Download KMA36-SPI Rotational and Linear Position Sensor IC SPECIFICATIONS

KMA36-SPI
Rotational and Linear Position Sensor IC
SPECIFICATIONS
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Contactless absolute 360° (180°) angle measurement
Programmable resolution up to 13 bit (0.04 degree)
Very low hysteresis
High accuracy mode
Incremental mode
Linear mode
Low power mode
Standard SPI interface (up to 2 MHz clock)
Sleep and automatic wake-up over SPI
Small Pb-Free package (TSSOP20)
RoHS compliant
For applications in harsh environments
The KMA36 is a highly reliable universal magnetic position sensor
IV for precise rotational or linear measurement with a resolution
up to 0.04 degree. This digital position sensor IC combines a
magnetoresistive sensor element along with analog to digital
converter and signal processing in a standard small TSSOP
package. By using Anisotropic Magneto Resistive (AMR)
technology, the KMA36 is able to determine accuractly and
contactless the magnetic angle of an external magnet over 360°,
as well as the incremental position on a magnetic pole strip with
5 mm pole length. Its sleep- and low power mode as well as
automatic wake-up over SPI make the KMA36 ideal for many
battery applications. Position data can be transmitted using a
PWM or digital two-wire (SDA, SCL) communication bus. Using
the programmable parameters of this digital position sensor, the
user can have access to a wide range of configuration to ensure
the maximum of freedom and functionalities.
Used both as a linear position sensor or a rotary position sensor,
the KMA36 magnetoresistive sensor IC is almost insensitive to
magnetic drift due to mechanical tolerances, changes in
temperature or thermal stress. The maintenance-free operation
and high bandwidth of this universal magnetic encoder makes it a
good choice for dynamic applications in harsh environments.
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KMA36-SPI
Contactless Rotational and Linear Encoder
KEY-FEATURES
Resolution
13 Bit / 0.04 degree
3.0 – 5.5V
Operating power supply range of 3V to 5.5V
Operating temperature
- 25 - +85 °C
Average current
10 – 30 mA
Sleep current
< 600uA (@VCC =3V)
Data Update rate
24 – 720 Hz
SPI Clockrate
Up to 2 MHz
APPLICATIONS
Industrial environment
Harsh environment
Handling machine
Machine tools
Robotics, IoT, process automation, general position feedback
Potentiometer replacement
Motor motion control
Simple but precise linear displacement
PIN ASSIGNMENT
Pin No.
KMA36
TSSOP
Symbol
Type
Description
1
NC
NC
Not connected
2
CS
I
SPI interface chip select pin
3
DVCC_SE
O
Drive pin to power sensor
4
DI
I
SPI interface data in pin
5
DO
O
SPI interface data out pin
6
SCK
I
SPI interface clock pin
7
GND_SE
S
Sensor supply ground pin
8
VCC_SE
S
Sensor power supply pin
9
NC
NC
Not connected
10
NC
NC
Not connected
11
NC
NC
Not connected
12
COILP
I
Coil power supply pin
13
COILN
I
Coil power supply pin
14
AREF
I
Asic analog reference
15
NC
NC
Not connected
16
GND_AS
S
Asic supply ground
17
NC
NC
Not connected
18
VCC_AS
S
Asic power supply
19
DCOILN
O
Drive pin to coil power supply
20
DCOILP
O
Drive pin to coil power supply
Figure 1: pin assignment
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KMA36-SPI
Contactless Rotational and Linear Encoder
ELECTRICAL CHARACTERISTICS
SENSOR
Magnet
Unless otherwise specified, all voltages are referenced to the
power ground supply VSS. Typical values are based on Top = 25
°C, VCC = 5 V. They are given only as design guidelines and are
not tested in production. Data based on characterization results,
design simulation and/or technology characteristics are indicated
in the table footnotes and are not tested in production.
AMPLIFICATION
Angle
MR
magnetic field
OP AMP
EVALUATION
Absolute maximum ratings are limiting values of permitted
operation and should never be exceeded under the worst possible
conditions either initially or consequently. If exceeded by even the
smallest amount, instantaneous catastrophic failure can occur.
And even if the device continues to operate satisfactorily, the
product lifetime may be considerably shortened.
COMMUNICATION
ADC
10 bit
PWM
PWM
CORE
Position
Parameter
I2C
ERROR
HANDLING
MODE
HANDLING
Figure 2: Functional block description
Absolute maximum ratings
CAUTION: Exceeding these values may destroy the product.
Symbol
Parameter
Condition
Min.
Typ.
Max.
Unit
Top
Operating temperature
- 25
+ 85
°C
Tsto
Storage temperature
- 40
+ 85
°C
Vcc
Operating voltage
2.9
6
V
Vin
Input voltage on any Pin
-0.5
6.5
V
Vin
Input voltage on A1
-0.5
13
V
Iin
DC Current through any I/O Pin
40
mA
Iin
DC Current through S Pin
200
mA
Max.
Unit
- 25
+ 85
°C
3
5.5
V
5.3
V
Except on A1
Table 1: Absolute maximum ratings
 Operating conditions
Symbol
Parameter
Condition
Min.
Typ.
Top
Operating temperature
Vcc
Operating voltage
Vin
Input voltage on I/O pin
-0.3
ARef
External Analog Reference
1.9
2.0
2.1
V
-
32
-
kΩ
RAREF
Analog Reference input resistance
Table 2: Operating conditions
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KMA36-SPI
Contactless Rotational and Linear Encoder

AC/DC characteristics
Symbol
Parameter
Condition
Min.
Iavg
Average current1)
Except in sleep
mode, Vcc = 5V
10
Isleep
Sleep current
Isleep
Typ.
Max.
Unit
30
mA
Vcc = 5V
1.2
mA
Sleep current
Vcc = 3V
600
uA
VIL
Input low voltage
Vcc = 5V, IOL = 10
mA
0.6
V
VIH
Input high voltage
Vcc = 5V, IOH = 10
mA
VOL
Output low voltage
Vcc = 5V, IOL = 10
mA
VOH
Output high voltage
Vcc = 5V, IOH = 10
mA
3
V
0.6
4.3
V
V
Table 3: AC/DC characteristics
1)
Current measurement has to been done with a standard circuit including a high impedance voltage divider on AREF
 System parameters
Symbol
Parameter
fdata
Update rate1)
tstart
Starting time
αr
Condition
Min.
Typ.
24
Max.
Unit
720 2)
Hz
5
ms
Resolution
H0=25 kA/m
Resolution
H0=25 kA/m
no missing codes
ΔαL
Linearity error
H0=25 kA/m 1)
Top=25°C
ΔαH
Hysteresis error
H0=25 kA/m 1)
Top=25°C
Vbwn
Brown-out reset voltage
tbwn
Brown-out reset pulse width
Hy
Applied magnetic field
15
25
60
kA/m
RCOIL
Internal coil resistance
75
100
150
Ω
αr
15
Bit
13
Bit
±0.3
±1
°
±0.1
±0.25
°
1)
1)
2.7
V
2
µs
Table 4: System parameters
1)
2)
System parameters apply only for recommended measurement setup (please refer to the arrangement section)
SPD Bit = 1, Oversampling = 2
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KMA36-SPI
Contactless Rotational and Linear Encoder
Update rate
fdata = 1 / (1.4 msec x oversampling / const)
SPD Bit
const
0
1
1
2
SPI INTERFACE
 Physical interface parameters
Symbol
Parameter
Clkrt
Clockrate
CSAL
Chip Select Active Level
Condition
Min.
Typ.
Max.
Unit
2
MHz
0
V
Table 5: Physical interface parameters
 Timing parameters
Symbol
Parameter
Condition
Min.
Typ.
Max.
Unit
SCK_tr
SCK Rise time
0.3
µs
SCK_tf
SCK Fall time
0.3
µs
CS_tr
CS Rise time
0.3
µs
CS_tf
CS Fall time
0.3
µs
Table 6: data timing parameters
 SCK
Figure 3: timing definitions
DI (input data) is sampled at positive edges, DO (output data) is changed at negative edges.
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KMA36-SPI
Contactless Rotational and Linear Encoder
 CS
The KMA36 is always operating as a pure slave.
CS = HIGH:
SPI-interface is disabled.
DO pin is set to tri state mode (high impedance).
Internal measurements are running continuously.
All registers (magnetic angle, incremental counter (if enabled) are updated at every
measurement cycle  please refer the update rate section).
CS = LOW:
SPI-interface is enabled.
DO pin is set to output mode.
Internal measurements are stopped.
CS must be hold LOW until all bytes are sent / received.
 DI
Data input (Master  KMA36). MSB first
 DO
Data out (KMA36  Master). MSB first
 Sending / Receiving data
Sending and receiving happens simultaneously. Every byte sent by the SPI-Master receives a return byte from the
KMA.
Byte
number
Send
Byte
Received
Byte
1
2
3
4
5
6
7
8
9
10
11
CONF
RES_high
RES_low
MASTER_CRC
dummy
dummy
dummy
dummy
dummy
dummy
dummy
dummy
MA_low
MA_high
MIA_Byte0
MIA_Byte1
MIA_Byte2
MIA_Byte3
CONF
RES_low
RES_high
KMA_CRC
 Configure the KMA36-SPI
Table 7: byte-order
For changing the configuration at least four bytes (including a valid MASTER_CRC byte) must be transmitted.
If less than 4 bytes - or an invalid MASTER_CRC byte - are received the data will be ignored and no configuration
changes happens..
Calculating the MASTER_CRC: 0xFF – (CONF + RES_high + RES_low) +0x01
Example:
CONF:
RES_high:
RES_low:
0x13
0x01
0x68
(MIAE enabled, Oversampling = 32)
(resolution = 360)
(resolution = 360)
 MASTER_CRC = 0xFF – (0x13 + 0x01 + 0x68) + 0x01 = 0x84
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KMA36-SPI
Contactless Rotational and Linear Encoder
 Receiving data
Reading data without changing the configuration is done by sending just dummy bytes including a NOT valid
MASTER_CRC byte.
Example:
Sending just “0xFF” bytes will result in an invalid MASTER_CRC byte and no configuration changes will
be done.
(0xFF – (0xFF + 0xFF + 0xFF) + 0x01 = 0x03 <> 0xFF
Reading only MA register:
Send: 0xFF (receive dummy), 0xFF (receive MA_low), 0xFF (receive MA_high)
Reading MA & MIA register:
Send: 0xFF (receive dummy), 0xFF (receive MA_low), 0xFF (receive MA_high),
0xFF (receive MIA_Byte1), 0xFF (receive MIA_Byte2), 0xFF (receive MIA_Byte3),
0xFF (receive MIA_Byte4)
The last byte transmitted by the KMA36-SPI is a CRC byte calculated by this formula:
MA_low + MA_high + MIA_Byte0 + MIA_Byte1 + MIA_Byte2 + MIA_Byte3 + CONF + RES_low + RES_high
Example:
0x00 + 0x7C + 0x77 + 0x00 + 0x00 + 0x00 + 0x00 + 0x03 + 0x00 + 0x80 = 0x0176  KMA_CRC = 0x76
(least significant byte of CRC sum)
 Registers (Overview)
The KMA36 contains the following I/O registers:
Register
CONF
RES
MA
MIA
Size
8 bit
16 bit
16 bit
32 bit
Registers of the KMA36-SPI
Read/Write
Function
R/W
Configuration bits
R/W
Resolution
R
Magnetic angle
R
Magnetic incremental angle
Table 8: Registers of the KMA36
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Contactless Rotational and Linear Encoder
 CONF (Configuration register, 1 byte, read / write)
The configuration register is used to control and monitor the status and modes of the system:
KCONF - Configuration
register
Bit
7
6
5
SLPE
LINE
Read/Write
W
R/W
R/W
Initial value
0
0
0
4
MIAE
R/W
0
3
LPWRE
R/W
0
2
SPDE
R/W
0
1
OVS1
R/W
1
0
OVS0
R/W
0
Bit 7 - SLPE: Sleep mode enable
Writing this bit to one enables the sleep mode. This bit will be always set to zero by hardware.
Bit 5 - LINE: Linear mode enable
Writing this bit to one disables the rotational mode and enables the linear mode.
Bit 4 - MIAE: Incremental mode
enable
Writing this bit to one enables the incremental angle counter.
By writing it to zero, the counter mode is turned off and the counter set to 0.
Bit 3 - LPWRE: Low power mode
enable
Writing this bit to one enables the low power mode.
Bit 2 - SPDE: Speed mode
enable
Writing this bit to one enables the fast speed mode.
Bit 1:0 - OVS1:0: Oversampling
These bits determines the accuracy of the angle evaluation.
Table 9: KCONF – Configuration Register
 SLPE-Bit
Please note: Wake up is initiated by pulling the CS pin to low level (minimum 3 µs). If this is done as part of a
complete SPI communication cycle received data is not valid.
 LINE-Bit
This mode enables an additional signal processing suited for linear measurements with a pole strip with 5mm pole
pitch.
 MIAE-Bit
In addition, there is an incremental angle counter implemented, which can be enabled by writing a one to this Bit.
Writing a zero to this Bit will reset the 32 Bit register ( 0x00000000).
 LPWRE-Bit
The power current consumption can be reduced with the low power mode accessible through this Bit.
In low power mode only 180° measurement are possible.
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KMA36-SPI
Contactless Rotational and Linear Encoder
 SPDE-Bit
The measurement update rate can be increased by activating the fast mode with SPD bit. In fast mode
measurement accuracy is reduced.
Update rate
fdata = 1 / (1.4 msec x oversampling / const)
SPD Bit
const
0
1
1
2
Table 10: Update rate
 OVS-Bits
To increase the measurement accuracy, it is possible to configure the oversampling rate by using the OVSx Bits.
Please notice that a higher accuracy leads to a reduction of the update rate (Please refer to the Update rate table)
OVS1
0
0
1
1
OVS0
0
1
0
1
Oversampling
2
4
8
32
Table 11: OVS - Oversampling

RES (Resolution register, 2 bytes, read / write)
The resolution can be set to any value between 1 and 32768. Any other value would lead to unexpected system
behavior.
Bit
RESH
RESL
Bit
Read/Write
Initial value
RES - Resolution
register
15
14
RES15
RES14
RES7
RES6
7
6
W
W
W
W
0
1
1
1
13
RES13
RES5
5
W
W
1
1
12
RES12
RES4
4
W
W
1
1
11
RES11
RES3
3
W
W
1
1
10
RES10
RES2
2
W
W
1
1
9
RES9
RES1
1
W
W
1
1
8
RES8
RES0
0
W
W
1
1
Bit 15:0 RES15:0: Resolution
Table 12: RES - Resolution Register
For example, a resolution of decimal 360 (send data: 0x0168) leads to rotational data in steps of 1 degree. A
resolution of decimal 3600 (send data: 0x0E10) results in steps of 0.1°.
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KMA36-SPI
Contactless Rotational and Linear Encoder
 MA (Magnetic angle register, 2 byte, read only)
The magnetic angle is stored in this register in relation to the configured resolution. If the system is not in sleepmode, this register is updated automatically on each measurement cycle ( Update rate).
 MIA (Magnetic incremental angle register, 4 byte, read only / reset)
In this register the magnetic angle is saved as signed incremental value.
Example: After 3 ½ rotations with a resolution set to 360 (0x0168) the value 0x000004EC is saved in this 32 Bit
register.
(3,5 x 360 = 1260 dec.  0x 00 00 04 EC)
If the system is not in sleep mode and MIAE-Bit is set, this register is updated automatically on each measurement
cycle ( Update rate).Clearing the MIAE-Bit will reset the 32 bit register to zero.
SYSTEM MAIN CONFIGURATIONS

Rotational measurement

used to measure the angle of a rotating magnet disc centered
above the magnetic sensor center of the KMA36. 1)
 LINE-Bit = 0
Linear measurement
used to measure the linear movement of the KMA36 along
a magnetic pole strip with 5mm pole length. A lookup table is used
for internal error correction 1)
 LINE-Bit = 1

Sleep mode
used to power down the KMA36. Wake up is initiated by SPI
communication.
 SLPE-Bit = 1
1)
Please refer to the arrangement section.
TYPICAL APPLICATION
 Electrical circuit
Figure 4: typical circuit
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KMA36-SPI
Contactless Rotational and Linear Encoder
SET UP ARRANGEMENTS
Due to the magneto resistive technology which senses the magnetic field in the sensor plane, it is advised to mount
the magnet disc centered above the sensor center. Please refer to the magnets and scales section for more
information about the magnetic center position of the KMA36. The magnetic scale should be placed perpendicularly
to the KMA36 as depicted in the following figure rather in the middle along the width of the scale. For best results
the KMA36 should be as close as possible to the magnet.

Rotational (recommended) setup (for best results)
Rotational mode
Bit LIN = 0
Pay attention to the magnetic center of the KMA36

Linear setup
Linear mode
Bit LIN =1
use magnetic pole strip with 5mm pole length for best results
Figure 5: Mounting
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KMA36-SPI
Contactless Rotational and Linear Encoder
MAGNETS AND SCALES
Rotational Mode
The KMA36 can be used with a magnet, preferably of disc or square shape or a magnet scale with pole pitch 5mm.
For development purposes, MEAS offers a magnet disc made of plastic bonded Nd-Fe-B magnetic material which
provides a homogenous magnetic field with sufficient magnetic field strength for typical application with the KMA36.
The following table describes typical magnets parameters. Please refer to the website
http://www.magnetfabrik.de (article number 67.044-1 ) and its application note section for more information.
Symbol
Parameter
Condition
Min.
Typ.
Max.
Unit
Ø
Diameter
Neofer 48/60p only
14
mm
T
Thickness
Neofer 48/60p only
2.5
mm
Br
Magnetic field strength
Neofer 48/60p only
540
mT
Top
Operating temperature
Neofer 48/60p only
150
°C
Table 13: Typical MEAS disc-magnet specification
Linear Mode
The linear mode of the KMA36 is designed for a magnetic scale with pole pitch 5mm. A magnetic scale is made of
a magnetic ferrite tape bonded on a steel support which guarantees mechanical stability. The steel support is made
of an optimum stainless steel alloy that provides no loss of magnetic field strength. MEAS offers a standard scale
with the following parameters for development purpose:
Symbol
Parameter
Condition
Min.
Typ.
Max.
Unit
LT
Length
MEAS magnetic scale only
1
m
LP
Pole length
MEAS magnetic scale only
5
mm
W
Width
MEAS magnetic scale only
10
mm
T
Thickness
MEAS magnetic scale only
1.3
mm
Δp
Accuracy
MEAS magnetic scale only
40
µm/m
Top
Operating temperature
MEAS magnetic scale only
-40
100
°C
Table 14: Typical MEAS magnet-scale specification
The correct magnet dimensions and assembly geometry depend on the specific arrangement of the application
and are part of the specification of the entire system.
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KMA36-SPI
Contactless Rotational and Linear Encoder
PACKAGE DRAWING
Figure 6: Package drawing (Magnetic center)
Figure 7: Package drawing
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KMA36-SPI
Contactless Rotational and Linear Encoder
COMMON DIMENSIONS (MILLIMETERS)
Symbol
Min.
Typ.
Max.
A
-
-
1.20
A1
0.05
-
0.15
A2
0.80
1.00
1.05
b
0.19
-
0.30
D
6.40
6.50
6.60
E
-
6.40
-
E1
4.30
4.40
4.50
e
-
0.65
-
L
0.45
0.60
0.75
N
-
20
-
R
0.09
-
-
S
0.20
-
-
Table 15: common dimensions
ORDERING CODE
Product
Description
Article number
KMA36-SPI
KMA36 TSSOP20
Coming soon
Table 16: Ordering codes
This data sheet contains data from the preliminary specification. Supplementary data will be published later.
Measurement Specialties reserves the right to change the specification without notice, in order to improve the
design and performance of the product.
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EUROPE
ASIA
Measurement Specialties, Inc.,
a TE Connectivity Company
1000 Lucas Way
Hampton, VA 23666
United States
Phone: +1-800-745-8008
Fax: +1-757-766-4297
Email: [email protected]
MEAS Deutschland GmbH (Europe)
a TE Connectivity Company
Hauert 13
D-44227 Dortmund
Germany
Phone: +49-(0)231-9740-0
Fax: +49-(0)231-9740-20
Email: [email protected]
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a TE Connectivity Company
No. 26 Langshan Road
Shenzhen High-Tech Park (North)
Nanshan District, Shenzhen 518057
China
Phone: +86-755-33305088
Fax: +86-755-33305099
Email: [email protected]
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SENSOR SOLUTIONS /// KMA36-SPI
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1/2016
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