Allegro Hall-Effect Sensors Target Automotive, Industrial, Consumer Markets

June 19, 2008—

Allegro Microsystems, Inc. has introduced a programmable, linear Hall-effect sensor with a 125 Hz pulse width modulated output. According to the company’s press release, the thin package and PWM output of the sensor would benefit current and position sensing applications. The A1351 device converts an analog signal to a digitally-encoded PWM output signal. A simple RC network can be used to convert the digital PWM back to an analog signal.

The BiCMOS, monolithic circuit inside integrates a Hall element and precision temperature-compensating circuitry to reduce the intrinsic sensitivity and offset drift of the Hall element. A high-frequency offset cancellation clock allows for a greater sampling rate, which increases the accuracy of the output signal and results in faster signaling capability, according to the company’s press release. The A1351 is supplied in a thin 4-lead SIP (K) package and is priced at $1.38 each in quantities of 1,000. It has a 12–14 week lead-time to market.

Allegro has also introduced the ACS756 family of low-noise, open-loop current sensors with bandwidth capability of 125 KHz. The Hall-effect sensor is appropriate for various 50 S to 100 A applications due to the high speed and increased accuracy, which result from the proximity of the magnetic signal to the Hall transducer, according to the company’s press release. Standard uses include motor control, load detection and management, power supplies, overcurrent fault protection and other applications involving high-side current sensing.

The sensor’s internal electrostatic shield forces the effects of voltage-transient spikes around the silicon to reduce the voltage ripple on the device output. The linear Hall sensor circuit has a copper conduction path near the die, so an applied current moves through the conduction path to generate a magnetic field, which the integrated Hall IC senses and converts into proportional voltage. The copper conductor is thick enough for the device to survive at five times overcurrent conditions. The conductive path terminals are isolated electrically from the sensor leads, so the ACS756 sensors are suitable for uses that require electrical isolation without using expensive isolation techniques, such as opto-isolators. Geared towards the industrial and consumer markets, the ACS756 is priced at $3.16 per unit in quantities of 1,000 with a 12–14 week lead-time to market.

Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcestor, MA 01606 
(508) 853-5000
(508) 853-3353