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.

  • TI Thinks Resolved

LM2903-Q1: comparator threshold level question

Expert 3080 points

Replies: 3

Views: 56

Part Number: LM2903-Q1

Hi Sir,

My customer is designing LM2903-Q1 as below schematic,

When they define  PHASEU_OC_4V5 = 4.5V as below waveform#1, when the Input signal arrive 3.9V will make the output change from High to Low.

When they define  PHASEU_OC_4V5 = 2.83V as below waveform#2, when the Input signal arrive 2.7V will make the output change from High to Low.

May I know the reason why the comparator input not reach the ref level in pin3 but it will trigger to change the status from high to low?

Could you please help to explain on it?

Thanks

Waveform#1_yellow=input, Blue=PHASEU_OC_4V5, Red=output

Waveform#2_yellow=input, Blue=PHASEU_OC_4V5=2.83V , Red=output

  • Hi Anne,

    you violate the common mode input voltage range:

    Make the following changes:

    Kai

  • Hi Anne,

    As Kai explained - you are violating the input voltage range. It will get worse at cold.

    Also please see the following application note for a full explanation, section 2.2:

     https://www.ti.com/lit/an/snoaa35a/snoaa35a.pdf

    Regards,

    Paul Grohe

    TI Comparators (CMPS) Applications Group

  • In reply to Paul Grohe:

    we have not seen any follow up response on this post, so it will be closed.

    if you require additional support, please reply or feel free to open a new post.

    thanks

    Chuck

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.