Low Power, SE Build Suggestions

We're looking at putting together a 'lesson' at my workshop for electronics noobies involving building a low-power single IC circuit. My entire experience is with a LM386, however I'm sure by now they've been superseded by something more modern and less noisy.

Basically, all I'm chasing is a 1-2w circuit with a decent response and minimal parts. I've found a few different designs using things such as a TBA820M/etc, however never really had experience with them.

Requirements:
*average signal response (signal will either be coming from an instrument or line-level source, with a matching pre-amp/buffer to suit)
*1-2w output to 8 ohm
* +9-12v input
*needs minimal other components to work (4-5 caps/resistors/etc is fine) and simple PCB layout
*minimal chance of getting fried by beginners
*8 pin DIP package
*low cost and easy to purchase

Has anybody built anything similar, and from what?
 

johnr66

Member
2009-03-05 1:55 pm
The TDA7267 is just what you need. It is the ideal low power audio amp IC, imho. This IC was the "dream chip" I've been looking for when searching for ICs that work in the 6-12v range. It has better output voltage swing into the load at a given supply voltage than any other IC that I have tried even though it doesn't use a bootstrap capacitor. I measured it to keep distortion low up until clipping. It is able to handle 4 ohm loads up to ~10 volts supply (the LM386 can't). All the pins on one side of the IC are ground and used for heat sinking which makes the board layout much easier for the novice. Gain is fixed on this chip but that means less extra parts. It has output current limit for one less chance for the noob to blow it up.

All seams like roses and rainbows, but the problem is that this IC was discontinued. Many good audio amp ICs have been discontinued over the last few years as the industry moves to surface mount and class D parts. One company, Dalbani, sells them on ebay, but are expensive (yes they are authentic). I don't trust the ones from Hong Kong to be authentic.

Another IC is the TDA7052. The voltage supply is less than your requirement but it is a bridged output so might be enough power.
 
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johnr66

Member
2009-03-05 1:55 pm
Another interesting IC is the LA4425A. It is not an 8 pin dip, but a 5 pin sip. It needs only 3 capacitors and can handle down to 2 ohm loads and has output protection. Supply range is 5-16 volts. It is what I consider a good and simple chip with one exception. For some odd reason they set the gain to be a sky high 45 db. While you can pad this down with resistors, it still means some background hiss with efficient speakers.
 
The TDA7267 is just what you need. It is the ideal low power audio amp IC, imho. This IC was the "dream chip" I've been looking for when searching for ICs that work in the 6-12v range. It has better output voltage swing into the load at a given supply voltage than any other IC that I have tried even though it doesn't use a bootstrap capacitor. I measured it to keep distortion low up until clipping. It is able to handle 4 ohm loads up to ~10 volts supply (the LM386 can't). All the pins on one side of the IC are ground and used for heat sinking which makes the board layout much easier for the novice. Gain is fixed on this chip but that means less extra parts. It has output current limit for one less chance for the noob to blow it up.

All seams like roses and rainbows, but the problem is that this IC was discontinued. Many good audio amp ICs have been discontinued over the last few years as the industry moves to surface mount and class D parts. One company, Dalbani, sells them on ebay, but are expensive (yes they are authentic). I don't trust the ones from Hong Kong to be authentic.

Another IC is the TDA7052. The voltage supply is less than your requirement but it is a bridged output so might be enough power.

TDA7052 looks great. Found them for incredibly cheap locally. I'll see if I can design a PCB today - this looks like a winner!

Another interesting IC is the LA4425A. It is not an 8 pin dip, but a 5 pin sip. It needs only 3 capacitors and can handle down to 2 ohm loads and has output protection. Supply range is 5-16 volts. It is what I consider a good and simple chip with one exception. For some odd reason they set the gain to be a sky high 45 db. While you can pad this down with resistors, it still means some background hiss with efficient speakers.

Pity about the noise - this looks great too!
 

Arty

Member
2011-02-24 5:04 pm
i'd still recommend sta-540.
8-22 volt as supply voltage,
and it has 4 lil amps inside it. it can be bridged with ease.
even in bridged mode it can drive 4 ohm impedance with 14.4 volt supply.
it features a lot of protection circuitry too including thermal and short circuit.

its so simple that i don't even recommend a pcb for it.
it basicly need input caps, a 100 nf cap to prevent it from oscillating, and a resistor and a cap for standby/mute fuctionality. i might recomend a 2-300 pf cap from input to ground to make sure it does not pick up a radio station , but its pretty stable and i found it can actually work with no (ZERO) external components if run from a battery.
in single ended it can handle 2 ohms, and this single chip can be wired up with 1 common input cap to be a bridge/paralell setup, driving 2 ohm loads at 14.4 volt supply.
pretty mutch impressing,
gain is fixed internally at 20 dBL, actually i think its about okay for this chip.
its allso ESD protected, and can take a lot of abuse.

not really shown on the datasheet, but i did try this thing from a 20 volt supply and bridged version pumping juice to a 4 ohm rated speaker, and it can handle it, if you can keep it cool so the protection does not kick in.
it allso has a quite sweet sound i have to say.