What was the chip that blew up and what is the chip you are thinking of using now?
SG

The one I had issues with was LMC7101BYM5-TR. I'm looking at using EL5111IWTZ-T7A. Looking deeper, the original op amp doesn't look like it is rated for sinking 10V... but the new one is.

 

The one I had issues with was LMC7101BYM5-TR.

Specs say 35ma max, surprised that the chip could not handle that assuming a 10ma max current on the dimmer.
Before proceeding further I would measure the current draw on the dimmer.
Can you post a link to dimmer?
SG

 

Specs say 35ma max, surprised that the chip could not handle that assuming a 10ma max current on the dimmer.
Before proceeding further I would measure the current draw on the dimmer.
Can you post a link to dimmer?
SG

The "dimmer" is the board I'm building. The lights I'm driving are a series of up to 80 of these (and a newer light using the same spec interface for dimming): www.cazabon.com/temp/ESW.SPEC_.3.2018.v1

 

The "dimmer" is the board I'm building.

I mean the power supply that is driving the LEDs.
BTW the link in the above post has a "404 Error".
SG

 

I mean the power supply that is driving the LEDs.
BTW the link in the above post has a "404 Error".
SG

Argh - missed the .pdf on the link: www.cazabon.com/temp/ESW.SPEC_.3.2018.v1.pdf

 

The datasheet does not support your understanding of the dimming control. It is simply an input that expects a voltage of 0-10V and draws 0.15mA, as far as I can tell.

Have you tried operating a single unit from a simple 10V supply and a 1K pot? My guess is it will work just fine.

Bob

 

The datasheet does not support your understanding of the dimming control. It is simply an input that expects a voltage of 0-10V and draws 0.15mA, as far as I can tell.

Have you tried operating a single unit from a simple 10V supply and a 1K pot? My guess is it will work just fine.

Bob

I agree that it doesn't line up That's why the first dimmer I built did exactly that. Unfortunately their data sheet doesn't match the reality of what they deliver. There are two industrial standards for 0-10V dimming - one where the dimmer provides a 0-10V source current, and one where the lights provide the current and the dimmer sinks it to get the right 0-10V voltage. They're providing the latter, despite what their spec sheet says.

A 10V supply on a POT will actually work with either version - you can source or sink current through it. So my first manual dimmer worked fine because that's all it was. When I naieve-ly built a DAC to supply 0-10V it blew up the op amp because it wasn't built to sink that voltage.

All is good though, I have two options ahead of me: my original op-amp design with a beefier op amp that can handle sinking 10V @ 65mA, as well as the PNP version above. The beefier op amp should be better because it can source or sink current as needed - so it has wider compatibility.

Thanks for the input!
Kevin.

 

Hmmm. So how much current do you have to sink to bring the voltage to zero?

Can you point me to the current sinking control standard?

Bob

 

Hmmm. So how much current do you have to sink to bring the voltage to zero?

Can you point me to the current sinking control standard?

Bob

General info on it: https://en.wikipedia.org/wiki/0-10_V_lighting_control

 

General info on it: https://en.wikipedia.org/wiki/0-10_V_lighting_control

Per the spec from the light supplier (which I don't 100% trust...), it's max 0.15mA per light. We have up to 80 in series, resulting in up to 12mA - not too much for an op amp to handle if it's really in that spec with no surge.

 

OK, thanks. So an opamp outputting 0-10V will work fine as long as it can sink 0.15 mA times the number of parallelled inputs.

Bob

 

MadCows4242 What was your final result to this. I am trying to make the exact same thing right now, and curious what you ended up with.

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