LT3083 as a Voc Clamp to power LTC4015

Question

Hello, 
 
 I am using the LTC4015 with Solar Panels that have Open Circuit Voltage (Voc) as high as 42V, but the maximum voltage that can go into the LTC4015 is about 36V. So I am looking for a Voltage clamp / Regulator that can output 36V/3A from a 42V/3A power input. 
 For this requirement my search lead me to LT3083, and specifically to the high voltage regulator mentioned on the datasheet (Page20). 
 
 Following are my questions 
 1. Is this a good solution for the requirement I have? or are there better alternatives? 
 2. For the above schematic to output 36V/3A apart from Rset, any other parts on the schematic will need changing? 
 3. I dont completely understand the input section FET circuitry, can someone explain this part? 
 
 Thanks.

ADIApproved · Answer

It should be noted that the customer is not looking for high efficiency while the LT3083 is active. My understanding is that this is mostly meant for OV protection and to get a little power through (unlike OV protection alone). The solar panel will have low current capability in the voltages where the LT3083 is active (operating near the solar panel's open-circuit voltage), so the actual power dissipated may be acceptible. 
 We do have some other solar chargers with higher voltages. You might consider LTC4013. However, we do not have any higher-voltage charger with the digital telemetry that the LTC4015 has. 
 Regards, 
 Zack

ARad · Answer

I apologize again but your system seems complicated to me and I don't have the resources to give you a good answer. I would at least make sure the system functions properly including stability in an LTspice simulation with reasonable models for the panel and load. Perhaps another way to answer is to say that I don't know of any reference designs - in articles, datasheets or my support history - where the LT3083 is used as you suggest. That does not mean it is not possible to use the LT3083 as you suggest because normally I get support requests when there is a problem - not when things work.

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LT3083 as a Voc Clamp to power LTC4015