Using AMC7135 drivers in series/parallel?

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MrNaz

MrNaz

Enlightened
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Jul 20, 2006
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Location
Melbourne, Australia
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?
 
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.
 
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.
 
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.
 
LukeA said:
That's only for the 10 pack of the 1400mA boards. All the others (the packs that exist) ship out fine.
Click to expand...

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

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.
 
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.
Click to expand...

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.
 
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.
Click to expand...

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?
 
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.
Click to expand...

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
 
Last edited:
what is the maximum current you can run through these if they wired in parallel ?
 
ironmang said:
i mean what is the maximum input current they can handle ?
Click to expand...

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.
 
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.
 
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