WTB: laser Power Supply

Want to buy a good, wokring unit power supply for laser diode

Input: 240 AC
Output: around 1.8 to 2.2 V at 40-45 Amps DC

Please PM me. Thanks!

Try eBay or Google it....

Jerry

40-45 amps is a lot, what are you trying to power? I make custom drivers myself, but I haven't build them for that much current.

Look into the TI PTH08T250W module. You can power it with an old computer power supply and get 50 Amps !! I'm working on mine now.

HMike

Thanks for the advise, Hemlock! I searched the web and found some specs that are very useful.

PTH08T250W has an input range of 4.5 to 14 V, if I use 12V rails from an PC power supply, will I able to get 40 amps from the module?

Also, the PTH08T250W is rated 50 amps, can I reduce it to 40 amps instead?

Bluefan, yes, my laser module is a high power FAP laser diode array that requires at least 2.2 V at 40 amps to lase.

The specs:

http://focus.ti.com/lit/ds/symlink/pth08t250w.pdf

The PTH08T250W is a voltage converter, that means it needs to be powered too. With an output of 2.2V and 45A that's 100W. So a 100+ watt power supply is needed too to feed this one, but it makes a nice conversion to the needed voltage.

To make it a proper driver some filters and a current regulation circuit needs to be added. I'd go for a MOSFET to control the current.

I bought a 40 watts laser diode; seller told me it is using 2.2v at 49 amps.
2.2 x 49 amps is defintely more than 40 watts. does this make sense?

The last thing I want is to blow the laser diode because it is over-driven!

So, a 40 watts laser diode can waste more than 50% power?

I hope you know what you have, because (no offence) you don't seem to have any experience with diode bars. How much experience do you have with (diode) lasers?

The 40W is the optical output, that's pure light. The conversion from the electrical power is veyr efficient, as in a few 10 percents. That means 100W of electrical input power, and 40W optical output power.

The rest is converted into heat, so you need to dump 60W of heat efficiently. The diode needs to be kept at a certain temperature for an optimum wavelength, around 25 degreee celcius. Rapid heating or cooling can damage the diode.

Be sure to have proper goggles, this thing can blind with ease. And a proper current regulated power supply, or it won't do anything at all.

Plus, just because you were told it needed 40A does not mean that it has to be steady. You can go 20A or 30A and get a correspondingly lower power from the diode. There is a threshold power where the diode will first start to lase that you will need to know. Above that you will have output ranging from 1-40W

Thanks for the information.

My diode bar is encased in a metal box with TEC cooling. The unit is made by Coherent.
I've designed a ATMEGA microprocessor circuit to control and monitor the temperature.
The temperature will be displayed on a HD44780 LCD 40x4.

So, the power to the laser comes from a relay controlled by the micro-p; so if the temperature is too hot, it will shut down.

The problem I face was how to get 1.5- 2.2V at 40 amps. I have tried a Vicor power unit but that did not turn out well.

I got my hands on the PTH08T250W now but I have some questions:

My configuration:
Input:
DC 12V from a PC power supply.

Output: adjustable by a pot
will try from 1V to 2.2V until the laser starts lasing
Current: 40-49 amps

Now my questions:

Can I test the PTH08T250W without load so I can measure the voltage?
I do not want to connect the laser to it first for fear it will blow it.

The PTH08T250W is so small; I thought it would be bigger; and there are no space for any heat sink... does this small part need a heat sink? If so, where to mount?

Thanks! Hope to hear from you guys soon!

I noticed you missed a current regulation in the list of item, this is crucial of you don't want to blow the diode in a single instance! Voltage regulation is NOT good enough! Unfiltered switched power supplies are very noisy, do not use them with sensitive stuff as laser diodes.
Get a linear current regulator after your power supply, a mosfet circuit with a current sensing resistor or something like that.

Thanks, bluefan.

When I read that the PTH08T250W supplies at 50A, I take it as it is a constant current driver at 50A. If not, then how is the current being sourced?

If that is the case, I'll need a separate current regulator.. do you have a circuit to share or point me to another intergrated solution?

Thank youy very much!!

Above 50A the PTH08T250W will shut down, but it is in no way current regulated or filtered enough. Somewhere on the forum was already a decent MOSFET based current regulation circuit posted, I'll see if I can find it.

Thanks. I am also googling to find out more..