Datasheet Linear Technology LTC2348-18

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Application Notes

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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. …

Design Notes

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  Micropower Op Amp Drives 8-Channel 18-Bit Simultaneous Sampling ADC without Compromising Accuracy or Breaking the Power Budget &mdash DN541
  PDF, 417 Kb, File published: Jun 23, 2015
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  Micropower Op Amp Drives 8-Channel 18-Bit Simultaneous
  Sampling ADC without Compromising Accuracy or Breaking
  the Power Budget
  Design Note 541
  Guy Hoover
  Introduction
  The op amps used to drive 18-bit analog-to-digital
  converters (ADCs) typically draw as much supply
  current as the ADC itself, often with a maximum offset
  spec that is well above that of the ADC. If multiple ADC
  channels are required, the power dissipation from these
  drivers quickly rises to unacceptable levels. consumption drops to 45mW (typical) by using the
  device’s NAP mode.
  The LT6020 is a dual micropower, 5V/Вµs precision
  rail-to-rail output op amp with input offset voltage of
  less than 30ВµV (maximum) that draws only 100ВµA per
  amplifier (maximum).
  The circuit of Figure 1 shows the LT6020 op amp
  configured as a noninverting buffer driving the analog
  inputs of the LTC2348-18. Maximum power dissipation
  of each op amp is only 3mW. For all eight channels
  this adds up to only 24mW, approximately half the
  ADC power consumption at 10ksps. If 18-bit precision is required (SNR, THD, VOS), but …

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Manufacturer's Classification

• Data Conversion > Analog-to-Digital Converters (ADC) > Precision ADCs (Fs < 10Msps) > Simultaneous Sampling ADCs | Multi Channel ADCs
• Space & Harsh Environment > Extended Temperature Plastic (H & MP) > Extended Temperature (H & MP) ADCs