SBAA631 January   2025 DAC80508 , INA592 , XTR111 , XTR300 , XTR305

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Analog Output Module Specification
  6. 3Analog Output Module Structure
  7. 4Multi-Channel Output Architectures
    1. 4.1 Fully Integrated DAC Architecture
    2. 4.2 Low Voltage DAC Plus an Output Buffer
    3. 4.3 Track and Hold Multiplexed Output
  8. 5Single-Channel Output Architectures
    1. 5.1 Fully Integrated DAC
    2. 5.2 Low-Voltage DAC Plus an Output Buffer
    3. 5.3 Pulse-Width Modulation Plus a Buffer
  9. 6Output Buffers
    1. 6.1 Unidirectional Current Buffer
    2. 6.2 Bidirectional Current Buffer
    3. 6.3 Voltage Buffer
    4. 6.4 Combined Voltage or Current Buffer
  10. 7Summary
  11. 8References

6.4 Combined Voltage or Current Buffer

For ultimate flexibility of the output channel, a combined voltage and current buffer can be used. The first implementation shown in Figure 6-4 is discrete implementation using a pair of dual op amps with disable function like OPA2990S. Figure 6-4 shows how TPS26614 loop protector can be used to protect the circuit from overcurrent or overvoltage. This circuit has bidirectional voltage output and unidirectional (sourcing) current. For more information about this circuit and the design process check Protected, Low-Noise, Combined V-I Output Stage as Analog Output Building Block.

The second implementation in Figure 6-4 is using the integrated XTR305 device which provides higher accuracy, requires less precision resistors, and has some output error signal feedback. The device requires headroom and footroom of 3V for operation. Please refer to Compact Programmable 4-mA to 20-mA and ±10-V Analog Output Reference Design for AC/Servo Drives D for more details about designing with XTR305.

Combined V/I Buffer Combined V/I BufferFigure 6-4 Combined V/I Buffer