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

4 Circuit 3: Difference Amp Approach

Figure 5 shows a circuit designed with the INA146. This part has built-in biasing components for attenuation and a user-programmable gain stage. Additionally, the difference amp offers excellent common-mode rejection.

circuit_3_INA146_sboa097.gifFigure 5. Circuit 3: INA146

The following equations relate the bias components:

Equation 5. Eq05_VOUT_sboa097.gif
Equation 6. Eq06_RF_sboa097.gif
Equation 7. Eq07_RF10_sboa097.gif

With RG = 10k.

Figure 6 shows the DC sweep of Circuit 3.

DC_sweep_of_circuit_3_sboa097.gifFigure 6. DC Sweep of Circuit 3