it's used in lots of products so chances are lots of stores will have it in stock in large quantities so at cheap prices. Why 470uF for the second ? 470uF is just a standard value and very common. These days bridge rectifiers are not more expensive than 4 separate diodes if you buy them in some small volume (like let's say 50-100 bridge rectifiers, you buy them at less than $0.2 each) If you want to build a lot of boards, replacing those diodes with a bridge rectifier may allow you to reduce the height of the pcb which in turn may allow you to put more boards on a single pcb panel and therefore you'd get more boards for your money.
#Viper smps design software manual#
Most cheap chinese s use separate diodes because manual work is super cheap, they buy 100k pieces 1n4006 and some worker will be paid a dollar a day to shove diodes on the pcb. Unless you go for the cheapest possible BOM (bill of materials) it's worth thinking about it. I'm not saying it's better to use bridge rectifiers instead of individual diodes, i'm just saying it looks nicer and takes less space on pcb and separates AC voltages from DC voltages much easier. Oh and some answers to your reply to my post. Those holes would allow for a bit of air movement around the transformer potentially cooling it a bit.
#Viper smps design software series#
it's probably not needed since your product is low current (only 5v 0.8a) but for higher currents some ers also like to drill a series of small holes (like the holes for a regular chip pins or slightly larger) on the center line where the transformer would be placed (at equal distance between the terminals of the transformer). If you go further and create a slot between the pins, it's even better. The distance between the pins of the optocoupler (if it's a DIP stile package) should be enough for this application (in my opinion). Quote from: mariush on January 03, 2017, 01:30:22 pm See this for clearance and creepage information : Also this: In your board, the easiest way to increase the clearance is to not put traces under the optocoupler and the, anything you put between the terminals of those components reduces the clearance distance. only if you plan on making more than a few of these boards. Once you get the other problems sorted, it may be worth investigating if you could use 2 x 470uF or 2x560uF capacitors there, i mean use the same capacitor instead of the 1000uF capacitor, simply as a way to reduce the number of different components (and get better price by ordering a bigger quantity of same component). If you go over 470uF, you'll probably get taller capacitors and for 5v 0.8A, it won't make much of a difference. Also, it can probably be found at the same height and diameter as smaller capacitance capacitors like 330uF or 270uF and the price differences would be pennies if you buy a bunch of them. Why 470uF for the second capacitor? 470uF is just a standard value and very common.
Most cheap chinese designs use separate diodes because manual work is super cheap, they buy 100k pieces 1n4006 and some worker will be paid a dollar a day to shove diodes on the pcb.
I don't think it's needed in your design. it's probably not needed since your product is low current (only 5v 0.8a) but for higher currents some designers also like to drill a series of small holes (like the holes for a regular chip pins or slightly larger) on the center line where the transformer would be placed (at equal distance between the terminals of the transformer). See this for clearance and creepage information : Also this: In your board, the easiest way to increase the clearance is to not put traces under the optocoupler and the capacitor, anything you put between the terminals of those components reduces the clearance distance.
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