Using AMC7135 drivers in series/parallel?

MrNaz · Feb 10, 2009

I need a regulated 3.7V @ ~3A output, and I've seen these driver units:
http://www.dealextreme.com/details.dx/sku.1886

I was wondering if it is possible to wire these babies up in parallel in a similar way to batteries to deliver the same voltage output, but double the current. One possible application could be as a poor man's P7 or MCE driver, as this would be 3.7V @ 2.8A, just perfect for those LEDs.

If not, how hard would it be to remove the AMC7135 chips and build my own driver board from scratch using 8 of them?

datiLED · Feb 10, 2009

They can be used in parallel. Myself and many others have done it with good results. I don't have time to post the links to the information, but there are several good posts detailing the specifics about removing the diodes, the on-board connections, and even making a multi-mode setup. I am sure that someone may chime in with a link, or two.

LukeA · Feb 10, 2009

Such a driver already exists, but you could certainly build your own. In fact that's how AMC boards can have different output currents. The board's output is just determined by how many AMC chips are in parallel.

Member StefanFS is the one who's done all the legwork with regards to modifying AMC7135 boards. Search for his username and go to his profile, go to Statistics and "Search for threads started by". There (among other threads), you should find the best library of AMC info out there.

kuksul08 · Feb 10, 2009

Here's a useful link just for general info about those
https://www.candlepowerforums.com/threads/192925

Good luck getting them though, it's been over a month waiting for me

LukeA · Feb 10, 2009

kuksul08 said:
Here's a useful link just for general info about those
https://www.candlepowerforums.com/threads/192925

Good luck getting them though, it's been over a month waiting for me

That's only for the 10 pack of the 1400mA boards. All the others (the packs that exist) ship out fine.

MrNaz · Feb 10, 2009

So if I wanted to wire 3 of those boards in series, I'd need to connect all the outer rings on the underside together and all the center pads on the underside together, right? Do I then use the LED+ and LED- of any one of the boards, or do I have to wire them all together as well?

Given that the 1400mA ones are likely not to come and that I need more than that anyway, I'm thinking of wiring 3 of the 1050mA boards to give a 3150mA driver. This would be used for a parallel array of P4 emitters that I feel is not getting as much out of its 4.8V NiMH battery pack as it could.

kuksul08 · Feb 11, 2009

LukeA said:
That's only for the 10 pack of the 1400mA boards. All the others (the packs that exist) ship out fine.

They all consistently say backordered at the same time as the 1400mA packs. How are you sure the other ones ship out recently?

LukeA · Feb 11, 2009

kuksul08 said:
They all consistently say backordered at the same time as the 1400mA packs. How are you sure the other ones ship out recently?

The other ones have all had ETAs. The 1400/10 ones only got an ETA within the past day or so, and they'll still be the last ones in. That's if they come in at all.

LukeA · Feb 11, 2009

MrNaz said:
So if I wanted to wire 3 of those boards in series, I'd need to connect all the outer rings on the underside together and all the center pads on the underside together, right? Do I then use the LED+ and LED- of any one of the boards, or do I have to wire them all together as well?

Given that the 1400mA ones are likely not to come and that I need more than that anyway, I'm thinking of wiring 3 of the 1050mA boards to give a 3150mA driver. This would be used for a parallel array of P4 emitters that I feel is not getting as much out of its 4.8V NiMH battery pack as it could.

You have to wire all the respective inputs and outputs together.

A driver will never get more power out of a pack than the pack will give. If the pack isn't supplying the rig direct drive a driver will only make it worse (because of the voltage drop associated with a driver). You should consider a li-poly or higher-capacity NiMH battery.

MrNaz · Feb 11, 2009

LukeA said:
A driver will never get more power out of a pack than the pack will give. If the pack isn't supplying the rig direct drive a driver will only make it worse (because of the voltage drop associated with a driver). You should consider a li-poly or higher-capacity NiMH battery.

I've considered all of that. I think that the reason the LEDs are still not being driven properly is because they are being powered by the NiMH batteries with a resistor in series. I want to remove the resistor and add in a driver so that I don't get the tapering output graph as the batteries discharge.

Will these drivers do that, or do I need a boost/buck circuit?

kuksul08 · Feb 11, 2009

LukeA said:
The other ones have all had ETAs. The 1400/10 ones only got an ETA within the past day or so, and they'll still be the last ones in. That's if they come in at all.

Oh trust me I've been tracking them often for the last month. They all have ETAs, then about 1-2 days before the ETA, it will switch to just saying 'back ordered'. A day or so later, they have a new ETA. They are somewhat out of sync with each other usually by a week, but backordered nonetheless. :scowl:

edit: Actually the 350mA ones are available..but who wants those. I need to find out of people are actually receiving these or if they have stopped shipping them entirely

ironmang · Apr 8, 2009

what is the maximum current you can run through these if they wired in parallel ?

LukeA · Apr 8, 2009

ironmang said:
what is the maximum current you can run through these if they wired in parallel ?

Each chip puts out 350mA. You can put as many chips (on as many boards as you'd like) in parallel as you want.

ironmang · Apr 8, 2009

i mean what is the maximum input current they can handle ?

LukeA · Apr 8, 2009

ironmang said:
i mean what is the maximum input current they can handle ?

They're current limiting chips. They only pass 350mA through, basically regardless of that the source is capable of delivering.

Naturally, though, when they're supplied with less than 350mA they just pass it though.

Justin Case · Apr 8, 2009

My 20-pack of the 1050ma boards finally shipped the other day. I think waited only about a month or month and a half from date of order.

old4570 · Apr 8, 2009

DX just posted the drivers I had on order , or at least they say so .

Using AMC7135 drivers in series/parallel?

MrNaz

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LukeA

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