Key differences in specification between the AD674BBD and BTD grades

Document created by analog-archivist Employee on Feb 23, 2016
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Key differences in specification between the AD674BBD and BTD grades

 

Here the key differences in specification between the AD674BBD and BTD grades.

The parts are pin for pin compatible. They both contain the same silicon chip
but are subject to production test programs which have different limits as
described in the datasheet.

The specs in the datasheet which differ are:
Accuracy Specs:    BBD   BTD
Linearity error over temperature   +/-0.5   +/-1
Bipolar offset drift over temperature  +/-1   +/-2
Full-scale Calibration drift over temperature +/-5   +/-7

Off all the differences, the linearity error is likely to be the most critical.
See datasheet page 6 for more information on linearity error. You will need to
check the accuracy requirements of your system design and decide whether this
reduction in maximum guaranteed linearity error can be tolerated.
The bipolar and full-scale drift can be removed by a simple two point
calibration routine. If your system already has a calibration routine then the
DC errors due to offset and gain errors will be removed.

Timing:      BBD   BTD
STS delay from CE    200ns   225ns
Data Valid After CE low     20ns   15ns (at-55degC)

The differences in timing limits will not affect your design provided you
operate within the temperature range -40 to +85 degC. The differences in timing
only occur at extremes of temperature range.

When corresponding with your customer, ask them if the why they chose the BBD
grade over the BAD grade. If the BAD grade would have been acceptable, then the
BTD will slot into this application without further consideration.

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