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Topic: Need advice on powering lots of chips (Read 1 time) previous topic - next topic


It looks like the chips require split +/-5V supply.

No, they don't require it at all, they will run with the analog rails (Vdd, Vee) from 3 to 18V apart.

However the logic inputs are referenced to Vss and Vdd - this means that it makes sense to
have Vee at -5V if dealing with analog signals that are AC centred around 0V.  In that case Vss will
be 0V to allow the logic inputs to work (Vss = 0V, Vdd = +5V, same as logic)

However you can common Vss and Vee if you want.  However the logic rails need to be approximately
the same voltage as the analog supply then - the logic LOW/HIGH thresholds are between Vdd and
Vss.  If Vss = 0V and Vdd = 9V then 5V logic probably won't drive it.  A level-shifter would be needed.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]


Jan 26, 2013, 02:04 am Last Edit: Jan 26, 2013, 11:37 am by kustom Reason: 1

just to make sure that you don't get brown outs I would connect a LM7805 or buck ic to the 9V supply and connect all the 5V ic's to it. You cant overdo it with the decoupling caps.

Okay is this acceptable then: 9V power supply regulated with LM7805 -> regulated 5V as source for every chip, including arduino?

EDIT: Does that even make sense, I mean, voltage from USB is also 5V. My guess would be that 5V from LM7805 is more stable, am I right?

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