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Audio amplifier IC or other low parts count method

Not really "audio"

Specs:

Supply voltage: 0 - 35V Load resistance: 10-20 Ohms Frequency: 1KHz to 25KHz Output swing: Rail-to-rail Distortion: Products above 30KHz 60dB down

My existing circuit uses the supply pins of an op-amp to turn on an NPN and PNP power transistors. It needs: 6 Resistors, two capacitors, the op-amp and the transistors. I am a bit pressed for space so I either need a lower parts count method or to use smaller parts.

Overload protect is currently done by having the transistors get so hot that they unsolder themselves. I am willing to stay with this because if there is an overload, the thing is already "broken" so "broken worse" doesn't matter. It is defended against starting a fire.

Reply to
MooseFET
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I'm not really sure what you're asking about... I'll just offer that one of my favorite audio amps is the Boomer line from National Semiconductor. I've used the LM4950-TA part in several designs. Very compact. Very few external components required. Plenty of oomph for what we were doing.

As for unsoldering, must be that new lead-free crap? :-)

-mpm

Reply to
mpm

Are you getting -60 dB distortion from that?

John

Reply to
John Larkin

Can you run the whole thing from a single supply and cut out one of the transistors?

George

Reply to
ggherold

Not rail to rail :(

Reply to
MooseFET

Max voltage =3D 18V vs my need for 35V.

No, it was a joke. There is no real protection. The transistor gets hot enough that the solder melts on the way towards the PCB smoking.

Reply to
MooseFET

No. I'm considering the harmonics one by one. There are a lot of them.

Reply to
MooseFET

It is single supplied but I am capacitively coupled to the load. I don't want to waste a huge amount of power so the output is a push pull ABish stage.

Reply to
MooseFET

I don't know of any of the shelf audio amp IC or power opamp that would allow for the rail-to-rail operation. If you drop this requirement, there is plenty of solutions.

For the similar purpose, I used a pair of FETs driven from the dual opamp. The part count was about the same as yours.

Vladimir Vassilevsky DSP and Mixed Signal Design Consultant

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Reply to
Vladimir Vassilevsky

I also have a MOSFET version or two. At one point I was considering the switch to MOSFETs. Biasing them and limiting the gate swings pushed the parts count up.

Reply to
MooseFET

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