Hello,
Im evaluating SM72442 chip for automotive Thermo-electric generator energy harvesting. I am confused about current limiting. In devices datasheet at page 8 capter Current limit settings it says that maximum current can be set via voltage on A4(or when bypass is on it can be set via I2C). Now what I dont understand is why in appnote AN-2121 there is also comparator current limiting which pulls up feedback of output voltage AVOUT in case of overcurrent. It seems to me like redundant when you can set current limit via A4. I suspect, that current limit via A4 could be only reseting circuit, but then this would be kind of inconsistend with documentation where it says maximum output current can be set via A4, maximum output voltage can be set via A0, and then one value serves to reset IC and other one as regulation setpoint.
So my question is how does A0 and A4 actualy affects chip behaviour, when limit is crossed for output voltage or current?
Im especially interested if I can set output voltage and maximum continuous output current via I2C bus or if I have to use external circuitry like in appnote.
Other confusing thing for me is if panel mode could be completely disabled? Again I think that by pulling up A6 (MPPT exit treshold = 0 and MPPT Start treshold = 0) should cause, that MPPT is started immediately after reset but Im not sure how A2 option is affecting later operation. Appnote doesnt use panel mode, so ii must be possible to disable it someho.
Thanks for any help
With best regards
Ing. Stanislav Subrt
EDIT after posting:
I just got another question: In my application I would like to keep SM72442 disabled while already reading values from input and output ADC conversions via I2C. Im wondering if NRST keeps whole device in reset or just switching. In first case would it be possible to use PM_OUT pulldown to activate panel mode, but with disconnected panel mode FETs, it would effectively stop buck/boost and disconnect output, but values could be read. What do you think?