SBOA097B June   2004  – May 2015 INA132 , INA146 , INA152 , OPA2205 , OPA2277 , OPA277 , OPA301 , OPA335 , OPA364 , OPA4205 , OPA725 , TLV2341

 

  1.   High-Voltage Signal Conditioning for Low-Voltage ADCs
    1.     Trademarks
    2. 1 Introduction
    3. 2 Circuit 1: The Modular Approach
    4. 3 Circuit 2: Single-Supply/Single-Port Approach
    5. 4 Circuit 3: Difference Amp Approach
    6. 5 Circuit 4: Differential Input with INA146
    7. 6 Circuit 5: Differential Input Modular
    8. 7 Voltage References and Ranges
    9. 8 References
  2.   Revision History

7 Voltage References and Ranges

The references shown in these examples are simple. They are for ratiometric applications where the ADC range is the rail. The references shown are VCC/2, or at the mid-scale of the ADC range. This proportion is required for these circuits. 3.3V or 5V can be used in any of these designs; the references would be 1.65V or 2.5V, respectively. These designs will work with absolute references as well, as long as the VREF is one-half of the ADC full-scale range.

The other requirement is a good buffer driving the reference signal. These designs put a wide range of loads on the reference, and a buffer is essential. For in-depth information on buffering references for precision and high-resolution designs, see Application Note Voltage Reference Filters (SBVA002).