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Sensor Technology I Product News

Linear current-sensor IC thermally enhanced for high precision

New from Allegro MicroSystems Europe the ACS770 is a fully integrated Hall-effect based linear current sensor IC that incorporates thermal enhancement for high precision. 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.

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. Device accuracy is optimised through the close

proximity of the magnetic signal to the Hall transducer. A precise output voltage that is proportional to the current flowing in the conductor is provided by the low-offset chopper- stabilised BiCMOS Hall IC, which is programmed and calibrated for accuracy at the factory. Low power loss results from the fact that the internal resistance of this conductive path is typically only 100 microhms. Allegro’s proprietary integrated shield technology provides high-level immunity to potential interference from current variations in the conductor path and stray electric fields, resulting in 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 at high overcurrent conditions. The terminals of the conductive path are electrically isolated from the signal leads, allowing the ACS770 sensor ICs to be used in applications requiring electrical isolation without the use of opto-isolators or other costly isolation techniques.

The new device is targeted at the automotive, industrial and renewable energy markets. The ACS770 family is lead (Pb) free. All leads

are plated with 100% matt tin, and there is no lead inside the package. The heavy gauge lead frame is made of oxygen-free copper. The ACS770 is available in a 5-pin package (suffix CB).

Allegro Microsystems |

Intersil introduces high reliability temperature sensor for space systems

Intersil Corporation has introduced the ISL71590SEH, a radiation-hardened, low power, current output temperature sensor able to deliver a high level of accuracy over radiation exposure, time and temperature. The temperature sensor is suitable for remote temperature sensing in satellites and other space applications. Developers of the most advanced next generation satellite systems require temperature sensors that provide accuracy over the mission life of a satellite, eliminating the need for expensive radiation lot acceptance testing or spot shielding. With the ISL71590SEH’s +/-1.7°C accuracy over temperature and at most -1°C change in accuracy over low dose rate radiation, the device is able to serve satellite temperature sensing functions that support most of a system’s telemetry data and calibration accuracy. It provides highly accurate, reliable temperature sensing and linearity over the full military temperature range of -55°C to 125°C, as well as over 50krad (Si) low dose rate and 300krad (Si) high dose rate irradiation. The ISL71590SEH temperature sensor features a high impedance current output that allows the part to be insensitive to voltage drops across long wires. With a voltage between 4V and 33V on

Vishay streamlines touchless remote control with new gesture control sensor board

A streamlined method of adding touchless swipe right, swipe left, proximity, and tap control to any device by using a digital proximity sensor and two discrete infrared emitters has been developed by the Optoelectronics group of Vishay Intertechnology. The gesture control sensor board consists of a Vishay Semiconductors VCNL4020 integrated proximity and ambient light sensor and two of Vishay's VSMF2890RGX01 infrared diodes mounted on either side of the sensor. The detection of gestures using these components is accomplished by comparing the signal of infrared light coming from each of the emitters. The emitted infrared light is reflected off an object - a hand, for example - and then detected by the VCNL4020 proximity sensor. In order to differentiate between the signals coming from either emitter, the emitters are multiplexed, meaning they are pulsed one after the other in quick succession. A high radiant intensity of 80 mW/sr typical at 200 mA allows for the detection of hand gestures up to 25 cm above the sensor board. The proximity signal is then read out between each pulse via the I”C bus interface. When a hand is in the proximity of the board, it will reflect more of the signal from the emitter over which it is directly located. If the hand is then moved across the board, the signal from one emitter will increase before the other. It is this

time difference of signal strength that is analysed to determine if a swipe gesture was made and in which direction. Sensors that recognise and respond to hand

gestures are being designed into consumer products with increasing frequency. For example, users can advance to the next page of a recipe displayed on a tablet PC without touching the screen.

The Vishay gesture control sensor board supports swipe right, swipe left, tap, and push in and out. For example, swipe right and left would be used to move to the next or previous page, picture, or selection. Tap would be used to make a specific selection and would be similar to touching the screen. Push in and out would be used to zoom in or out, turn the volume up or down, or change backlighting intensity.

Vishay Intertechnology |

High sensitivity dual element thermopile sensor targets gas analysis applications

Hamamatsu Photonics have developed a new series of thermopile infrared detectors designed to meet the growing demand for low cost sensors with high S/N for gas analysis applications.

the input pin, the ISL71590SEH acts as a temperature sensitive current source with a scale factor of 1 A/K (i.e. 1 A/°C). It operates in the full temperature range without the need of additional circuitry, to produce results with ±1.7°C accuracy. The device also offers power advantages, with

requirements as low as 1.5mW (5V supply at 25°C). This allows it to be used in satellite signal chains and in applications such as temperature compensation networks, flow rate analysis, and biasing proportional to temperature.

Intersil |

The T11722-01 is a high sensitivity dual element thermopile sensor with a D* of 1.3x108. The sensor is housed within a compact TO-5 package with two bandpass filtered windows

transmitting at 3.9μm and 4.3μm, making it suitable for CO2 detection. This approach gives a simultaneous reference and gas absorption signal from a single package. The T11722-01 also benefits from a low element resistance and low temperature coefficient of element resistance (TCR).

Thermopile sensors are created by connecting a number of thermocouples in series, where a thermocouple is a junction between two different metals that produces a voltage related to a temperature gradient across the junction. The device’s output is proportional to incident radiation (DC coupled) and the detector features

very low impedance compared to a pyroelectric sensor which allows for simplified associated circuitry for the thermopile and less affects from extraneous radiation and electrical noise. Compact and low cost T11722-01 is intended for CO2 monitoring in the environmental, medical, process control and security industries.

Hamamatsu Photonic |

New IO-Link reference design for small scale smart industrial sensors

Renesas Electronics Europe has released a new reference design for small scale IO-Link smart industrial sensors. The solution, the result of cooperation between Renesas and TMG Technologie und Engineering and Maxim Integrated, combines Renesas’ RL78, its 16-bit ultra-low power microcontroller, an IO-Link transceiver and a miniature sensor from Maxim Integrated. TMG completes the solution from the software and applications side with its IO- Link v1.1 device stack operating on the microcontroller. The IO-Link protocol is an open standard

according to IEC61131-9, making use of conventional 3-wire sensor cables for the transmission of serial digital communications

38 December 2013/January 2014

between sensors/actuators and industrial automation systems. Renesas is introducing the RL78

microcontroller family into IO-Link applications for designers looking to bring smart and intelligent features to miniature sensors. The solution fits on a PCB and can interface directly with the board via an industry standard M12 connector and cable. The board offers a debug interface that allows users to flash/debug the on-board microcontroller and to develop their own applications. The board comes with a full software evaluation setup and a programming/debugging adapter doubling as an extended prototyping area. The reference design includes a RL78/G1A

Components in Electronics

microcontroller and new features include: 64KB on-chip programmable flash memory with 1.8V operating voltage, high accuracy 12- bit A/D converters, and 32MHz high speed on- chip oscillator with +/- 1% accuracy over the temperature and voltage range. The RL78/G1A features 4KB on-chip data flash with background operation for IO-Link sensor data storage, numerous advanced safety features, an on-chip temperature sensor, 16-bit multifunction timers, and multiple serial communication channels for interfacing with sensor components. The on-board MAX44008 offers the user a variety of options for sensor application development. It integrates six sensors: red,

green, blue (RGB) sensors; an ambient light sensor; a temperature sensor; and an ambient infrared sensor with an I2C interface. The IO-Link device stack supports the IO- Link functionality according to specification V1.1. It is based on a modular software design with a strict separation of protocol stack, application and hardware abstraction. The stack provides performance and efficiency, whereby the sensor data is already prepared before the reception of the master command. It also ensures the consistent process data exchange.

Renesas Electronics |

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