I recently put together an LM3409 based LED driver for driving 3 white LEDs in series. I would like to analyze the output to the LEDs to check ripple, frequency, etc to ensure it's working as designed and how various parameters change with respect to each other. However, I'm having a hard time seeing any kind of recognizable output waveform with my scope. The scope is a Rigol DS1054Z 4Ch 50MHz. At nominal voltage, my calculated frequency for the driver is 230kHz.
Is there a guide, or some tips for accurately measuring the output from my driver? I was expecting something like what is shown in the datasheet, such as: http://i.imgur.com/QLGxGF9.jpg
Can anyone provide some guidance with this? Proper methodology, recommended settings, expectations, etc. Thanks :) It's definitely a learning process.