FREE DIY open source BOOST driver!!! Tested & working!!

I think if there is any part to be upgraded due to thermal properties it should be the ic (like RHD said get the one with the exposed GND pad for heatsinking) and get larger resistors, capacitors don't get hot usually but if its close to a hot component i can sort of understand why you'd want one capable of high heat.

We spend a lot of time and effort trying to heat sink everything, including the drivers. It seems very logical to choose components that can handle higher temps to begin with.

I'm not sure that I am up for a google search to show that a component rated at 85C will have a shorter lifespan near that temp than a component rated at 125C that is running near 85C. I think it is pretty certain that would be the case though.

I would put the effort in if I were trying to convince others to buy these parts, but I'm not. I'm choosing them for myself because I believe that it is so.

I am not an E.E. but I do have a (long unused and lots forgotten) Engineering Degree and everything I do remember leads me to believe that this is not snake oil. There is no way they are getting more money to say the parts are rated at 125C vs 85C without it making a difference in the right application. The buyers of these chips are too savvy for that - especially the automotive certified stuff.

That is an area where I do have a lot of recent experience and I can assure you that heat is the enemy in everything we do, and lowering heat or raising the heat tolerance in materials is a huge improvement in lifespan of parts.

It also goes for computers. Most of our heatsinking materials (except perhaps custom diode sinks) are based on videogame or PC chips being heatsinked. The more you heat sink PC chips, the longer they will live unless they weren't being driven near the limit at all

EVERYTHING we do seems aimed at overdriving every link in the chain. We overdrive the diodes HARD. We overdrive the drivers and start putting heat sinks on them in the hopes they will live. Even the boost drivers got some heat sinking when Moh was testing them.

If you have a component that doesn't even go into thermal protection for another 40C then you are very likely to increase duty cycles, and perhaps not even reach 125C to need thermal protection.

It just seems like common sense to me.

Snake oil is when you are selling a placebo (or worse) and claiming it does something it really doesn't. In this case, I am buying something that almost certainly does what it claims to do - and that is tolerate heat better. Whether I need that tolerance is up to debate, but I don't think the chip makers are just making this stuff up. I believe those chips can handle higher temps without failing and I think that is worth paying for personally.

:beer:

AnthoT said:

I think if there is any part to be upgraded due to thermal properties it should be the ic (like RHD said get the one with the exposed GND pad for heatsinking) and get larger resistors, capacitors don't get hot usually but if its close to a hot component i can sort of understand why you'd want one capable of high heat.

Click to expand...

That was the first thing that I did AnthoT - and RHD rode my tail about that too!

http://www.newark.com/national-semi...ic-led-drvr-5-sot-23/dp/55R3975?ref=lookahead

I have to agree with rhd here. Higher temp rated caps is bs. Not saying they can't stand the higher temp, just that you don't need them too.

I also thought the "automotive grade" lm3410 was pointless too (it's the exact same chip...) but I think this about the caps is a bit ridiculous.

Not trying to be harsh here, just saying my opinion This driver is open to all, feel free to make it with whatever parts you want

1206 caps can support higher voltages with higher capacitance at lower price .. I guess that's the only real difference

tsteele93 said:

We spend a lot of time and effort trying to heat sink everything, including the drivers. It seems very logical to choose components that can handle higher temps to begin with.

There is no way they are getting more money to say the parts are rated at 125C vs 85C without it making a difference in the right application. The buyers of these chips are too savvy for that - especially the automotive certified stuff.

That is an area where I do have a lot of recent experience and I can assure you that heat is the enemy in everything we do, and lowering heat or raising the heat tolerance in materials is a huge improvement in lifespan of parts.

EVERYTHING we do seems aimed at overdriving every link in the chain. We overdrive the diodes HARD. We overdrive the drivers and start putting heat sinks on them in the hopes they will live. Even the boost drivers got some heat sinking when Moh was testing them.

It just seems like common sense to me.

LM3410XQMF/NOPB - NATIONAL SEMICONDUCTOR - IC, LED DRVR, 5-SOT-23 | Newark

Click to expand...

I agree with you on your part choice logic...
We ALWAYS try to over design for the few pennies it costs more
to add to any possible increase in MTTF.

If you are running a circuit on 12 VDC we always use electronic
components that can handle at least twice that voltage for only
a few pennies more.

Of course 12Volt components could be used but at a decreased
MTTF. (Mean Time To Failure).


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

lasersbee said:

If you are running a circuit on 12 VDC we always use electronic
components that can handle at least twice that voltage for only
a few pennies more.

Click to expand...

See, I think that's ^ logical.

If you're choosing caps, I'd never go for a 10V cap on a boost driver that was boosting to say 6.5V. Even though it would seem to be fine, I'd go for a 16V cap instead.

But that's because the voltage of the cap is an actual meaningful measurement of that cap's performance in our application. Some supposed temperature rating is not.

rhd said:

If you really wanted to improve the "quality" of your driver, you'd take the design, fork it, double the width of each important trace, swap in the TSSOP version of the IC, use a larger package Shottky, a larger package set resistor, and get new PCBs make.

While only incurring perhaps a 25% additional size penalty, that might actually improve the quality of your driver.

But this business of wasting time micromanaging capacitor "temperature ratings" is not.

Click to expand...

One other thing, I just wanted to point out. That is an interesting idea and if we could keep it within size limits that would still work well for most lasers that would be great.

But in this discussion there is a practical limitation. - I have 100 of Moh's R9 version boards.

That is what I am working with and that is what I am trying to find the highest reliability (within reason on price) parts to use.

I don't want to redesign the driver - I just am trying to understand what I can do to improve lifespan/performance/reliability on that board.

Some things are easy. A resistor has an ohm value that it needs to be, and then all I have to do is find one that FITS (looks like 0805 is my world on the R9 board - except the 100kohm which is 0603?) and then I can pick the highest quality version of that resistor that I want to pay for...

But when it comes to some things, like schottkys and mosfets and lm3410's, I'm not as practically familiar with these components. I studied the basics 25 years ago in college and then ignored my degree and went into a totally different field.

The last time I was picking out resistors, they were round things with colored bands around them and I was proud that I had memorized the colors and could tell you the resistance by looking at the color codes. It is a whole new world to someone who had a 65-in-one electronic kit when they were 12 years old (and that was the mac-daddy version - SIXTY FIVE!) compared to now when someone decided that K meant 10% (wtf - k always means thousand!!1) and R is a zero or decimal point or something.

I don't even know what the important specs are on the schottky and the MOSFET. I'd like to be able to go search for them, but unlike a 100kohm resistor, which I can plug 100kohm resisitor 0805 thick film sense resistor and then choose the one that looks most robust, I don't even know which data point is important for the schottky and the mosfet to work from.

Anyway, you get my point. I'm relearning things I forgot and it is compounded by the fact that everything is different so I have to learn naming and packaging, etc.

My long-winded point is this...

I'm not insulting RHD and Ben. I'm saying, "Hey, I like this driver you came up with - it is really awesome." I'm an old fart with a little more money to waste/spend on my builds and I'd like to know if certain parts will work on this board because I'd like build it in a "zero defect/high temp" automotive quality spec fashion.

Could you please help me understand what I have to use and let me know what specs are optional?

Again, I am not preaching that anyone else needs to do this. I disagree with Ben that the LM3410Q version is the "same thing" as the others because you can't convince me that the automotive industry is going to pay more for something that isn't different.

I am aware that caps aren't heating up very high themselves, but they are soldered to a board that IS potentially getting very hot in a small 1 square inch or less enclosed space with a hot driver attached to them on one side and a constantly increasing temperature heat sink from a high powered laser diode on the other side. Until someone has good measurements on the temperature of that space, I don't see how it is a bad idea to use a cap that can operate in 125C conditions IF I can find one that doesn't cost $6 each and IF I can find one that fits.

Will it make any difference in the build? I have no idea, but I actually got them ON SALE from Newark for cheaper than DigiKey or Mouser and Future Electronics doesn't have them in stock - so why does that matter?

Wouldn't it be ok just to say, "Hey Tom, you are wasting money on these higher priced parts and we wouldn't recommend that anyone on a budget waste their money on these parts - but YES that part will work." Or "NO, that part won't work - here is why."

That is all I am asking for...

:beer:

tl;dr I'm not criticizing the design or parts choice that Ben and RHD made, I'm just looking for help on finding potentially higher temp, higher reliability parts that cost more for my builds and would like help in knowing whether a particular component will work in place of another in the schematic.

Double post on purpose here - just want to clarify for anyone looking in:

Here are some of the grades available in descending order...


ESCC 3009 (Space Quality)

IECQ-CECC (Aviation)

AEC-Q100/Q200 (Automotive)

MIL Grade (Almost meaningless)

Standard Components

With the automotive grade, you are able to get components tested at some pretty extreme humidity and temps (grade 0 is up to 150C and more commonly grade 1 is up to 125C) at prices that aren't astronomical like aviation and space grade components.

Definition of Part Operating Temperature Grade

Grade 0: -40°C to +150°C ambient operating temperature range
Grade 1: -40°C to +125°C ambient operating temperature range
Grade 2: -40°C to +105°C ambient operating temperature range
Grade 3: -40°C to +85°C ambient operating temperature range
Grade 4: 0°C to +70°C ambient operating temperature range

That is my reasoning. Why put 85C standard components in a hotbox that we are already heat-sinking as much as possible?

AT THE VERY LEAST, it seems like you would get better duty cycles.

You can read all about AEC-Q100/Q200 here if you like - AEC Documents

rhd said:

But that's because the voltage of the cap is an actual meaningful measurement of that cap's performance in our application. Some supposed temperature rating is not.

Click to expand...

I really don't follow you here. The AEC-Q100/Q200 specs are put together by Autoliv, Continental, Delphi, Johnson Controls, TRW Automotive, and Visteon.

http://www.aecouncil.com/Documents/AEC_Q100-008A.pdf

3.2 General ELFR Procedure

"The parts shall be tested per the High-Temperature Operating Life (HTOL) requirements in JESD22-A108 with the following special condition. The ambient test temperature and duration shall be per the applicable operating temperature grade as follows:

Grade 0: 48 hours at 150°C or 24 hours at 175°C
Grade 1: 48 hours at 125°C or 24 hours at 150°C
Grade 2: 48 hours at 105°C or 24 hours at 125°C
Grade 3: 48 hours at 85°C or 24 hours at 105°C
Grade 4: 48 hours at 70°C or 24 hours at 90°C

3.3 Acceptance Criteria

The parts shall be electrically tested within 48 hours after completion of high temperature exposure.

Testing shall be at room temperature followed by high temperature. Failures during this test are not acceptable and indicate that corrective action must be taken. The supplier shall notify all interested users of this non-conforming condition and the corrective action that has / will take place. The user(s) must approve of the corrective action for the part to be qualified."



You make it sound like these temperature numbers are some "made up" marketing scam numbers, but these companies take them very seriously in the design of automotive parts where they do not want to be on the hook for a huge recall of tail-lights because an IC couldn't handle the environment.

BEST OF ALL, we are talking about circuits that are VERY SIMILAR to what we are doing - a lot of the parts we are using are being used in the automotive industry to drive LED headlights and other LED lighting and they are using very similar circuits and probably some of the very same parts as we are using in lasers.

So my take on this is that we're all missing a bit of perspective (seriously, all of us).

None of this driver stuff is really decided on the basis "having more [or less] money to waste/spend" on our builds. At the stage where we're reflowing our own boards for $3 or $4 bucks, I really don't think cost is an issue for anyone. I can't imagine that anyone putting together a build that they value at few hundred dollars would actually care about the plus or minus of a few bucks on driver components.

In the era of $60 dollar dual flex-drive setups, then sure, "cutting some corners" by avoiding a flex in favour of something cheaper, might had been logical (heck, that's why this boost driver was born). But when you're talking about $8.00 vs $8.50 for a dual driver setup, I really don't think that anyone is making serious decisions based on that 50 cents.

People make decisions based on what is reasonably likely to have an actual impact on their build. Since we're talking about caps, this has implied a few changes for me:

- I made the switch to 1206 instead of 805 so that they'd be less tall and thus less likely to short from contact with the heatsink.
- I often go with 22uF instead of 10uF.
- I also try to at least double if not triple the voltage I actually expect to need.

Those are decisions that in my mind are worth paying attention to. Not because of their relative expense or in-expense, but rather because they have some rational potential to actually matter.

- But I simply do not believe that some capacitor with a "125 degree C" rating is going to perform better for our purposes, in any way, than a cap rated for "85 degrees C". We reflow these at what, around 215 degrees C?

Hey, tsteele

I am nearly 100% sure that all the lm3410s are the same. The "automotive grade" ones are randomly tested to higher temps/conditions than the others, but the chip is the same. They don't actually design a new version of the exact same chip that can hold up to higher temps, they just test them higher. So maybe a few out of every 10,000 (or whatever) may fail but you aren't actually getting a "better" chip. The automotive grade really doesn't matter unless you are buying in huge quantities and want to makes sure less than 1 per 100,000 fails instead of 10 per 100,000 (again, pulled those figures out of my ... but you get the idea)

Also about the caps, like rhd said, my first prototypes of this driver were using 22uf 0805 caps (expensive!) but rhd tried 10uf and they worked fine. The first versions cost closer to $10 each, but we wanted it to be as cheap as possible So if you wanted to upgrade something about them that would be a good place to start.

Thanks guys, that is really what I'm trying to get at - what CAN be changed if we want to make them a bit more reliable. I can see not going with a $10 capacitor, and I have no idea whether the LM3410's are better, different or whatever - I just ended up being able to get the Q versions cheaper at Newark than the regular versions at Digikey or mouser. So why not I figured?

I guess one out of 100,000 of my builds will fail vs one out of 10,000 of yours. (LOL! - I'll let you know when I get to 10,000!)

Anyway, that is really helpful to me. I did not realize that the capacitance was an adjustable unit (upward) so that is interesting.

RHD said:

But I simply do not believe that some capacitor with a "125 degree C" rating is going to perform better for our purposes, in any way, than a cap rated for "85 degrees C". We reflow these at what, around 215 degrees C?

Click to expand...

I'm under the impression that is long-term usage without breaking down, not short-term soldering.

You may be correct, but I still feel like there is enough heat in the pill area that a higher temp rated part is worth pursuing if it is economically feasible. The best part, is other than money - there is no downside I can see to doing it. There are always tradeoffs in decisions you make - but in this case it is a relatively small amount of money (on most of the components I've seen) and an IC that is rated to run for long periods of time at very high temps. Why not?

benmwv said:

22uf 0805 caps (expensive!)

Click to expand...

like I said

1206 caps can support higher voltages with higher capacitance at lower price

I use 0805 22uF in my drive and they are hell lota more expensive than regular 10uF or 1206 at 22uF

foulmist said:

like I said

1206 caps can support higher voltages with higher capacitance at lower price

I use 0805 22uF in my drive and they are hell lota more expensive than regular 10uF or 1206 at 22uF

Click to expand...

Yeah, those 0805 22uf are really expensive. I'm wanting to say they are close $1 each on digikey?

Edit: 70-77 cents each!

Would these caps work and what would be the downside?

TMK212BBJ106KG-T Taiyo Yuden Multilayer Ceramic Capacitors (MLCC) - SMD/SMT 0805 25V X5R 10uF 10% $0.20 USD at 100count

TDK Multilayer Ceramic Capacitors (MLCC) - SMD/SMT 22uF 10% 16Volts 0805 (2012 metric) $0.46 USD at 100count

foulmist said:

like I said

1206 caps can support higher voltages with higher capacitance at lower price

I use 0805 22uF in my drive and they are hell lota more expensive than regular 10uF or 1206 at 22uF

Click to expand...

Tom,

Why not use 1206 on your driver?

Nobody?

tsteele93 said:

Nobody?

Click to expand...

Those will work fine :beer: