| FQ1077 |
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FQ1077: I am using a WLD3343 (with heat sink and fan) with a laser diode (2W, photodiode and LD isolated, B type). It needs approximately 2.5A to deliver the 2W. The problem is that I get less than about 1.7A from the WLD3343. It is connected using constant power mode, Rsense: 0.5Ohm and 1K preset for Rlimit. Vmod is 0 to 2V (to adjust power). When Vmod=2V, I adjust Rlimit and the current goes up until 1.7A and stops there. I am using a 5V supply and the LD drops 2V, so I think that the compliance is OK, but eventually I can use more voltage (6V, still in the safe operation area).
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WLD3343
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See pages 8-10 of the WLD3343 Datasheet/Manual).
The current limit resistance value (RLIM) may be set too high, as you have indicated a 1kΩ preset. As you decrease the value of RLIM, your current limit will increase, but you may not be decreasing that resistance enough.
You can also/instead try decreasing RSENSE to 0.4Ohms. Using Equation 1 on page 8, RSENSE=1.25/ILDMAX (for constant power mode), should get you to 2.5A if RLIM is adjusted correctly, but the 0.5Ω resistor you are using may not be exactly 0.5Ω, they are usually ± some %, if you can find the right value resistor this will make the biggest difference.
Other than that, the 5V supply should be sufficient. With this you will be able to get a maximum current of about 2.2A.
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Related downloads:
WLD3343 Product Data Sheet
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| Last updated 2004-03-08 12:56:59. | |
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