DER-301 modification

Posted by: jonzpogi on 11/26/2011

HI,

I'm trying to build a LED candle driver base on DER-301 reference design, however i want to know if what changes do i have to make if i want to adjust the output to 40mA/100VDC or 20mA/200VDC. Basically im using a HV DC LED source with low forward current, 2 HV leds are inside the LED source and can be connected in either series or parallel. Series (20mA), parallel (40mA). thanks.

Comments

You might need to change the following components in the DER-301,

1) R3 and R5 for lower output current
2) C7 for higher output voltage
3) VR1 for higher OVP (vout + 20 V)
4) Remove R7, C8, and R6 for non dimming application

what should be the value of r3 and r5 if i want 20ma and 40ma?
what should be the value of C7 if i want a 200VDC output?
VR1 value should be as per the required Vf of the LED?
what about the values of the other components?
where can i find application note with the formulas?
i live in dubai, who is the responsible distributor in our region and how can i get the samples?

thanks.

1)Since the current sense resistor value of 80 mA is 4.5 ohms, the sense ressitor values for 40mA will be around 9 ohms and 18 ohms for 20 mA.

2)C7 can be 6.8 uF / 250V for 200 V output.

3)The voltage rating of VR1 for 200V output will around 220V.

4)There is no any other component value need to to be changed.

5)The only LinkSwitch-PL Application Note is the AN-50 up to this point.

6)Digi-Key and Farnell are the PI's world wide distributor.