This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TL074H: Suitable OPA on Current Sensor application

Part Number: TL074H
Other Parts Discussed in Thread: OPA4188, TL084, OPA828, OPA1656

Team, Customer is looking for an operational amplifier (OPA) suitable for differential amplifier circuits in current signal detection(CT Module) applications, with a high Common Mode Rejection Ratio (CMRR) and compatible with a ±15V power supply environment. Previously, they used ST's TL084AIDT and later TI's TL084ACDR. In the same operating conditions and with unchanged input/output resistance, the TL084ACDR seems to trigger the current peak detection protection mechanism more easily. This research direction is leaning towards common-mode or differential-mode signal interference.

Customer is considering other OPAs to replace the TL084AITD and OPA4188, which we found unsatisfactory due to its larger input offset current and input bias current affecting circuit stability and accuracy. Additionally, its Gain Bandwidth Product (GBW) is relatively low, making it susceptible to signal interference.

Here are customer's application conditions and requirements along with the comparative data for the TL084 series:

  • Power Supply Voltage: ±15 V
  • Input Signal Voltage Range: ±5 V
  • Operating Frequency (Fsw): 15 kHz

Key requirements:

  • High CMRR (especially near 15 kHz)
  • High Power Supply Rejection Ratio (PSRR)
  • Low Input Offset Voltage
  • Low Input Bias Current
  • Low Temperature Drift
  • Sufficient GBW and Slew Rate

Please let me know if you need any assistance or recommendations based on these criteria.

  • Hi Brian, 

    From my understanding the TL084ACDR isn't working in this application. Do we know why? Can you share a schematic of this application circuit? To achieve higher performance in regards to CMRR you may consider the OPA828 which is a high performance JFET input device. Alternatively you may consider the OPA1656. Both devices have greater GBW than that of the TL084. Below is a comparison. 

    OPA828

    OPA1656

    Best Regards, 

    Chris Featherstone