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LM5022: FB pin voltage drift by Temp

Roy Chou1
Genius 13565 points
Part Number: LM5022

Hi Team,

I see the figure.2 in datasheet. it shows that FB voltage will drift due to temp. In figure, 25C = 1.25V ; -25C = 1.248 , it's only 1.25-1.248 = 0.002V

Could you let me know whether we have this drift voltage spec? (max and min)

Is it possible there is 0.02V drift voltage between 25C and -25C?

Roy

  • 0
    TI__Guru 73270 points

    Hi Roy,

    Thank you for posting.  First, Figure 2 is measured from a single IC. Owing to process tolerances, another IC may have similar curve but the curve may shift up or down depending on that IC's actual setting point at 25C.   The curve basically implies that the variation over temperature is small, and the most VFB variations are caused by process tolerances. 

    The only guaranteed min and max are the total variations including both the process tolerance and temperature effects over -40C to +125C.  There is no data \to support the statement of 0.02V between 25C and -25C, although it may be a close guess. 

    Thanks,

    Youhao Xi, Applications Engineering

  • 0
    TI__Expert 7450 points

    Hi Roy,

    Is the 0.02V drift observed on different IC or the same IC?

    Thanks,

    Yinsong

  • 0 in reply to Yinsong Cai1
    TI__Genius 13565 points

    Hi Yisong and Youhao,

    Thank you for your comments. We understand that we only guaranteed min and max are the total variations including both the process tolerance and temperature effects over -40C to +125C.

    For below figure, we could know this specific IC drift voltage is 0.002V from temp = 25C to -25C. We would like to know whether 0.02V drift voltage (10 times to 0.002) is make sense or not.

    Ps. 0.02V is single IC measurement. 

    Regards,

    Roy

  • 0 in reply to Roy Chou1
    TI__Guru 73270 points

    Hi Roy,

    20mV appears large although it is still inside the spec limits.  Could you elaborate how you measured the voltage?  

    Thanks,

    Youhao

  • 0 in reply to Youhao Xi
    TI__Genius 13565 points

    Hi Youhao,

    I agree your point. Now I tell customer using shortest path and using multi-meter to do the measurement.

    Roy

  • 0 in reply to Roy Chou1
    TI__Guru 73270 points

    Hi Roy,

    Please let us know if we can be of further assistance.

    Thanks,

    Youhao

  • 0 in reply to Youhao Xi
    TI__Guru 73270 points

    Hi Roy,

    May I assume the issue has been resolved?  I would like to close this thread.  Please add a new post if you want to re-open it. 

    Thanks,

    Youhao