• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 48 subscribers
  • Views 222 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMV331: OP AMP output voltage issue

Hicham Lhachimi
Prodigy 10 points
Part Number: LMV331

Hi all,

In fact, based on the LMV331 datasheet supply voltage range shown below:

 

 

Normally, if the Voltage supply is below 2.7V, the output voltage VF2 should be 9V.

Based on the simulation, the output voltage is 0.388V.

 

I want to know the reason behind that result and thank you in advance.

  • +1
    TI__Genius 11701 points

    Hi Hicham

    Thank you for your patience.

    I’m not sure what version of the model you have but please see attached.

    In the model, when the supply voltage is outside of the recommended range (below 2.7V or above 5.5V), that will give an error condition where the output will float to mid supply. This does NOT occur in the real device. You can see below the output is 1V (mid of 2V).

    In the real device, LMV331 does not have a power on reset (POR) circuit so the output will be in an unknown state below 2.7V. We do not have enough data on the LMV331 to provide a warranted startup condition.  Most likely the LMV331 will start high Z at the output but as it reaches the recommended operating range, it is possible that some unpredictable output conditions could occur.

    -Chi

    LMV331.TSC

  • 0 in reply to Chi Nguyen1
    Prodigy 10 points

    Concerning the LMV331, below 2.7V, the comparator output should be floating since it has an open collector configuration. How can the output be below 2.7V if the output is connected to 9V via the resistor ?

  • +1 in reply to Hicham Lhachimi
    TI__Genius 11701 points

    Hi Hicham,

    LMV331 has ESD diode clamps on the output connected to the supply, so the output will be diode-clamped to the supply if its above the supply. So for a 2V supply, the output will be about ~2.7V. I've edited the model to reflect this. However, if below 2.7V supply, you'll still see the mid supply error condition. But in the real device, we cant guarantee the output behavior below the 2.7V supply. 

    4113.LMV331.TSC

  • 0 in reply to Chi Nguyen1
    Prodigy 10 points

    Thank you for your reply, I got the point.