|
Drivers
for high power LEDs are now becoming more common. However, the noise performance may not necessarily be top notch
as the driver modules are often sold for use as a component in a system - leaving the onus for compliance on the
system designer.
The examples below cover the usual EN55XXX range of 0.15 - 30MHz although EN55015 (lighting products) extends down
to 9kHz at relatively higher limits. The class 'B' quasi-peak limit is shown in red.
Here, you can see that on the Ormitech design, on a 60 x 10mm pcb to fit a prototype product, the noise has been forced right down
(just above
the noise floor) whilst delivering the
highest efficiency.
The same approach, but on a larger scale, was used in the case of the 270W dc-dc converter described on the power page. Low noise in LED drivers
is important in automotive applications, where the CISPR25 standard can require emissions to be especially low,
the compliance class being agreed with the vehicle manufacturer. The conducted emissions in this standard have
to be measured all the way up to 108MHz.
|
