Re: Relationship of VDD and VCC
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Hi Kees
The 1N4148 diode in the 3.3V power supply is to isolate the 78M33 when the SMPS is being used and the 78M33 is off.?
Vdd and Vcc rails are NOT connected anywhere. The "Vdd" on the IC402P/IC403P names is just a remnant of the library component! I will change it in future to avoid confusion.??
Hans,?
Yes, VDD vs VCC can get a little messy especially since the two appear to be connected together on the little IC402P/IC403P power pin schematic. My point was why is there not a 1N4148 blocking diode (or is that just a fixed voltage drop for the LDO) on both VDD power sources (the 3.3V LDO output D103 and the 3.3V output from the switcher Q111).?
Maybe I misread the schematic and VCC is not connected to VDD anywhere.
73 Kees K5BCQ
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