SBOA443 March   2021 INA293

 

  1.   Trademarks
  2. 1Introduction
  3. 2The SAR ADC Switching Model
    1. 2.1 Acquisition Time
    2. 2.2 ADC Resolution
    3. 2.3 Sample Rate
  4. 3The ADC Charge Bucket Filter
    1. 3.1 The Filter Capacitor, CFILT
    2. 3.2 Output Filter Resistor, RFILT
  5. 4Output Filter Discussion and Design
    1. 4.1 INA293 With the ADC Switching Model
  6. 5Summary
  7. 6References

1 Introduction

In many modern applications, the focus in signal chain often begins with the analog to digital converter (ADC) and its specifications. The designer begins by defining the resolution needs of the their specifications and works backwards to select a suitable driver that will provide the specifications necessary to deliver the desired throughput, resolution, and noise specifications required by the system.

When working with sensors, however, the opposite is quite often the case: the designer has chosen a specific sensor, such as a current sensing amplifier (CSA), to meet a specific requirement in their respective system, and therefore the desire is to find a way to capture the maximum throughput starting from the input side of the signal chain and moving forward. This application report aims to perform this type of analysis, examining the INA293 as the chosen sensor of interest, and discussing techniques to maximize throughput. Output impedance is examined to discern when a device may be capable of driving an ADC on its own, and when a buffer would be required to ensure optimal performance.