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OP07: Batch replacement caused output anomalies

zhang ping
Genius 3885 points

Part Number: OP07

We have been using OP07C for more than 3 years. The OP07C purchased from Arrow in August 2025 had abnormal output, but the OP07c purchased in 2024 had normal output. The circuit diagram is shown below. We would like to know if the device has been modified and if there are any parameter changes that have caused this phenomenon? Or help analyze the cause of the output exception.
The circuit is powered by ± 15V. Normally, after the chip is powered on, the output of pins 1 and 8 is positive voltage. However, when replacing the chip purchased in 2025, the output of pin 8 is negative voltage. The silk screen versions of the two are significantly different; The one with a red check mark represents the chip procurement in 2024, while the other with a red box represents the chip procurement in 2025;

sch.jpg

 

old 1.jpg

erro 1.jpg

  • 0
    TI__Expert 5270 points

    Hi Zhang,

    This is a creative use of the input offset null pins that seems to fall outside of a normal input offset null application. Pins 1 and 8 are not output pins. Please see Nulling Input Offset Voltage of Operational Amplifiers for more details on the purpose of these pins.

    That being said, the internal resistances connected to the pins were modified as part of a FAB transition. The functionality of the pins is the same when used as intended, but the internal resistances connecting to the offset adjustment pins are not the same, which might be contributing to the differences you've observed.

    Please see the relevant PCN here, and this E2E post for the new resistance values.

    Best Regards,

    Alex Curtis