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Pinguino 26J50 kit
04-11-2014, 09:55 PM,
#17
RE: Pinguino 26J50 kit
(23-07-2013, 09:48 AM)regis Wrote: Hi,
There is something wrong somewhere.
R must be chosen so that R = (Vin - Vz) / (Iz + Iout)
Iout = 200mA max. (cf. PIC Datasheet)
Iz = 80mA and 3.1V < Vz < 3.5V (cf. BZX85C3V3 Datasheet)
So R should be theoretically about 6 Ohm.
150 Ohm gives me 3.476V @ 5.2V,
Are you sure of your Zener diode ? Which one do you use ?
Can you try the same circuit with a 10kΩ load instead of the PIC18F26J50 ? Do you get the same values ?





(23-07-2013, 02:22 AM)Pinguino Wrote: The resistance solution was to increase the 150 ohm resistor to 150K. To arrive at this, I tried 330R, 470R, 750R, 1K, 2K, 12K, 18K, 47K, 82K, 100K and finally 150K.

150K produces these results:

o USB input voltage is 5V, 3V3 is 3.30V
o USB input voltage is 5.17V, 3V3 is 3.43V

Hi, if you choose R2=150 ohm, you have a problem with the current.
the current in R2 is 5v-3.3v / 150 = 0.0113 A this current - Iz is the board current, as you can see is too low to supply the board.
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Messages In This Thread
Pinguino 26J50 kit - by keithfuller - 24-02-2013, 02:39 PM
RE: Pinguino 26J50 kit - by regis - 25-02-2013, 09:55 AM
RE: Pinguino 26J50 kit - by Pinguino - 07-04-2013, 06:46 AM
RE: Pinguino 26J50 kit - by regis - 07-04-2013, 08:09 PM
RE: Pinguino 26J50 kit - by Pinguino - 08-04-2013, 12:56 AM
RE: Pinguino 26J50 kit - by keithfuller - 07-04-2013, 12:56 PM
RE: Pinguino 26J50 kit - by Pinguino - 07-04-2013, 02:09 PM
RE: Pinguino 26J50 kit - by pingotg - 07-04-2013, 04:32 PM
RE: Pinguino 26J50 kit - by Pinguino - 20-07-2013, 01:40 AM
RE: Pinguino 26J50 kit - by Pinguino - 23-07-2013, 02:22 AM
RE: Pinguino 26J50 kit - by regis - 23-07-2013, 09:48 AM
RE: Pinguino 26J50 kit - by ayoras - 04-11-2014, 09:55 PM
RE: Pinguino 26J50 kit - by Pinguino - 23-07-2013, 03:53 PM
RE: Pinguino 26J50 kit - by djsbriscoe - 26-01-2014, 05:17 PM
RE: Pinguino 26J50 kit - by regis - 27-01-2014, 09:29 AM
RE: Pinguino 26J50 kit - by djsbriscoe - 27-01-2014, 10:49 AM
RE: Pinguino 26J50 kit - by regis - 27-01-2014, 12:10 PM

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