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Need Assistance with Headphone Amplifier Circuit

post #1 of 6
Thread Starter 

I want to use a TPA6111A2 with a split supply.

 

As you may know, it's pin-for-pin compatible with the old Nat'l LM4881.

It's designed to be used with a single 5V supply - along with output capacitors.

 

Why I like this old chip is that it can easily drive 16 ohm loads - even small 8 ohm speakers!

 

But I'm looking for someone who has successfully accomplished this (using it with a split supply).

 

Here is the circuit as I see it so far - but has ANYONE made this work (with a split +/- power supply?)

What do you do about pin 3 "Shutdown" or pin 1 "Bypass"?

 

post #2 of 6

Just put all the caps from the datasheet circuit back in and connect all the points marked ground to the negative rail. Don't connect the PSU ground to anything.

 

biggrin.gif

 

w

post #3 of 6

can't say I have any experience with this chip, but the datasheet gives no indication that you can circumvent the in-built rail splitter. wakibaki's spot on about reintroducing the (very possibly required) ac-coupling capacitors to allow the internal reference to work. Datasheet has a lot of info on what size caps and where to stick 'em - sounds like a plan to me...

post #4 of 6

I have used this chip many times, and I dont think you can get around the in built rail splitter, and really I don't think you need to it's a good chip as it stands

 

cheers

FRED

post #5 of 6

I have the feeling you want to eliminate the output caps.

 

I don't see any reason why using a split rail supply would not work.

Leave the input caps as shown in the data sheet.

Connect the bypass cap to the negative supply rail.

Don't connect the shutdown to anything.

Check output offset voltage before connecting to anything important.

If offset less than 10 mV then you should be good to go.

post #6 of 6

I was just thinking...

 

Because it has a built in rail splitter, you could "tweak" the offset

by adjusting the rail voltages.

 

Let us know how the experiment goes.

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