Allegro features new power semiconductors and Hall-effect sensing devices

PCIM Europe 2016 Exhibition

Allegro MicroSystems: At PCIM 2016, Allegro MicroSystems Europe is featuring its comprehensive ranges of power semiconductor devices and Hall-effect sensor ICs, including a number of new products.

Being previewed at the exhibition is the ACS780xLR: a fully integrated linear current sensor IC in a new coreless package designed to sense AC and DC currents up to 150 A. The automotive-grade, low-profile (1.5 mm thick) sensor IC package has a very small footprint of 6.4 × 6.4 mm.

The Hall sensor technology used in the ACS780xLR incorporates common-mode field rejection to optimise performance in the presence of interfering magnetic fields generated by nearby current-carrying conductors.

The device consists of a precision, low-offset linear Hall circuit with a copper conduction path located near the die. Applied current flowing through this copper conduction path generates a magnetic field which the Hall IC converts into a proportional voltage. Device accuracy is optimised through the close proximity of the primary conductor to the Hall transducer and factory programming of the sensitivity and zero-ampere output voltage at the Allegro factory.

The chopper-stabilised signal path and digital temperature compensation technology also contribute to the stability of the device across the operating temperature range. High-level immunity to current conductor dV/dt and stray electric fields is offered by Allegro’s proprietary integrated shield technology, which provides low-output voltage ripple and low-offset drift in high-side, high-voltage applications.

The thickness of the copper conductor allows survival of the device under high overcurrent conditions. The terminals of the conductive path are electrically isolated from the signal leads, allowing the device to operate safely with voltages up to 100 V peak on the primary conductor. This product is “coming shortly” and has not yet been released to production, but samples are available now.

Other new current sensing devices being featured at PCIM include the ACS724KMA high-accuracy, high-isolation, differential current sensor IC, offering improved performance in a low profile, small footprint package for applications that require very high voltage isolation.  

The ACS724KMA is available in a very small package that is ideal for space-constrained applications and also saves cost through reduced board area. It is packaged in a high-isolation SOIC16 wide-body surface mount package that provides reinforced isolation allowing it to be connected directly to line voltage without needing additional isolators. The differential sensing technology provides immunity to interfering common-mode magnetic fields from adjacent current traces or motors. Typical applications include motor control, load detection and management, switched-mode power supplies, and overcurrent fault protection.

Also on show is the new ACS770: a fully integrated Hall-effect based linear current sensor IC incorporating thermal enhancement for high precision. The industry-leading total output accuracy of the ACS770 is achieved by using a new piecewise linear digital temperature compensation technique for offset and sensitivity. This greatly improves the IC’s accuracy and temperature stability without influencing the high-bandwidth (125 kHz) operation of the analogue output. Outstanding noise performance results from the use of proprietary amplifier and filter design techniques. The ACS770 can measures up to 400 A and can handle 200 A continuous current at an ambient temperature of 85 ̊C.

Allegro is also showing a number of new products in its family of LED and motor driver ICs, including the A4963 sensorless brushless DC controller, the A594x family of brushless DC fan driver ICs and the A1569 LED driver with integrated Hall-effect switch.

The A4963 is a three-phase, sensorless, brushless DC (BLDC) motor controller for use with external complementary P-channel and N-channel power MOSFETs. It can be used as a stand-alone controller without requiring a local microprocessor or in a close-coupled system with a local microcontroller. The motor is driven using block commutation (trapezoidal drive) where phase commutation is determined, without the need for independent position sensors, by monitoring the motor back EMF. The sensorless start-up scheme allows the A4963 to operate over a wide range of motor and load combinations.

Dedicated circuits allow the device to operate over a wide range of motor speeds, from less than 100 rpm to in excess of 30,000 rpm, depending on the supply voltage and motor capability. Several operational modes are available including duty-cycle (voltage) control, current (torque limit) control and closed loop speed control. Operating mode and control parameters can be altered through an SPI compatible serial interface.

Motor operation is controlled by a programmable PWM input that can be used to define the motor operating state and provide the proportional input for the selected operating mode.

Integrated diagnostics provide indication of undervoltage, overtemperature and power bridge faults and can protect the power switches under most short-circuit conditions. Faults are indicated by a single open-drain output than can be used to pull the PWM input low.

The A594x family is a new series of 3-phase brushless DC fan drivers that offer low audible noise and vibration in addition to improved efficiency. These new sinusoidal driven ICs include both sensorless and sensor-based commutated ICs. Typical IC features include: PWM duty or analogue voltage for speed control; adaptive phase advance for improved efficiency; rotor lock detection with auto restart; FG speed output; overcurrent protection; undervoltage lockout; thermal shutdown; and few external components for small PCB footprints and reduced system cost.

Target applications include desktop cooling/ceiling fans, notebook/PCs, refrigerator and other white-goods products, and other consumer/industrial fans and blowers. For automotive applications Allegro has a series of AEC-Q100 qualified fan driver ICs targeted at seat cooling fans, LED headlamp fans, and battery cooling fan applications.

The A1569 is a highly integrated solution that combines a Hall-effect switch with a linear, programmable current regulator, providing up to 150 mA to drive one or more LEDs. With the addition of only two passive components and one or more LEDs, the A1569 forms a complete, magnetically actuated lighting solution that is small, flexible, elegant, easy to design, rugged, and reliable. The A1569 features a highly sensitive chopper stabilised omnipolar Hall-effect switch, linear current driver with elegant ramp control of output current for LED fade on/off, output short circuit detection with shutdown, and thermal overload protection - all in a single integrated circuit. It is optimised for consumer electronics, white goods, boats, RVs, motorcycles, and interior and auxiliary automotive lighting applications such as glove boxes, centre consoles, vanity mirrors, trunks/boots and truck beds.

About Allegro

Allegro MicroSystems, LLC is a leader in developing, manufacturing and marketing high-performance semiconductors. Allegro's innovative solutions serve high-growth applications within the automotive market, with additional focus on office automation, industrial, and consumer/communications solutions. Allegro is headquartered in Worcester, Massachusetts (USA) with design, applications, and sales support centers located worldwide. Further information about Allegro can be found at www.allegromicro.com

Allegro MicroSystems Europe, headquartered in Chertsey, United Kingdom, is the European sales and marketing operation, and operates a network of representatives and distributors throughout Europe.  Allegro also has an engineering design centre in Edinburgh in Scotland and an application and marketing centre in Annecy in France.