[flixering]

I would like to power an opamp from USB, the opamp would be the final stage for a DAC-AMP(for headphones). 
But an opamp needs +-5V, but I only have 5V from USB. I`ve seen in some schematics(like grubDAC) a DC-DC booster converter, like TPS61040. The TPS can give max 400mA, but an opamp only needs 40mA(IMO). 
Is there something cheaper than the TPS?
 
PS: Specifically, I`m talking about the LM4562 opamp.
(sorry for my English)
 

 

[TrollDragon]

Linear Technology has a lot of power converters, you should check some of them out and see if they are what you need.
 
Such as the LT3582 Which you can sample for free...
http://www.linear.com/product/LT3582
 

 

[flixering]

Quote:

Linear Technology has a lot of power converters, you should check some of them out and see if they are what you need.
 
Such as the LT3582 Which you can sample for free...
http://www.linear.com/product/LT3582
 

Thanks, the LT3582 seems too expensive for my amp, but i`ve seen some good cheap ICs. 
What if I use a converter from 5V to -5V, would that make between the -5V and 5V, a regulated  10V? 

 

[TrollDragon]

I am not understanding what you are looking for, do you require dual potential ie +5 and -5 rails with a common ground. Or are you just looking to get 10V out of a USB port?
 
There are many good TI headphone amp chips that will run on a single 5V supply, why not use one of them?
http://www.ti.com/product/lm4810 for example, they have MANY different choices.
 
Just use their parametric search engine for Headphone Amplifiers for example.
 

 

[cobaltmute]

But an opamp needs +-5V, but I only have 5V from USB. I`ve seen in some schematics(like grubDAC) a DC-DC booster converter, like TPS61040. The TPS can give max 400mA, but an opamp only needs 40mA(IMO). 

Just for clarity, the grubDAC does not have a discrete component for the job of creating the negative rail - it is part of the DAC chip.

The pupDAC uses one.

No matter what chip you chose, you need to be aware of voltage droop on the rail - as the load gets higher the inverted rail voltage may move away from your ideal. You will also want to check the frequency of the inversion, and if it will be in the audible band. My personal preference would be to have the inverted rail higher than required and the regulate down so you can ensure a stable rail and filter some of the noise.

That being said, the Carrie project executed this idea quite well.

 

[joneeboi]

Good to see I haven't been forgotten after a super long hiatus.