Choosing AC-DC Converter

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Hi #PowerIntegrations Team 
Actually I'm working on a product and require AC-DC Converter of output 5V 2A and then I got across this

But as this is huge and its taking a lot of space and height,then I consulted one person and he guided me to go through Power Integrations,and gone through your website but unable to choose which will be required for me.

So it'll be a great help if you guide me through this 
Thanks in advance 

Help appreciated Thanks

Hi ish,


Thank you for considering Power Integrations products.  For your 5V/2A requirement, it is best to move your post to our Low Power Forum.  Our team there can then advise some options for you, depending on whether you are seeking a CV/CC, CV, or CP solution.



Also, I forgot to mention.  Our free PI Expert Online tool should also be able to assist you in the decision process.



Thanks for moving the post to Low Power Forum.

As I said I'm looking for an AC-DC Converter which is very small in size ?
is there anything like that?

can we keep 0.1uF/275VAC in between Phase & Neutral, Phase & Earth , Neutral & Earth as X & Y Caps?
will this prevent the board from Shocks & Fire Hazards?

Hi ish,

Good day! You may want to look at reference design below.

It is a 5V/2A design with 85-264Vac input. The PCB size is 31mmx50.8mm (please see section 5 of the pdf file) which can be optimize if you don't need the USB receptacle on the board.

It may also help if you provide additional info such as application, input range, target size etc.. 

Regarding on X and Y caps, the design has Ycap at 0.1uF and without Xcap and passed both conducted and radiated EMI.

There should already prevent electric shock since no Xcap is needed and Ycap is kept at 0.1uF to minimize leakage current.


rdr420.pdf4.67 MB


Thanks for such a good explanation and quick reply.

My application is a relay board with 6 relays and 1 raspberry Pi connected to switch ON/OFF relays. (A type of Home Control)

If we want to keep X-Cap then can we keep 0.1uF/275VAC? (I've attached pic below)

1 more doubt,will be of much help if you guide me

can we use Thyristors(TRIAC,SCR) in place of Relays to control the AC Loads?
and if yes how can we do that?
or do we have any IC which can be replaced inplace of Relays to turn ON/OFF AC using DC?

x y caps.JPG35.1 KB

Hi Ish,

Regarding X and Ycap, they are only used to supress EMI noise. You don't need them as safety feature on your circuit. The are only called safety capacitors since they fail safe during component failure(For example, your X capacitor brokedown the safe failure would be an open capacitor. As oppose to normal capacitor which sometimes fail short which would be devastating if connected from Line to Neutral). For the reference design it only use one Ycap which is at 0.1uF/275Vac so there would be no problem.

As for the relay replacement we don't offer any product from PI. It is better to use relays if you can use them since you can easily drive them using your raspberry Pi. Although I think you cannot directly switch the relay with the raspberry PI. But what you can do is to use drivers or opto isolator which can also act to isolate the noise coming from inductor relays during switching.


Thanks for such a good explanation.

Ya I do have opto isolator circuit to drive the relay.

I just heard that even TRIACs can also be used in place of relays. Will they really be efficient? durability? life? 


Hi Ish,

It is better to use relay since the drive requirement is in 5V or 12V while if you use triacs you would still need totempole circuit to drive. Durability won't be an issue for relays as long as you select the correct rating on which application you would use. Relays are commonly used in home appliances such as washing machines, etc.. Relays also have minimum life in terms of number of switches that manufacturer guarantee.



ThankYou, I'll just try once using TRIAC inplace of Relay and update you with the durability of that circuit.

Thanks for guiding me till here.