LYT4228E 60W driver design

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Hi support,

 

I'm about to deisgn a LED driver as in subject. However I can't find any sufficient design support on how to dimension all components in my design. I'm not talking about EMI section which obviously needs to be tested in real life but all components around secondary outoput and auxiliary output.

Also PIXLs gives some tips like: RV1, RV2, RFB1 & RFB2 but I can't guess what's that exactly in relation to my circuit. Is there any Deisgn Note for LYT family?

 

BR,

Paul 

Please refer to Key Application Considerations and Application example on the LYT-Switch IC's datasheets. You can also further look at the documentation of Design Examples for a particular IC which briefly discuss the component selections.

Hi again,

 

having some design examples of LYT-4  IC in on one hand and my protype in the  other I was trying to get this working.

First, my design won't start without additional 100nF cap hooked at FB pin. Next - BP hooked cap must be 47uF - not 4u7F - otherwise it also won't get started either.

 I did some measurements:

I out is >2Amps (while I request 1.8A)

Ifb exceeds 220uA while it shall be lower - don't know why

But most problematic issue is that light flickers with 50Hz.

I made two prototypes and both behave identically.

Any tips, please?

 

BR

Paul 

 

 

The capacitor hooked into the BP pin depends in which mode you are using the device. For full power mode 4.7uF, for reduced power mode its 47uF. This mode you need to enter on the design spreadsheet.

IFB and Iv are in uA and careful layout should be observed to eliminate noise t corrupt these signals. IFB is directly proportional to yout Vout (via bias) so you have the full control of it thru the RFB resistor(resistor between bias and FB pin.

This is non-dimming right? I need to see the waveform of your output current and drain current to understand the 50Hz ripple. Normally, the output contains 2xline frequency ripple but not the fundamental. This ripple is due to the pfc action of the converter.

br