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problems with USB power when using ADC 12bit in JM Family

Question asked by Cristian Martinez on Nov 24, 2010
Latest reply on Dec 1, 2010 by Cristian Martinez

Hi all,

3 weeks ago I posted questions about which Micro use for 12 bit ADC conversions. I chose JM family and we spoke about the problems I would found in 12bit conversions, specially Mac who post some design issues steps:


Well! Im running with a JMDemo Board, 12bit ADC, and reading the values in Excel, I take an average of 50 values and it works fine.


Problem: Instability in Vcc.


There is no noise in the data signals, all works better than good, but the problem is that I take the power from the USB, and when I looked with the Multimeter I realized why the values moves a little in the ADC. Is the USB Power!


So, Data acquisition units that take the power from the USB... what they do? Can anyone shed some light in this?


The goal is to stabilize the 5V USB Power signal, but I dont know any common method to do it.

Do I need to reduce to around 3V to stabilize it? (cause the stabilizer chip)


What do you think?