LYTSwitch-4 Input Voltage vs Output Regulation

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I designed 60W 1.4A CC Led Driver according to attached PIXLS and schematic. 

The problem is driver works normally just between 230-290VAC. Below the 230VAC, IC is loosing CC control.

I tried all the combination like changing Fb resistor, Bypass resistor and Filter resistor (R14), Bypass Capacitor (47uF and 4u7) without exceeding

190uA. All these effected just a few volts for the AC input.

Also I tried different Voltage sense resistors (higher and lower). It changed significantly. But this time

AC working area shifted like 180-230VAC.


What can be tried else?


Best Regards,



첨부 파일Size
60W-1400mA.pixls49 KB
60W-1400mA.pdf36.65 KB

When you say losing CC control, how much does it change? Is the regulation way off?

Please check your drain current and make sure that it does not hit the current limit. This is to make sure that there is nothing wrong in the transformer. The PIXLS predicts that the operating current is well below the current limit so it should not exceed it in actual.

You are right to check the FB current and make sure that it does not exceed its useful range. I am still curious about what the CC line regulation looks like. If it's not too bad, then adding a pull-down resistor from Vpin to Source helps shape the CC. Try changing the 4Meg RV resistor to 3.9M and add a 1.4M divider resistor. LNK-PH PIXLS has a trimming option for that. You may use the PIXLS to trim the values since LYT4 PIXLS does not have the trimming option.