Dimmable LED drivers - leading and trailing

4 posts / 0 new

Hi All,

I'm looking to start a design based on the LYTSwitch 7 - becuase the DER-561 sample looks to fit the bill for my client. Which is roughly :

approx 7-8W Led power

univeral input


non-isolate (for cost and size)

Less worried about efficiency as such - this is not a light bulb, there is a large aluminium housing to help with heat.


Worth asking those who have gone before me :

a) am I on the right track?,

b) does the LYTSwitch-7 handle trailing edge dimmers as well as triacs?

c) Might it be possible to feedback a portion of the current sense resistor voltage using a pot to control the set brightness as well as the brightness varying with dimmer input.

Thanks in advance


Reply to:

a. DER-561 works with universal input but is optimized for low-line dimming. If high-line dimming is required, then a larger damper resistor may be required.

b. LYTSwitch-7 in buck configuration may not work on some trailing-edge dimmers because the dimmer might not detect the zero-crossing properly.  You can configure LYT-7 in high-side, buck-boost configuration that better handles trailing-edge. However, we are still working on a design tool that could take some time to get published. If you are able to contact our Sales team in your region, our FAE can help you.

c. You may use a trimpot to vary the output current.

OK thanks for this - I'll get in touch with our local FAE when he's back in the new year.

Is there a dev kit for buck boost of any sort - I was hoping to try this out with a quick and dirty prototype so we can do some EMC testing as it is a pretty sensitive application from that point and I doubt using something in Buck mode would be representative... I am guessing this will be a no - but please let me know!

We still don't have the dev kit for buck-boost. Attach is the reference schematic if you want to convert buck to buck-boost.

You can use the component values you have for buck and just adjust the feedback resistor.

LYT1 Buckboost.png23.39 KB