other at right angles, where possible.
BrianGT said:Why not just use an LM4780 chip? It offers 2 3886 channels on a single chip, and should allow for a more compact stereo layout.
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Brian
i think he is determined with single layer pcb.lm4780's pins is too compact to deal with.maybe lm4766?lm4766 is a dual 40w power chip.
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Zang
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