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Original question:

TLV9054: DC input under no power condition

TLV9054： Background of (2) note in "Absolute Maximum Ratings"

Takashi Onawa
Genius 13200 points

Part Number: TLV9054

Hi Team,

My customer wants to know the background (2) note in "Absolute Maximum Ratings".

They argues that (1) and (2) are contradictory if (1) violation under regulated less than 10mA could affect device life reliability.
Could you tell me what is the intention of the Note (2) in "Absolute Maximum Ratings"? I thought that this intended that the power rating of the ESD Diode built into the V⁺ from the Signal Input pin is 0.005W (0.5V*10mA), is that wrong?

My customer's design review has been stopped due to the reason we discussed that in the following E2E thread. And I need to explain the background in meeting with them

e2e.ti.com/.../971315

Regards,

Takashi Onawa

  • 0
    Guru 322010 points

    Footnote (2) says that when the current is limited, the voltage limit no longer applies. You are correct that both limits are intended to prevent thermal damage.

    In footnote (1), "absolute-maximum-rated conditions" means conditions that exceed the recommended operating conditions, and are near the absolute maximum ratings.

    Exceeding the absolute maximum ratings, even for a short time, can damage the device immediately.
    Absolute-maximum-rated conditions can slowly degrade the device.

    If you stay well below the absolute maximum ratings (e.g., 0.1 mA instead of 10 mA), no measurable degradation will occur.

    (At a current of 10 mA, the forward voltage of the diode will be larger than 0.5 V, so the actual power rating is somewhat higher.)

  • 0
    TI__Genius 15410 points

    Hi Takashi-san,

    If the current is limited to less than 10mA (abs max current rating) then you will not catastrophically destroy the device (cracked or chipped packaging). However, by violating the absolute maximum voltage rating (Vin > 500mV above or below supplies) then you will stress the device beyond what the device is designed for. If the abs max voltage rating is exceeded you may see accelerated degradation of the device.

    Thank you,

    Tim Claycomb 

  • 0 in reply to kai klaas69
    TI__Genius 13200 points

    Hi All,

    Thanks for your comments on this topic.

    In my understanding, the operation in the range from absolute maximum ratings to recommended operating voltages does not accelerate device aging, although it is a range that is not guaranteed to work with the specifications on the datasheet.

    I understand that absolute maximum ratings are very important thresholds for ensuring device reliability, but I have not received any official comments from Tim on the background of the (2) Note. Could you please mention this point? I don't think this statement is necessary in the datasheet if it concerns the reliability of the device (I think the point is whether this ESD current could cause this part to fail first due to the small leakage).

    As far as I can tell from the TINA TI, the voltage between Input and Vcc rises to around 0.5V even if a tiny current flows, and the trip point appears to be around 10mA. In the simulation, the voltage does not exceed the Input-Vcc voltage until around 10mA, but depending on the variation of Vf and the noise environment, it may appear to exceed 0.5V.

    [Vin voltage sim]

    [Customer's circuit on this issue ]

    Regards,

    Takashi Onawa

  • 0 in reply to Takashi Onawa
    TI__Genius 15410 points

    Hi Takashi-san,

    Note 2 is there to inform users that the inputs have ESD diodes to the rail and that if the abs max input voltage is exceeded excessive current may flow into the inputs damaging the device. So they must limit the current if they are expecting this to occur.

    Thank you,

    Tim Claycomb

  • 0 in reply to Tim Claycomb
    TI__Genius 13200 points

    Hi Tim-san,

    Data sheets for non-Amp products do not describe such a supplement, and if it says Vcc+0.5 V, every engineer know that an ESD diode is inserted for that Pin and take care the voltage sequence for the pins.
    The problem is that supplement (2) appears to allow for conditions that exceed the absolute maximum rating under limited current condition. If there is a negative impact on reliability, then this statement is not necessary.
    So the background you are describing does not seem to be a reason to bother stating (2).

    Could you please check with designer or system engineer about the intent of this text?
    (What I want to clarify is whether there is any negative impact on reliability under the limited current condition.)

    Regards,

    Takashi Onawa

  • 0 in reply to Takashi Onawa
    TI__Genius 15410 points

    Hi Takashi-san,

    I have checked with the quality and the designers. Exceeding the supply voltage will stress the device more than what is designed for. You will see accelerated aging of specification if you violate the input voltage absolute maximum rating. The intent of the text is to ensure that the user knows that the internal ESD diodes will conduct current when the input voltage exceeds the supply and the current must be limited to less than 10mA otherwise damage will occur.

    In addition, Note 1 of the table, which applies to all specification in the table, states that "Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability".

    Thank you,

    Tim Claycomb