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| Most Frequently Asked Questions |
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| FQ 1064 |
I have a WTC set up so the current limiting is set to 1.2A (3.12 Kohms) on the cooling side (LIMA) and 0A (1.5 Kohms) on the heating side (LIMB). Why is the WTC3243 able to put out as much as 1.8A when the set point called for more cooling current than the LIMA setting was supposed to allow? Just how 'hard' is the current limiting---brick wall cutoff or really soft, or somewhere in between? | |
| FQ 1076 |
We would like to use the WLD3343 and WTC3243 to control a fiber-coupled laser diode which has laser diode anode ground. This ground is connected via the case to the thermistor ground. We are not using the photodiode, we scan through a range of currents to wavelength-tune the laser. When I look at your specification for the WLD3343, the picture on page 13 shows the laser diode anode connected to pin 14 i.e. 5V. None of the other circuits show a grounded laser anode. Is the WLD3343 in fact compatible with an anode ground system? I'm worried because I can't see how it can be, if its supply is 0 and 5V, yet I need to connect the cathode to something less than 0V. | |
| FQ 1077 |
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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| FQ 1078 |
Working with the WLD3343, constant current, we observe a non linearity between Vset and ILD. We chose Rsense to get 2A (about 0.35Ohms) and trim Rlim not to exceed 2A and we adjust R between pin 6 and pin 5 (1K) to get 1A with Vset=1V. But there is a strong non-linearity. Is this normal? Should I use external feedback between Imon and Vset? | |
| FQ 1079 |
Using the WLD3343 with a C-mount 2W 808nm diode, we burned up two units. My question is: in addition to the standard care one should observe, do you recommend something else? What do you think of putting a 100Ohm resistor, 0.1uF capacitor and a fast diode (inverse), all in parallel with the LD? | |
| FQ 1080 |
What is the best way to minimize the current noise when using the WLD3343? | |
| FQ 1081 |
Can the WLD3343 laser diode driver be externally modulated with an analog signal, if so what would be the bandwidth? | |
| FQ 1082 |
What sensor would you recommend to be used with the WTC3243 temp controller: an AD590 temp transducer or a thermistor? Would a larger mass increase the stability? | |
| FQ 1083 |
Could the laser diode driver and the temperature controller be powered with batteries directly? | |
| FQ 1075 |
With the WLD3343 Driver and WLD3393 Demo Board, when using them for a constant power application, must there be an external circuit that can provide the modulation bandwidth? | |
| FQ 1074 |
I am designing a laser driver circuit using the WLD3343. On page 8 of the data sheet there is a discussion about choosing R(LIM). Apparently, R(SENSE) sets the allowable current range of the laser driver, and R(LIM) then limits the actual current limit to something less than what R(SENSE) allows. The first paragraph says "Divide the maximum laser diode current (determined in Section 1) into the desired maximum operating current for your laser diode." Following the interpretation above, that means dividing a larger number into a smaller number, which is greater than 1. Following example 1, I believe that I want the reciprocal of that number. Are these correct interpretations? | |
| FQ 1073 |
We have a requirement for the WLD3343 laser diode driver for +5V or +12VDC operation. Can it be used for driving a 4W CW laser diode whose threshold current is 1.5A? The diode is to be operated in common cathode configuration. | |
| FQ 1065 |
What is the heatspreader temperature rise with the heatsink and fan attached? | |
| FQ 1066 |
I am using the WTC3243 and I would like to know if I could use a single power supply for both VDD and VS? | |
| FQ 1067 |
Using the WTC3243 for controlling the temperature of an aluminum block, at 1A with a 12V power supply, what is the power generated? | |
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