Allegro demo Hall-effect sensor ICs at Sensor & Test

Posted By : Nat Bowers
Allegro demo Hall-effect sensor ICs at Sensor & Test

At Sensor & Test 2014, Allegro MicroSystems has revealed that it will exhibit new products in its family of Hall-effect sensor ICs targeted at current and position sensing in automotive and industrial applications. Products on show include the ACS764 low-noise precision digital current sensor IC and the ATS605 dual-output speed and direction sensing IC.

The ACS764 is a low-noise precision digital current sensor IC targeted at server, telecomms and power monitoring IC applications at up to 100V within the industrial, consumer and computer markets. This fully integrated Hall-effect current sensor IC is the first digital current sensor IC released by Allegro, and is designed for applications that require digital current sensing and reporting through an I²C bus. Factory programming of the offset and gain, including the temperature coefficients, stabilises the offset and gain over the operating temperature range. This programming greatly reduces the device total error, typically less than 2% over the operating temperature range.

An integrated low-resistance conductor means that external shunt resistors are not required and, by employing Hall-effect sensing technology, eliminates the error normally associated with the sensor resistance varying with temperature. The device allows 16 unique I²C bus addresses, selectable via external pins. A digital synchronisation input pin also provides the ability to obtain multiple sensor readings with the same time stamp. The device is highly configurable and includes an averaging filter that is user controlled. Full-scale current-sensing ranges of 16 and 32A (unidirectional sensing) are available as standard options. The device also incorporates a digital over-current fault output and internal averaging filter, both of which are user configurable through the I²C bus.

The ACS764 is provided in a compact 24-pin QSOP package (suffix LF). The leadframe is plated with 100% matt tin, which is compatible with standard lead (Pb) free printed circuit board assembly processes. Internally, the device is lead-free, except for flip-chip high-temperature lead-based solder balls, currently exempt from RoHS.

Also featured is the ATS605 dual-output speed and direction sensing IC designed for use in rotational position sensing applications in conjunction with a ferrous gear target. This device incorporates three Hall sensing elements which are used to create two independent differential channels. Signals from these channels are then processed by the IC, which contains a sophisticated digital circuit designed to eliminate the detrimental effects of magnet and system offsets. The differential signals are used to produce a highly accurate speed output and, if desired, provide information on the direction of rotation.

Advanced calibration techniques are used to optimise signal offset and amplitude. This calibration, combined with the digital tracking of the signal, results in accurate switch-points over different air gaps and temperature. The open-drain outputs provide voltage output signals which mirror the sensed target’s shape, with a phase separation between the two channels proportional to the size of the target teeth compared with the Hall element spacing. Incorporating all the sensing and processing circuitry within a single IC package eases mechanical design and installation and provides the capability to sense small or higher-resolution teeth for added accuracy.

The sensor is optimised for a variety of applications requiring dual-phase gear speed and position signal information or simultaneous high-resolution gear speed and direction information. The ATS605 is targeted at the automotive, industrial, white goods and commercial markets for end applications that include industrial motor control in forklift trucks, robotics and rotational gearing, electric motor position controls and sliding-door/long-travel bi-directional sensing. The ATS605 is available in a 4-lead SIP package (suffix SG). The SG package incorporates a rare earth pellet for ease of manufacturing, consistent performance over temperature, and enhanced reliability.

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