LM2577 boost voltage regulator

[Laibsch]

Hello,

I have two questions about boost volt regulators based on the LM2577.  These sell on ebay for around 2$ a piece, item 271032180004 is an example.

First, the seller claims output regulation up to 35V.  http://www.ti.com/product/lm2577 says the LM2577 can only go up to 15V.  Is this a typo on the TI page?

Second question is that I wonder if they can be modded to be a poor-mans MPPT similar to what is described in http://www.fieldlines.com/index.php/topic,146685.0.html  There is a Pin similar to the On/Off Pin.  On the LM2596 it's labelled On/Off, for the LM2577 it's Switch.  Is that "the same"?

Regards

Rolf

[Wolvenar]

I am likely missing something, but I cannot see how this can even basically imitate what we are looking for in a MPPT.

Can someone explain please?

[Laibsch]

Can someone explain please?

I'm probably the worst person to do this, but I'll give it a try.  Let's see 

I will assume you have read the thread.  The normal mode of operation for any of the voltage regulators is to regulate the output voltage.  Over at fieldlines they were discussing modifications or rather additions to the LM2596 boards to regulate input (!) voltage.  The goal is then to regulate input voltage (= cell output voltage) to Pmax.  Does this make sense now?

In v1.0 there is indeed no "tracking" over time or temperature variations but those could be added in a more complicated setup they say.

[rossw]

Over at fieldlines they were discussing

They also seem to permit discussion about overunity, just don't try to discuss THAT with the owner, he gets all pissy, denies it and then storms off.