KMA36-SPI Rotational and Linear Position Sensor IC

Transcription

1 Rotational and Linear Position Sensor IC SPECIFICATIONS 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. SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 1

2 KEY-FEATURES Resolution 13 Bit / 0.04 degree Operating power supply range of 3V to 5.5V V Operating temperature C Average current ma Sleep current < 600uA (@VCC =3V) Data Update rate 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 SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 2

3 ELECTRICAL CHARACTERISTICS Magnet magnetic field SENSOR Angle MR AMPLIFICATION OP AMP 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. ADC 10 bit ERROR HANDLING EVALUATION CORE MODE HANDLING COMMUNICATION PWM I2C PWM Position Parameter 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. Figure 2: Functional block description Absolute maximum ratings CAUTION: Exceeding these values may destroy the product. Top Operating temperature C Tsto Storage temperature C Vcc Operating voltage V Vin Input voltage on any Pin Except on A V Vin Input voltage on A V Iin DC Current through any I/O Pin 40 ma Iin DC Current through S Pin 200 ma Table 1: Absolute maximum ratings Operating conditions Top Operating temperature C Vcc Operating voltage V Vin Input voltage on I/O pin V ARef External Analog Reference V RAREF Analog Reference input resistance kω Table 2: Operating conditions SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 3

4 AC/DC characteristics Iavg Average current 1) Except in sleep mode, Vcc = 5V ma Isleep Sleep current Vcc = 5V 1.2 ma Isleep 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 3 V VOL Output low voltage Vcc = 5V, IOL = 10 ma 0.6 V VOH Output high voltage Vcc = 5V, IOH = 10 ma 4.3 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 fdata Update rate 1) ) Hz tstart Starting time 5 ms αr Resolution H0=25 ka/m 1) 15 Bit αr ΔαL ΔαH Resolution Linearity error Hysteresis error H0=25 ka/m 1) no missing codes H0=25 ka/m 1) Top=25 C H0=25 ka/m 1) Top=25 C 13 Bit ±0.3 ±1 ±0.1 ±0.25 Vbwn Brown-out reset voltage 2.7 V tbwn Brown-out reset pulse width 2 µs Hy Applied magnetic field ka/m RCOIL Internal coil resistance Ω Table 4: System parameters 1) System parameters apply only for recommended measurement setup (please refer to the arrangement section) 2) SPD Bit = 1, Oversampling = 2 SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 4

5 Update rate f data = 1 / (1.4 msec x oversampling / const) SPD Bit const SPI INTERFACE Physical interface parameters Clkrt Clockrate 2 MHz CSAL Chip Select Active Level 0 V Timing parameters Table 5: Physical interface parameters 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. SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 5

6 CS The KMA36 is always operating as a pure slave. CS = HIGH: CS = LOW: 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). 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 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 Table 7: byte-order Configure the KMA36-SPI 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: 0x13 (MIAE enabled, Oversampling = 32) RES_high: 0x01 (resolution = 360) RES_low: 0x68 (resolution = 360) MASTER_CRC = 0xFF (0x13 + 0x01 + 0x68) + 0x01 = 0x84 SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 6

7 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: Registers of the KMA36-SPI Register Size Read/Write Function CONF 8 bit R/W Configuration bits RES 16 bit R/W Resolution MA 16 bit R Magnetic angle MIA 32 bit R Magnetic incremental angle Table 8: Registers of the KMA36 SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 7

8 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 SLPE - LINE MIAE LPWRE SPDE OVS1 OVS0 Read/Write W R/W R/W R/W R/W R/W R/W R/W Initial value 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. SLPE-Bit Table 9: KCONF Configuration Register 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 ( 0x ). 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. SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 8

9 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 f data = 1 / (1.4 msec x oversampling / const) SPD Bit const OVS-Bits Table 10: Update rate 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 OVS0 Oversampling Table 11: OVS - Oversampling RES (Resolution register, 2 bytes, read / write) The resolution can be set to any value between 1 and Any other value would lead to unexpected system behavior. RES - Resolution register Bit RESH RES15 RES14 RES13 RES12 RES11 RES10 RES9 RES8 RESL RES7 RES6 RES5 RES4 RES3 RES2 RES1 RES0 Bit Read/Write W W W W W W W W W W W W W W W W Initial value 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. SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 9

10 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 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 SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 10

11 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 SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 11

12 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 (article number ) and its application note section for more information. 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 Linear Mode Table 13: Typical MEAS disc-magnet specification 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: 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 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. SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 12

13 PACKAGE DRAWING Figure 6: Package drawing (Magnetic center) Figure 7: Package drawing SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 13

14 COMMON DIMENSIONS (MILLIMETERS) Symbol Min. Typ. Max. A A A b D E E e L N R S 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. NORTH AMERICA Measurement Specialties, Inc., a TE Connectivity Company Phone: customercare.hmpt@te.com EUROPE MEAS Deutschland GmbH (Europe) a TE Connectivity Company Phone: customercare.dtmd@te.com ASIA Measurement Specialties (China), Ltd., a TE Connectivity Company Phone: customercare.shzn@te.com TE.com/sensorsolutions Measurement Specialties, Inc., a TE Connectivity company. Measurement Specialties, TE Connectivity, TE Connectivity (logo) and EVERY CONNECTION COUNTS are trademarks. All other logos, products and/or company names referred to herein might be trademarks of their respective owners. The information given herein, including drawings, illustrations and schematics which are intended for illustration purposes only, is believed to be reliable. However, TE Connectivity makes no warranties as to its accuracy or completeness and disclaims any liability in connection with its use. TE Connectivity s obligations shall only be as set forth in TE Connectivity s Standard Terms and Conditions of Sale for this product and in no case will TE Connectivity be liable for any incidental, indirect or consequential damages arising out of the sale, resale, use or misuse of the product. Users of TE Connectivity products should make their own evaluation to determine the suitability of each such product for the specific application TE Connectivity Ltd. family of companies All Rights Reserved. SENSOR SOLUTIONS /// KMA36-SPI 06/2017 Page 14