MA800GQ-P

MagAlpha MA800 8-Bit Contactless Angle Encoder with Push Button Function DESCRIPTION FEATURES The MA800 is an easy-to-use, magnetic, angle encoder with a digital output designed to replace analogic potentiometers or rotary switches. The MA800 is designed for slow operation such as human-machine interface, manual controls, etc. where the rotating speed remains below 200 rpm. The sensor detects the absolute angular position of a permanent magnet attached to a rotating shaft.   The magnet shapes and configurations are very flexible. Typically, the MA800 is used with a diametrically magnetized cylinder of 2 - 8mm in diameter. The MA800 features programmable magnetic field strength thresholds, which allow for the implementation of a push or pull button function. These are output as two logic signals. On-chip non-volatile memory provides storage for the configuration parameters, including the reference zero angle position and magnetic field detection threshold settings.      8-Bit Resolution Absolute Angle Encoder Contactless Sensing for Long Life with No Wear SPI and SSI Serial Interface Programmable Magnetic Field Strength Detection for Push/Pull Button Detection 3.3V, 12mA Supply -40 to +125°C Operating Temperature Available in a QFN-16 (3mmx3mm) Package APPLICATIONS      Rotary Knob Control Interfaces Manual Controls Encoders Automotive White Goods All MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. For MPS green status, please visit the MPS website under Quality Assurance. “MPS” and “The Future of Analog IC Technology” are registered trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 1 MA800 – 8-BIT, DIGITAL ANGLE SENSOR ORDERING INFORMATION Part Number* MA800GQ Package QFN-16 (3mmx3mm) Top Marking See Below * For Tape & Reel, add suffix –Z (e.g. MA800GQ–Z) TOP MARKING AXV: Product code of MA800GQ Y: Year code LLL: Lot number PACKAGE REFERENCE TOP VIEW N/C GND MISO N/C CS 8 7 6 5 9 4 MOSI 3 N/C TEST 10 MGL 11 2 N/C SCLK 12 1 SSD 17 PAD 13 14 15 VDD N/C SSCK 16 MGH QFN-16 (3mmx3mm) MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 2 MA800 – 8-BIT, DIGITAL ANGLE SENSOR ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance Supply voltage ............................ -0.5V to +4.6V Input pin voltage (VI) ................... -0.5V to +6.0V Output pin voltage (VO) ............... -0.5V to +4.6V (2) Continuous power dissipation (TA = +25°C) ..................................................................2.0W Junction temperature ............................... 125°C Lead temperature .................................... 260°C Storage temperature .................. -65°C to 150°C QFN-16 (3mmx3mm) ............ 50 ....... 12 ... °C/W MA800 Rev. 1.02 6/15/2018 (3) θJA θJC NOTES: 1) Exceeding these ratings may damage the device. 2) The maximum allowable power dissipation is a function of the maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD (MAX) = (TJ (MAX)-TA)/θJA. 3) Measured on JESD51-7, 4-layer PCB. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 3 MA800 – 8-BIT, DIGITAL ANGLE SENSOR ELECTRICAL CHARACTERISTICS Parameter Symbol Condition Recommended Operating Conditions Min Typ Max Units Supply voltage VDD 3.0 3.3 3.6 V Supply current IDD 10.2 11.7 13.8 mA Operating temperature Applied magnetic field Top B -40 30 125 60 °C mT MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 4 MA800 – 8-BIT, DIGITAL ANGLE SENSOR GENERAL CHARACTERISTICS VDD = 3.3V, 45mT < B < 100mT, temp = -40°C to +125°C, unless otherwise noted. Parameter Resolution Symbol Condition 3σ deviation of the noise distribution Effective resolution Noise rms Refresh rate Data output length Response Time Power-up time Latency Min Typ 8 0.005 850 8 Constant speed propagation delay Filter cutoff frequency Accuracy (4) Fcutoff At room temperature over the full field range Over the full temperature range and field range INL at 25°C INL between -40°C to +125°C (5) Units bit 0.01 980 (4) (5) Max 0.02 1100 8 deg kHz bit 20 ms 4 ms 90 Hz 0.7 deg 1.1 deg Output Drift Temperature induced drift at (5) room temperature Temperature induced variation Magnetic field induced From 25°C to 85°C From 25°C to 125°C (5) (5) 0.015 0.04 deg/°C 0.5 1.0 0.005 1.2 2.1 deg deg deg/mT 0.3 deg/V (5) Voltage supply induced Magnetic Field Detection Thresholds (5) Accuracy (5) Hysteresis (5) Temperature drift Digital I/O VIH VIL Input high voltage Input low voltage Output low voltage 5 6 -600 MagHys (5) Output high voltage (5) VOL VOL = 4mA VOH VOH = 4mA RPU RPD Pull-up resistor Pull-down resistor (4) Rising edge slew rate (4) Falling edge slew rate TR TF CL = 50pF CL = 50pF mT mT ppm/°C 2.5 5.5 V -0.3 0.8 V 0.4 V 2.4 V 46 66 97 kΩ 43 55 97 kΩ 0.7 0.7 V/ns V/ns NOTES: 4) Guaranteed by design. 5) Guaranteed by characteristic test. MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 5 MA800 – 8-BIT, DIGITAL ANGLE SENSOR TYPICAL CHARACTERISTICS VDD = 3.3V, Temp = 25°C, unless otherwise noted. Current Consumption at VDD = 3.3V Filter Transfer Function Error Curves at 50mT 2 12 5 1.5 11 10.5 1 0 25癈 125癈 0.5 -3 dB ERROR (deg) FILTER TRANSFER FUNCTION (dB) SUPPLY CURRENT (mA) 11.5 -5 -45癈 0 -0.5 -10 -1 -15 -1.5 10 -2 -50 0 50 100 150 -20 0 1 10 100 TEMPERATURE (癈 ) 1000 10 50 100 150 200 250 300 350 4 ANGLE (deg) f (Hz) Non-Linearity (INL and Harmonics) 1.5 NON-LINEARITY (deg) INL 1 H1 0.5 H2 0 0 20 40 60 80 100 MAGNETIC FIELD (T) MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 6 MA800 – 8-BIT, DIGITAL ANGLE SENSOR PIN FUNCTIONS Package Pin # Name SSD Description Data out (SSI). 1 2, 3, 6, 9, 14 4 MOSI 5 CS 7 MISO 8 10 11 12 13 15 GND TEST MGL SCLK VDD SSCK Chip select (SPI). CS has an internal pull-up resistor. Data out (SPI). MISO has an internal pull-down resistor that is enabled at a high impedance state. Supply ground. Factory use only. Connect TEST to ground. Digital output indicating field strength below MGLT level. Clock (SPI). SCLK has an internal pull-down resistor. 3.3V supply. Clock (SSI). SSCK has an internal pull-down resistor. 16 17 MGH PAD Digital output indicating field strength above MGHT level. Exposed pad. NC MA800 Rev. 1.02 6/15/2018 No connection. Leave NC unconnected. Data in (SPI). MOSI has an internal pull-down resistor. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 7 MA800 – 8-BIT, DIGITAL ANGLE SENSOR BLOCK DIAGRAM Figure 1: Functional Block Diagram MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 8 MA800 – 8-BIT, DIGITAL ANGLE SENSOR OPERATION Sensor Front-End The magnetic field is detected with integrated Hall devices located in the center of the package. The angle is measured using the SpinaxisTM method, which digitizes the direction of the field directly without complex arctangent computations or feedback loop-based circuits (interpolators). The SpinaxisTM method is based on phase detection and generates a sinusoidal signal with a phase that represents the angle of the magnetic field. The angle is then obtained by a time-to-digital converter, which measures the time between the zero crossing of the sinusoidal signal and the edge of a constant waveform (see Figure 2). The time-to-digital is output from the front-end to the digital conditioning block. Sensor – Magnet Mounting The sensitive volume of the MA800 is confined in a region less than 100µm wide and has multiple integrated Hall devices. This volume is located both horizontally and vertically within 50µm of the center of the QFN package. The sensor detects the angle of the magnetic field projected in a plane parallel to the package’s upper surface. This means that the only relevant magnetic field is the in-plane component (X and Y components) in the middle point of the package. By default, when looking at the top of the package, the angle increases when the magnetic field rotates clockwise. Figure 3 shows the zero angle of the unprogrammed sensor, where the cross indicates the sensitive point. Both the rotation direction and the zero angle can be programmed. Top: Sine Waveform Bottom: Clock of the Time-to-Digital Converter Figure 2: Phase Detection Method The output of the front-end delivers a digital number proportional to the angle of the magnetic field at the rate of 1MHz in a straightforward and open-loop manner. Digital Filtering The front-end signal is further treated to achieve the final effective resolution. This treatment does not add any latency in steady conditions. The filter transfer function can be calculated with Equation (1): H(s)  1  2s (1  s)2 (1) Where τ is the filter time constant related to the cutoff frequency by τ = 0.38/Fcutoff. See the General Characteristics table on page 5 for the value of Fcutoff. MA800 Rev. 1.02 6/15/2018 Figure 3: Detection Point and Default Positive Direction This type of detection provides flexibility for the design of an angular encoder. The sensor only requires the magnetic vector to lie essentially within the sensor plane with a field amplitude of at least 30mT. Note that the MA800 can work with fields smaller than 30mT, but the linearity and resolution performance may deviate from the specifications. The most straightforward mounting method is to place the MA800 sensor on the rotation axis of a permanent magnet (i.e.: a diametrically magnetized cylinder) (see Figure 4). The recommended magnet is a Neodymium alloy (N35) cylinder with dimensions Ø5x3mm inserted into an aluminum shaft with a 1.5mm air gap between the magnet and the sensor (surface of package). For good linearity, the sensor is positioned with a precision of 0.5mm. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 9 MA800 – 8-BIT, DIGITAL ANGLE SENSOR In general, the MagAlpha works well with or without the exposed pad connected to anything. For optimum conditions (electrically, thermally, and mechanically), it is recommended that the exposed pad be connected to ground. Figure 4: End-of-Shaft Mounting Figure 5 shows an example of sensor and magnet mounting in a contactless switch assembly. A Neodymium alloy magnet is inserted into an aluminum shaft. The air gap between the magnet and the sensor is 1.0mm. The sensor is positioned on the rotation axis with a precision of 0.5mm. Figure 5: Example of Potentiometer-Like Assembly Electrical Mounting and Power Supply Decoupling It is recommended to place a 1µF decoupling capacitor close to the sensor with a low impedance path to GND (see Figure 6). Serial Interface The sensor supports the SPI serial interface for angle reading and register programming. Alternatively, the SSI bus can be used for angle reading (programming through SSI is not supported). SPI SPI is a four-wire, synchronous, serial communication interface. The MagAlpha supports SPI Mode 3 and Mode 0 (see Table 1 and Table 2). The SPI Mode (0 or 3) is detected automatically by the sensor and therefore does not require any action from the user. The maximum clock rate supported on SPI is 25MHz. There is no minimum clock rate. Note that real-life data rates depend on the PCB layout quality and signal trace length. See Figure 7 and Table 3 for SPI timing. All commands to the MagAlpha (whether for writing or reading register content) must be transferred through the SPI MOSI pin and must be 16 bits long. See the SPI Communication section on page 12 for details. Table 1: SPI Specification SCLK idle state Data capture Data transmission CS idle state Data order Mode 0 Mode 3 Low High On SCLK rising edge On SCLK falling edge High MSB first Table 2: SPI Standard CPOL CPHA Data order (DORD) Mode 0 Mode 3 0 1 0 1 0 (MSB first) Figure 6: Connection for Supply Decoupling MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 10 MA800 – 8-BIT, DIGITAL ANGLE SENSOR tcsL CS tsclk tsclkL tsclkH tcsH tMISO tMISO tidleAngle tidleReg tnvm SCLK tMISO MISO hi-Z MOSI MSB X LSB MSB hi-Z MSB X LSB MSB tMOSI Figure 7: SPI Timing Diagram tidleAngle tidleAngle tidleAngle tidleReg tidleReg tidleAngle tnvm tidleReg CS MISO Angle Angle Angle Angle Reg Value Angle Angle Reg Value Angle MOSI 0 0 0 Read Reg Cmd 0 0 Write Reg Cmd 0 0 Figure 8: Minimum Idle Time Table 3: SPI Timing Parameter (6) Description Min Max tidleAngle Idle time between two subsequent angle transmissions 150 ns tidleReg Idle time before and after a register readout 750 ns tnvm Idle time between a write command and a register readout (delay necessary for non-volatile memory update) 20 ms tcsL Time between CS falling edge and SCLK falling edge 80 ns tsclk SCLK period 40 ns tsclkL Low level of SCLK signal 20 ns tsclkH High level of SCLK signal 20 ns tcsH Time between SCLK rising edge and CS rising edge 25 ns tMISO SCLK setting edge to data output valid tMOSI Data input valid to SCLK reading edge 15 15 Unit ns ns NOTE: 6) All values are guaranteed by design. MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 11 MA800 – 8-BIT, DIGITAL ANGLE SENSOR SPI Communication The sensor supports three types of SPI operation:    Read angle Read configuration register Write configuration register Therefore, angle reading can be optimized without any loss of information by reducing the number of clock counts. In the case of a 12-bit data output length, only 12 clock counts are required to get the full sensor resolution. MSB Each operation has a specific frame structure described below. SPI Read Angle Every 1µs, new data is transferred into the output buffer. The master device triggers the reading by pulling CS low. When a trigger event is detected, the data remains in the output buffer until the CS signal is de-asserted (see Table 4). LSB MISO Angle(15:4) MOSI 0 If less resolution is needed, the angle can be read by sending even fewer clock counts (since the MSB is first). In case of a fast reading, the MagAlpha continues sending the same data until the data is refreshed (see the refresh rate in the General Characteristics table on page 5). Table 4: Sensor Data Timing Event CS falling edge CS rising edge Action Start reading and freeze output buffer Release of the output buffer See Figure 9 for a diagram of a full SPI angle reading. See Figure 10 for a diagram of a partial SPI angle reading. A full angle reading requires 16 clock pulses. The sensor MISO line returns: MSB LSB MISO Angle(15:0) MOSI 0 Figure 9: Diagram of a Full 16-Bit SPI Angle Reading The MagAlpha family has sensors with different features and levels of resolution. Check the data output length in the General Characteristics table on page 5 for the number of useful bits delivered at the serial output. If the data length is smaller than 16, the rest of the bits sent are zeros. For example, a data output length of 12 bits means that the serial output delivers a 12-bit angle value with four bits of zeros padded at the end (MISO state remains zero). If the master sends 16 clock counts, the MagAlpha replies with: MSB MISO MOSI MA800 Rev. 1.02 6/15/2018 Figure 10: Diagram of a Partial 8-Bit SPI Angle Reading LSB Angle(15:4) 0 0 0 0 0 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 12 MA800 – 8-BIT, DIGITAL ANGLE SENSOR SPI Read Register A read register operation is constituted of two 16-bit frames. The first frame sends a read request which contains the 3-bit read command (010) followed by the 5-bit register address. The last eight bits of the frame must all be set to zero. The second frame returns the 8-bit register value (MSB byte). See Figure 11 for a complete transmission. For example, to get the value of the magnetic level high and low flags (MGH and MGL), read register 27 (bit 6, bit 7) by sending the following first frame: MSB The first 16-bit SPI frame (read request) is: MSB MISO LSB Angle(15:0) command reg. address MOSI 0 1 0 A4 A3 A2 A1 A0 MOSI Angle(15:0) command 0 1 0 reg. address 1 1 0 1 1 0 0 0 0 0 0 0 0 reg. value MISO MGH MGL X X X X X X 0 0 0 0 0 0 0 0 MSB 0 0 0 0 0 0 0 0 MSB MOSI reg. value MISO V7 V6 V5 V4 V3 V2 V1 V0 0 0 0 0 0 0 0 0 In the second frame, the MagAlpha replies: The second 16-bit SPI frame (response) is: MOSI LSB MISO LSB 0 See Figure 12 for a complete example. LSB 0 Figure 11: 16-Bit Frames Read Register Operation Figure 12: Example Read Magnetic Level Flags High and Low (MGH, MGH) on Register 27, Bit 6 to Bit 7 MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 13 MA800 – 8-BIT, DIGITAL ANGLE SENSOR SPI Write Register Table 7 shows the programmable 8-bit registers. Data written to these registers are stored in the on-chip non-volatile memory and reloaded during power-on automatically. The factory default register values are shown in Table 8. A write register operation is constituted of two 16-bit frames. The first frame sends a write request, which contains the 3-bit write command (100) followed by the 5-bit register address and the 8-bit value (MSB first). The second frame returns the newly written register value (acknowledge). The on-chip memory is guaranteed to endure 1,000 write cycles at 25°C. It is critical to wait 20ms between the first and second frame. This is the time taken to write the non-volatile memory. Failure to implement this wait period results in the register’s previous value being read. Note that this delay is only required after a write request. A read register request and read angle do not require this wait time. The second 16-bit SPI frame (response) is: reg. value MISO V7 V6 V5 V4 V3 V2 V1 V0 0 0 0 0 0 0 0 0 MSB LSB MOSI 0 The read-back register content can be used to verify the register programming. See Figure 13 for a complete transmission overview. For example, to set the value of the output rotation direction (RD) to counterclockwise (high), write register 9 by sending the following first frame: MSB MISO LSB Angle(15:0) command MOSI 1 0 0 reg. address 0 1 0 0 1 reg. value 1 0 0 0 0 0 0 0 Send the second frame after 20ms of wait time (see Figure 8). If the register is written correctly, the reply is: reg. value MISO 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 The first 16-bit SPI frame (write request) is: MSB MISO LSB Angle(15:0) command reg. address reg. value MOSI 1 0 0 A4 A3 A2 A1 A0 V7 V6 V5 V4 V3 V2 V1 V0 MSB MOSI LSB 0 See Figure 14 for a complete example. Figure 13: Overview of Two 16-Bit Frames Write Register Operation MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 14 MA800 – 8-BIT, DIGITAL ANGLE SENSOR Figure 14: Example Write Output Rotation Direction (RD) to Counterclockwise (High) on Register 9, Bit 7 SSI SSI is a 2-wire synchronous serial interface for data reading only. The sensor operates as a slave to the external SSI master and supports angle reading only. It is not possible to read or write registers using SSI. SSI Communication Unlike SPI, the sensor SSI supports angle reading operation only. It is not possible to read or write registers using SSI. The SSI timing communication is shown in Figure 15 and Table 5. Figure 15: SSI Timing Table 5: SSI Timing Parameter Description Min tssd Max Unit 15 ns tssck SSCK period 0.04 16 µs tssckL Low level of SSCK signal 0.02 8 µs tssckH High level of SSCK signal 0.02 8 µs tm Transfer timeout (monoflop time) 25 µs tp Dead time: SSCK high time for next data reading 40 µs SSI Read Angle The bit order of the transmitted data is MSB first and LSB last. Every 1µs, new data is transferred into the output buffer. The master device triggers the reading by pulling SSCK down. Just like with an SPI reading, a full reading requires 16 clock counts, but if the data length is less than 16, the 16-bit output word is completed by zeros. Therefore, reading can MA800 Rev. 1.02 6/15/2018 also be performed with fewer than 16 clock counts (see Figure 16). When a trigger event is detected, the data remains in the output buffer until the clock rising edge for the LSB bit 0 and the transfer time out time has passed. See Table 6 for sensor data timing. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 15 MA800 – 8-BIT, DIGITAL ANGLE SENSOR When a trigger event is detected, the data remains in the output buffer until the clock rising edge for the LSB bit 0 and the transfer time out time has passed. See Table 6 for sensor data timing. Table 6: Sensor Data Timing Trigger event Release of the output buffer First SSCK falling edge SSCK rising edge + time out tm (Fig 15) Figure 16: Full 16-Bit SSI Angle Reading For consecutive angle readings, see the timing diagram in Figure 17. Figure 17: Two Consecutive 16-Bit SSI Angle Reading with the Required Dead Time between the Frames MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 16 MA800 – 8-BIT, DIGITAL ANGLE SENSOR REGISTER MAP Table 7: Register Map Bit 7 MSB No Hex Bin Bit 6 Bit 5 Bit 4 0 0x0 00000 Z(7:0) 1 0x1 00001 Z(15:8) 6 0x6 00110 9 0x9 01001 RD - - - - 27 0x1B 11011 MGH MGL - - - MGLT(2:0) Bit 3 Bit 2 Bit 1 Bit 0 LSB - - - - - - - - MGHT(2:0) Table 8: Factory Default Values No Hex Bin Bit 7 MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 LSB 0 0x0 00000 0 0 0 0 0 0 0 0 1 0x1 00001 0 0 0 0 0 0 0 0 6 0x6 00110 0 0 0 1 1 1 0 0 9 0x9 01001 0 0 0 0 0 0 0 0 Table 9: Programming Parameters Parameters Symbol Number of Bits Description See Table Zero setting Magnetic field high threshold Magnetic field low threshold Z 16 Set the zero position 10 MGHT 3 Sets the field strength high threshold. 14 MGLT 3 Sets the field strength low threshold. 14 RD 1 Determines the sensor positive direction 12 Rotation direction MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 17 MA800 – 8-BIT, DIGITAL ANGLE SENSOR REGISTER SETTINGS Zero Setting The zero position of the MagAlpha (a0) can be programmed with 16 bits of resolution. The angle streamed out by the MagAlpha (aout) is given by Equation (2): aout  araw  a0 (2) Where araw is the raw angle provided by the MagAlpha front-end. The parameter Z(15:0), which is zero by default, is the complementary angle of the zero setting. It can be written in decimals using Equation (3): a0  216  Z (15 : 0) (3) Table 10 shows the zero setting parameter. 0 1 2 … 65534 65535 Zero pos. a0 16-bit (dec) 65536 65535 65534 … 2 1 Table 12: Rotation Direction Parameter RD Positive Direction 0 1 Clockwise (CW) Counterclockwise (CCW) Magnetic Field Thresholds Push Button Detection The MA800 has two threshold options (MGHT or MGLT), which are complementary in operation. The flag MGH becomes TRUE (logic 1) if the magnetic field increases above MGHT. The flag MGL becomes TRUE (logic 1) if the magnetic field falls below MGLT (see Figure 19). Table 10: Zero Setting Parameter Z(15:0) Figure 18: Positive Rotation Direction of the Magnetic Field Zero pos. a0 (deg) 360.000 359.995 359.989 … 0.011 0.005 Example To set the zero position to 20 deg, the Z(15:0) parameter must be equal to the complementary angle shown in Equation (4): Z (15 : 0)  216  20 deg 16 2  61895 360 deg (4) In binary, this is written as 1111 0001 1100 0111. Table 11 shows the content of registers 0 and 1. Table 11: Register Content Reg Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 0 1 1 0 0 0 1 1 1 1 1 1 1 1 0 0 0 1 Rotation Direction By default, when looking at the top of the package, the angle increases when the magnetic field rotates clockwise (CW) (see Figure 18 and Table 12). MA800 Rev. 1.02 6/15/2018 Figure 19: MGH and MGL Signals as a Function of the Field Strength The MGL and MGH flags can be used for detecting an approaching magnet (e.g.: when a button is pressed). With the 5mmx3mm magnet example, if the MGHT threshold is set to binary 110 (106 - 112mT), the MGH signal is set to logic high when the sensor-magnet airgap is smaller than 1.0mm (see Figure 20). www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 18 MA800 – 8-BIT, DIGITAL ANGLE SENSOR Table 14: MGLT and MGHT Binary to mT Relation MGLT or (8) MGHT 000 001 010 011 100 101 110 111 Figure 20: Magnetic Field Produced by a 5mmx3mm N35 Magnet as a Function of the Airgap with Threshold Set to 110mT In this way, it is possible to implement a push or pull action. MagHys, the hysteresis on the signals MGH and MGL, is indicated in the General Characterisitcs table on page 5. The MGLT and MGHT thresholds are coded on three bits and stored in register 6 (see Table 13). Field threshold in mT From low to high magnetic field 26 41 56 70 84 98 112 126 (7) From high to low magnetic field 20 35 50 64 78 92 106 120 NOTES: 7) Valid for VDD = 3.3V. If different, then the field threshold is scaled by the factor VDD/3.3V. 8) MGLT can have a larger value than MGHT. The alarm flags (MGL and MGH) can be read in register 27 (bit 6 and bit 7), and their logic state is also given at the digital output pins 11 and 16. To read the MGL and MGH flags by SPI, send the 8-bit command write to register 27: command 0 1 0 reg. address 1 1 0 1 1 value LSB 0 0 0 0 0 0 0 0 MSB Table 13: Register 6 The MA800 answers with the register 27 content in the next transmission: Reg Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 6 MGLT MGHT Reg Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 27 MGH MGL x x x x x x The 3-bit values of MGLT and MGHT correspond to the magnetic field (see Table 14). MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 19 MA800 – 8-BIT, DIGITAL ANGLE SENSOR TYPICAL APPLICATION CIRCUITS Figure 21: Typical Configurations using SPI Interface Figure 22: Typical Configuration Using SSI Interface and Output Signals MGL, MGH MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 20 MA800 – 8-BIT, DIGITAL ANGLE SENSOR PACKAGE INFORMATION QFN-16 (3mmx3mm) MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 21 MA800 – 8-BIT, DIGITAL ANGLE SENSOR APPENDIX A: DEFINITIONS Resolution (3σ noise level) Smallest angle increment distinguishable from the noise. The resolution is measured by computing three times σ (the standard deviation in degrees) taken over 1,000 data points at a constant position. The resolution in bits is obtained with log2(360/6σ). Refresh Rate Rate at which new data points are stored in the output buffer. Latency Time elapsed between the instant when the data is ready to be read and the instant at which the shaft passes that position. The lag in degrees is lag  lantency  v , where v is the angular velocity in deg/s. Power-Up Time Time until the sensor delivers valid data starting at power-up. Integral Non-Linearity (INL) Maximum deviation between the average sensor output (at a fixed position) and the true mechanical angle. Figure A1: Integral Non-Linearity Drift MA800 Rev. 1.02 6/15/2018 Angle variation rate when one parameter is changed (e.g.: temperature, VDD) and all the others, including the shaft angle, are maintained constant. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 22 MA800 – 8-BIT, DIGITAL ANGLE SENSOR APPENDIX B: SPI COMMUNICATION CHEATSHEET Read Angle Read Register Write Register NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. MA800 Rev. 1.02 6/15/2018 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2018 MPS. All Rights Reserved. 23