Hallo Everyone,

I wanna design a status LED for 300V DC..

Normally the low voltage status LED 's (5V and 12 V) are designed using a resistance in series to the supply voltage as it creates the required voltage drop.

But for 300 V DC , a resistance in series is not the economical way due to high loss.....
can someone please give me other suggestions???

 

The super easy way to do it would be to buy a small 240 VAC input switching power supply, a "wall wart" - connect an LED to the output (and maybe a dummy load to reduce the time it takes to turn off) - Done.

The switching supply will care not that it's getting DC.

 

The super easy way to do it would be to buy a small 240 VAC input switching power supply, a "wall wart" - connect an LED to the output (and maybe a dummy load to reduce the time it takes to turn off) - Done.

The switching supply will care not that it's getting DC.

I am looking for a simple circuit that would solve this issue so that I could integrate it in my PCB..
Thanks anyways..

 

Ahh. got it.

Now it's a bit more tricky. Beyond a resistor, the next level is still 10 X more complex and expensive, a switching buck regulator.

It doesn't have to regulate well or isolate, so it could be a simple design.

 

Why not use a neon instead of the LED? But even a LED should do, if its's an ultra-bright type which will give reasonable light at very low current.

 

Is your 300VDC really pure DC? If it has even a small AC component, you might be able to harvest a little power off that.

 

I'm not really familiar with CB design, but I'll throw
out an idea....What if you used a current meter to sense the current and turned on the LED with a relay or IC?

 

Why not use a neon instead of the LED? But even a LED should do, if its's an ultra-bright type which will give reasonable light at very low current.

Something like a LED which works at 1-2mA?

I found a LED , which has a forward voltage drop of 1.9V,@2mA.

If my supply voltage is 300 V DC,
then I would need a 150 K Ohm resistor with a power handling capability of 1W in series to my supply voltage.

The loss is estimated to be 0.6 W

Is this loss too much??
I have also attached a datasheet from VISHAY. Please check

Thank you..

 

That LED looks fine; but I'd try running it at, say, ~1mA. R = 330k 1W, loss = 0.27W. 300V is potentially LETHAL. Take due safety precautions.

 

That LED looks fine; but I'd try running it at, say, ~1mA. R = 330k 1W, loss = 0.27W. 300V is potentially LETHAL. Take due safety precautions.

Thanks for your help and concern..

And I have attached my circuit which explains the need of such status LEDs , where MOSFETs are used as high side switches.

 

I note the company name on the paper in the pdf. Hope there's no confusion when customers were expecting to buy condoms .

 

I note the company name on the paper in the pdf. Hope there's no confusion when customers were expecting to buy condoms .

Let me know if you need free samples..