Considerations on Practical Implementation of Current Source Mode Single-Inductor Multiple-Output LED Driver

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article presents a very interesting aspect of light control in LEDs. The Authors described the state of knowledge and compared previous solutions to the proposed ones. While reading the article, questions and doubts arose, which please explain and supplement in the content of the publication.

1. There is no current balance in the system, formula (1) is insufficient

2. Figure 8 is illegible because it does not indicate the control algorithm or lacks information about the brightness (flux) of the LEDs

3. It was not indicated how the luminous flux of LED diodes was measured - in the integrating sphere or on the base of the detector (lux meter head, etc.)

4. Fig. 10 shows the characteristics but does not describe how much better the performance is compared to the reference solution

5. The Authors did not comment on the LEDs used in the experiment: white or multicolored. Will the parameters of different diodes affect the correct operation and regulatory characteristics?

Author Response

• the explanation is given in reference following the equation
• We think Figure 8 is applicable as a sample of symmetrical placement of binary weighted LEDs. We added several other combinations, but we think it is not necessary to show them all. This segmented module was built as one color/channel module, but it is applicable as a sample of possible implementation. This segmented module was built by the authors during the previous studies and there are no any proprietary issues with this module.
• explanation about used measurement instruments now is added, experiments more detailed described, and more experimental data added
• light flux measurement indirect by luxmeter, white LEDs were used fo validation, more detailed description in article in experimental validation section

Reviewer 2 Report

Comments and Suggestions for Authors

The article discusses the current issue of controlling the luminous flux of LED sources.

Generally, the layout of the article is correct, but there needs to be more content. As far as I know, the minimum number of words in an article to be published is 4000. In this case, I didn’t count how many words there are, but my impressions indicate that the number is lower.

 

The article is so interesting that it is suitable for publication in an Electronics journal after its development.

However, the issues related to the LED luminaire's electronic part are very interesting, and the results are promising.

The incorrect technical terminology of concepts related to lighting technology irritates me. For example, the words "light flux" and "light amount" appear in the summary, but they appear throughout the entire article. In the lighting technique - luminous flux.

Figure 9c is not of poor quality, but its inscriptions are not legible.

Author Response

• The article generally has been updated with a more detailed analysis of references, the total number of words increased approx. by 20%.

• The term "light amount" in the whole article is replaced by the term "luminous flux", also in Figures

• Figure 9c improved to make inscriptions readable.

Reviewer 3 Report

Comments and Suggestions for Authors

Title: Considerations on Practical Implementation of Current Source Mode Single-Inductor Multiple-Output LED Driver

Line 9: „produced light amount”. No, better luminous flux, as you have in line 11.

Line 10: „… specialized variable 9 tone/color lights for ambient lighting, …” Better CCT Correlated Color Temperature.

 Keywords: „ LED lamps” is not keyword, discussion about luminaires are absent in paper.

„LED ballasts” is not correct, you have LED driver already in title.

 Line 28: „… adjustable light temperature applications…” Maybe is the same CCT?

 Citations are not relevant: [2] to [5] and [6] to [10], not a word about papers. Citations are a scientometric tool, it is important to cite with some reason.

 Main hypothesis, line 249: “Constant current mode SIMO LED driver is a good candidate for the implementation of a color regulation system for LED lamps”. But the binary weighted number of LEDs in separate branches introduce some important restrictions: For example, a binary series for a total of 50 W (as in Figure 10) will be 0.793; 1.587; 3.174; 6.35; 12.70; 25.40W. The proportion of changing the color (or CCT) will be very modest: the branch of 12.70W is comparable with 6.35 W or 25.4W but not with other branches. This situation makes the applicability of the method questionable.

 I think the interpolation of the points in figure 10 is false, it is not mandatory to distribute according to a sinusoid. More points should be obtained from the measurements, and it is possible to obtain them in the form of a cloud of points.

Author Response

• The term "light amount" in whole article is replaced by term "luminous flux", also on Figure 6 caption of one of y axis changed accordingly

• “variable tone/color” replaced by “Correlated Color Temperature”

• „ LED lamps” removed from keywords, “LED module configurations”; “segmented LED light sources”

• „LED ballasts” replaced by “LED drivers”

• "adjustable light temperature" replaced by “adjustable correlated color temperature (CCT) applications”
• Citations are relevant. The introduction has been updated to show the relevance of the cited papers. The authors of lot of papers use the same approach, when saving space for other sections in the article. In this case it was not an issue, so we make the introduction more fruitful by your advice.
• Thus we highlight this approach is suitable for certain applications and the structure of segmented LED light source (placement, relative position of different color LEDs) is critical in this case. This topic (optimal SLLS configuration, optimal LED placement) may be a further separate study. Figure 8 was updated to show symmetrical placement example. 

• The additional measurements were prepared and summarized in new figure 10 and figure 11 without any interpolation for efficiency of considered in this paper CCS+LR configuration by your advising, the tendency is better visible now.

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The improvements are obvious, and the dialog on the paper was accepted.