SDAA511 September   2026 OPA192 , PGA855

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Detailed Description
    1. 2.1 ATE Testing Card and Signal Sensing
    2. 2.2 Signal Sensing Requirements
    3. 2.3 Signal Sensing
    4. 2.4 General Purpose Sensing
    5. 2.5 Precision Signal Sensing
      1. 2.5.1 Middle and High Voltage Signal
      2. 2.5.2 Current Signal with Middle and High Common Mode Voltage
      3. 2.5.3 Signal Which Requires Very Low Current Leakage
      4. 2.5.4 Fast Voltage Signal
      5. 2.5.5 Ultra-High Voltage Signal
  6. 3Summary
  7. 4References

2.5.2 Current Signal with Middle and High Common Mode Voltage

Figure 2-4 shows a typical current sensing topology. For a low common-mode-voltage current signal, a PGA or INA may be used directly for sensing the current signal. For an over-36V common-mode-voltage current signal, a discrete buffer and difference op amp (difference op amp, INA, or PGA) are mostly used instead.

Typical Current Sensing Topology Figure 2-4 Typical Current Sensing Topology

The buffer and PGA are the same as above. The difference op amp and INA (Table 2-2) can be selected as shown in Table 2-2.

Table 2-2 Difference Amplifiers
PN Key Feature
INA597 Input voltage -54~+54V, 2Mhz, input impedance = 12k ohm, CMRR=94dB, En=6uVpp, THD+N=6.6ppm, offset drift=1.4uV/°C, gain drift=0.25ppm/°C
INA592 Input voltage -54~+54V, 2Mhz, input impedance = 24k ohm, CMRR=94dB, En=6uVpp, THD+N=6.6ppm, offset drift=0.7uV/°C, gain drift=0.2ppm/°C
INA149 Input voltage -275~+275V, 0.5Mhz, input impedance = 200k ohm, CMRR=100dB, En=20uVpp, offset drift=0.7uV/°C, gain drift=0.2ppm/°C
INA851 36V, 22Mhz, 37V/us, Ib=5nA(typ), CMRR=96dB(gain=1), THD+N=3.5ppm, En=12uVpp
Input Offset drift=5uV/°C, output offset drift=5uV/°C, gain drift=35ppm/°C (gain>1)
INA823 36V, 1.9Mhz, 32V/us, Ib=1.2nA(typ), CMRR=110dB(gain=1), En=0.4uVpp
Input Offset drift=0.2uV/°C, output offset drift=1uV/°C, gain drift=12ppm/°C (gain>1)
INA818 36V, 2Mhz, 0.9V/us, Ib=0.15nA(typ), CMRR=105dB(gain=1), En=2.6uVpp
Input Offset drift=0.4uV/°C, output offset drift=5uV/°C, gain drift=35ppm/°C (gain>1)
INA821 36V, 4.7Mhz, 2V/us, Ib=0.15nA(typ), CMRR=105dB(gain=1), En=2.5uVpp
Input Offset drift=0.1uV/°C, output offset drift=5uV/°C, gain drift=35ppm/°C (gain>1)