If I leave the circuit set up as is, but connect my PWM to the feedback pin, wouldn’t that increase the current at the feedback, and thus dim the LED? The LM circuit needs to be modded similar to how you add current limiting to a x regulator. Theoretically it could be several amperes. Originally Posted by DeepOne. If so, what PWM frequency is suitable for various switching frequencies? Happily, this device is that good-natured, that it will not stop completely if one component is slightly off the calculated value.

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That’s the best case if the dropout is at 0. Unless I turn up the supply voltage to around 8 or 9V, it only allows less than ma each through. Warloxx 1 4. Happily, this device is that good-natured, that it will not stop completely if one component is slightly off the currnt value. Can you give any examples or links of linear current source designs that do require less drop?

Input Voltage [V]

This means measuring the exact Vfwd of each LED, and buying the correct value resistor for each one. I independently arrived at a similar version – works reasonably well. How to upload a counter value to a website automatically 3.


Home Questions Tags Users Unanswered. Low drop out, hopefully? A buck converter will improve on the above. During start-up, the duty cycles will be higher and this can cause all manner of problems; one way to control the start-up into a heavy load is to step the operating frequency low frequency permits a longer turn-on time for an effectively longer duty cycle.

Originally Posted by Artlav.

Mar 1, You will need at least 2. I’ve only recently begun soldering SMT parts, but I’ll be having PCBs made for all of this, so I can go surface mount where needed, to keep things small. Sign up using Email and Password. By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.

Of course it should be somehow different than those which already exist in the web. It’s a shame they didn’t send menthe board with the PT on it cos it’s so easy to make Dimmable. During start-up, the inductor is being charged with a cinstant to ground and this current is not going through your sense resistor.

The present is theirs; the future, for which I have really worked, is mine. You may want to use the circuit tool, when you say output what do you mean? That should tie the input high as well but when when the capacity on the gate is charged the connection is broken. John Birckhead 4, clnstant Your benchtop supply runs at 2 amp maximum and you are running a switched mode power supply with 1 amp of output current from your inductor. Right, that makes some sense but: Buy a lot of crystals: OR is there another way you could dim the LED?


Efficient constant-current regulator for ma LEDs – Electrical Engineering Stack Exchange

MikeP 1, 5 7. Decreasing gain while the circuit is operating leads to an increasing in gain, and the output stays stable.

I know this works on other constant current chips but they actually say in the data sheet that you can do it. NSI – unsuitable Datasheet: May be cheaper than more modern IC.

That is a peak current limit resistor, though. IEE Floating Point addition 7. Oct 18, 1.