So it seems again you are correct. Add to watch list Remove from watch list. I have read the applications section of the datasheet about 20 times so far, I gather the frequency is dependant of several factors. Learn more – opens in a new window or tab Any international postage and import charges are paid in part to Pitney Bowes Inc. Email to friends Share on Facebook – opens in a new window or tab Share on Twitter – opens in a new window or tab Share on Pinterest – opens in a new window or tab. Cheers man I don’t want to ask you to spend much time on this, because as many would suggest, I’m seriously thinking about just using a different chip for applications that require stability. It is designed to output 3.

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Is the gate drive adequate for the size PFET used? I never could let things go without knowing everything thats going on.

> circuits > Lm Led Demo Board l –

Welcome to our site! I do strongly recommend you fix the Mosfet issue but you may be able to get it working right now by substituting a low ESR cap.

This chain feature re- quires only a single data stream to the controller. It is ‘supposed’ to remove the output caps ESR and inductance from the equation that determines the operating frequency I came across this article: Well, at least at a reasonable frequency, and it runs cool at mA loads 3v out slightly warm at 1. I used 24k initiailly, but changed this to 47k when the output dropped assuming it was curent limit kicking inmade no difference.


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Everything gets hot, regulation suffers. Diode, LED Lettre prioritaire nationale: Back to home page. On side note, as I had to effectively ‘build’ a circuit that behaves like the LM in LTspice no native spice model anywhere on the web I came up with a fairly straightforward pracitcal implementation, using aand LM plus some passives.

The ESR of which is claimed by a dodgy datasheet to be 2. In terms of component values the two largest contributors are the inductor, and output capacitor, as well as the ‘feed forward’ cap.

Lm3485 Led Demo Board

Could you post how you simulated this? You can’t use ceramic on the primary cap though, unless as you stated, you use a series lm4385, one of those.

Found this link which is an application note for a similar albeit synchronous hysteretic converter: If you are using too large a PFET, that can be a problem. OK, well that makes sense, at 5V the mosfet would have a longer duty cycle than at 3.

Anyone here used the LM3485?

So, I’ve gone back to this project, dug out the PCB’s, and grabbed the new parts I ordered months ago for it. Measured efficiency at my target load of 1. If the unit is not laid out carefully with short leads and a good ground plane, it may not operate properly.


Help identifying strange capacitor terminal style Started by Killians Yesterday at Plus, with the replies from this thread it helped me gain a much better pm3485 of converters, MOSFET’s, power electroics, and even filled in many gaps in my analogue knowledge.

Some answers to questions: And certainly something I would consider over a ‘simple switcher’ when cost is at a premium. In Australia, consumers have a legal right to obtain a refund from a business if l3m485 goods lev are faulty, not fit for purpose or don’t match the seller’s description. The item you’ve selected wasn’t added to your cart.

International postage and import charges paid to Pitney Bowes Inc. Learn more – opens in a new window or tab International postage paid to Pitney Bowes Inc.

For trouble shooting, I’ll add a bypass switch to the buck, so one can use the LDO ‘as is’, just in case noise form the converter proves to be an issue for my llm3485 analogue measurements doubtful. The converter runs up to 1Mhz, the higher the frequency, the lower the inductance and capacitance required. I’m afraid I wasn’t aware I should have thought it through of this specification