MA730GQ-P

MagAlpha MA730 14-Bit, Digital, Contactless Angle Sensor with ABZ Incremental & PWM Outputs DESCRIPTION FEATURES The MA730 detects the absolute angular position of a permanent magnet, typically a diametrically magnetized cylinder on a rotating shaft. Fast data acquisition and processing provide accurate angle measurements at speeds from 0 to 60,000 rpm.    The MA730 supports a wide range of magnetic field strengths and spatial configurations. Both end-of-shaft and off-axis (side-shaft mounting) configurations are supported. The MA730 features magnetic field strength detection with programmable thresholds to allow sensing of the magnet position relative to the sensor for creation of functions, such as the sensing of axial movements or for diagnostics. On-chip non-volatile memory provides storage for configuration parameters, including the reference zero angle position, ABZ encoder settings, and magnetic field detection thresholds.       14-Bit Resolution Absolute Angle Encoder Contactless Sensing for Long Life SPI Serial Interface for Digital Angle Readout and Chip Configuration Incremental 12-Bit ABZ Quadrature Encoder Interface with Programmable Pulses Per Turn from 1 - 1024 PWM Output 14-Bit Programmable Magnetic Field Strength Detection for Diagnostic Checks 3.3V, 12mA Supply -40°C to +125°C Operating Temperature Available in a QFN-16 (3mmx3mm) Package APPLICATIONS     General Purpose Angle Measurements High-Resolution Angle Encoders Automotive Angle Robotics 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 MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 1 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS ORDERING INFORMATION Part Number* MA730GQ Package QFN-16 (3mmx3mm) Top Marking See Below * For Tape & Reel, add suffix –Z (e.g. MA730GQ–Z) TOP MARKING AZA: Product code of MA730GQ Y: Year code LLL: Lot number PACKAGE REFERENCE TOP VIEW GND MISO 8 PWM 9 TEST 10 MGL SCLK 7 B CS 6 5 4 MOSI 3 Z 11 2 A 12 1 SSD 17 PAD 13 14 VDD N/C 15 16 SSCK MGH QFN-16 (3mmx3mm) MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 2 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS 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 MA730 Rev. 1.01 10/13/2017 (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. © 2017 MPS. All Rights Reserved. 3 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS ELECTRICAL CHARACTERISTICS Parameter Symbol Condition Recommended Operating Conditions Supply voltage VDD Supply current Operating temperature Applied magnetic field MA730 Rev. 1.01 10/13/2017 IDD Top B From -40°C to +125°C Min Typ Max Units 3.0 3.3 3.6 V 10.2 11.7 13.8 mA 125 °C mT -40 40 60 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 4 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS GENERAL CHARACTERISTICS VDD = 3.3V, 45mT < B < 100mT, temp = -40°C to +125°C, unless otherwise noted. Parameter Absolute Output – Serial Effective resolution Noise RMS Refresh rate Data output length Response Time Power-up time (4) Latency (4) Filter cutoff frequency (4) Accuracy Symbol Condition 3σ deviation of the noise distribution Constant speed propagation delay INL between -40°C to +125°C (5) Output Drift Temperature induced drift at room temperature (5) Temperature induced variation (5) Magnetic field induced (5) Voltage supply induced (5) Absolute Output – PWM PWM frequency Fpwm PWM resolution Incremental Output – ABZ ABZ update rate Resolution - edges per turn Pulses per channel per PPT+1 turn ABZ hysteresis (5) H Systematic jitter Random jitter (3σ) Overall ABZ jitter (5) MA730 Rev. 1.01 10/13/2017 Typ Max Units 13.0 0.003 850 16 13.8 0.004 980 14.5 0.007 1100 16 bit deg kHz bit 260 10 23 ms µs Hz 0.7 deg 1.1 deg 8 Fcutoff INL at 25°C (5) Min At room temperature over the full field range Over the full temperature range and field range From 25°C to 85°C From 25°C to 125°C 840 13 0.015 0.04 deg/°C 0.5 1.0 0.005 1.2 2.1 0.3 deg deg deg/mT deg/V 1090 14.0 Hz bit 970 13.8 16 MHz Programmable 4 4096 Programmable 1 1024 For PPT = 1023, between 0 and 100krpm, up to 60mT For PPT = 127, between 0 and 100krpm For PPT = 255, between 0 and 100krpm For PPT = 127, between 0 and 100krpm Up to 60mT www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 0.1 deg 11 % 7 % 4.2 % 0.5 % 0.2 deg 5 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS GENERAL CHARACTERISTICS (continued) VDD = 3.3V, 45mT < B < 100mT, temp = -40°C to +125°C, unless otherwise noted. Parameter Symbol Condition Magnetic Field Detection Thresholds Accuracy (5) Hysteresis (5) MagHys Temperature drift (5) Digital I/O Input high voltage Input low voltage Output low voltage (5) Output high voltage (5) Pull-down resistor Rising edge slew rate (4) Falling edge slew rate (4) VIH VIL VOL VOH RPD TR TF Min Typ 5 6 -600 2.5 -0.3 IOL = 4mA IOH = 4mA CL = 50pF CL = 50pF Max 2.4 43 Units mT mT ppm/°C 5.5 0.8 0.4 V 97 kΩ V V V 55 0.7 0.7 V/ns V/ns NOTES: 4) Guaranteed by design. 5) Guaranteed by characteristic test. MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 6 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS TYPICAL CHARACTERISTICS VDD = 3.3V, Temp = 25°C, unless otherwise noted. Current Consumption at VDD = 3.3V ABZ Jitter at PPT = 255 Filter Transfer Function 5 6 FILTER TRANSFER FUNCTION (dB) 12 5 SUPPLY CURRENT (mA) RANDOM JITTER (%) 11.5 4 3 11 10.5 0 -3 dB -5 -10 -15 2 -20 1 10 1 0.1 1 10 100 1000 10 4 10 -50 5 0 50 100 10 100 1000 10 4 150 f (Hz) TEMPERATURE (癈 ) ROTATION SPEED (rpm) Non-Linearity (INL and Harmonics) Error Curves at 50mT Effective Resolution (3σ) 14 1.5 2 NON-LINEARITY (deg) ERROR (deg) INL 25癈 125癈 1 EFFECTIVE RESOLUTION (bit) 13 -45癈 0 -1 1 H1 0.5 12 11 10 H2 9 -2 8 0 50 100 150 200 250 300 350 ANGLE (deg) 0 0 0 20 40 60 80 100 20 40 60 80 100 120 MAGNETIC FIELD (mT) MAGNETIC FIELD (T) Noise Spectrum at 50mT 1/2 NOISE DENSITY (deg/Hz ) 0.01 0.001 0.0001 0.1 1 10 100 1000 10 4 FREQUENCY (Hz) MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 7 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS PIN FUNCTIONS Package Pin # 1 2 3 4 5 6 Name Description SSD A Z MOSI CS B Data out (SSI). Incremental output. Incremental output. Data in (SPI). MOSI has an internal pull-down resistor. Chip select (SPI). CS has an internal pull-up resistor. Incremental output. Data out (SPI). MISO has an internal pull-down resistor that is enabled at a high impedance state. Supply ground. PWM output. Factory use only. Connect TEST to ground. Digital output indicating field strength below MGLT level. Clock (SPI). Internal pull-down. 3.3V supply. No connection. Leave NC unconnected. Clock (SSI). Internal pull-down. Digital output indicating field strength above MGHT level. 7 MISO 8 9 10 11 12 13 14 15 16 GND PWM TEST MGL SCLK VDD NC SSCK MGH MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 8 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS BLOCK DIAGRAM Figure 1: Functional Block Diagram MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 9 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS 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 MA730 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 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. MA730 Rev. 1.01 10/13/2017 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 40mT. Note that the MA730 can work with fields smaller than 40mT, but the linearity and resolution performance may deviate from the specifications. The most straightforward mounting method is to place the MA730 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. © 2017 MPS. All Rights Reserved. 10 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS In general, the MagAlpha works well with or without the exposed pad connected to anything. For optimal conditions (electrically, thermally, and mechanically), it is recommended that the exposed pad be connected to ground. Figure 4: End-of-Shaft Mounting If the end-of-shaft position is not available, the sensor can be positioned away from the rotation axis of a cylinder or ring magnet (see Figure 5). In this case, the magnetic field angle is no longer directly proportional to the mechanical angle. The MA730 can be adjusted to compensate for this effect and recover the linear relation between the mechanical angle and the sensor output. With multiple pole pair magnets, the MA730 indicates multiple rotations for each mechanical turn. Figure 5: Side-Shaft Mounting 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). 3.3 V MGL MGH A B 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 13 for details. Table 1: SPI Specification SCLK idle state Data capture Data transmission CS idle state Data order Table 2: SPI Standard MOSI SCLK 1 mF MA730 Mode 0 Mode 3 Low High On SCLK rising edge On SCLK falling edge High MSB first Z MISO VDD 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). CS GND SSCK CPOL CPHA Data order (DORD) Mode 0 Mode 3 0 1 0 1 0 (MSB first) SSD TEST Exposed pad PWM Figure 6: Connection for Supply Decoupling MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 11 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS 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. MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 12 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS SPI Communication The sensor supports three types of SPI operation:    Read angle Read configuration register Write configuration register Angle reading can be therefore 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 fast reading, the MagAlpha continues sending the same data until the data is refreshed. See the refresh rate section in the General Characteristics table on page 5. Table 4: Sensor Data Timing Event Action Start reading and freeze CS falling edge output buffer CS rising edge Release of the output buffer See Figure 9 for a diagram of a full SPI angle reading. See Figure 10 for 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 The MagAlpha family has sensors with different features and levels of resolution. See the data output length section 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 MagApha replies with: MSB MISO MOSI MA730 Rev. 1.01 10/13/2017 LSB Angle(15:4) Figure 9: Diagram of a Full 16-Bit SPI Angle Reading Figure 10: Diagram of a Partial 8-Bit SPI Angle Reading 0 0 0 0 0 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 13 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS SPI Read Register A read register operation is constituted of two 16-bit frames. The first frame sends a read request, which contains the three-bit read command (010) followed by the five-bit register address. The last eight bits of the frame must be all set to zero. The second frame returns the eight-bit register value (MSB byte). MOSI 0 See Figure 11 for a complete transmission overview. 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 MISO LSB Angle(15:0) MOSI command reg. address MOSI 0 1 0 A4 A3 A2 A1 A0 0 0 0 0 0 0 0 0 reg. value MISO V7 V6 V5 V4 V3 V2 V1 V0 command 0 1 0 reg. address 1 1 0 1 1 0 0 0 0 0 0 0 0 LSB 0 0 0 0 0 0 0 0 In the second frame, the MagAlpha replies: reg. value MISO MGH MGL X X X X X X The second 16-bit SPI frame (response) is: MSB LSB Angle(15:0) 0 0 0 0 0 0 0 0 MSB MOSI LSB 0 See Figure 12 for a complete example overview. Figure 11: Two 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 MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 14 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS 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 at 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 readback 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 MOSI LSB Angle(15:0) command 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 a 20ms 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) MSB MOSI LSB 0 See Figure 14 for a complete example. command reg. address reg. value MOSI 1 0 0 A4 A3 A2 A1 A0 V7 V6 V5 V4 V3 V2 V1 V0 Figure 13: Overview of Two 16-Bit Frames Write Register Operation MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 15 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS 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 only angle reading. It is not possible to read or write registers using SSI. SSI Communication Unlike SPI, the sensor SSI only supports angle reading operation. 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 driving SSCK high. A full reading requires up to 17 clock counts (see Figure 16). MA730 Rev. 1.01 10/13/2017 The first clock is a dummy clock to start the transmission. The data length is up to 16 bits long. See the data output length section in the General Characteristics table on page 5 for the number of useful bits delivered at the serial output. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 16 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS The first data MSB is transmitted on the second clock count. If the data length is less than 16, the 16-bit output word is completed by zeros. Therefore, the reading can also be performed with fewer than 16 clock counts. For example, for a part with a 12-bit data length, it is only necessary to send the first dummy clock to start the transmission plus 12 clocks to read the angle data. When a trigger event is detected, the data remains in the output buffer until the clock falling edge for the LSB bit 0 and the transfer timeout time has passed (see Table 6). Table 6: Sensor Data Timing Trigger event Release of the output buffer First SSCK pulse rising edge SSCK falling edge + time out tm (Fig 15) Figure 16: Diagram of a Full 16-Bit SSI Angle Reading (with First Dummy Clock) For consecutive angle readings, see the timing diagram in Figure 17. Figure 17: Diagram of Two Consecutive 16-Bit SSI Angle Reading with the Required Dead Time between the Frames MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 17 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS REGISTER MAP Table 7: Register Map Bit 7 MSB Bit 6 Bit 0 LSB - ETY ETX - - - - - - - - - - - Bin 0 0x0 00000 Z(7:0) 1 0x1 00001 Z(15:8) 2 0x2 00010 BCT(7:0) 3 0x3 00011 4 0x4 00100 5 0x5 00101 6 0x6 00110 9 0x9 01001 RD - - - - 27 0x1B 11011 MGH MGL - - - - Bit 4 Bit 1 Hex - Bit 5 Bit 2 No Bit 3 - PPT(1:0) ILIP(3:0) PPT(9:2) MGLT(2:0) 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 2 0x2 00010 0 0 0 0 0 0 0 0 3 0x3 00011 0 0 0 0 0 0 0 0 4 0x4 00100 1 1 0 0 0 0 0 0 5 0x5 00101 1 1 1 1 1 1 1 1 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 Zero setting Bias current trimming Z Number of Bits 16 BCT 8 Enable trimming X ETX 1 Enable trimming Y ETY 1 Pulses per turn PPT 10 ILIP Index length / index position Magnetic field high threshold Magnetic field low threshold Rotation direction MA730 Rev. 1.01 10/13/2017 Description See Table Set the zero position For side-shaft configuration: reduce the bias current of the X or Y Hall device Biased current trimmed in the X direction Hall device Biased current trimmed in the Y direction Hall device Number of pulses per turn of the ABZ output 10 4 Parametrization of the ABZ index pulse Fig 26 MGHT 3 Sets the field strength high threshold 16 MGLT 3 Sets the field strength low threshold 16 RD 1 Determines the sensor positive direction 12 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 13 14 14 17 18 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS 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 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). (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) Figure 18: Positive Rotation Direction of the Magnetic Field Table 10 shows the zero setting parameter. Table 10: Zero Setting Parameter Zero pos. Zero pos. Z(15:0) a0 16-bit (dec) a0 (deg) 0 65536 360.000 1 65535 359.995 2 65534 359.989 … … … 65534 2 0.011 65535 1 0.005 Table 12: Rotation Direction Parameter RD 0 1 Example To set the zero position to 20 degrees, the Z(15:0) parameter must be equal to the complementary angle and can be calculated with Equation (4): Z (15 : 0)  216  20 deg 16 2  61895 360 deg (4) In binary, this is written as 1111 0001 1100 0111. Positive Direction Clockwise (CW) Counterclockwise (CCW) BCT Settings (Bias Current Trimming) Side Shaft When the MA730 is mounted on the side of the magnet, the relation between the field angle and the mechanical angle is no longer directly linear. This effect is related to the fact that the tangential magnetic field is usually smaller than the radial field. Define the field ratio k with Equation (5): k  Brad / Btan (5) Where Brad and Btan are the maximum radial and tangential magnetic fields (see Figure 19). Table 11 shows the content of registers 0 and 1. Table 11: Register 0 and 1 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 Figure 19: Side-Shaft Field MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 19 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS Table 13: Example of BCT Settings E (deg) Magnet Ratio (k) BCT(7:0) 0 1.0 0 11.5 1.5 86 19.5 2.0 129 25.4 2.5 155 30.0 3.0 172 33.7 3.5 184 36.9 4.0 194 39.5 4.5 201 41.8 5.0 207 The ratio k depends on the magnet geometry and the distance to the sensor. Having a k ratio different from one results in the sensor output response not being linear with respect to the mechanical angle. Note that the error curve has the shape of a double sinewave (see Figure 21). E is the amplitude of this error. The X-axis or the Y-axis bias current can be reduced in order to recover an equal Hall signal for all angles and therefore suppress the error. The parameters ETX and ETY control the direction in which sensitivity is reduced. The current reduction is set by the parameter bias current trimming BCT(7:0), which is an integer from 0 to 255. In side-shaft configuration (i.e.: the sensor center is located beyond the magnet outer diameter), k is greater than one. For optimum compensation, the sensitivity of the radial axis should be reduced by setting the BCT parameter as shown in Equation (6):  1 BCT (7 : 0)  258 1    k (6) Determining k with the MagAlpha It is possible to deduce the k ratio from the error curve obtained with the default BCT setting (BCT = 0). For this purpose, rotate the magnet over one revolution and record the MagAlpha output. Then plot the error curve (the MagAlpha output minus the real mechanical position vs. the real mechanical position) and extract two parameters: the maximum error (E) and the position of this maximum with respect to a zero crossing am (see Figure 21). k can be calculated with Equation (7): The graph in Figure 20 shows the optimum BCT value for a particular k ratio. k tan(E  a m ) tan(a m ) (7) 200 40 150  2E m 100 Error (deg) BCT 20 50 0 -20 0 1 1.5 2 2.5 3 3.5 4 4.5 5 k Figure 20: Relation between the k Ratio and the Optimum BCT to Recover Linearity Table 13 shows some typical BCT values. -40 0 50 100 150 200 250 300 350 rotor angle (deg) Figure 21: Error Curve in Side-Shaft Configuration with BCT = 0 Some examples are given in Table 13. Alternatively, the k parameter can be obtained from the graph in Figure 22. MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 20 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS Magnetic Field Thresholds The magnetic flags (MGL and MGH) indicate that the magnetic field at the sensor position is out of a range defined by the lower (MGLT) and upper magnetic field thresholds (MGHT) (see Figure 24). 5 4.5 4 k 3.5 3 2.5 2 1.5 1 0 5 10 15 20 25 30 35 40 E (deg) Figure 22: Relation between the Error Measured with BCT = 0 and the Magnet Ratio k Sensor Orientation The dot marked on the package shows whether the radial field is aligned with the sensor coordinate X or Y (see Figure 23). Figure 24: MGH and MGL Signals as a Function of the Field Strength MagHys, the typical hysteresis on the signals MGH and MGL is 6mT. The MGLT and MGHT thresholds are coded on three bits and stored in register 6 (see Table 15). Table 15: Register 6 Register 6 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 MGLT MGHT - The 3-bit values of MGLT and MGHT correspond to the magnetic field (see Table 16). Figure 23: Package Top View with X and Y Axes Determine which axis needs to be reduced (see the qualitative field distribution around a ring in Figure 19). For instance, with the arrangement depicted in Figure 23, the field along the sensor Y direction is tangential and weaker. The X-axis should be reduced (ETX = 1 and ETY = 0). Note that if both ETX and ETY are set to 1, the current bias is reduced in both directions the same way (i.e.: without side-shaft correction) (see Table 14). Table 14: Trimming Direction Parameters ETX Enable Trimming of the X Axis 0 Disabled 1 Enabled ETY Enable Trimming of the Y Axis 0 Disabled 1 Enabled MA730 Rev. 1.01 10/13/2017 Table 16: MGLT and MGHT Binary to mT Relation MGLT or MGHT (8) 000 001 010 011 100 101 110 111 Field threshold in mT (7) From low to high magnetic field 26 41 56 70 84 98 112 126 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. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 21 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS To read the MGL and MGH flags by SPI send the 8-bit command write into register 27: command 0 1 0 reg. address 1 1 0 1 1 value LSB 0 0 0 0 0 0 0 0 MSB The MA730 answers with the register 27 content in the next transmission: MGH MGL x R[7:0] x x x x x ABZ Incremental Encoder Output The MA730 ABZ output emulates a 12-bit incremental encoder (such as an optical encoder) providing logic pulses in quadrature (see Figure 25). Compared to signal A, signal B is shifted by a quarter of the pulse period. Over one revolution, signal A pulses n times, where n is programmable from 1 to 1024 pulses per revolution. The number of pulses per channel per revolution is programmed by setting the parameter PPT, which consists of eight bits split between registers 0x4 and 0x5 (see Table 7). The factory default value is 1023. Table 17 describes how to program PPT(9:0) to set the required resolution. PPT(9:0) 0000000000 0000000001 0000000010 0000000011 … 1111111100 1111111101 1111111110 1111111111 Table 17: PPT Pulses per Edges per Revolution Revolution 1 4 2 8 3 12 4 16 … … 1021 4084 1022 4088 1023 4092 1024 4096 Figure 25: Timing of the ABZ Output Signal Z (zero or index) raises only once per turn at the zero-angle position. The position and length of the Z pulse is programmable via bits ILIP[3:0] in register 0x5 (see Figure 26). Figure 26: ILIP Parameter Effect on Index Shape MIN … MAX By default, the ILIP parameter is 0000. The index rising edge is aligned with the channel B falling edge. The index length is half the A or B pulse length. ABZ Hysteresis A hysteresis larger than the output noise is introduced on the ABZ output to prevent any spurious transitions (see Figure 27). For example, to set 120 pulses per revolution (i.e.: 480 edges), set PPT to 120 - 1 = 119 (binary: 0001110111). Registers 4 and 5 must be set as shown in Table 18. Table 18: Example PPT Setting for 120 Pulses R4 R5 B7 1 0 B6 1 0 B5 0 0 B4 0 1 B3 0 1 B2 0 1 B1 0 0 B0 0 1 Figure 27: Hysteresis of the Incremental Output MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 22 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS ABZ Jitter The ABZ state is updated at a frequency of 16MHz, enabling accurate operation up to a very high rpm (above 105 rpm). The jitter characterizes how far a particular ABZ edge can occur at an angular position different from the ideal position (see Figure 28). Figure 28: ABZ Jitter The measurable jitter is composed by a systematic jitter (i.e.: always the same deviation at a given angle) and a random jitter. The random jitter reflects the sensor noise. Therefore, the edge distribution is the same as the SPI output noise. Like the sensor resolution, it is defined as the 3σ width of this distribution. In fact, the random jitter is a function of the rotation speed. At a lower speed, the random jitter is smaller than the sensor noise. This is a consequence of the fact that the probability of measuring an edge at a certain distance from the ideal position depends on the number of ABZ updates at this position. PWM Absolute Output This output provides a logic signal with a duty cycle proportional to the angle of the magnetic field. The PWM frequency is indicated in the General Characteristics table on page 5. The duty cycle is bounded by a minimum value (1/514 of the period) and a maximum value (513/514 of the period), so the duty cycle varies from 1/514 to 513/514 with a resolution of 14 bits (see Figure 29). The angle can be retrieved by measuring the on time. Since the absolute PWM frequency can vary from chip to chip or with the temperature, accurate angle detection requires the measurement of the duty cycle (i.e.: the measurement of both the on time (ton) and the off time (toff)). The angle can be calculated with Equation (8): angle (in deg)   tON 360   514  1 (8) 512  tON  tOFF  Figure 29 shows one period of the PWM signal. The period (T) is 1/FPWM, where FPWM is the PWM frequency indicated in the general characteristic table. T/514 tOFF tON T/514 The minimum field for ABZ reading is 40mT. T Top Signal: 0° Bottom Signal: Full Scale (i.e.: 360°(1-1/16384)) Figure 29: PWM Output Timing MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 23 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS TYPICAL APPLICATION CIRCUITS Figure 30: Typical Configurations Using SPI Interface and MGH/MGL Signals Figure 31: Typical Configuration Using ABZ Interface MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 24 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS PACKAGE INFORMATION QFN-16 (3mmx3mm) MA730 Rev. 1.01 10/13/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 25 MA730 – 14-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS APPENDIX A: DEFINITIONS Effective 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. ABZ Update Rate Rate at which a new ABZ state is computed. The inverse of this rate is the minimum time between two ABZ edges. 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  latency  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 (see Figure A1). 400 sensor out (deg) 350 300 lag 250 ideal sensor output 200 150 INL 100 0 sensor out best straight fit resolution ( ? 3 ) 50 0 100 200 300 400 500 600 700 rotor position (deg) Figure A1: Resolution, INL, Lag INL can be obtained from the error curve err(a) = out(a) - a, where out(a) is the average over 1000 sensor output, and a is the mechanical angle indicated by a high precision encoder (