isolation problem.and isolation needed

[manikandan123]

hi freds!
I want to use isolation between LED driver (it is powered by DC supply.& It is DC to DC converter.) and my circuit(It is powered by AC to DC transformerless power supply.).How do i use isolation between two without using Transformer. IS any ideas? Please help me.

 

[betwixt]

You first must tell us why the isolation is needed. Transformers can provide a safety barrier, the most practical alternative is a capacitive isolator which may not provide such a barrier.
More information please...

Brian.

 

[ard]

Hi, it depends on what you want to drive on the high voltage side, but the ideal solution would be to use an opto-isolator like the PC814/817 (4 pin dip) or MOC3041 (6 pin dip).

Regards,

Anand

 

[manikandan123]

You first must tell us why the isolation is needed. Transformers can provide a safety barrier, the most practical alternative is a capacitive isolator which may not provide such a barrier.
More information please...

Brian.

My circuit is powered by transformerless power supply. so it is non isolated one. suppose if i do like LED driver IC's GND should be connected with my circuit ground,then it will lead some problem(i am not checking just assuming).. so only i want isolation between two. and making better resolution to this one.

---------- Post added at 13:38 ---------- Previous post was at 13:35 ----------

Hi, it depends on what you want to drive on the high voltage side, but the ideal solution would be to use an opto-isolator like the PC814/817 (4 pin dip) or MOC3041 (6 pin dip).

Regards,

Anand

Thanks anand. is any circuit ?... my output is PWM to drive the LED driver IC.

 

[ard]

Its very simple, really. Drive the input such that you pass about 5 ma thru' the LED; the output can be used as an open collector transistor. What do you intend to drive with the output?

 

[adnansarwar2050]

Relays can also be used for isolation form high voltage to low voltage

 

[betwixt]

It still isn't clear what you are isolating. Is it a control signal to turn the LED driver on and off, with the power being provided elsewhere or is it the actual power to the LED?

Referring to the ground mentioned earlier, NEVER connect a ground to a non-isolated AC supply. To do so would cause a current path between AC mains and ground and cause damage. The only safe way to use a non-isolated supply is when it is packaged so that no part of it can be touched.

Brian.

 

[manikandan123]

It still isn't clear what you are isolating. Is it a control signal to turn the LED driver on and off, with the power being provided elsewhere or is it the actual power to the LED?

Referring to the ground mentioned earlier, NEVER connect a ground to a non-isolated AC supply. To do so would cause a current path between AC mains and ground and cause damage. The only safe way to use a non-isolated supply is when it is packaged so that no part of it can be touched.

Brian.

Thanks Brian. RECOM DC to DC converter IC is my driver to LED. My PWM created by LM358 op-amp with non isolated Powersupply . Driver IC having the GND pin. I want to connect that IC GND pin to my circuit GND pin .I thing it may problem. so only i want isolation. Is any Ideas?