I am working with the ADIS16362 and was wondering about some of the specs. If the devices are calibrated during their manufacturing process, why is the specifcation for "Initial Bias Error" listed as ±3°/sec? Sensitivity listed as ±1%?
The answer to this question comes from ADI's philosophy in specifying their products. The word, "initial" can mean, "the performance that the device exhibits during electrical screening." Our philosophy goes beyond that and seeks to communicate the performance expectations over the lifetime of the product. If we observe opportunity for parametric drift in normal operating conditions, we prefer to communicate that up-front in the datasheet, so that system developers can account for them in their use of the device. This includes any observations that we make, based on accelerated aging tests, such as HTOL (High-Temperature Operating Life), temperature cycling and shock. With respect to the sensitivity, many of the devices fall well within the +/-1% window, but a relatively small number of units experienced this drifts that approach +/-1% in the accelerated-aging tests for this device. With respect to the initial bias error, the same explanation applies but managing this behavior warrants more discussion. First, the initial bias drift and temperature-dependent drift are two separate parameters. While the initial bias experiences rate random walk (RRW) behaviors over time, the temperature-dependent behavior tend to exhibit stronger stabiliy. This preserves the value of the ADIS16362's temperature-based correction formulas and means that the entire bias/temperature curve can be corrected, using a single-condition bias adjustment. AN-1041 offers some tips on optimizing a single-condition bias adjustment for devices like the ADIS16362.
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