Hello all,
I'm new here. Electronics is my hobby and consumes most of my free time. Now I have big problem with IR diode. Diode need 1.3V/60A and I need regulate current in range 5-60A (5A - threshold current), so this isn't a simple matter (parameters). I'm searching all time internet but I don't have any precised idea. I will be grateful for some hints, etc.
Suppose you can provide a regulated reference voltage...
then you can vary it through a potentiometer...
then you can current control a mosfet.
To illustrate:
I do not know specifically what volt level needs to be on the gate, in order to send 60A through your load.
I just picked 170 V because it is easy to obtain from 120 VAC mains.
Nor do I know what supply voltage will be sufficient to push 60A through load and mosfet combined. Of course it will be easier on the mosfet if you apply the lowest supply voltage that will do the job.
The mosfet will need to be rated (and heat-sunk) to carry the amps.
I need 1.3 V.
My schematic shows 60 A through a 0.022 ohm load. That makes 1.3 V across the load.
I read about atx supply, I have one - 200w with ka7500b IC.
It's possible to use this supply ?
Well a supply like the LTC3738 is basically the best solution in terms of performance and efficiency. Did you actually build that circuit yourself, or get an evaluation kit? Did you set it up to regulate output current or output voltage? Were you testing it with the actual IR diode as the load at the time?Hello all,
First of all thank You very much for answers. This is laser IR diode and this is 60 amps, not mA.
Sorce at this point is labolatory supply (0-30VDC). I tried with LTC3738 (65A Power Supply for VRM10, page 30 in datasheet), but this system was damaged at 10 amps (probably transistors). I need only positive voltage.
I need 1.3 V.
There are tons of possible explanations for the failure. Mainly I would be very cautious about using a voltage regulated output on a diode. It's possible that it had a high Vf temperature coefficient, causing thermal runaway.I built this circuit myself base on datasheet. Voltage I set by combination beetwen VID0 - VID5. I tested this circiut with resistors - 0,2 ohm. Circuit worked about 1 minute, after this I saw smoke.
You may use ATX psu but need some modifications. Check if there are transformer window space to add 1+1 litz wire or Cu sheet (calculated for 60A); if not space, may try to remove original seconday windings. Remove all outputs components after TR, add a 80-100A double diode connected to those 1+1 wire, some low ESR caps and "construct" feedback voltage with 5V standby (1.3V is below 2.5V IC reference, or better modify IC reference also to 1.3V) for KA7500b IC (TL494). Sure, much beter is a psu with multi-phase IC controller and corresponding power switchs if you need high BW modulation.
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