jtr1962
Flashaholic
Glad to be of help! Enjoy the drivers!
So the extra IC would be for PWM dimming?See page 5 of the datasheet for some typical dimming methods. ... all of these methods may be employed.
Increasing the inductor value just smooths the current to the LED a bit more, that's all. The new version uses a smaller value inductor but has a ceramic cap in parallel with the LED. The capacitor also smooths the current.So the extra IC would be for PWM dimming?
Why do some of these photos have a 22µH inductor and some a 47µH one? (I think those units are right.) I noticed that for the first version too. What difference does more than doubling the value of the inductor make?
Does it? This pic shows it marked 470, and has the board fully populated except for R6.The new version uses a smaller value inductor ...
Have you noticed that all the photos on the product page are new? In the first photo (link above) it's called IC1 and marked as 82FE.Regarding PWM, not sure what extra IC you're referring to here. Can you be more specific? In all the photos I see there's just the PT4105 driver IC. All the rest of the parts are either resistors, inductors, capacitors, or diodes.
Sorry, I didn't even look at the product page until now, so I really had no idea what you were referring to. Electronically, there's not much difference between a 22µH and a 47µH inductor. It was probably a matter of one part being cheaper or more available than the other. IC1 is probably a voltage regulator but it could also be a transistor or a diode mislabeled as an IC. It does indeed look like it has something to do with PWM. If I had to guess, I'd say it's a transistor which pulls the FB pin high in order to turn the LED off via a PWM signal.Does it? This pic shows it marked 470, and has the board fully populated except for R6.
Have you noticed that all the photos on the product page are new? In the first photo (link above) it's called IC1 and marked as 82FE.
Sounds good. 3 pins, so I wouldn't think diode.IC1 is probably a voltage regulator but it could also be a transistor or a diode mislabeled as an IC. It does indeed look like it has something to do with PWM. If I had to guess, I'd say it's a transistor which pulls the FB pin high in order to turn the LED off via a PWM signal.
And it's just a link. :thinking: Apparently a board tuneable for multiple applications. We could do with some sort of application notes for this particular board.Hmm... I wonder what those extra components add to the driver? All the drivers I have are just like the one in the photo on top of the page. No IC1 no resistors... but I have the R6
Sounds like what the initial run of this new version had, as per the pic posted by MikePL.Or else by removing IC1, R4, R5 and then installing a piece of wire for R6.
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If the set resistor is 0.2 ohms, is the output now 1A instead of the old 750mA?
Thank you for that confirmation. The datasheet indicates it shouldn't be run at 1A with less than 9V in, so I'm a little surprised at that change.But I noticed something different. With R1 set at .200 ohms, the driver drives the LED with about 1 amp of current. So the LED runs a lot brighter than previous versions of the driver (the old version of the driver ran at around .8 amps I think).
In general, step-up drivers are the ones in danger of burning out if no load is connected. What happens is that the output voltage increases without limits until it exceeds the ratings of the pass element or the output capacitor. Once that happens, you get catastrophic failure (in layman's terms lots of smelly smoke). Some step-up drivers have output voltage limits to prevent this from happening.I have one more question about this driver. Can it be powered without the LED connected on the other end? I heard that some drivers need an output in order not to burn. I am about to make a light and I would like to have a switch which would either power one LED or three. While switching there is always a 'gap' which lasts 0.2s and I would like to know it such a repeated switching can damage it.
Would a zener diode do that job? :thinking:Some step-up drivers have output voltage limits to prevent this from happening.