ADVANCED ON-CHIP LINEARIZATION IN THE A1335 ANGLE SENSOR IC
■Numerous applications in industries—spanning from industrial automation and robotics, to electronic power steering and motor position sensing—require monitoring the angle of a rotating shaft either in an on-axis or off-axis arrangement.
■The design of any successful angle measurement system for the above applications must be based on the needs of the particular application. These include: arrangement (off-axis or on-axis), air gap, accuracy, and temperature range, among others.
■A magnetic angle measurement system has two main sources of error:
◆Sensor IC related errors:
▲Intrinsic nonlinearity
▲Parametric temperature drift
▲Noise
◆Magnetic input related errors:
▲Field strength variation
▲Field nonlinearity
■Each Allegro angle sensor IC is tested and calibrated during production at Allegro using a homogenous magnetic field. As a result, intrinsic IC nonlinearity and temperature drift are reduced to a minimum before the angle sensor IC is shipped to customers. Refer to product datasheets for temperature drift information.
■When using a magnet in a design, the magnetic input will most likely not be homogenous over the entire range of rotation—it will have inherent errors. These magnetic input errors cause measurement error in the system.
■These factors become especially important when considering side-shaft or off-axis designs that have higher intrinsic magnetic errors. Even the most accurately calibrated angle sensor IC will produce inaccurate results if the error contribution from the magnetic input dominates. In most cases, even on-axis magnetic designs suffer from relatively large misalignments that occur during the assembly of the customer module in the production line. These magnetic error sources are inevitable and mitigating them is almost always expensive and often impossible.
■The approach of the Allegro A1335 angle sensor IC is to solve this problem by using advanced linearization techniques to compensate for these errors at the customer’s end-of-line manufacturing location.
■This document shows how magnetic-input-related errors in excess of ±20 degrees can be linearized by the A1335 to as low as ±0.3 degrees—roughly a 65× improvement.
■This linearization can be performed based on data from a single rotation of the target magnet around the angle sensor IC. The angle readings from this rotation are used to generate linearization coefficients which can then be stored into on-chip EEPROM, optimizing that angle sensor IC, for that magnetic system. Allegro can provide the necessary software and/or DLLs to help customers program these devices at their end-of-line
|
|
|
|
Solutions |
|
|
|
|
Please see the document for details |
|
|
|
|
|
|
|
|
|
|
|
English Chinese Chinese and English Japanese |
|
|
March 22, 2022 |
|
|
Rev. 1 |
|
|
AN296127 |
|
|
1.3 MB |
- +1 Like
- Add to Favorites
Recommend
All reproduced articles on this site are for the purpose of conveying more information and clearly indicate the source. If media or individuals who do not want to be reproduced can contact us, which will be deleted.
Integrated Circuits
Discrete Components
Connectors & Structural Components
Assembly UnitModules & Accessories
Power Supplies & Power Modules
Electronic Materials
Instrumentation & Test Kit
Electrical Tools & Materials
Mechatronics
Processing & Customization
