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TL074: Inquiry Regarding Diode-Mode Measurement Results for TL074CDR (Lot Variation)

TRINH DAO THI MY
Prodigy 10 points

Part Number: TL074

Dear Texas Instruments Technical Support Team,

We would like to request your technical clarification regarding diode-mode measurement results observed on the TL074CDR operational amplifier.

The device under question has the following information:

  • Part number: TL074CDR

  • Lot number: 5277617ML5

  • Date code: 2515+5

When measuring this lot using a digital multimeter in diode test mode, all measured pins show an open-loop (OL) result. However, for another TL074CDR lot that we purchased in 2024, diode-mode measurements consistently show approximately 0.77 V. Furthermore, after soldering those devices onto the PCB, the diode-mode measurement still reads around 0.7 V under the same test conditions.

Both measurements were performed using the same multimeter and the same diode test method.

We kindly request your support to confirm:

  1. Whether measuring TL074CDR using a multimeter in diode test mode is a valid and appropriate method.

  2. The possible technical reasons why two different lots of the same part number would exhibit significantly different diode-mode readings (OL versus ~0.7 V).

  3. What measurement method or test procedure you would recommend to correctly evaluate the input/output junction behavior of TL074CDR devices.

Your guidance will help us better understand whether this behavior is related to internal design differences, process variations, ESD protection structures, or measurement limitations.

Thank you very much for your support. We look forward to your technical advice.

Best regards,
DAO THI MY TRINH

  • 0
    TI__Expert 4570 points

    Hello Dao Thi My Trinh,

    The TL074 went through a design update, the detail of which can be found in this PCN here. This device moved to a new process technology, and the differences you are seeing are due to updated ESD structures. For more information about this, please see Section 6 of the app note ESD Cells in Op amps. The updated TL07X uses nontraditional ESD protection, which can be further explained by looking at Sections 3 & 4 of the previously mentioned app note.

    Using a multimeter in diode test mode is a valid method when the device uses traditional diode-to-supply protection. However, if the operational amplifier uses non-traditional ESD protection methods, such as a level-triggered protection scheme, the multimeter in diode test mode is not a sufficient method to test for ESD protection. 

    Section 6 of this app note explains one way to test the ESD protection in a device. Grounding both supplies and inserting a small current into the the input, and then measuring the corresponding voltage is one way to characterize the ESD protection in the op amp.

    Please note that the change in ESD protection should not affect the op amp during normal operation, as ESD cells are only triggered during abnormal device operation, such as electrical overstress.

    Best regards,
    Carrie