# Efficiency of DC-DC converters



## machine87 (Oct 25, 2012)

Hello guys i'm trying to build boost and buck converters using IC/chips but I want to use simple circuit with less components and efficiency of about 90% or better. Which IC/chip would you recommend and also can easily be bought at local electronics store


----------



## JimE (Apr 16, 2009)

I assume your title is wrong? 

There would be no reason to convert DC to DC.


----------



## Done_Fishin (Oct 10, 2006)

Sorry Dogg but a DC-DC converter is used to convert one DC voltage to another like in the Primary part of Power supplies that run your PC .. mains Voltage in is rectified and smoothed then "pulsed" through a transformer where it is the rectified again to much lower DC Voltages.

likewise one could create (and these are sold on the market) a 1,5V to 5V circuit to charge mobile phone batteries from a single cell battery .. something similar to a Power Monkey


----------



## JimE (Apr 16, 2009)

Hadn't considered that, I was thinking AC to DC or DC to AC. So I guess the next question would be what output voltages are needed from what type of input?


----------



## Done_Fishin (Oct 10, 2006)

www.bucek.name/pdf/mc34063.pdf

whilst voltage accuracy can be simply defined by the IC & the components used, I think that efficiency is something that depends upon the switching frequency, the quality of components being used and of the course fine tuning the capacitor & Inductor values ... Efficiency does NOT come with simple or cheap circuits, Manufacturers are having a hard time designing circuits that are efficient and most come with complicated additional circuitry with special IC's working alongside the SMPS controllers.


----------



## Kefali (Nov 11, 2012)

Here's an example.

I have two deep discharge 6v batteries, in series, driving a 12v DC -> 110v AC inverter to keep my computer system running during power cuts. It's good down to 10.5v DC.

As the ADSL router runs off 12 volts, I had it connected directly to the 12v battery supply but it won't tolerate more than 14v or less than 12.0v. Consequently, I bought a "Smart car adapter" model number ST-S-090-1200AC. This accepts 10v - 30v DC input and provides a regulated output of 12.0v DC.

It appears to be quite efficient - judging from the fact that it doesn't even feel warm and the fact that the battery voltage doesn't change when I connect it.


----------

