A3518

Calibrated linear Hall devices, which can be used to determine the actual flux density presented to the sensor in a particular application, are available.

For safe, reliable operation, the output should not be pulled above the supply voltage or pulled below the device ground.

For optimum performance, a 0.1 F capacitor between the supply and ground, and a 100 pF capacitor between the output and ground, should be added.

The ratiometric feature is especially valuable when these devices are used with an analog-to-digital converter.  A/D converters typically derive their LSB step size by ratioing off a reference voltage line.  If the reference voltage varies, the LSB will vary proportionally.  This is a major error source in many sensing systems.  The A3517xUA and A3518xUA can eliminate this source of error by their ratiometric operation.  Because their gain and offsets are proportional to the supply voltage, if they are powered from the A/D reference voltage, the sensor output voltage will track changes in the LSB value.

These devices can withstand infrequent temperature excursions, beyond the Absolute Maximum Ratings, to T_A   = 170°C provided the junction temperature, T _J, does not
exceed 200°C.

Extensive applications information on Hall-effect sensors and magnets is also available in the "Hall-Effect IC Applications Guide", which can be found in the latest issue of the AllegroMicroSystems Electronic Data Book, AMS-702 or Application Note 27701, or at www.allegromicro.com