Power Supply, i2c controlled continued


Time to actually test the concept :
The schematic is below. 
You'll note it is probably overkill, lots of follower opAmp to avoid impedance troubles, but LM358 are really cheap, so not worth the trouble. The only downside is they consume lots of space on the board, unplanned originally.

The Voltage/Max current references are given by two MCP4725 12 bits DAC.
They have 2 interesting features :
  • They are very cheap
  • They can be programmed to have a default value. We'll take  500 mv so that vout = 500mv*11= 5.5 v by default, and 100 mv=>100mA for default max current.
They are driven by a 3.3v rail, so that they can be interfaced with STM32 later without extra check.





One thing has been added : If FBI > FBV, it means we are in current control mode, so the CC pin will go high (+ a SMD LED will lit up)

Preliminary testing shows it works fine, except it seems a bit slow to converge. Need to look into that closer at a later time.

The usual messy craftsmanship :


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