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INT LP2950

Rocson He
Intellectual 1830 points
Other Parts Discussed in Thread: LP2950

Hi, team,

Now we have one question about LP2950 from Customer. They are now using it for 10 bit ADC with 1% resistor divider. When doing the -25 degree low temperature test, the maximum output change of LP2950 5V is 14mV,  thus would lead to ADC detect error as the reference would also change. 

In the spec of LP2950, there is one parameter indicating temperature coefficient is 100ppm maximum in Page5, during the -40 -125 degree with Loading current at 100uA. Then how is the ppm behave when the load is heavier, like 5mA? Can we ensure the lower than 100ppm ?

The spec also describe LP2950 as 2% accuracy over temperature, then the max error output is 100mV during changing temperature, right? Then it’s conflicted with PPM description.

Thanks .

  • 0
    TI__Guru**** 165166 points

    Rocson,

    The ppm/C equation is (VOUT[max]-VOUT[min]) / 5V /165C * 1,000,000 over the full temperature range. It is the average over the whole temperature range.  Any sub-section of the temperature range may have a lower or higher ppm. Over a 25C to -25C range, your observed ppm/C is 14mV/5V/50C*1e6= 56 ppm/C.

    The temperature range allows for only 50mV more variation over the 25C limits. 5mA is still a light load and only a small potion of load regulation specification will degrade VOUT. 

    You may need a device with lower ppm/C temperature coefficient.