Can I generate extra CV output for LinkSwitch-PH

Posted by: lbaerd on 07/09/2010

Hi,

I would like to know if I could generate auxiliary CV 5V on top of the LED CC output using LinkSwitch-PH. Is there anyone out there that could provide me with the info. I am posting a new thread because nobody reply my previous thread for more than 1 week.

Thanks
John

Comments

Can you please provide more information, such what's the purpose of this 5V, what's the load current and is it at primary side or secondary side?

Thanks for your reply.
In fact, I would need 2 output.
1) 50VDC, 0.3A
2) 5VDC, 0.1A
The 50VDC will be used to power up LED. The extra 5VDC auxiliary output will be used to power up a microcontroller. This microcontroller will be used for other functions such as remote on/off and dimming.

In fact if possible, what I would like to achieve is a constant voltage output using LinkSwitch-PH. LinkSwitch-PH simple PFC design is attractive and I would like to know if I could generate CV using this switcher. From what I have read from the datasheet, it seems like it could only generate CC.

Thanks
John

LinkSwitch-PH maintains CC while LED string voltage changes. For your 5V CV, maybe you can use a separate winding and linear regulator to get it.

Thanks for your suggestion.
I have 2 more questions

1) Refering to Page 9 of 42 of the document RDR194 - Reference Design Report for TRIAC Dimmable 14W LED Driver Using LinkSwitch-PH LNK406EG.pdf
"Resistor R1 provides a discharge path for C3 with a time constant much longer than that of the rectified AC to prevent the V pin current being modulated at the line frequency."

I would like to change C3 to Polyester Cap with lower capacitance e.g 0.22uF/400V and change R1 to 1MOhm. Is that fine? This will roughly come up with the same time constant.

2) Do you have any recommended standard heatsink for Linkswitch-PH?

Thanks
John

Thanks