Schottkey Diodes as blocking diodes for battery management in solar panel

[Mattjd]

Looking over some IC for battery management systems for batteries used in PV cell applications.

Looking at LT3652 specifically.

https://www.analog.com/media/en/technical-documentation/data-sheets/3652fe.pdf

The exact application of this battery manager is for a cubesat.

I was wondering if someone could give a brief rundown on those blocking diodes function in the datasheet.

Another source I found is calling them day and night diodes for Day-Night switching. I am guessing during eclipse of the cubesat, somehow those diodes switch to use battery as source?

https://imgur.com/a/8PRp1Ae

[Mattjd]

Really what I am thinking is that when the voltage from solar panels drops during eclipse it causes that diode connected to the battery to conduct and thus the battery discharges.

[Jwillis]

I'm not sure if this is important.Schottky diodes havea very fast recovery compared to conventional diodes  but  schottky diodes also exhibit higher leakage current than conventional diodes as the temperature increases .More so at higher voltages.

I should correct by saying that Schottky diodes have no recovery because of design. No p-type semiconductor so no holes when reverse biased. So nothing to recover.

[BravoV]

Google for SM74611

[David Hess]

Schottky diodes are just used for lower forward voltage drop.  Standard rectifiers could be used with some loss of efficiency or transistors could be used for greater efficiency.

The first diode isolates the panels from the battery when operating on battery and the second diode isolates the battery from the panels when operating on the panels.  This mode of operation will not be suitable if the load is expecting a restricted voltage range because the panel voltage is not regulated.

The application examples at the end of the datasheet lack both diodes and connect the load directly to the battery

I should correct by saying that Schottky diodes have no recovery because of design. No p-type semiconductor so no holes when reverse biased. So nothing to recover.

That is not strictly true in most cases.  Because of how high voltage schottky diodes are constructed with a guard ring, which is practically all of them, they have an additional PN junction in parallel so at high currents the PN junction also conducts creating reverse recovery which is revealed as a long recovery tail.  In most applications this can be ignored unless the peak currents are high.