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Author Topic: Small Class D amplifier  (Read 29 times)
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If this isthe wrong forum and this should be in electronics, please move, but this seems right...

So I need to amplify a small pulse, with modestly high peak power and low average power.  Battery life is concern #1 so I am looking at class D amps.  Power needs are still up in the air, but probably on hte order of 5W.  I am currently using a TDA2030 which is a lovely but obsolete monolithic AB amp that is super easy to use, but I want to try and up the efff w./ a class D.  The catch is since it is battery powered, I want to stick with a single +13v supply to keep things simple and not have a neg source eating up power.  THe pulse itself is only positive going, so there is no need for a negative supply anyways.  output will be into a speaker network, i am hoping I can put several in parallel to dropthe eff resistance to whatever the minimum the amp can handle will be to try and boost the power, otherwise I will need to boost the amp voltage which is not a thing i want to have to do.

So tell me, does anyone know of a low power class D amp that comes as an all in one chip, and can be run from a single supply?
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Maybe search out the datasheet for the PAM8610  chip used in module like this:

http://www.ebay.com/itm/Digital-Amp-Audio-Amplifier-Module-10W-10W-2-Channel-Class-D-/221239184525?pt=US_Home_Audio_Amplifiers_Preamps&hash=item3382e20c8d
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Single supply amps for driving speakers:

http://www.parts-express.com/2x8w-at-4-ohm-tpa3110-class-d-audio-amplifier-board-only--320-329
http://www.parts-express.com/pam8610-2x10w-class-d-audio-amplifier-board--320-604
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Adafruit has several, the one I looked at has very low standby current.

http://www.adafruit.com/search?q=class+d
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Quote
i am hoping I can put several in parallel to dropthe eff resistance to whatever the minimum the amp can handle
A Bad, bad, bad, idea! smiley-sad   The general rule is NEVER connect outputs together. (That's why you use an audio mixer to mix audio signals.)   Solid state amplifiers have very low internal source impedance (often less than one Ohm).   The output of one amp "shorts out" the output of the other.

The most common "trick" is to make a bridge amplifier.    That doubles your peak-to-peak output voltage (theoretically 26V P-P = 9V RMS) with a 13V power supply) and that gives you 4 times the power into the same load.  Doubling the voltage doubles the current, so an 8-Ohm speaker "looks like" a 4-Ohm speaker to each amplifier.   In theory you can get about 10W into 8 Ohms, but there is some voltage drop across the transistor/MOSFET and you can't actually get the full power supply voltage across the speaker.

High power automotive amplifiers have a voltage-boosting power supply.

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