KMA221
Programmable angle sensor
Rev. 1 — 16 July 2013
Product data sheet
1. Product profile
1.1 General description
The KMA221 is a magnetic angle sensor module. The MagnetoResistive (MR) sensor
bridges, the mixed signal Integrated Circuit (IC) and the required capacitors are integrated
into a single package.
This angular measurement module KMA221 is pre-programmed, pre-calibrated and
therefore, ready to use.
The KMA221 allows user-specific adjustments of angular range, zero angle and clamping
voltages. The settings are stored permanently in a non-volatile memory.
1.2 Features and benefits
High precision sensor for magnetic
angular measurement
Single package sensor module with
integrated filters for improved
ElectroMagnetic Compatibility (EMC)
Automotive qualified in accordance with
AEC-Q100 Rev-G
Programmable user adjustments,
including zero angle and angular range
Fail-safe non-volatile memory with write
protection using lock bit
Independent from magnetic field
strength above 35 kA/m
Ready to use without external
components
High temperature range up to 160
C
Analog ratiometric output voltage
Overvoltage protection up to 16 V
Programming via One-Wire Interface
(OWI)
User-programmable 32-bit identifier
Magnet-loss, power-loss and broken
bond wire detection
Factory calibrated
NXP Semiconductors
KMA221
Programmable angle sensor
2. Pinning information
Table 1.
Pin
1
2
3
4
Pinning
Description
analog output or data interface
ground
supply voltage
not connected
Simplified outline
Symbol
OUT/DATA
GND
V
DD
n.c.
1
2
3
4
3. Ordering information
Table 2.
Ordering information
Package
Name
KMA221
SIL4
Description
plastic, single in-line package
Version
SOT1188-1
Type number
KMA221
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2013. All rights reserved.
Product data sheet
Rev. 1 — 16 July 2013
2 of 36
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Product data sheet
Rev. 1 — 16 July 2013
3 of 36
KMA221
V
DD
ANALOG
VOLTAGE
REGULATOR
(CLEAN)
ANALOG
VOLTAGE
REGULATOR
(SWITCHING)
DIGITAL
VOLTAGE
REGULATOR
POR
UNDERVOLTAGE
DETECTION/
POR
POWER-LOSS
DETECTION
POWER-LOSS
DETECTION
GND
LOW-PASS
FILTER
MULTIPLEXER (MUX)
4. Functional diagram
NXP Semiconductors
All information provided in this document is subject to legal disclaimers.
MAGNETORESISTIVE
SENSOR BRIDGES
Cblock
differential
amplifier
output
buffer
ADC
OSCILLATOR
DAC
OUT/DATA
LOW-PASS
FILTER
ONE-WIRE
INTERFACE
GND
CL
DEMUX
NON-VOLATILE
MEMORY
TEST
CONTROL
CLOCK
GENERATOR
DIGITAL
FILTER AND
AVERAGING
OFFSET
CORRECTION
ANGLE
CALCULATION
ANGULAR
RANGE
ADJUSTMENT
SERIAL
INTERFACE
GND
SIGNAL CONDITIONING INTEGRATED CIRCUIT
INTEGRATED
CAPACITANCES
001aan661
Programmable angle sensor
© NXP B.V. 2013. All rights reserved.
KMA221
Fig 1.
Functional diagram of KMA221
NXP Semiconductors
KMA221
Programmable angle sensor
5. Functional description
The KMA221 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. After a digital-to-analog conversion, the
analog signal is provided to the output as a linear representation of the angular value.
Zero angle, clamping voltages and angular range are programmable. In addition, two
16-bit registers are available for customer purposes, such as sample identification.
The KMA221 comprises a Cyclic Redundancy Check (CRC) and an Error Detection and
Correction (EDC). It also has magnet-loss and broken bond wire detection to ensure
a fail-safe operation. If either the supply voltage or the ground line of the mixed signal IC
is interrupted, a power-loss detection circuit pulls the analog output to the remaining
connection.
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 internal
Digital-to-Analog Converter (DAC) and analog output stage are used for the conversion of
the angle information into an analog output voltage, which is ratiometric to the supply
voltage.
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.
KMA221
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2013. All rights reserved.
Product data sheet
Rev. 1 — 16 July 2013
4 of 36
NXP Semiconductors
KMA221
Programmable angle sensor
α
H
ext
1
2
3
4
008aaa276
Fig 2.
Angular measurement directions
Since the Anisotropic MR (AMR) effect is periodic over 180, the sensor output is also
180-periodic. The angle is calculated relative to a freely programmable zero angle. The
dashed line indicates the mechanical zero degree position.
6. Analog output
The KMA221 provides one analog output signal on pin OUT/DATA. The measured angle
is converted linearly into a value, which is ratiometric to the supply voltage V
DD
. Either a
positive or a negative slope is provided for this purpose.
Table 3
describes the analog output behavior for a positive slope. For example, if
a magnetic field angle, above the programmed maximum angle
max
but below the clamp
switch angle
sw(CL)
, is applied to the sensor, the analog output is set to the upper
clamping voltage. If the magnetic field angle is larger than the clamp switch angle, the
analog output switches from upper to lower clamping voltage. If there is a negative slope,
the clamping voltages are changed.
Table 3.
Analog output behavior for a positive slope
Analog output
V
(CL)u
V
(CL)l
Magnetic field angle
max
<
<
sw(CL)
sw(CL)
<
<
ref
+ 180
The analog output voltage range encodes both angular and diagnostic information. A valid
angle value is between the upper and lower clamping voltage. If the analog output is in the
diagnostic range, that is below 4 %V
DD
or above 96 %V
DD
, an error condition has been
detected. The analog output repeats every 180.
KMA221
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2013. All rights reserved.
Product data sheet
Rev. 1 — 16 July 2013
5 of 36
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