LYTxxxx device based flyback to drive LEDs and an additional 5V, 2.5 A output.

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Hello, 

 

I am designing LED driver with non-dimmable features. I am selecting flyback topology given in DER350. I have got idea about what to do for making it a non dimmable i.e. changing reference pin resistance and removing SCR damping and active bleeder circuit. I have two querries as follow:

 

1. I need a additional 2.5 A, 5 V output. I understand that LED driver current control is without using any sensor and draining current, feedback pin current, and voltage sense current are used for this control. Would it be possible to have the required additional output and still LED current remains controlled ?

 

2. LYT43xx devices can be made non-dimmable by simply changing reference pin resistance. While, LYT42xx devices are titled as non-dimmable, should I use LYT43xx devices or LYT42xx device ?

1. If your 5V has a fixed load of 2.5A (meaning it always consume 2.5A), the led current can still be regulated. However if your 5V changes load say 0A to 2.5A, the Led output current will also change with your 5v load

 

2. Use LYT43xx devices for dimming and 42xx for non-dimming.