School me on drivers

6 posts / 0 new
Last post
Electroman187
Offline
Last seen: 1 month 2 weeks ago
Joined: 03/07/2011 - 18:47
Posts: 223
Location: New Hampshire
School me on drivers

I'd like to know more about all these LED drivers.  I understand some have DC-DC converters built-in for multi-voltage usage.  And then obviously many are multimode.  Are they MOSFET with PWM?  BJT driven?  Is there a sticky anywhere I can read?  Where can I find schematics?  Thanks for the help!

 

brted
brted's picture
Offline
Last seen: 1 week 4 days ago
Joined: 01/12/2010 - 19:44
Posts: 2371
Location: Atlanta

You can read this: http://flashlight-wiki.com/Driver

Most of the budget ones with modes seem to be PWM driven by an ATMEL or PIC chip. Some have linear regulators and some have inductors. There may be some schematics around somewhere.

Driver stuff goes in the DIY and modding section usually.

Electroman187
Offline
Last seen: 1 month 2 weeks ago
Joined: 03/07/2011 - 18:47
Posts: 223
Location: New Hampshire

Mods, please relocate this thread to Flashlight Modding.

brted, thanks for the information.  I learned some but not too much.  I imagine the linear regulators are the least efficient and least desirable.  Do the buck/boost converters come as a chip or are they as simple as an inductor, mosfet and diode?  Anyone know the make and model of the ICs used?  Datasheets?  This stuff is pretty interesting to me.

brted
brted's picture
Offline
Last seen: 1 week 4 days ago
Joined: 01/12/2010 - 19:44
Posts: 2371
Location: Atlanta

You see Atmel ATTiny13A on a lot of them. There is a sticky in the mods section about re-programming those chips to get any kind of modes you want using AVR.

The linear regulators are actually really efficient (90%) and desireable as long as the input voltage is just above the Vf for the LED (about 3.5V). They're just not real flexible in terms of input voltage range. You see a lot of drivers rated for 3.7-4.2V that use linear regulators. That works out really well with a single lithium ion cell, but not much else.

Most of the buck and boost drivers I've seen are using inductors.

Some of the budget lights seem to just be direct drive (maybe some kind of voltage limiting) and then use PWM to get lower modes.

Don
Don's picture
Offline
Last seen: 2 years 1 month ago
Joined: 01/12/2010 - 16:32
Posts: 6617
Location: Scotland

Don't think I've said hello, Electroman.

 

Welcome to BLF - hope you enjoy it as much as I do!

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Electroman187
Offline
Last seen: 1 month 2 weeks ago
Joined: 03/07/2011 - 18:47
Posts: 223
Location: New Hampshire

Hi Don,

I appreciate the welcome!  I tend to phase in and out of various interests, but I'll stick around for a while cuz it's interesting and I know I'll learn some stuff. 

Be-Seen Triker,

What is this 16/17 modes you speak of?