ADS1148-Q1: ADS1148-Q1

Gerald,


Your question was not clear to me, however change in the ADC data is covered under several drift specifications. All of these drift specifications are listed in the electrical characteristics table on page 7 of the ADS1148-Q1 datasheet.

First, the offset drift is listed as a typical 100nV/°C for a gain of 1. With a reference of 2.048V, the LSB this is 0.0016 LSB/°C. It also lists the typical offset drift as 15nV/°C for a gain of 128. This translates to a drift of 0.03 LSB/°C.

Next the gain error drift is listed as a typical 1ppm/°C at gain of 1 and -3.5ppm/°C at gain of 128.

The typical reference error is 20 ppm/°C with a maximum of 50 ppm/°C. If the internal reference is used as the ADC reference, the reference error can be considered part of the gain error. Using the internal reference, this drift error would likely be the largest contributor of drift error to the measurement.

The IDAC current sources also have some contribution to drift if they are used. However, depending on the setup and the measurement topology, the error from the drift of the IDAC currents is generally not a large factor in ratiometric measurements. It can be also be reduced through chopping current sources in a three-wire RTD measurement.


Joseph Wu