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LMH6628QML-SP: Supply Current

Part Number: LMH6628QML-SP

Hello support team.

For a current product we assemble the LMH6628WG-QML several times and we do have an issue with the current consumption. The datasheet states a max. supply current of 25mA for the whole part when no load is appliced (quiescent current).

  1. In my understanding this maximum value contains the impact of all effects: Initial tolerance, temperature, radiation, end of life, maybe even some margin. Is this correct?
  2. Do you have any detailed information on the impact on the supply current due to the individual effects?

The reason for my question is as follows:
At 25degC we measure a supply current (no load) of 16mA. So the initial tolerance is already covered. How much increase in current consumption should I consider due to temperature, radiation, end of life?

I think the increase due to temperature will be max. 1mA as the datasheet states 24mA for subgroup 1 and 25mA for subgroup 3. Is this correct?

I attached a file that shows my understanding of the individual elements that affect the supply current.

Best regards
Markus Kübler

  • hey Markus, there is no file attached. 

    The commercial version shows this, obviously not a supply current trimmed device, pretty incredible Icc span here, there are several other more recent similar devices with Icc trim, but likely not S qualified. 

  • Hey Michael, thanks for your response.

    You are right, this is a big span. What I want to know is: When I measure the initial supply current of the component at laboratory condition, how can I estimate the max. supply current of this individual component.

    I tried to visualize in the above figure.

    Regards Markus

  • Hello Kai, thank you for the link.

    I carefully studied this and tried to understand it. Unfortunately I cant find any information on  long-term stability for the supply current of the LMH6628QML-SP. There is only some information on drift values in the datasheet:

    I am not sure if this belongs to long-term stability.

    Regards Markus

  • Hello Markus,

    1. Maximum value would not include impact of all the effects listed. The maximum value in our portfolio determines a few factors depending on the specification which will be noted: via gaussian distribution, via design simulation, or via test prior to unit distribution. Specifically for the quiescent current of the device, the value is physically tested prior to unit distribution. In this case, the supply current max is a set maximum value the device can consume before distribution under the conditions listed (load, temperature, amplifier configuration). If the supply current is over this value, the device/unit will be discarded.

      1. Since, this is a higher rated unit for space/military qualification, the unit also takes in consideration under radiation as described in the footnote 1). Also, the specifications are all tested with regards to sub-groups 1-11 as per MIL-STD-883, Method 5005 qualification (Military). 

    2. Space-qualified devices require additional tests such as single-event effects and total ionizing dosage. Also, they must pass the tests to be certified under MIL-PRF-38535 groups A, B, C, D. 
      1. LMH6628QML-SP Qualification and Material Summary can be found under device's product folder under the Order & Quality tab. 
      2. LMH6628QML-SP Test Documents for test in accordance to (device class Q and M) and space application (device class V). This includes supply current within high temperature and operating life conditions described in certifications. These high temperature testing over usually 1000 hours can correspond to EOL conditions to accelerate product life during testing. 
      3. LMH6628QML-SP Total Ionizing Dose (TID) report which shows supply current and other specifications variance over total radiation dosage. 
      4. Texas Instruments Engineering Evaluation Units versus MIL-PRF-38535 QML Class V Processing. This document shows list of tests for QML rated devices.
      5. Understanding Quality Levels for HiRel-rated Components. This document covers in detail tests for QML rated devices. Table on last page is helpful for temperature range and extra qualifications done.
      6. Radiation Handbook. This document covers details on general TID and SEE testing on Chapter 7. 
      7. Kai shared an E2E blog on long-term effect variance. This is a video form of the blog which also covers how EOL conditions can be met through accelerating life condition of the device via high environment stress conditions. 

    Thank you,

    Sima 

  • Hello Sima, thank you for the detailed explanation.

    1. The link that you added at point b. shows the DLA SMD Datasheet. Was that your intention because the title suggests that measurement results are included in this document.

    2. I had a close look on the extensive information and tried to estimate the supply current under consideration of the various effects. This is my outcome:

    The datasheet for the space component (5962-02545, B) states in Table I:

    As you explained, the supply current maximum value is a set maximum value the device can consume before delivery to the customer.

    I) Based on the information of the linked video in point g of your list, I assume that the supply current wont change when it is measured at 25°C and 125°C. When the supply current is measured at -55°C it may increase by maximal 1mA. Is this correct?

    II) According to Note 2: “Pre and Post irradiation values are identical unless otherwise specified in table I.” This is also confirmed by the results in ‘LMH6628QML-SP Total Ionizing Dose (TID) report’ where the measured current values are the same regardless the Total Dose.

    Table IIB shows the following:

    III) The Delta Limits for the supply current are given with -1.0 / +1.0mA.

    In summary my estimation for the supply current of an individual component is as follows:
    Measured current at 25°C + 1mA,max (due to high temperature) + 0mA (due to radiation) + 1mA,max (due to operating life).

    With a measured supply current of 18mA (@25°C) the maximum expected supply current would be 20mA. Is this correct?

    Best Regards, Markus

  • Hello Markus,

    1. Yes, for measurement results it looks to be more detailed information on the specifications in datasheet and qualification assurance. I apologize for confusion there. 
    2. Thank you for pointing out these snippets from the documents:     
      1. I) That is correct. As you have pointed out in image, -55C max supply current will be 25mA rather than 24mA. 
      2. II) Understanding is correct. Both documents point to no supply current change up to the 300kRads. 
      3. III) That is correct. The test done for this specific part from the document is in accordance with method 1005 of MIL-STD-883 at the device's maximum operating conditions to determine the Steady-state life test conditions of the device.

      The estimated summary is correct in accordance to above. I do agree that most likely the 18mA device would have a maximum of 20mA (especially considering the raw data shown on pages 9 and 10 of the TID report), but I would still say to expect a maximum supply current with estimated summary. 

    Thank you,

    Sima 

  • Hello Sima,
    thank you for the in-depth discussion.

    Based on these knowledge, I can now prepare a theoretical estimation for the maximum currents to be expected.

    But most importantly, I can determine the maximum supply current of individual assemblies based on actual measurement.

    Best regards, Markus