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ADuC7060/61: Effects of bypassing PGA (Main A/D) and Buffer (Auxiliary A/D)

Question asked by V.M. on Jun 24, 2011
Latest reply on Jun 30, 2011 by V.M.

The electrical specs do not provide any idications as to what the input impedances are for both Main and Aux A/Ds when they are using PGA/Buffer, or when the bupasses are activated.

 

Can this be spec'd?

Input resistance? Input currents? Dependence of input current on the input voltage? For various situations -- with and without PGA/Buffer..

The input structure of the A/Ds must be some form of a switched-capacitor arrangement, so it will probably behave as a pure resistor (for signal frequencies) -- for the unbufferred operations.

 

(A separate discussion reveals that, for example, the Reference inputs, in a specific configuration (unbufferred, of coarse), may require 3 uA of current.)

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