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SN74LVC157A: Maximum Output rating

Hirotaka Matsumoto
Guru 27585 points
Part Number: SN74LVC157A
Other Parts Discussed in Thread: SN74AXC1T45

Hi all

Would you mind if we ask SN74LVC157A?
There is the description "Maximum Output rating VCC+0.5V" on the datasheet.
Does "this 0.5V" mean protection diode between output and VCC?
How much is the maximum current for this diode?

As the background of this question, our customer would like to use this device as follow conditions.
-Vcc=2.5V
-there is the pull up with 3.3V
->In this case, output is more than absolute maximum rating. So, we would like to confirm whether "VCC+0.5V" is due to protection diode or not.

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Guru 58030 points
    Hirotaka san,

    Your understanding is correct.
    Please refer to the faq below on applying greater than Vih to a device:
    e2e.ti.com/.../723607

    Is the customer doing a translation? If yes, we have solutions for these in the translation portfolio like the SN74AXC1T45? Let me know.
  • 0 in reply to ShreyasRao
    Guru 27585 points

    ShreyasRao san

    Thank you so much for your relp.

    How much is the maximum current for this diode?
    ->As your information, maximux out clamp is 50mA, right? Therefore, if the customer uses this device with 5mA, the device doesn't damage, right?

    Is the customer doing a translation? If yes, we have solutions for these in the translation portfolio like the SN74AXC1T45? Let me know.
    ->OK, we will confirm it.

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Guru 58030 points
    Hirotaka-san,

    The output clamp current reading should read +/-50mA to indicate the positive clamp diode. We will have to get that updated.
    I would never recommend using the abs max rating for designing. The recommended operating conditions suggest that the output voltage max is at Vcc and the abs max rating is violated once the voltage is pulled greater than Vcc+0.5V. We can only say that the with limiting the current, the device is unlikely to be damaged.
  • 0 in reply to ShreyasRao
    Guru 27585 points

    Shreyas san

    Thank you so much for your help.

    OK, we got it!

    Kind regards,

    Hirotaka Matsumoto