KMA215 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2014. All rights reserved.
Product data sheet Rev. 1 — 24 February 2014 4 of 50
NXP Semiconductors
KMA215
Programmable angle sensor with SAE J2716 SENT
5. Functional description
The KMA215 amplifies two orthogonal differential signals from MR sensor bridges and
converts them into the digital domain. The angle is calculated using the COordinate
Rotation DIgital Computer (CORDIC) algorithm and transmitted in a SENT frame
compliant to SAE J2716 SENT standard. Zero angle and angular range are
programmable. In addition, eight 12-bit Original Equipment Manufacturer (OEM) registers
are available for customer purposes, such as sample identification.
The KMA215 comprises a Cyclic Redundancy Check (CRC) and an Error Detection and
Correction (EDC) for the non-volatile memory. It also has magnet-loss and broken bond
wire detection.
After multiplexing the two MR Wheatstone bridge signals and their successive
amplification, the signal is converted into the digital domain by an Analog-to-Digital
Converter (ADC). Further processing is done within an on-chip state machine. This state
machine controls offset cancelation, calculation of the mechanical angle using the
CORDIC algorithm, as well as zero angle and angular range adjustment. The SENT
protocol generator converts the angular information into SENT messages that are
repeatedly sent via the SENT output.
The configuration parameters are stored in a user-programmable non-volatile memory.
The OWI (accessible using pin OUT/DATA) is used for accessing the memory. In order to
protect the memory content, a lock bit can be set. After locking the non-volatile memory,
its content cannot be changed anymore.
5.1 Angular measurement directions
The differential signals of the MR sensor bridges depend only on the direction of the
external magnetic field strength H
ext
, which is applied parallel to the plane of the sensor.
In order to obtain a correct output signal, exceed the minimum saturation field strength.
