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ADS7841-Q1: Consideration of temperature for TUE calculation

na na78
Guru 16770 points
Part Number: ADS7841-Q1

Hi

We want to know the right way to consider temperature characteristic when TUE to be calculated.

We can estimate TUE using :

TUE=sqrt(sq(Offset Error) + sq(Gain Error) + sq(INL))

1. How to estimate TUE with variation of temperature?

2. According to the datasheet, there are two type of figure for "CHANGE IN SIGNAL TO NOISE vs TEMPERATURE", 5Vcc and 2.7Vcc. These characteristics seem to be dissimilar. Do you know why difference of VCC impact to them?

BestRegards

  • 0
    TI__Guru 52646 points

    Hi Na,

    -The offset, Gain and INL maximum specifications on the ADS7841-Q1 cover the complete temperature range from -40C to +125C.  Therefore, Calculating TUE using the max specification will give you a good estimate of worst case. If you wish to quantify the effect of temperature on TUE, you can refer to the typical curves of Change in Offset vs Temperature and Change in Gain vs Temperature. Using these typical curves, and the TUE equation, you could get an estimate of the TUE change for a given temperature change.  I don't have data on the INL Change vs Temperature since this device was originally developed in 2001.

    - The plots with VCC=5V are generated using VREF=5V and the plots with VCC=2.7V use VREF=2.5V.  The Least Significant Bit (LSB) size is smaller when using  VREF=2.5V, and therefore the  Signal-to-Noise-and-Distortion measurements will be more sensitive to the intrinsic noise of the ADC device as well as to external noise sources and other variations on the device as temperature changes.  The LSB size with VREF=5V is 1.22mV and the LSB size with VREF=2.5V is 0.610mV.

    Thanks and Regards,

    Luis