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DI-131 LED driver ripple current.

Posted by: treez on
Hello, In DI-131 design there is an offline LED driver which fits into the base of a GU10 bulb. The circuit shown in DI-131 shows an output capacitance of just 2.2uF. Why has such a low value been used since there will be significant ripple in the output current and voltage ? Since LEDs are so expensive, i thought it's best to drive them at rated forward current, with no ripple, since if you have ripple then you must ensure your peak current never exceeds the rated forward LED current, and that in turn means your average LED current is too low, in turn meaning one is under-driving one's LEDs......which in turn is bad since LEDs are so expensive. I would be very grateful for your rectifying thoughts on this

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Submitted by PI-Sarek on 12/03/2008

Hi,

The example circuit shown in DI-131 is a buck converter. For an application such as the LED, the converter operates at full load all the time.

The ripple current in the LED in this example is dependent on the inductor size, this being a buck converter. The ripple current could be reduced further if necessary by using a bigger inductor.

Regards

PI-Sarek