# Source for AMC chips?



## VanIsleDSM (Apr 4, 2008)

Interested in some of the different AMC chips.. I've seen the AMC7135 in drivers around here.. the 7140 also interests me and I'd like to purchase some but I can't find any supplier for them.


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## NetKidz (Apr 4, 2008)

Hi VanIsleDSM,

Maybe you could contact micro-bridge? [email protected]

I bought some AMC7140 from them about two years ago. It's US$2/pcs, but I don't know the price now.


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## chimo (Apr 4, 2008)

Edit: Sorry, never mind. Mis-read the question.


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## knabsol (Apr 4, 2008)

Those look interesting. I just built a current regulator yesterday and it worked good but these look easier. But I suppose they get fairly hot when having too alot more input power than led forward voltage?

It would be nice to build a few small encapsulated boxes to just plug and play. What is your goal with these VanIsleDSM? 
Maybe we could get a simple design and order? I´m in the need of about 20 current regs for a vin of up to 30v. at 350 or 700mA.


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## VanIsleDSM (Apr 4, 2008)

Thanks netkidz, I'll try that.

They are linear regulators, not switching.. but if you can design your system with 0.5-1v or so higher than you need.. it won't even get hot.. plus, for the current setting resistor you only need a 880ohm for 700mA, that means you're only passing ~1400uA.

When I use an LM317 for a constant current device it needs 2.5-3 volt over the LED Vf drop. And to achieve 700mA the set resistor is a 1.8ohm resistor.. The LM317 easily wastes another 2.5-3 watts of power.

I also emailed national semiconductor to see if they have a chip like the LM317 that has a low dropout voltage and a lower current sensing resistor, but I haven't heard back from them yet.

I just plan to use these to make some LED lighting for my house.. 5x CREE @ 700mA = 17.5v... with an 18.5v laptop PSU that'll make a fairly efficient, economical light.


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## VanIsleDSM (Apr 11, 2008)

Hmm.. I emailed them last weekend and haven't heard anything back yet.. Strange... 

I suppose I'll try again.


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## VegasF6 (Apr 12, 2008)

If I seem to be following you around on your posts it's only because I am interested in your home lighting project. Have you tried Linear Express yet? Here are some contact #'s to try.
http://www.linear.com/contact/salesoffices/usa_disty.jsp#disty
Otherwise, maybe National Semiconductor?
http://www.national.com/mpf/LM/LM317.html#Availability

Oops, I missed this part of your thread
"I also emailed national semiconductor to see if they have a chip like the LM317 that has a low dropout voltage and a lower current sensing resistor, but I haven't heard back from them yet."

So the suggestion for national semiconductor wasn't a very good one.

You probably aren't interested in any more LM317's either than. But, just in case, they are .50 cents each right now at allelectronics.


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## VanIsleDSM (Apr 14, 2008)

I emailed them again asking for a price quote for 20 AMC7140 chips.. still no answer.

Are they just completely ignoring me because this order is too small?

Netkidz, how many pieces did you order?

I would really like to get my hands on some of these chips.. I can't find anything else like them from anybody else.

You'd think they would maybe at least respond to tell me of a minimum quantity? Then maybe I could coerce some CPFers to go in on an order together.


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## Gryloc (Apr 14, 2008)

VanIsleDSM,

I would be interested in these, too. I am not sure how many I will need yet (I need to look my projects over), but it would be not more than a dozen. I will try to keep you updated as I get to pondering it further...

The only way I can think to get these is pay for the 1400mA AMC boards from DX/KD and harvest them yourself. I did the math a while ago and found that it is more economical to buy the converter boards with higher current output (more AMC chips), but I do not remember how much it would run you per chip that way. It is too bad that shipping is something you have to really plan for with these guys. At least it is one source for them.

Good luck with the searching. It is unfortunate that you have not received a response yet. Have you thought about asking the owners of DX and KD if you can get some deeper contact info for the company? Maybe they can forward to the little round converter board assembling company, and that company that buys the chips individually, can forward you further. Just a though...

-Tony


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## NetKidz (Apr 15, 2008)

VanIsleDSM said:


> I emailed them again asking for a price quote for 20 AMC7140 chips.. still no answer.
> 
> Are they just completely ignoring me because this order is too small?
> 
> ...


 
I'm not sure if things changed. I remember they replied fast and directed me to a sales I could talk to. I orderred 10 AMC7140 and AMC7135 that time. 

I'm not sure if the sales is still there since it's about two years ago. I'll e-mail him to see if he could sell me small qty again. 20 AMC7140?


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## VanIsleDSM (Apr 15, 2008)

Gryloc you're thinking of the AMC7135.. the 350mA fixed output chip.

I'm interested in the AMC7140, up to 700mA adjustable current.. with an enable pin for optional PWM.

Netkidz, if you somehow get in touch with them please let me know.. I really need to get my hands on some of these.


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## NetKidz (Apr 15, 2008)

Hi VanIsleDSM,

I've contacted the sales in Taiwan branch, he said they prefer to sale one reel (2500pcs). But he also said China main office happens to have one cutted reel and could sale in 100 or 200pcs. The price is US$1.2/pcs for 100pcs. (Seems not firmly :shrug.

I could buy them and ship to you. If you want to talk to him directly, please PM me and I could forward his e-mail to you.

Thanks.


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## Gryloc (Apr 16, 2008)

Oops! Yeah, I must have read the numbers while in a fog or something. Sorry. 

I will have to check out the main site again. I remember that there was a higher current IC that I was drooling over, but I forgot the number of it since it was several months ago. I gave up on it because I thought that I would never find a distributor. I will look into this later and get re-informed on the features of the ICs, as well as re-read the first posts. That part I was interested in may have been that 7140 IC. Hmmm...


For now, ignore me...

-Tony


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## VanIsleDSM (Apr 16, 2008)

Excellent!

I really appreciate it.. PMing now.


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## NetKidz (Apr 16, 2008)

@Gryloc,

Maybe it's AMC7150? 1.5A max, 4v~40v, adjustable PWM frequency.


@VanIsleDSM,

PM replied.


Thanks.


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## VidPro (Apr 16, 2008)

linkey (using the above suplied data)
http://www.micro-bridge.com/AMC7140.asp
A half volt voltage drop 

http://www.micro-bridge.com/AMC7150.asp
hmm wonder what it does when it drops BELOW 4v, like fails to fully trigger its internal transister gate?

why do we always gotta go to china or hong kong to get this stuff, whats a matta with american entrapenurialship.

i just got screwed with another across 'da planet buy deal  they are killing me.


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## VanIsleDSM (Apr 16, 2008)

Haha..

It's not the American entrepreneurship.. the American entrepreneurship gets everything made in China now.. it's the American people who love Wal-Mart so much who killed American production of goods and manufacturing that you have to blame.

Now America's biggest industry is finance.. America makes more money of people owing money than anything else.. It's the same thing that happened to the Romans when they collapsed, and the Brits when their empire fell apart.. and the Dutch too... but for reasons other than Wal-Mart.

And what's with the 0.5V drop sad face? that's awesome!


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## VidPro (Apr 16, 2008)

VanIsleDSM said:


> And what's with the 0.5V drop sad face? that's awesome!


 
because a 1/2 volt drop on a Linear regultor thing is just like the 1.5V drop on a voltage regulator thing, its waste, and waste that comes out as heat.
but mostly because i am still looking for the high powered driver, to assemble pure simplicity. 1 Huge li-ion, 3 hard driven leds, regulation to about 3Volts, and somehow levels.

and its still rather confusing, sounds to me like a Stack of the 7135s turned on progressivly 1, then 2, and 3 and 4 and . . . 12  would be the way to go  and still its out of regulation just a bit to early.

they often dont have enough AMPS to do what i want, and putting batteries in SERIES complicates the battery aspect of it, balancing and all. these SMD electronic parts are not AMP wise, like the old days when even a small relay could pipe 10-25 amps through.
old school mechanical switching didnt HAVE voltage drops, 2 metal contacts connected deerect.
the new school Mosfet switching can be tightened up to a .1V drop, and could have big fat parts that handle amps through it, and it could work at lower voltages. but they arent working twards a part that is 2X overrated, they are working on, teeney and just barely survives.

not all of us are Adept enough (like you) to make thier own drivers, and i shouldnt have to, that is just mean to make me solder them teeney parts, with hair width connections. (that fall off the board, yup had 2 teeney hair connect parts fall right off my PDAs, and not from heat)

i somehow want substantial capacity, full size parts, longevity, and of course levels , complicating it further.
and taking 5 days to learn how and create from scratch is not nessisarily a savings over paying $50 for something that works well, the first time and for a long time, unless its to "market" a product for everyone, and i already have a job.


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## VanIsleDSM (Apr 16, 2008)

For a linear regulator 0.5v drop is about as good as it gets.

And there is no low dropout linear regulator designed for LEDs with such a low Rsns as this chip.. or you usually end up wasting a watt of heat just in the set resistor.

This chip wins for it's simplicity and cost. I know of no other linear constant current regulator that's even close to as efficient as this.

Things are moving towards higher voltage and less amperage.. because things can be made much more efficient, and much smaller that way.

I've made many LED drivers.. and my job is seasonal, so I have a lot of free time while not working... I don't mind making a custom driver for someone, but minimum order quantities limit me to having to make at least 10 at a time for $10-25 each depending on what you need.. in the 100s prices come down dramatically, but I'm not equipped to produce like that.


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## VidPro (Apr 16, 2008)

VanIsleDSM said:


> For a linear regulator 0.5v drop is about as good as it gets.
> 
> And there is no low dropout linear regulator designed for LEDs with such a low Rsns as this chip.. or you usually end up wasting a watt of heat just in the set resistor.
> 
> ...



i was hoping your interest in creating your own, would cause you to accidentally (positivly on purpose) become another driver creator , so we have more choices 

high voltage is certannly the way to go, which keeps the amps down, and is how all these parts like to function. but me i have Fat D sized li-ions, and short mags that fit in the hand perfectally. the fat Ds have ample amps, are single items, have huge energy to weight size ratios, and dont have to be balanced or have reverse charge issues.

the perfect driver for me is one that does a DC-DC convert (type) will take li-ion voltages from 4.3v to about 3.0-2.8v and drive 3 leds in series or parellel to as high as 1.5amps and has levels.

taskled.com (george) has some masterfull creations, but they are mostly designed for more input voltage, or are boost curcuits.

the GD is great, but i would need 3 and Levels somehow still.

the hong cong things would have "worked" falling out of regulation early, but i have ordered from both places now, and after months i got NOTHING .

a .5v drop would be worse than a resister, when it comes to SINGLE li-ion, wouldnt be a problem for many batts in series.


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## TorchBoy (Apr 16, 2008)

VanIsleDSM said:


> For a linear regulator 0.5v drop is about as good as it gets.
> 
> And there is no low dropout linear regulator designed for LEDs with such a low Rsns as this chip.. or you usually end up wasting a watt of heat just in the set resistor.
> 
> This chip wins for it's simplicity and cost. I know of no other linear constant current regulator that's even close to as efficient as this.


The AMC7135 - as you probably know - is a constant current linear regulator, with a dropout voltage of 0.12V. Sadly it doesn't have an external current sense resistor, but that doesn't mean it isn't a linear regulator.


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## crampedson (May 29, 2008)

Have you considered National's LM3410? It's a switching boost converter which can drive up to 24V worth of LEDs at 1.5A max and has a input range of 2.7-5.5V (2.3V when in boot-strap mode). Looks pretty good at $1.25 a pop.


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