L272 (power op amp) for headphone amp

[todd.dukes]

Can you use this with a 78L05 or do you need more current capability?

The chip is 130mW per channel, at 5V
That's 260mW/5V= 52mA..
Assuming the efficiency of the amp is over 80%, 52mA/80% = 65mA

It should work fine with a 78l05 (100mA max)

Thanks!

I was worried because the data sheet said max TSSOP power dissipation was 755mW. I couldn't find anything about efficiency in the data sheet. The
power dissipation vs. output power graph is getting close to 500mW and doesn't go all the way to 130mW output, which is the stated max output.

[merlinb]

+1 That circuit works surprisingly well as a cheap and dirty headphone amp. Use a TL07x and a 150R resistor (instead of 220R) and you get about 10mW into 32 ohms (or 15mW into 16 ohms!) before 1% distortion. 220R is still a good choice if you need it to keep working when the battery is nearly flat, if you don't mind more distortion. In fact, distortion never really drops below 0.5% at best, because of the crossover problem, but for guitar monitoring that's bearable. What's nice is that the idle current is so low -purely the TL07x (about 3.5mA)- and only increases when needed, to about 10mA at full output.

Compare that with a naked NE5532 which can deliver 10mW into 32 ohms with maybe 0.02% distortion, but it consumes 9mA at idle!

[dschwartz]

Can you use this with a 78L05 or do you need more current capability?

The chip is 130mW per channel, at 5V
That's 260mW/5V= 52mA..
Assuming the efficiency of the amp is over 80%, 52mA/80% = 65mA

It should work fine with a 78l05 (100mA max)

Thanks!

I was worried because the data sheet said max TSSOP power dissipation was 755mW. I couldn't find anything about efficiency in the data sheet. The
power dissipation vs. output power graph is getting close to 500mW and doesn't go all the way to 130mW output, which is the stated max output.

Well, maybe the extra circuitry inside dissipates more power.
I forgot the charge pump that creates the negative voltage so the output is referenced to gnd..
Imho it will work with 78l05, but i would not use it for production.
I use a 1 amp regulator for it on the omnicabsim.

[composition4]

Thanks for the further replies all. I still think I'll go with an NJM4556 because I like the greater output. I'm thinking of somehow having an arrangement (maybe with a switching headphone jack of some sort?) to only power the op amp when the headphones are plugged in.

Is there such a thing as a normally open switching stereo 1/4 jack so the opamp ground is disconnected when unplugged then connected when headphones are plugged in?