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36V to 5V step down converter__good in light load

36V to 5V step down converter__good in light load

36V to 5V step down converter__good in light load

(OP)
Hello,

this is my step-down converter:

..it is for ...
Vin = 36V
Vout = 5V
Pout = 1.67W Max

SCHEMATIC:
http://i55.tinypic.com/28lwh9s.jpg

It must go into skip-cycle in light load, hence the comparator.

It has a lot of components, but i see no cheaper way of doing this...since i need a good efficiency in light load, and a controller with low operating current.

I found some Buck IC's but they had high internal FET current limits
and so they would have high "staircase" current at start-up and POTENTIALLY blow the 500mA fuse which lies ahead of the above circuti on the 36V rail.
-Also, the Buck IC's were extremely expensive, and most dod not have pulse-skipping in light load.


by the way here is the LTSpice simulation file:-

http://www.2shared.com/file/yKEnT4cl/5V_SEPIC__with_tripler_bias_FO.html

do you know of a cheaper way?  

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