lpcware

ADC settling time

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by IanB on Mon Sep 29 05:27:33 MST 2014
What is the settling time of the ADC input multiplexer?

NXP MCU FAQ and design tipssays that it is important to observe it but doesn't say what it is.
AN11031 doesn't mention it at all.
Neither the Data sheet or the User Manual mentions it either.

I do know that it depends on the source impedance of the signal to be measured.
I know the source impedance - it 5kΩ maximum.
So how long should I wait after changing the multiplexer to the channel I want to measure before starting the ADC - allowing time for the multiplexer to change state and the ADC input capacitance to charge to the new value through all the circuit resistances?

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