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LM5156: UVLO Threshold vs Temperature

nickerchen
Prodigy 20 points
Part Number: LM5156

Tool/software:

Hi Team

In "Electrical Characteristics" in the datasheet there is a table for UVLO threshold voltages (rising and falling) and hysteresis current.
in "Typical Characteristics" there is a graph that shows "UVLO Threshold vs Temperature".
The graph is totally flat from -40°C to 150°C but the voltages in the table differ by as much as 5.5%

Can you please explain where the values come from ?
Are the values in the table variations across components but each single component is stable over the whole temperature range ?

Thanks for your help.

  • 0
    TI__Expert 4090 points

    Hi nickerchen,

    Thanks for using the E2E forum. 

    The values in table shows that all devices tested in lab had a UVLO threshold voltages (rising and falling) in this Min and Max range.

    The data for device under test shown in datasheet had a rising and falling UVLO value at 1.5V and 1.45V, respectively.  

    Best Regards,

    Hassan  

  • 0 in reply to Hassan Jamal
    Prodigy 20 points

    So the hysteresis current range is already included in the range of the threshold voltages, because it influences the falling threshold voltage, right ?

  • 0 in reply to nickerchen
    TI__Expert 4090 points

    Hi Nickerchen,

    The hysteresis current range also shows that all devices would have their internal current source for the UVLO block with in this range.

    Whereas, the UVLO hysteresis is accomplished with an internal 50-mV voltage hysteresis and an additional 5-μA current source that is switched on or off. When the UVLO pin voltage exceeds the UVLO threshold, the current source is enabled to quickly raise the voltage at the UVLO pin. When the UVLO pin voltage falls below the UVLO threshold, the current source is disabled, causing the voltage at the UVLO pin to fall quickly. 

    Thus, the falling threshold voltage is not affect by this hysteresis current source.

    Best Regards,

    Hassan