Precision contactless position sensing.

The A31316 3D Hall-effect position sensor is the the latest addition to Allegro MicroSystems' 3DMAG™ line of 3D sensors. Offered in an industry-smallest 4 × 4 mm body PCB-less package, this new sensor is ideal for automotive safety and advanced driver assistance systems (ADAS) applications that require high levels of flexibility and reliable performance in harsh conditions such as powertrain and chassis applications, as well as industrial applications that require linear or rotary sensing.

Powertrain and chassis applications, passenger restraint systems, and shifter systems, are subjected to environmental vibrations and contaminants that can degrade performance. The position sensors used in powertrain and chassis applications typically require support components, like PCBs and capacitors, and—when a position sensor is required in a dirty, high-vibration environment—the assembly of system components can become corrupted by debris and vibration, which can inhibit the performance of the assembly. The same is true for many industrial linear and rotary sensing applications. Designers are challenged to fit robust designs within the allotted dirty, high-vibration space.

The A31316 3D Hall sensor eliminates the need for a PCB or other external components. This sensor integrates the die and capacitors in a single package to address the need for high-performance, compact position sensors that are robust to these environments. For vibration-robust designs, the A31316 pins can be welded or soldered directly to connector leadframes and can be overmolded or potted for a tight seal. These integration options greatly reduce the ability for contaminants and vibration to affect performance and can bring new design flexibility to spaces where mechanical vibration and contamination are potential issues.

Designed for both rotary and long-stroke linear applications, the A31316 maintains high angle accuracy across the full Grade 0 temperature range (–40°C to 150°C). Its flexible calibration table (33 fixed points or 22 freely placed points) enables options that can reduce the time and complexity of end-of-line calibration and minimise errors due to mechanical misalignment. The A31316 contains advanced on-chip diagnostic features to ensure reliable, safe operation.

“Vehicles are becoming more complex with each passing year, and the number of sensors needed in modern safety and ADAS applications is increasing rapidly. System designers are looking for options that are both flexible and robust, and the A31316 meets that need,” says Scott Milne, Business Line Director for Position Sensors at Allegro. “It’s a great option for safety-critical applications—such as restraint and shifter systems, parking locks, and inhibitor switches—or for challenging applications—such as transmissions and braking systems, where heat and moisture can degrade performance. We’re excited to enable the next generation of vehicle safety systems with this technology.”

The 3DMAG family of rotary and linear magnetic position sensor ICs for automotive and industrial applications combine Allegro’s proven planar and vertical Hall-effect technologies to measure magnetic field components along three axes (X, Y, Z), enabling true 3D sensing capabilities with a wide magnetic dynamic range without saturation. The newest addition to Allegro’s 3DMAG family of magnetic sensors, the A31316, is Allegro’s first magnetic position sensor to provide multi-direction measurement in a PCB-less SIP package. The A31316 provides designers with a configurable signal path and flexible linearisation for end-of-line calibration to optimise measurement accuracy. The IC can compensate for nonlinear fields and static sensor-to-magnet misalignment errors, and the high degree of configurability makes it easy for designers to optimise for accuracy and calibration time. This helps minimise processing in the electronic control unit (ECU) and maximises end-of-line yield for nonideal magnets and mechanical assembly tolerances. Multi-level output using binning can integrate the functions of multiple magnetic switch ICs into a single A31316.

Advanced Functionality Ensures High Performance.
The A31316 integrates a Manchester interface for programming the EEPROM through the output pin, which eliminates the need for a separate programming interface. It reliably stores factory and customer-programmed calibration settings, with dedicated registers for customer use. A high-voltage supply is not required for EEPROM programming, and the A31316 can be programmed directly with a 5 V supply voltage enabling integration with microcontrollers or other low supply devices.

The IC includes the industry’s fastest SENT protocol with 0.5 µs to 10 µs tick times, and includes a pulse-width modulation (PWM) interface with 125 Hz to 16 kHz carrier for simple digital interface to microcontrollers.

Following Safety Element out of Context (SEooC) functional safety guidelines, the A31316 sensor supports ASIL B system-level integration in accordance with ISO 26262 and is automotive qualified to AEC-Q100 Grade 0.

The A31316 is available in a three-pin PCB-less SIP package (UC suffix).

@allegromicro @NapierPR #Transport

Tiny Hall-effect sensor.

Industry’s smallest sine/cosine 3D position sensor.

A new A33230 sine/cosine 3D Hall-effect position sensor IC has been announced by Allegro MicroSystems. The A33230 is the smallest sine/cosine 3D sensor currently available in the market, and offers system designers a cost-effective solution for automotive and industrial applications with a quick time to market.

Pricing and Availability

The A33230 is available in a 5-pin SOT23-W package (suffix LH). The package is RoHS compliant and lead (Pb) free with a 100% matt-tin leadframe plating. For product pricing and samples, contact an Allegro sales office or authorised distributor. For datasheets and more information on Allegro’s comprehensive magnetic position sensor family, including the A33230, please visit the Allegro website.

The A33230 contains two discrete analogue signal paths for superior high-speed performance, and the tiny SOT23-W package size makes it ideal for situations where PCB space is at a premium. The IC can also be used as an angle sensor, provided the system includes an electronic control unit (ECU) capable of performing CORDIC calculations on the two outputs.

The A33230 incorporates vertical and planar Hall-effect elements with sensing axes that are orthogonal to one another, providing 90° of phase separation, which is inherently independent of magnet pole spacing and air gap. It comes pre-programmed to measure angle in any plane (XY, XZ, or YZ) while providing independent sine and cosine outputs.

“With the ability to sense fields in X, Y and Z planes, Hall-effect sine/cosine sensors are reliable, proven options for many applications,” said Scott Milne, Business Unit Director for Position and Angle Sensors at Allegro. “The introduction of the A33230 gives Allegro customers access to an expanded selection of position and angle sensors for automotive and industrial applications such as factory robotics, windshield wipers, in-cabin motors and more. It’s a cost-effective solution with a small footprint that makes it ideal for legacy applications where a designer needs to minimize PCB size, or is looking for an opportunity to reduce BOM cost.”

@allegromicro @NapierPR #Pauto

Automotive safety systems enhanced by acquisition.

Acquisition pairs leading eye-safe photonics with Allegro’s extensive portfolio optimized for high growth ADAS applications in semi-autonomous and autonomous vehicles

Allegro has acquired Voxtel, Inc, a privately held company specializing in advanced photonic and 3D imaging technology including long-range, eye-safe Light Detection and Ranging (LiDAR). This acquisition brings together Voxtel’s significant laser and imaging expertise with Allegro’s automotive leadership and scale to enable the next generation of Advanced Driver Assistance Systems (ADAS).

Typical Voxtel Photoreceiver

LiDAR Enables Safer, Smarter Vehicles

LiDAR typically uses lasers, photodetectors, and read-out integrated circuits (ROICs) with time-of-flight (TOF) capability to measure distance by illuminating a target and analyzing the reflected light. LiDAR technology provides the high-resolution, three-dimensional infor-mation about the surrounding environment necessary to make fully autonomous driving a reality. It also supports adaptive cruise control, complements car cameras and radar and adds situational awareness.

Voxtel has been pioneering photonics since 1999, developing cutting-edge solutions for aero, space, automotive and surveillance applications. Its ultra-miniature lasers, read-out integrated circuits (ROICs), and near-infrared (NIR) and short-wavelength infrared (SWIR) photodetectors, supported by more than 38 US patents, represent one of the broadest LADAR/LiDAR photonic technology suites available in the market today. Allegro’s innovative portfolio of motor drivers, position sensors, regulators, and current sensors, when combined with photonics, provides most of the key semiconductor components in the transmit and receive blocks of automotive LiDAR systems. This increases Allegro’s foothold in the car of the future.

“Allegro is a market leader in magnetic sensors for the automotive market. Annually, we ship more than 1 billion devices into automotive systems – 100 million of which are shipped into advanced automotive safety systems, including semi-autonomous vehicle systems,” said Ravi Vig, CEO of Allegro. “Our experience, scale and design for quality uniquely position us to enhance the Voxtel LiDAR portfolio for ADAS applications, aiming to make LiDAR systems safer, cost-effective, and widely adopted features in the cars of the future.”

Historically, a barrier to broad adoption of LiDAR technology in vehicles has been the restriction of maximum power output of the laser in order to comply with eye safety guidelines. As a result of this acquisition, Allegro’s photonics portfolio now includes devices made in silicon and InGaAs, providing components for both eye-safe, long-range 1D or 2D scanned front-facing LiDAR and side- or rear-facing FLASH LiDAR. Devices based on InGaAs operate at wavelengths at which the human eye is less sensitive (1500 – 1600nm), enabling higher laser power levels for longer range object detection beyond 200 meters.

“We are combining Voxtel’s proven LiDAR technology born out of an impressive history in ranging and space applications, with Allegro’s automotive expertise, world class IC design, proven quality systems, and high-volume manufacturing proficiency,” said Mike Doogue, Senior Vice President of Business Development. “Our OEM and Tier-1 customers will now have access to this advanced technology with Allegro’s assurance of world-class global support and the scale needed to support automotive manufacturing volumes.”

@allegromicro @ArmitageComm #Voxtelopto #Automotive

Speed & Direction sensing.

Latest addition to Allegro’s transmission speed sensor family improves system design efficiency for optimal fuel economy

The ATS19580, just announced by Allegro MicroSystems, is the industry’s first fully-integrated, back-biased giant magneto-resistive (GMR) transmission speed and direction sensor. Achieving the highest level of in-system performance for this application, the ATS19580 reduces system size, complexity and cost - resulting in improved fuel economy.

Combining GMR technology with Allegro’s transmission algorithms and packaging, the ATS19580 offers the highest performance transmission sensor to date, including:

• The widest dynamic range of operating air gap (50% larger)
• Industry-leading vibration immunity
• EMC protection
• Robust to common-mode stray fields

“By monolithically integrating our proprietary GMR technology with leading digital processing we’ve set a new standard for transmission speed sensing, achieving the highest level of in-system performance ever,” explains Peter Wells, Business Unit Director for speed sensors at Allegro. “The ATS19580’s ability to reach formerly unachievable airgaps with the best vibration performance on the market simplifies the customers Speed Sensor integration and allows them to design safe, fuel efficient systems.”

The device’s GMR technology improves performance and extends air gap capability over existing Hall solutions, which allows for more installation flexibility. Key in the automotive industry, this flexibility reduces system size, which in turn, reduces costs for automakers and improves fuel economy.

Monolithic integration not only allows for the highest levels of in-system performance - like vibration immunity, dynamic air gap capability, and accurate direction detection - it also allows for ease of design-in with IC, magnet, and protection components in a single, overmolded package. Allegro’s advanced digital algorithms in the ATS19580 also allow for flexible design-in and system compensation.

This back-biased IC is provided in a 3-pin SIP package (suffix SN) that is lead (Pb) free, with tin leadframe plating.

The ATS19580 complements Allegro’s recently released ATS19420 and ATS19520 fully-integrated, Hall-effect transmission speed sensors, as well as Allegro’s family of front-biased Hall-effect and GMR products for magnetic target sensing. These ICs, combined with the soon-to-be released ATS19480, a GMR transmission speed only sensor, provides customers the broadest portfolio of transmission speed sensors available on the market. All of these devices are built upon Allegro’s 20 years of application-specific experience and technological advancement - and in direct response to the needs of today’s automotive manufacturers.

#PAuto @allegromicro @ArmitageComm

Hall-effect sensor IC.

Allegro Microsystems Europe has announced the release of its A17301, a new Hall effect sensor IC ideal for two-wheeled vehicles, particularly in position and timing applications like speedometers and tachometers for engine control.

Integrating electromagnetic capability (EMC) components into a small SIP package, the A17301 is a robust solution for digital ring-magnet sensing or ferromagnetic target sensing when coupled with a back-biasing magnet. This new device eliminates the need for external filter capacitors while improving reliability and reducing the cost of a final sensor assembly. The IC incorporates dual Hall-effect elements with 2.2 mm spacing and signal processing that switches in response to differential magnetic signals.

“The A17301 uses Allegro’s differential architecture, which inherently avoids the flatline and chatter issues that single Hall element solutions often face,” explained Bob Fortin, Vice President of Allegro’s Sensor Business Unit. “This part is ideal for obtaining speed and duty cycle information for position and timing applications.”

The A17301 contains sophisticated digital circuits to reduce system offsets, to calibrate the gain for airgap independent switch points, and to achieve true zero-speed operation. Running mode recalibration provides immunity to environmental effects such as micro-oscillations of the target or sudden air gap changes. The use of a digital peak detector for output switching control ensures that the input signal is continuously and accurately tracked, regardless of the amount of signal shift between output edges.

Allegro’s A17301 is available in a 3-pin SIP (suffix UC). The package is lead (Pb) free with 100% matt-tin lead frame plating and an operating ambient temperature range of -40°C to 160°C.

@allegromicro #Transport

3-wire differential speed sensor IC.

Allegro MicroSystems has announced a new optimised Hall-effect three-wire differential speed sensor integrated circuit (IC) and permanent magnet pellet combination.

Their ATS668 has integrated EMC protection components to provide a user-friendly solution for true zero-speed digital gear tooth sensing. It is offered in a small single over-mould package that can be easily assembled and used in conjunction with a wide variety of gear tooth sensing applications. The ATS668 is designed for automotive transmission systems making it ideal for non-automotive applications such as recreational vehicles, industrial equipment, white goods, and exercise equipment.

The device incorporates a dual element Hall IC that switches in response to differential magnetic signals created by a ferromagnetic target. The IC contains a sophisticated compensating circuit designed to eliminate the detrimental effects of magnet and system offsets. Digital processing of the analogue signal provides zero-speed performance independent of air gap and dynamic adaptation of device performance to the typical operating conditions found in automotive applications (i.e. vibration and runout). High-resolution peak detecting DACs are used to set the adaptive switching thresholds of the device. Hysteresis in the thresholds reduces the negative effects of any anomalies in the magnetic signal associated with system or target anomalies typically seen in many automotive applications.

The fully integrated package and industry proven algorithm performance makes the ATS668LSM an ideal solution for a wide range of speed sensing needs. This device is available in a lead (Pb) free 3-pin SIP package (SM) with matt-tin leadframe plating.

@allegromicro #PAuto

Stamp out magnetic tampering!

The new A1266 from Allegro MicroSystems Europe is a unique 3-dimensional sensor IC incorporating a combination of vertical and traditional planar Hall-effect sensor ICs that can detect a magnetic field of either polarity in any direction. The omnipolar, omnidirectional sensitivity of the new device makes it ideal for detecting magnetic tampering in smart meters, ATMs, gambling/gaming machines, ticket machines and electronic locks. The A1266 can also serve as a general-purpose magnetic switch that is virtually insensitive to magnet orientation or polarity in applications such as games, consumer electronics and white goods. This compact surface-mount SOT23 IC is functionally equivalent to an array of three standard Hall-effect sensors mounted in three different orientations: something that is not possible using a single circuit board and all surface-mount components. With a typical BOP operating point of 25 G, the A1266 has higher sensitivity than most conventional Hall-effect switches, leading to high-sensitivity 3D tamper or proximity sensing in less space with lower assembly cost. Each device integrates, on a single silicon chip, three Hall-voltage generators, a small-signal amplifier, chopper stabilisation, a Schmitt trigger, and one or more NMOS outputs. Allegro’s proprietary dynamic offset cancellation technique means that the magnetic operating characteristics are specified across the operating voltage and temperature ranges. The A1266 is designed for operation in green and battery-powered systems; it can be powered from a 2.5 - 5.0 V supply and the average supply current is typically 7.5 µA at 2.5V. The operating temperature range is -40° to +85°C. Two configurations are available: one with a separate output for each sensing direction (X, Y, Z) and one with a combined output (X+Y+Z). Package type LH is a modified SOT23W surface-mount package that is RoHS-compliant and lead (Pb) free (suffix -T), with a 100% matt-tin plated leadframe.

Customer-programmable current-sensor IC in standard inline package.

Allows easy integration with magnetic core to create current-sensing module –

The new A1369 from Allegro MicroSystems Europe is a customer-programmable, high-accuracy linear Hall-effect-based current sensor IC packaged in a slimline 3-pin single-inline package which allows for easy integration with a magnetic core to create a highly accurate current sensing module.

The A1369 is designed for use with customer-provided steel or other ferromagnetic cores, where its programmable nature allows it to compensate for manufacturing tolerances in the final current sensing module assembly. The accuracy of the device is enhanced by the programmability of both the sensitivity and the quiescent output voltage (QVO - the output with no magnetic field present) on the output pin for end-of-line optimisation without the added complexity and cost of a fully programmable sensor.

The device features one-time programming using non-volatile memory to store the desired sensitivity and QVO for a given application or circuit. Allegro programs the sensitivity temperature coefficient and QVO temperature coefficient during end-of-line testing to minimise programming requirements for the customer.

The A1369 is a ratiometric Hall effect sensor IC that provides a voltage output that is proportional to the applied magnetic field. The quiescent voltage output is user adjustable around 50% of the supply voltage, and the output sensitivity is programmable within a range of 8.5 mV/G to 12.5 mV/G for the A1369-10 and 22 mV/G to 26 mV/G for the A1369-24.

The features of this linear device make it ideal for use in industrial applications requiring high accuracy and a guaranteed wide temperature range of –40°C to +85°C. Current-sensing modules using the A1369 can be used in a variety of applications including electric power distribution and solar and wind power applications.

The A1369 is available in a through-hole single in-line package (TO-92).

Direction detection sensor

The new A1233 from Allegro MicroSystems Europe is a dual-channel, Hall-effect direction detection sensor IC that provides digital output signals indicating the speed and direction of a rotating target.

The A1233 is a highly sensitive, temperature-stable magnetic sensing device ideal for use in ring-magnet based speed and direction systems in harsh automotive and industrial environments.

A key feature of the device is the fact that the Hall sensing elements are photolithographically aligned to better than 1 µm. This accurate mechanical location between the two active Hall elements eliminates the major manufacturing hurdle commonly encountered in fine-pitch detection applications.

The A1233 is a monolithic device containing two independent Hall-effect bipolar switches located 1.63 mm apart. It provides excellent speed and direction information for small-geometry targets. Extremely low-drift amplifiers guarantee symmetry between the switches to maintain signal quadrature. A patented high-frequency chopper-stabilisation technique cancels offsets in each channel and provides stable operation over the full specified temperature and voltage ranges.

The high-frequency chopping circuits also allow an increased analogue signal-to-noise ratio at the input of the digital comparators in the IC. As a result, the A1233 achieves industry-leading digital output jitter performance: something that is critical in high-performance motor commutation applications.

An on-chip low dropout (LDO) regulator allows the A1233 to be used over a wide operating voltage range. Post-assembly factory programming at Allegro provides sensitive switch-points that are symmetrical between the two switches.

The A1233 is available in a plastic 8-pin SOIC surface mount package (L) and a plastic 4-pin single-inline package (K). Both versions are available for a temperature range from -40°C to +150°C. Each package is lead (Pb) free, with 100% matt tin-plated leadframe.

Bipolar Hall-effect switch offers excellent repeatability

General-purpose device offers temperature stability and stress resistance -

New from Allegro MicroSystems Europe, the A1250 is a bipolar Hall-effect switch IC incorporating a high-speed chopping circuit which cancels out offsets and dramatically improves switching repeatability through enhanced temperature stability and stress resistance.

The new device is especially suited for operation over extended temperature ranges to +150 °C. This superior high-temperature performance is made possible through dynamic offset cancellation, which reduces the residual offset voltage normally resulting from device overmoulding, temperature dependencies, and thermal stress.

The A1250 includes, on a single silicon chip, a voltage regulator, Hall voltage generator, small-signal amplifier, chopper stabilisation, Schmitt trigger, and a short-circuit-protected, open-collector output. Advanced BiCMOS wafer fabrication processing takes advantage of low-voltage requirements, component matching, very low input-offset errors, and small component geometries.

The device can act as a latch, with a south pole of sufficient strength turning the output on, and a north pole turning the output off. It can also act as a switch because there is no switch point symmetry around zero Gauss.

An on-board regulator permits operation with supply voltages from 3.0 to 24 V. The advantage of operating at 3.0 V is that the device can either be used in 3 V applications or, with additional external resistance in series with the supply pin for added protection, in applications that can supply higher voltages.

The A1250 is targeted at the automotive, industrial and consumer markets.

Two package styles provide a magnetically optimised package for most applications. Package type LH is a modified SOT-23W surface-mount package, while the UA package is a three-lead, ultra-miniature single-inline package for through-hole mounting. Each package type is available only as lead (Pb) free with a 100% matt tin-plated lead frame.

Hall-effect sensor IC

Customer-programmable linear Hall-effect sensor IC with pulse-width-modulated two-wire output

The new A1357 from Allegro MicroSystems is a high-precision, customer-programmable, linear Hall-effect sensor IC with a pulse-width-modulated current-sourced two-wire output.

Featuring a wide ambient temperature range of -40°C to +150°C, the A1357 device is targeted at the automotive and industrial sectors, particularly in applications where signals have to travel over relatively long distances in noisy environments.

The A1357 converts an analogue signal from its internal Hall sensor element to a digitally encoded PWM output signal with a frequency of 1 kHz and a duty cycle that is proportional to an applied magnetic field. The coupled noise immunity of the digitally encoded PWM output is far superior to the noise immunity of an analogue output signal.

The monolithic BiCMOS circuit in the A1357 integrates a Hall element, precision temperature-compensating circuitry to reduce the intrinsic sensitivity and offset drift of the Hall element, a small-signal high-gain amplifier, proprietary dynamic offset cancellation circuits, and PWM conversion circuitry. The dynamic offset cancellation circuits reduce the residual offset voltage of the Hall element, which is normally caused by device overmoulding, temperature dependencies, and thermal stress.

The high-frequency offset cancellation (chopping) clock allows for a greater sampling rate, which increases the accuracy of the output signal and results in faster signal processing capability.

The A1357 sensor IC is supplied in a lead (Pb) free 3-pin single inline package (KB suffix), with 100% matt tin lead-frame plating.

Two-wire Hall-effect latch

The A1244 from Allegro Microsystems,  is a two-wire Hall-effect latch featuring on-chip transient protection and a zener clamp to protect against overvoltage conditions on the supply line.

The new device, which is programmed at the factory to optimise the magnetic switch point accuracy, uses the same patented high-frequency, 4-phase, chopper-stabilisation technique that is used on the company's complementary family of unipolar switches. This results in lower noise on the output, less switch-point variation over temperature, and faster settling times.

The improvement in noise and switch-point drift allows the device to realise much better switching accuracy, which means better switching repeatability. Moreover, the improved high-voltage transient protection allows the A1244 to survive the conditions specified in ISO 7637-2 and 40 V load dump.
Allegro's advanced BiCMOS wafer fabrication process is used to achieve magnetic stability over temperature and to eliminate the offset inherent in single-element devices when exposed to harsh application environments.


Two-wire latches are particularly advantageous in cost-sensitive applications, such as automotive transmission position sensing and motor commutations applications, because they require one less wire for operation compared with the more traditional open-collector output latches. In addition, the user inherently gains diagnostic capabilities, because there is always current flowing at one of two specified levels. Any output current outside these two narrow ranges is a fault condition.

The A1244 is available in two package styles: the "LH" is a SOT-23W style, miniature low-profile package for surface-mount applications, and the "UA" is a TO-92 style, three-lead ultra-miniature single inline package (SIP) for through-hole mounting. The A1244 is also offered with two supply-current options: -I1 from 5.0 to 6.9 mA, and  -I2 from 2.0 to 5.0 mA.

Stepper motors

The A3981 and A4980 from Allegro MicroSystems Europe are two new automotive-grade programmable stepper-motor driver ICs that are designed to operate bipolar stepper motors in full-, half-, quarter- and sixteenth-step modes at up to 28 V and ±750 mA in automotive, consumer and industrial applications.

Both devices offer a single-chip solution with internal digital timing circuitry and a built-in translator for ease of operation. The A3981 can be controlled by simple step and direction inputs, or through an SPI-compatible serial port that also can be used to program many of the integrated features and to read diagnostic information.

The A4980 is identical to the A3981 except for a low-voltage operation feature which will allow the IC to run down to a load supply voltage of 3.3 V (compared with 7 V on the A3981). This low voltage operation may be necessary in some automotive applications where the battery voltage during cold cranking can drop to a critically low level.

The built-in current regulator can be programmed to operate in fixed off-time or fixed-frequency PWM modes, with several decay modes available to reduce audible motor noise and increase step accuracy. In addition, the phase current tables can be programmed via the SPI interface to create unique microstepping current profiles to further improve motor performance for specific applications.

The current in each phase of the motor is controlled through a DMOS full bridge, using synchronous rectification to improve power dissipation. Internal circuits and timers prevent cross-conduction and shoot-through when switching between high-side and low-side drives. The outputs are protected from short circuits, and features for low load current and stalled rotor detection are included. Chip-level protection includes hot and cold thermal warnings, overtemperature shutdown, and overvoltage and undervoltage lockout.

The A3981 and A4980 are supplied in a 28-pin TSSOP power package with an exposed thermal pad (package type LP). This package is lead (Pb) free with 100% matt-tin lead-frame plating.

Two-wire Hall-effect unipolar switches

The new A1152/3/5/6 from Allegro MicroSystems Europe are a range of two-wire unipolar Hall-effect switches designed for automotive sensing applications in seat-belt buckle, seat position, and steering lock applications.

The new devices are produced using the Allegro® advanced BiCMOS wafer fabrication process, and include improved high-voltage transient protection: a critical factor for automotive applications where external protection circuitry cannot be located close to the sensor.

These Hall-effect switches are factory trimmed to optimise the accuracy of the magnetic switch points, and employ a patented high-frequency four-phase chopper-stabilisation technique to achieve magnetic stability over temperature and to eliminate the offset inherent in single-element devices, when exposed to harsh automotive environments. The advanced chopping technique also provides significantly reduced jitter and shorter power-on times.

Two-wire unipolar switches require one less wire for operation than the more traditional open-collector output switches, and also offer diagnostic capability as there is always current present at one of two specified levels. Any output current outside these two narrow ranges is a fault condition.

In addition to the on-chip transient protection, a Zener clamp protects against overvoltage conditions on the supply line. The enhanced high-voltage transient protection allows these devices to survive ISO 7637-2 and 40 V load dump for up to 0.5 seconds with minimal, and sometimes no, protection from discrete components. Electrostatic discharge protection has also been enhanced to the extent that the devices are capable of handling a transient of 8.0 kV Human Body Model (HBM).

The A1152/3/5/6 devices are utilised in automotive applications to sense seat track position, seat-belt buckle presence, bonnet and boot latching, and steering-lock position, as well as in gear-shift selectors.

All family members will be offered in two package styles: the SOT-23W miniature low-profile package for surface-mount applications (suffix LH) and the TO-92 style three-lead "ultra-mini" single inline package (SIP) for through-hole mounting (suffix UA).

Smoke detector application

Smoke-detector integrated circuit features ultra-low current consumption and networking capability

The new A5303 from Allegro MicroSystems Europe is a low-current BiCMOS photoelectric smoke detector integrated circuit designed to be used with an infrared optical chamber to sense light scattered from smoke particles.

Key features of the new device include 3 V operation with ultra-low standby current that results in an average 10-year battery life, plus a networking capability that allows units to be interconnected so that if any unit senses smoke all units will sound an alarm. Also included are a latching alarm indicator and a timer function that minimises standby power consumption by controlling the duration of the reduced sensitivity period.

The A5303 incorporates a variable-gain photo-amplifier which can be directly interfaced to an infrared emitter-detector pair. The amplifier gain levels are determined by two external capacitors, and are internally selected depending on the operating mode. Low gain is selected during standby and timer modes. During a local alarm, this low gain is increased (internally) by approximately 45% to provide hysteresis. High gain is used during pushbutton test and to periodically monitor the chamber sensitivity during standby.

The internal oscillator and timing circuitry minimise standby power by sensing for smoke for only 100 µs in every ten seconds. A special three-stage-speedup sensing scheme is incorporated to minimise the time to an audible alarm and also to reduce false triggering. Chamber sensitivity is periodically monitored, with two consecutive cycles of degraded sensitivity required for a warning signal to occur.

The A5303 is supplied in a low-profile (less than 1.2 mm overall height) 20-pin TSSOP package (0.65 mm nominal lead pitch). The package is lead (Pb) free with 100% matt tin lead-frame plating.

DC motor pre driver IC

The new A4936 from Allegro MicroSystems Europe is a three-phase brushless DC motor pre-driver IC targeted at applications within the office automation sector including laser printer and copier drum drives.

The new device incorporates outputs for the direct high-current gate drive of an all N-channel power MOSFET three-phase bridge with a maximum supply voltage of 38 V. Also included in the A4936 device are three Hall-element inputs, a sequencer for commutation control, fixed off-time pulse width modulation (PWM) current control, and locked-rotor detection.

Output current is scaled by the capability of the external MOSFETs, and locked-rotor detection delay is set by an external capacitor on the CLD terminal. The PWM, DIR, BRAKE and STOP inputs can be used to control motor speed, position, and torque. The motor speed can be determined using the motor's FG (frequency generator) coil signal, which is amplified and shaped with the internal differential amplifier and comparator to produce a digital FG signal output.

The external MOSFETs can be pulse-width-modulated by using an external signal on the PWM input or the internal PWM current regulator. In either case, the synchronous rectification capability of the A4936 reduces power dissipation by turning on the appropriate MOSFETs during current decay.

The Hall elements can be inexpensive types, and are used in conjunction with internal noise filtering to prevent false commutation signals. The A4936 provides a regulated 7.5 V supply to power the three Hall elements. Internal circuit protection includes thermal shutdown with hysteresis, undervoltage lockout and dead-time protection. Special power-up sequencing is not required. The operating temperature range is -20°C to +105°C.

The A4936 is supplied in a 5 x 5 mm, 32-terminal QFN package with exposed thermal pad. This small footprint package is lead (Pb) free with 100% matt tin leadframe plating.

Protection against voltage transients & high temps

Hall-effect latches withstand high-voltage transients and high temperatures

The new A1225, A1227 and A1229 from Allegro MicroSystems Europe are a family of Hall-effect latch ICs that combine enhanced protection against high transient voltages with the ability to operate over extended temperature ranges up to +150°C.

These extremely temperature-stable and stress-resistant sensor ICs are especially suited for applications that require high-voltage transient protection close to the sensors, but where space or distance considerations preclude the use of external protection devices. Typical uses include motor commutation in sunroofs and power windows within the automotive market.

The A1225/7/9 devices include Allegro’s advanced offset cancellation technique which, along with high-speed 4-phase chopping, gives lower noise on the output, less switch-point variation with temperature, and faster settling times. The resulting improvements in noise and switch-point drift lead to much better switching accuracy and repeatability.

Superior high-temperature performance is made possible through a Schmitt trigger circuit that maintains operate and release point symmetry by compensating for temperature changes in the Hall element. In addition, the internal compensation circuitry provides magnetic switch points that become more sensitive with temperature, hence offsetting the usual degradation of the magnetic field with temperature. The symmetry capability makes these devices ideal for use in pulse-counting applications where duty cycle is an important parameter.

The improved high-voltage transient protection allows the devices to survive the tests specified in ISO 7637-2 and a 40 V load dump for less than 0.5 s with minimal external protection. In addition, enhanced ESD (electrostatic discharge) prevention structures provide ESD protection of up to 8 kV HBM (human body model) without the need for external protection components.
The three basic devices (A1225, A1227 and A1229) are identical except for magnetic switch points. Each device includes, on a single silicon chip, a voltage regulator, Hall-voltage generator, temperature compensation circuit, signal amplifier, Schmitt trigger, and a buffered open-drain output to sink up to 25 mA. The on-board regulator permits operation with supply voltages of 3.8 V to 24 V.

The first character of the part number suffix determines the device operating temperature range, with suffix ” L” denoting -40°C to +150°C. Two package styles provide a magnetically optimised package for most applications. Suffix “LT” is a miniature SOT89/TO-243AA transistor package for surface-mount applications, while suffix “UA” is a 3-lead ultra-miniature single-inline package. Both packages are lead (Pb) free with 100% matt tin leadframe plating.