L6599A and L6599AT datasheets are different, and this difference causes confusion.

[FBaro.11]

There are three variants of the L6599 product, but we are using the L6599AT so we will focus on just two of these variants: the L6599A, and the L6599AT.

Here is the problem: The datasheet for the L6599A seems to be quite comprehensive and complete, whereas the datasheet for the "AT" variant is missing a complete section. If you compare the two datasheets, it seems that the "AT" datasheet is missing Section 6 Typical electrical performance. This section contains very important information - 17 charts of various parameters.

Why is this information not included for the AT?

(I just looked now at the datasheet for the AF variant, and this has the same problem.)

May I make a suggestion that will hopefully help both ST (the supplier) and us (your customers): just have one datasheet that covers all the different variants. Most of the information will be the same, all that needs to change is the tables should clearly show how the parameters values for the variants (AT, AF) are different from the standard product (the "A").

Also, I could not find a convenient way to advise ST of this problem from the website. There should be an easy way for me to directly tell you of this problem from the website where I found the problem - most of your competitors have this (eg: Texas Instruments, who actually have a special link for "documentation feedback" right in their datasheets). But it seems I could not find it, and in frustration, it seems the only option available is to post here on the Q&A section of the Power Management community - but this is not the sort of problem that should waste the time of the community.

For completeness, here are the links to each of these products:

https://my.st.com/content/my_st_com/en/products/power-management/ac-dc-converters/resonant-controllers/l6599a.html

https://my.st.com/content/my_st_com/en/products/power-management/ac-dc-converters/resonant-controllers/l6599at.html

https://my.st.com/content/my_st_com/en/products/power-management/ac-dc-converters/resonant-controllers/l6599af.html

[Cristiana SCARAMEL]

Hi @FBaro.1​ ,

the L6599A is standard temperature range device, the other two AT and AF versions are special selections.

The parameters in the Electrical characteristics table of each device are 100% tested in production while the curves on diagrams are coming from characterization of device.

We guarantee parameter 100% tested, characterization parameters cannot be guarantee on whole temperature range of the extended versions AT and AF, therefore are removed from data sheets.

In case needed, user can refer to L6599A parameters within the given temperature range.

Please click on the 'Select as Best' button if my reply fully answered your question.

[FBaro.11]

Hello Cristiana, yes, I understand that parameters values must have a range (typ, min, max) that are only true under certain test conditions, and these conditions are normally stated by the datasheet. But the point that I am trying to make is that it is much easier for everyone (including ST!) if just one (1) datasheet is issued and is prepared in such a way that can all the information of the product and its variants including any "special selections" are dealt with by simply noting where they differ. It is always easier to have a good understanding of any product and then what the slight differences are, rather than having to relearn the parameter values all over again, or to do a visual side-by-side comparison of 2 or 3 datasheets trying to spot the differences - if any exist.

For example, a quick comparison of Section 5 "Electrical characteristics" of each of these devices shows that the tables list all parameters in the same order, and seem to have identical values in all columns (even including the column "Test Conditions") - yes, there are 1 or 2 values that are slightly different but we can discuss those later as exceptions. The major difference, of course, is that the Tables apply at different temperatures, which is clearly stated at the top of the table, which is copied here below in each case for your reference-

For the "A": TJ = 0 to 105 °C, Vcc = 15 V, VBOOT = 15 V, CHVG = CLVG = 1 nF; CF = 470 pF; RRFmin = 12 k�?�; unless otherwise specified.

For the "AT": TJ = - 40 to 125 °C, VCC = 15 V, VBOOT = 15 V, CHVG = CLVG = 1 nF; CF = 470 pF; RRFmin = 12 k�?�; unless otherwise specified.

For the "AF": TJ = - 50 to 125 °C, VCC = 15 V, VBOOT = 15 V, CHVG = CLVG = 1 nF; CF = 470 pF; RRFmin = 12 k�?�; unless otherwise specified.

There are seven (7) parameters listed here. Of these seven, six have values that remain the same for all variants, and only one (1) parameter has values that are different between each product "special selection". So, buried in a slab of 3 x 7 =21 pieces of data, there are only three (3) bits of data that are different. Now you can see that only difference is the value for Tj - but I have made it easy for you by lining up each parameter so the reader (you, in this case) can just run their eye down the page and see where the values are the same, and where they are different. This is not so easy to do when the values are printed on different pages of different documents; furthermore, this process is prone to simple human error (we all make mistakes!).

The differences between all the variants can be much more easily and simply stated as follows:

[start]

The Electrical Characteristics table shows parameter values that are 100% tested in production for all L:6599xx devices under the following conditions:

TJ = 0 to 105 °C, Vcc = 15 V, VBOOT = 15 V, CHVG = CLVG = 1 nF; CF = 470 pF; RRFmin = 12 k�?�; unless otherwise specified.

For the AT variant, the temperature range is extended to TJ = - 40 to 125 °C.

For the AF variant, the temperature range is extended to TJ = - 50 to 125 °C.

[end]

And where the values in the table are different, simply indicate this with a note. This used to be done "in the old days" before electronic documents because databooks were heavy and hard to source, carry, and store. In modern times it seems we are drowning in a sea of "information" but we have lost understanding - we can no longer see the forest for all the trees in the way. :smiling_face_with_smiling_eyes:

Here is a challenge: which of cells in the Section 5 tables of the 3 datasheets have different values? I spotted a total of 7 - there may be more, after all, I am only human, and I make mistakes. :grinning_face:

It would be easier to have the same table, and just list out the differences with good old-fashioned "footnotes", as I will try to demonstrate with the following screenshot that I have marked up (the table is for the "A" variant:

 

The footnote in that screenshot above in red is what I added - it is a hint to at least one difference between these tables - but it contains another difference, can you spot it? ;)

I would suggest that the charts present in the datasheet for the "A" but missing from the datasheet for the AT and AF can indeed be presented "as-is" for the AT and AF, but with a simple covering note along the lines of: "These charts are typical data only under the stated test conditions, and do not represent guaranteed performance." If that is done, then I would claim that one datasheet can indeed be applied to all these devices, and that would have benefits for all people involved with the L6599xx: ST (you), and the customer (me). And you would only have one datasheet to update as the product changes in the future, not three - think of the savings.

So, I hope you can forgive my rather long-winded attempt to explain why I prefer to have fewer datasheets that impart more understanding, rather than have mountains of information which require very careful reading - and wasting much time - to find that key piece of data - it's like trying to find a needle in a haystack.

Regards,

-F. Barone.

[Cristiana SCARAMEL]

Hi @FBaro.1​,

I understand your point of view. I will pass your feedback to the people in charge of these devices.