KMA200 datasheet(4/33 Pages) PHILIPS

4 / 33 page

KMA200

All information provided in this document is subject to legal disclaimers.

Product data sheet

Rev. 8 — 7 December 2011

4 of 33

NXP Semiconductors

KMA200

Programmable angle sensor

Functional description

The KMA200 amplifies two orthogonal sinusoidal signals delivered by the MR-sensor

element and converts them into the digital domain. Using the COordinate Rotation DIgital

Computer (CORDIC) algorithm, the angle is calculated. Angle output is either analog or

digital. The KMA200 comprises diagnostic features that ensure a complete online

supervision of all essential functional blocks including verification of input and output

signals and temperature supervision. In addition, the circuit is protected against reverse

polarity, overvoltage and short circuit at all external pins.

Two instrumentation amplifiers and

-modulators convert the amplified signals into two

high-speed digital bit streams. The bit streams are filtered and decimated by two digital

decimation filters to obtain digital signals with higher resolution at a lower speed.

Further processing is done within an on-chip calibration microcontroller. This includes

offset cancellation, calculation of the mechanical angle using the CORDIC algorithm,

zero-angle and angular-range adjustment.

In addition, the calibration microcontroller performs diagnostic tasks to ensure the validity

of its results. The calibration microcontroller takes calibration constants from an on-chip

EEPROM and stores intermediate results in a Random Access Memory (RAM). The

calculated angle is given out either digitally with an SPI-compatible serial interface or

analog via the analog output stage. Several output characteristics can be selected.

In case of analog output the analog output stage is used for conversion of the angle

information into two analog output voltages ratiometric to the supply voltages. For this

purpose, the analog output stage contains two resistor-string Digital-to-Analog Converters

(DACs) which share the same resistor string. The two analog output voltages are buffered

by two offset-compensated amplifiers.

The internal circuitry is protected against overvoltage with special protection circuits.

Protection against reverse polarity is realized with the help of a current limiting circuit.

In addition, there are various support circuits like bias generators, a free-running oscillator

including an oscillator fail-safe circuit and a power-on reset circuit which generates a reset

in dependence of the supply voltage.

KMA200 Datasheet(PDF) 4 Page - NXP Semiconductors