To introduce basic knowledge of Hall-effect sensors, and Allegro ACS current sensor IC family

1. Hall-Effect Based Current Sensors Source: Allegro Microsystems

2. Introduction Purpose To introduce basic knowledge of Hall-effect sensors, and Allegro ACS current sensor IC family Outline Hall-Effect sensors basics Hall-effect based current sensing technology ACS current sensor family ACS application examples Content 13 pages

3. Hall-Effect Basics Semiconductor material B = flux density d = plate thickness e = electron charge n = charge carrier density VH = -(I • B) / (d • e • n)

4. Hall-Effect Sensor ICs Linear output Hall-Effect Sensor ICs An amplifier and voltage regulator are used to improve the sensor’s output and allow it to operate over a wide range of supply voltage. Digital output Hall-Effect switches A Schmitt-trigger threshold detector and an open-collector NPN transistor gives the Hall-effect circuit digital output capabilities Analog Output Sensor Digital Output Switch

5. Hall-Effect Current Sensors Hall-effect sensor ICs are superb devices for ‘open-loop’ current-sensing designs. The magnetic field generated by the current is sensed by the integrated Hall IC and converted into a proportional voltage. High Current Applications Low Current Applications

6. Current Sensing for Energy Efficient Markets The prime applications for cost-effective Hall-effect sensors for current sensing include: Current Imbalance Current Monitoring Operator/User Safety and Security Overcurrent Detection/System Protection System Diagnosis and Fault Detection Test and Measurement Energy Efficient Appliances and Motor Control Hybrid Vehicle Renewable Energy Inverters / Metering

7. ACS71x Current Sensor ICs Measurement range up to ± 20A SOIC8 with integrated 1.2m Ω conductor Isolation for line power applications <4% typical error over -40 to 150ºC range Low noise, 80 KHz bandwidth current sensor Integrated shield reduces output spiking in high dV/dt applications Noise management Current path

8. ACS75x Current Sensor ICs Measurement range up to 200A Small physical size 100 µ Ω integrated conductor, galvanic isolation for line powered system Enhanced accuracy, typically < 4% total error from -40 to 150ºC range Low noise, > 100KHz bandwidth sensor IC Integrated shield reduces output spiking in high dV/Dt applications

9. Block Diagram Hall element

10. Chopper Stabilization Technique Chopper Stabilization minimize the offset voltage of a Hall element and an associated on-chip amplifier. This offset reduction technique is based on a signal modulation-demodulation process. A low-pass filter suppresses the modulated DC offset while the magnetically induced signal passes through the filter. The anti-aliasing filter prevents aliasing from happening in applications with high frequency signal components.

11. Application Example 1 – Battery Monitoring Using a Hall-effect device as a shunt solution provide higher accuracy for lower charge and discharge currents; This solution also provides more signal over the measurement range.

12. Application Example 2 – UPS The input and output currents of a UPS are monitored both for protection and to be able to show the battery state of charge with a level of confidence.

13. Additional Resource For ordering ACS current sensors, please click the part list or Call our sales hotline For more product information go to http://www.allegromicro.com/en/Products/Categories/Sensors/currentsensor.asp Visit Element 14 to post your question www.element-14.com For additional inquires contact our technical service hotline or even use our “Live Technical Chat” online facility Newark Farnell