voltage and current ripple in dc output

6 posts / 0 new

Hallo !! 

Good afternoon !

We have designed and tested led driver of 35w using LNK419. We are facing problem of light fliker due to ripple voltage in dc . . Please can you explain how to reduce peak to peak voltage and current riple  (100 Hz ) . 

Sandeep Mulik

Hi,

Single stage converter with PF will normally have a output current ripple propotional to 2 X Freq on AC line.  One way to reduce the output ripple is by increasing the output capacitance.

Regards,

PI-Jono

Thank you PI-Jono.

We have already increased filter capacitors but we are looking for 50mv to 75mv peak to peak ripple on dc output to led .

After adding electrolytic capacitors of 2200uf each , such four in parallel . (2200uf x4) . But after adding these caps , driver  takes 30 seconds to give a full load voltage.

So how to overcome this problem ?

Best Regards

Sandeep Mulik

Hi,

It seems like the target ripple voltage is too low for a single stage power corrected power supply.  If ripple is one of the key requirement then it is recommended to use low PF converter.  Instead of increasing the output capacitor, increase the input capacitance to 100uF. 

Regards,

PI-Jono

Hi all,
We have designed led driver tester ,it is like you can test different driver ;but im getting some issues like boosting(increasing) dc output current automatically.so can you help me to sort this issue

there is no solution to solve this issue, choosing two stage ac-dc solution or using low PF solution.