REG1117: expected temperature drift and comparable parts

Please excuse a delay in response due to the US Holiday.

Very Respectfully,
Ryan

No worries,

happy 4th of july.

BR Michael

Hi Michael,

These particular regulators were originally designed by different companies which have since been acquired by TI. As shown in the REG1117 datasheet it was originally released by Burr-Brown. LM1117 was originally released by National Semiconductor. The temperature drift for REG1117 is slightly better over 0 to 80C. This information is shown in figure 6 of LM1117 and the bottom left curve of REG1117. The REG1117 also has a better transient response.

Very Respectfully,
Ryan

Hi Ryan,

yes, that's all clear to me as i basically wrote all this in my initial post.
I don't want to sound to harsh, i know i somethimes do, additionally as i'm new in this Forum to, but that's not an answer i'm happy with to be honest.

I really need to know more on this whole temperature drift topic and understand more on how to "read" the datasheets information regarding it. What can i expect from the graphs, which technology should be used/preferred, which technology does provide the smallest spread (drift wise) by design, etc.

I really hope somebody can help me on this questions because i need to be sure (as close as i can get) how much the actual parts deviate from the typical value. That's my goal at the end, to really estimate what the spread will be and not only typically.

I believe it's not easy to say, but i guess there is information which will help me to come closer to the truth and not just expect that each part manufactured follows the typical value.

Thanks anyway for your reply,
Best regards,
Michael

Hi again,

hmmm, so it seems nobody is abler to help me on that.

Beside that, can somebody at least help me on that question, it arised when i searched the forums a Little:

See thread: REF3030: temperature drift correlation

I wrote there

Dear Diego,

sorry for highjacking this topic/discussion, but may i ask you on this:

The temperature coefficient is determined using a box method, therefore the max could appear at any temperature.

While most parts will have a similar shape, we do not guarantee that the max will be at any specific temperature.

Is this true for temperature drift information of LDOs too? I mean the background to it beeing the method used?

And additionally, is it true for basically all temperature drift data f.e. for amplifiers also?

Thanks in advance, best regards

Michael

And got that answer:

Hi Michael,

I'll answer this in place for Diego. From my understanding that is true because if it's not a EC spec then its typical and not guaranteed. But for more accurate answer or confirmation, I would suggest you to ask this in the LDO subforum.

-MZ

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So, i'm asking for an statement regarding the underlined sentence and additionally why that is the case, in easy words.

I hope somebody is able to answer me that.

Best regards Michael

Hi Michael,

Something very similar to the box method is used for most LDO testing and as MZ in the other forum mentioned it doesn't guarantee that the maximum or minimum will occur at any specific temperature. Now, that being said most LDO's use a bandgap reference and have a Vout drift that looks like a parabola which is pointing down, y=-(x^2), and peaks somewhere around 60C and 85C. However, there are some older devices which use a Zener reference and the temp drift on those tends to look more like a sine wave (starts low, increases, decreases, and then increases)

As MZ alluded to the devices in a particular family will have a very similar shape however, we don't test parts in such a way that can guarantee the shape or where the maximums/minimums occur. In general since our LDOs are power management products they are usually used in applications where accuracy over all conditions is more important than the accuracy at any specific point (Temp, Vin, Iout, etc...) so our tests are directed at overall accuracy. 

As for the applicability of this to other products, the references should have similar drift shapes if we are talking about parts that use the same type of reference (bandgap, Zener, etc...). However, they may have different tests or data that is available since the use cases for the products are so different. 

I hope that helps you understand the factors involved a bit more. 

-Kyle

Hi Kyle,

thanks for your answer as well.

Best regards Michael