This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

SM72445EVM schematic

Other Parts Discussed in Thread: SM72445

Hello,

I am using TI parts for the 1st time.  I bought a SM72445 eval board to use as a solar battery charger.  A solar panel (Vmp~18V) will be on the input and the battery voltage (~12V) will be at the output of the EVM.  I have several questions that I cannot figure out from the SM72445EVM or SM72445 data sheets.

1) The output of the EVM has a soft output of 40V.  I want to set the output voltage of the EVM to certain battery charge voltages, say 8-15V depending on the battery type and charge mode.  I need to be able to change the voltage at A0 to change the output voltage limit. In order to do this, I need to change the input and output resistor values (using Vout_max equation pg 8 from SM72445 datasheet) on the EVM so that I can change the max output voltage.  However, the schematic & board layout in the SM72445EVM datasheet (page 7) are very difficult to read, almost impossible in certain places.  Thus, I can't tell which resistors to change.  Actually instead of changing resistors already placed on the board, can I add calculated resistors after R51 and R52 to ground on DNP or empty pads that were not used, like pads just below R51 & R52, in order to set a lower voltage limit?  I want the max current, so I do not intend to modify that just yet.

2) I assume the parts that were not placed DNP were done so for us to own settings at A0, A2, A4, A6?  Is this correct?  If not, why weren't these parts placed? How can I match the DNP parts of the schematic to the board layout? I would like to use some of these pads. I cannot read the DNP part designations on the schematic in order to find the corresponding empty pad on the board.  Will you please send a better image of the schematic and board layout?

3) Does the output of the EVM have a "safety feature" that will stop charging if the output voltage is below a certain level, say 8V? If so, how do I disable this feature? I want to charge regardless of how low the battery voltage is, then stop once it reaches a set max voltage.

4) On page 8 of the SM72445 data sheet (not the EVM data sheet), I interpret the "maximum output voltage" paragraphs to say that the max voltage limit is only a true limit in MPPT mode.  However, when the EVM is in any other model, the voltage limit will only be enforced if my output voltage is higher than my solar panel voltage.  Does it mean the solar panel voltage or the actual voltage on A0, should be more than the output voltage? For an uncharged battery, my panel voltage will be higher than the output voltage, at other times when the sun is low or the panel gets heavily shaded and a fully charged battery, the panel voltage may be lower than the battery voltage. Can you explain this soft limit futher?