EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: wemme on August 14, 2015, 02:37:38 am
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Hello.
I am looking at using some discrete LED Filaments for a custom lighting design which will be powered from 12 to 30 Vdc
These have a forward voltage requirement of 75Vdc which is outside the drive range of most LED driver chips.
Has anyone come across a suitable driver chip ??
I have had a look at TI and Linear tech so far and nothing has come up worth while.
Regards
Bart
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A better bet may be to use a boost converter with separate low-side LED drivers. There are some LED driver ICs that are actually designed to be used with an external switching converter; they have an analog output intended to driver the converter's feedback node to trim the voltage up or down to maximize efficiency. The Atmel MSL2041 is one such, but there are others out there.
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Thanks for the reply
I was looking at the LTC3805-5 as a boost converter and then just tweak the voltage but that would be better.
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Just found these guys which will all do the boost and current control.
AP306, TPS61196, LT3755 and RT8475.
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Thanks for the reply
I was looking at the LTC3805-5 as a boost converter and then just tweak the voltage but that would be better.
Do you need to switch the LEDs individually? If not then you could use the LTC3805-5 and take the feedback from a current sense resistor, rather than a potential divider.
If you're using an MCU to switch the LEDs then you could use a constant voltage supply and add an emitter resistor to each switching transistor to form a constant current sink.
(https://www.eevblog.com/forum/projects/nixie-tube-clock-without-the-nixie-tubes!/?action=dlattach;attach=142825;image)