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TMP112: TMP112 application question

Part Number: TMP112

Hello expert,

My customer has several questions on TMP112, could you kindly help to reply below questions?

  • Do we have to use 1.8V/3.3V at TMP112B/A? Could we use 1.8V/2.5V/3.3V at whatever TMP112A/B? They need to decrease power consumption and they want to use 2.5V as power supply which has loadswitch to control on/off.
  • What is the Iq for TMP112A/B individually with different V+? Or are these two devices' Iq the same?
  • How long can we power on TMP112 after power off(power recycle period limitation?
  • Is VIH 0.7*V+ or 0.7V? If it is 0.7*V+, then I2C bus voltage need to meet this requirement, right?
  • Can we power TMP112A/B with 2.6V and I2C bus is 1.8V which is SOC host SMBus spec?

Thanks a lot!!

Best regards,

Ann Lien

  • Dear Ann - 

    The datasheet for the TMP112x is here: https://www.ti.com/lit/ds/symlink/tmp112.pdf

    • Do we have to use 1.8V/3.3V at TMP112B/A? Could we use 1.8V/2.5V/3.3V at whatever TMP112A/B? They need to decrease power consumption and they want to use 2.5V as power supply which has loadswitch to control on/off.

    TMP112x Supply Range: 1.4 V to 3.6 V

    • What is the Iq for TMP112A/B individually with different V+? Or are these two devices' Iq the same?

    The TMP112x devices are specified to operate over supply voltages from 1.4 to 3.6 V with the maximum quiescent current of 10 µA over the full operating range.

    • How long can we power on TMP112 after power off(power recycle period limitation?

    The TMP112 part was subjected to accelerated lifetime testing (high temp for 1000hrs) during the qualification process, which is roughly equivalent to 9-10 years i think, maybe longer - so you should be able to power it on continuously under normal temp conditions for at least that amount of time, most likely much longer.

    • Is VIH 0.7*V+ or 0.7V? If it is 0.7*V+, then I2C bus voltage need to meet this requirement, right?

    VIH is minimum 0.7*Vin

    • Can we power TMP112A/B with 2.6V and I2C bus is 1.8V which is SOC host SMBus spec?

    Most likely you should use a level shifter, but you might consider also powering the TMP112x device from 1.8VDC rail, too - to save on BOM cost. 

  • Hello Josh,

    Thanks for checking! I would like to double check question 1 and 3.

    For question 1, TMP112A/B is good at PSR for 3.3V/1.8V, right? Is this the reason why we separate as two devices? 

    For question 3, that's a misunderstanding on it, sorry not to explain it clearly. We would like to know the time period as below case.

    Best regards,

    Ann Lien

  • Ann  -

    as the TMP112 datasheet https://www.ti.com/lit/ds/symlink/tmp112.pdf specifies (on page 6), the part can be operated from 1.4 to 3.6VDC. 

    Regarding the diagram you posted...are you asking if there is a specification on time between power cycles?

  • Hello Josh,

    Thanks for reply and yes I would like to know the time spec between power cycles.

    Best regards,

    Ann Lien

  • Dear Ann - 

    there is no spec on this device for time between power off and power on. is there a reason they are power cycling the device quickly? why not just leave it on?  

  • Hello Josh,

    They plan to use 2.5V which could be turned off when power save mode on V+. So they are wondering if we have limitation on power recycling. If there is no spec on it, it should be fine. Thanks a lot!!

    Best regards,

    Ann Lien