I am looking for a proven design which can convert 210 to 250 VAC in to 24VDC; i am looking for a following specification in this design
1) This converter has to work from input variance in the range from 210 to 250 VAC supply voltage (most of the time its normally work on 230VAC voltage but need to consider the AC fluctuation)
2) 24VDC output voltage has to be pure regulated supply
3) O/P current of the 24VDC should be near about 5A
4) Circuit has to be small, efficient and most importantly low cost
5) Is it possible to design transformer less (without transformer) design?
You need to use some wound component for this.
Often, you can't have small, efficient and low cost simultaneously. You need to compromise somewhere, either in cost, or in size.
Is this a 1-off or a production item? For 1-off, the low-cost way will probably be the conventional transformer based supply.
yeah , i can agreed that some wound components are needed...but it is the easiest n i thnk low cost method too...somewhere matter of size wudnt considered here.
Here is one approach, see here, in diagram 42 is a 19V 8A power supply. With some design changes, it would support your 24V 5A requirement, and the datasheet contains the design calculations.
If you want a non-switching design, then you need a large transformer, some diodes or a bridge rectifier, a few capacitors and a linear regulator circuit. In other words, a classic transformer based PSU (for which you can google) followed by a linear regulator. There should be some ideas for the regulator portion in threads like here.