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TLV3691: Have some delay during inverting at -51C operating temperature.

Lenny Lin
Prodigy 30 points
Part Number: TLV3691
Other Parts Discussed in Thread: TLV7031, TLV7011

Hi,

I am using TLV3691IDPFR as an inverter to convert 3.3V to 0V or 0V to 5V. MCU MSP430F2274MRHATEP provides TTL control between 3.3V and 0V to feed TLV3691IDPFR. TLV3691IDPFR is biased with 5V so the output of TLV3691IDPFR swing between 5V and 0V. 

When I use this comparator as an inverter and operate at -51C low temperature, I observer few seconds delay at output of pin#4. For example when I switch from 0 to 3.3V at pin#3, it takes few seconds for pin#4 to change from 5V to 0V. If I raise the temperature up to -40C or higher and the delay does not occur. 

I verify TI's TLV3691 datasheet. On page1 it indicates industrial temperature range is -40C to 125C. However on page 4 absolute maximum rating is -55C to 150C. 

My first question is: if few seconds delay is causing by running the comparator lower than -40C? 

My second question is: Is the same device TLV3691 come with different package which can operate down to -51C? or any similar comparator with same package as TLV3691IDPFR I can drop in to replace without make design change? Please advise. Thanks.

Regards,

Lenny Lin

  • 0
    TI__Guru 63416 points

    Hello Lenny,

    Yes, It is failing because you are operating outside of it's designed operating range. Being a nanopower (75nA!) supply current device, it is already running on fumes at cold..

    Absolute Maximum ratings mean that the device will not be damaged, but does not imply proper operation. The "Specified" range of -40 is the guaranteed operation range.

    See note 1 of the Abs Max table:

     "....These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions...."

    Unfortunately, we do not have a drop-in, pin-for-pin replacement that goes down to -55°C. The main limitation is the pin-out and temp range.

    Devices that go down to -55 will be either Military grade or Enhanced Product (EP) devices.These also tend to be in larger packages (ceramic or enhanced plastic).

    And, no, before you ask...We cannot say if a commercial device will operate at -55 as we cannot condone operation outside of the specified ranges. It would be up to your discretion to use a -40 commercial device at -55.

    The main knock-out is the temperature range.

    Is the supply current critical? What is your current limitation? Can you do a re-layout?

  • 0 in reply to Paul Grohe
    Prodigy 30 points

    Thanks for the information.

    Supply current is not critical for comparator. I have like more than 50mA margin for using different comparator if it can operate down to -55C. 

    Re-layout is not the first option at this moment and only if I have no other better choice. 

    My bottom line now is: this delay issue would not be a problem for my customer's application because my customer would not send TTL control to the comparator back and forth. My customer only set either low or high from TTL before power on the unit. After unit power on, no more TTL changing. Therefor my customer could live with this issue and I am just seeking any quick replacement I could totally solve the problem on the background. 

    Regards,

    Lenny

  • +1 in reply to Lenny Lin
    TI__Guru 63416 points

    Hi Lenny,

    Unfortunately, the TLV3691 is the only device that comes in the 1x1mm X2SON DPF package. There are no other drop-in replacements.

    There are subtle differences in the X2SON packages so that it is really difficult to do a P2P replacement.

    It's looking like you will need to do a re-layout if you wish to replace.

    The closest small package device would be the TLV7011 (10uA) or TLV7031 (900nA) in a smaller 0.7x0.7mm X2SON, Neither are rated to -55...but....The higher power device may have a better chance at cold....Just sayin'.

    Sorry you are having this problem...the TLV3691 was just not designed for -55°C operation.

    Have you looked into the logic level translation devices?

     https://www.ti.com/logic-voltage-translation/voltage-translators-level-shifters/overview.html

    You may wish to post to the Interface E2E forum and ask if there is a solution to translate 3.3V to 5V at -55°C. They would know better than I..

     https://e2e.ti.com/support/interface-group/interface/f/interface-forum

  • 0 in reply to Paul Grohe
    Prodigy 30 points

    Hi Paul,

    Thanks for providing me some option of replacement although it is not same package. I will keep this information for future upgrade. Currently I would just live with the issue without making any change. Thanks again for your time.

    Regards,

    Lenny

  • +1 in reply to Lenny Lin
    TI__Guru 63416 points

    Glad we could help!