Question
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?
Answer
A rectified and smoothed voltage can work as your power source, but the stability of the system will be affected.
The WTC controller is capable of 0.001°C stability, and for that performance we recommend a regulated power supply with 85 dB suppression of noise and ripple. If slightly reduced stability is sufficient for your application, perhaps 0.01°C, then the rectified voltage supply may be sufficient. The “size” of the thermal load also must be considered, and smaller loads will be more successfully controlled with rectified voltage supplies than larger loads. A “small” load for the WTC is one that requires 200 – 400 mA of current at thermal stability, and also exhibits a 1 – 2 second thermal response time to temperature setpoint changes.
Similarly, the performance of the WLD laser controller will be affected if you use a smoothed-rectified voltage. Our products are tested and specified using regulated power supplies, such as our PWRPAK products, so if you are using a noisier power supply you may have different results than indicted in our datasheets.
You can try your solution to see if it will satisfy your performance requirements. If the stability and accuracy are not sufficient then you may need to use a regulated power supply.