simple adjustable switching regulator

[carmusic]

Hi i need your idea to desing a simple dc dc converter non-isolated. my input will be around 15V- 24V and the output must vary at least from 6 to 12 volt at 1.5A.

to make it simple i would need an ic to replace an old linear lm317 with 1.5A output

I found out lm2576 chip that would work but efficiency is very poor for a switcher (77%!!) .
i found also a5972d ic but it is not available!

i also think of usint ptn78000h dc converter but they are expensive (i will have to make few hundreds of those so pricing is important.

i also found a lot of others but some of them are very complicated with a lot of external parts. i want an integrated switch and the lowest possible parts count (some resistors, inductor and capacitor)
Thanx

 

[blueroomelectronics]

National Semiconductor simple switcher.

 

[saturn1bguy]

Yes, just go to nsc.com and use their Simple Switcher WebBench. Input your design values, and the program will return a list of parts that'll work. Select one, and let the software design and sim the circuit for you.

 

[blueroomelectronics]

And even at 77% it's still better than any linear regulator.

 

[carmusic]

Thanx for the info
i have decided to use lm2676-adj
**broken link removed**

, but my concern now is how to choose the best output capacitor and inductor since my load will vary and output voltage also
the output will vary from 6 to 12 volt
and the load may be from 0.1A to 1.3A
there is a graphic on page 15 (right bottom) but i dont understand it

 

[saturn1bguy]

but my concern now is how to choose the best output capacitor and inductor

What does their design software say to use? Design with your two extremes in mind (do two sims) and see what it gives you for L and C...