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I use the WLD3343 in collaboration with the WHY5640 and a Peltier element to keep the laser diode temperature constant. After I set the LD current to 40 mA and start changing the temperature from about 16°C to 50°C the LD current starts to rise to 60 mA.

Does that have to do with the characteristic’s of the LD? I know that some things vary depending on the temperature but then I would expect the WLD3343 to adjust the current. It does keep the current constant very well if the temperature stays constant.

With the WLD3343, I discovered a normal delay between the SHD signal and power to the Laser Diode (slow start). I need to produce pulses of zero to set power (which is set in VSET), and 100 to 1000 ms width. I thought to use SHD control, but the delay is a problem. Which is the best way to put the LD on and totally off with no (or little) delay? Or, how much is this delay, in msec, in order to modify the control software? Eventually, I can use constant power or constant current mode.

I want to drive a 1550 nm laser diode, 5 mW output, <150 mA of current, at a modulation frequency of 1-2 MHz. The WLD3343 will do this fine, right? At 1 or 2 MHz mod, what modulation depth do you typically see with the WLD? The next step will be to go to a 10 MHz modulation frequency, will the WLD be OK? We want the best modulation depth we can get. Will we see 100% depth at 1 MHz, and do you have a feeling for the modulation depth we would get at 10 MHz?

Can you give me some hints for minimizing current noise when using the WLD3343?

I’m using the WTC3243 to drive a TEC using a 10kΩ thermistor. How do I get a measurement of the actual temperature (or something proportional to it)?

What is the display accuracy of the LFI3751?

I am planning on using the WHY5640 with the WEV302 heatsink/fan assembly. How is the WXC304 fan terminated (i.e. what type of connector, if any, is on it)?

What are the pressure vs. air flow characteristics for the WXC303 fan?

My question has to do with the EXT VSET connector on the WTC3243. How is the voltage I apply to the EXT VSET related to the temperature setting? What is the relationship between this applied voltage and the temperature that will result as the set value? I cannot find a transfer function in the manual.

My question has to do with the EXT VSET connector on the WLD3343. How is the applied EXT VSET voltage related to the current supplied to the LD in CC mode? Is it a 1:1 ratio? Also, in CP mode, how is the applied voltage on EXT VSET related to the photodiode current?

What is the compliance voltage for the WTC3243-B?

I have a 4.5 V TEC that can draw (up to) 2.85 A. Based on your WTC3243 datasheet I believe I would require a supply voltage of 6.06 V. I will limit the current applied to 2.3 A via the current-limit resistors. Based on the info in your datasheet I will be running in zone 2 (middle shade of blue) of your “Safe Operating Area” plot. This indicates to me that my design will require a heatsink plus a 3.5 CFM fan. Am I more or less correct here?

I have a WTC set up so the current limiting is set to 1.2 A (3.12 kΩ) on the cooling side (LIMA) and 0 A (1.5 kΩ) on the heating side (LIMB). Why is the WTC3243 able to put out as much as 1.8 A 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?

What is the heatspreader temperature rise with the heatsink and fan attached?

I am using the WTC3243 and I would like to know if I could use a single power supply for both VDD and VS?

Using the WTC3243 for controlling the temperature of an aluminum block, at 1 A with a 12 V power supply, what is the power generated?

I am developing a new design with the WTC3243 and WLD3343. Is it necessary to feed both circuits with a regulated power supply? Is a rectified voltage with a “smoothing” capacitor sufficient?

What is the difference between the WTC3243 Rev A and Rev B?

Would any overheating issues arise from placing the WLD3343 and WTC3243 in a closed area ~ 7″x5″x3″? If so, would the associated thermal solution kits help to relieve this problem?

We have a requirement for the WLD3343 laser diode driver for +5 V or +12 VDC operation. Can it be used for driving a 4 W CW laser diode whose threshold current is 1.5 A? The diode is to be operated in common cathode configuration.

I am designing a laser driver circuit using the WLD3343. On page 11 of the datasheet there is a discussion about choosing RLIM. Apparently, RSENSE sets the allowable current range of the laser driver, and RLIM then limits the actual current limit to something less than what RSENSE allows. Is this a correct interpretation?

I’d like to use the WLD3343 Driver and WLD3393 Evaluation Board to modulate a laser in constant power mode. Do I need any additional or external circuitry?

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. 5 V. 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 5 V, yet I need to connect the cathode to something less than 0 V.

I am using a WLD3343 (with heat sink and fan) with a laser diode (2 W, photodiode and LD isolated, B type). It needs approximately 2.5 A to deliver the 2 W. The problem is that I get less than about 1.7 A from the WLD3343. It is connected using constant power mode, RSENSE: 0.5 Ω and 1 kΩ preset for RLIMIT. VMOD is 0 to 2 V (to adjust power). When VMOD = 2 V, I adjust RLIMIT and the current goes up until 1.7 A and stops there. I am using a 5 V supply and the LD drops 2 V, so I think that the compliance is OK, but eventually I can use more voltage (6 V, still in the safe operation area).

We’re working with the WLD3343 in constant current mode, and we think we observe a non linearity between VSET and ILD. Is the non-linearity normal? Should we use external feedback between IMON and VSET?

We chose RSENSE = 0.35 Ω to get 2 A, trim RLIM not to exceed 2 A, and we adjust R between pins 5 and 6 to get 1 A output with VSET = 1 V.