Datasheet Linear Technology LTC2357-18

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  Buffered ADC Family Eliminates Signal Conditioning Complexity &mdash AN167
  PDF, 1.3 Mb, File published: Sep 20, 2017
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  Application Note 167
  September 2017
  Buffered ADC Family Eliminates
  Signal Conditioning Complexity
  Joe Sousa, Andrew Thomas, Clement Wagner, Mark Thoren
  Engineers often assume that analog-to-digital converter
  inputs are high impedance. Direct-sampling SAR ADC
  inputs will often be high impedance when not converting, but will draw “spikes” of current at the beginning
  of sample acquisition. On average, this behavior can be
  modeled as a crude nonlinear resistance that is inversely
  proportional to the sample capacitor size and sample rate,
  but instantaneously the signal chain must be able to settle
  completely in response to this abuse before acquisition
  ends and a conversion begins. Coupling a signal chain to an ADC is an art form, often requiring a combination of theory
  and experimentation. By contrast, the LTC2358 family of
  multi-channel, buffered high voltage SAR ADCs offers
  truly high impedance inputs that simplify or eliminate the
  need for signal conditioning in many cases. When signal
  conditioning is required, it can be directly connected to
  the LTC2358 inputs without regard to its ability to drive
  a switched capacitor. The following circuits show some
  applications that take advantage of the properties of the
  LTC2358 inputs. …

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Manufacturer's Classification

• Data Conversion > Analog-to-Digital Converters (ADC) > Precision ADCs (Fs < 10Msps) > Simultaneous Sampling ADCs