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ArcticMyst Security by Avery

TPS63020 Based Driver

R

rfhv

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This is very similar to what another member posted a few weeks ago. I built this driver and found it can do 2 A with 4 V input. It shuts off when the battery gets to 3 V. Mine is currently driving an M140 diode at 1.25 A and barely gets warm. I calculated the efficiency to be 82% into my diode at 1.25 A.

I don't want to make it too easy for someone to copy and sell these so I won't give a PCB layout. Feel free to design a layout and give this driver a try.

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laserdriversch-sm.png


See my full build at Chris's Electronics Page
 

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Wolfman29

Wolfman29

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Hey - I like that you used that ZXCT1009 to change your FB pin from voltage to current adjustment... but care to explain how that works? It outputs a voltage proportional to the current traveling through the load... and you used that voltage in the FB pin to regulate the voltage which in turn regulates which decides how the voltage is regulated (in a way that it regulates current instead of voltage)?

Sorry if I am not making any sense!
 
R

rfhv

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The ZXCT1009 is a voltage to current converter. It takes the voltage between its + and - terminals and puts out a current that is proportional to that voltage difference on its out pin. The TPS needs a voltage input though, so I made a current to voltage converter with a resistor and a pot and fed that back into the TPS63020.
 
Wolfman29

Wolfman29

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On the Datasheet of that it says that the output voltage of the IC is
Vout = 0.01 x Vsense x Rout

I think I figured it out... :p
 
benmwv

benmwv

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Wow, this is extremely similar to one I designed, right down to the zxct1009!

Kind of dissapointing actually, I thought I was going to have a unique design.

Ive been waiting to get my pcb's for a month now...
 
Wolfman29

Wolfman29

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Question: What's the purpose of the mosfet at the first part of the circuit?
 
R

rfhv

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A diode would have at least a 0.5 V drop. My MOSFET has a resistance of about 0.03 Ohms worst case. At 3 A, I will loose about 0.09 V across the FET.

The choice was 0.5 V or 0.09 V. I chose the more efficient option.

A FET can make the difference between 65% efficiency and 80% efficiency.
 
Wolfman29

Wolfman29

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Hmm. That's fascinating! I'll keep that in mind in my design, if and when I add in reverse polarity protection.

Question: how big is your board?
 
foulmist

foulmist

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Well I made my board even simplier without any voltage to current converters with this IC :D and still works in current mode ;)

It's still pretty nice though :beer:
 
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Wolfman29

Wolfman29

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I coulda sworn I saw a zener in your design earlier. Now I am really curious... -.-
 
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