A1335 Precision Hall-Effect Angle Sensor IC with I 2C, SPI, and SENT Interfaces DESCRIPTION FEATURES AND BENEFITS * 360 contactless high-resolution angle position sensor * CVH (Circular Vertical Hall) technology * Available with either a single die or dual independent die housed within a single package * Digital output format selectable among SPI, I2C, and SENT (Single-Edge Nibble Transmission) * SENT output is SAEJ2716 JAN2010 compliant, with Allegro proprietary enhanced programmable features * Customer-programmable SENT tick times, ranging from 0.5 to 7.9 s * SPI interface allows use of multiple independent sensor ICs for applications requiring redundancy * Refresh rate: 32 s, 12-bit resolution * Programmable via Manchester encoding on the VCC line, reducing external wiring * Automotive temperature range: -40C to 150C * AEC-Q100 automotive qualified * Two types of linearization algorithms offered: harmonic linearization and segmented linearization Enables off-axis operation The A1335 is a 360 contactless high-resolution programmable magnetic angle position sensor IC. It is designed for digital systems and is capable of communicating via an I2C, SPI, or SENT interface. This system-on-chip (SoC) architecture includes a front end based on Circular Vertical Hall (CVH) technology, programmable microprocessor-based signal processing, and features an interface capable of supporting I2C, SPI, and SENT. Besides providing full-turn angular measurement, the A1335 also provides scaling for angle measurement applications less than 360. It includes on-chip EEPROM technology, capable of supporting up to 100 read/write cycles, for flexible programming of calibration parameters. Digital signal processing functions, including temperature compensation and gain/offset trim, as well as advanced output linearization algorithms, provide an extremely accurate and linear output for both end-of-shaft applications as well as offaxis applications. Continued on the next page... PACKAGES: The A1335 is available as a single die in a 14-pin TSSOP, or dual die in a 24-pin TSSOP. Both packages are lead (Pb) free with 100% matte-tin leadframe plating. Not to scale Single SoC, 14-pin TSSOP (suffix LE) The A1335 is ideal for automotive applications requiring highspeed 360 angle measurements, such as: electronic power steering (EPS), transmission, torsion bar, and other systems that require accurate measurement of angles. The A1335 linearization schemes were designed with challenging off-axis applications in mind. Dual Independent SoCs, 24-pin TSSOP (suffix LE) V+ VCC (also programming) BYP To all internal circuits Analog Front End SOC Die Regulator Multisegment CVH Element SENT CBYP(VCC) SENT Interface Diagnostics Digital Subsystem SDA/MISO SCL/SCLK CBYP(BYP) SA0/CS I2C/SPI Interface 32-bit Microprocessor SA1/MOSI ISEL DGND VCC (Programming) EEPROM AGND ADC Industry-leading linearization enables off-axis (side-shaft) operation Functional Block Diagram A1335-DS, Rev. 4 MCO-0000137 July 30, 2018 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 FEATURES AND BENEFITS (continued) * Programmable range--can scale 22.5 to full-scale digital output * Microprocessor-based output linearization * EEPROM with Error Correction Control (ECC) for trimming calibration * 1 mm thin (TSSOP) package * Improved air gap performance, based on continuous background calibration SELECTION GUIDE Part Number System Die Package Packing* A1335LLETR-T A1335LLETR-DD-T Single 14-pin TSSOP 4000 pieces per 13-in. reel Dual 24-pin TSSOP 4000 pieces per 13-in. reel *Contact Allegro for additional packing options ABSOLUTE MAXIMUM RATINGS Characteristic Symbol Notes Rating Unit Forward Supply Voltage VCC 24 V Reverse Supply Voltage VRCC -18 V All Other Pins VIN Operating Ambient Temperature TA Maximum Junction Temperature Storage Temperature -0.5 to 5.5 V -40 to 150 C TJ(max) 165 C Tstg -65 to 170 C L temperature range THERMAL CHARACTERISTICS: May require derating at maximum conditions; see application information Characteristic Package Thermal Resistance Symbol RJA Test Conditions* Value Unit LE-14 package 82 C/W LE-24 package 117 C/W *Additional thermal information available on the Allegro website. Table of Contents Features and Benefits............................................................ 1 Description........................................................................... 1 Packages............................................................................. 1 Functional Block Diagram...................................................... 1 Selection Guide.................................................................... 2 Absolute Maximum Ratings.................................................... 2 Thermal Characteristics......................................................... 2 Pinout Diagrams and Terminal Lists......................................... 3 Operating Characteristics....................................................... 4 Functional Description........................................................... 7 Overview.......................................................................... 7 Operation.......................................................................... 7 Diagnostic Features......................................................... 10 Programming Mode...........................................................11 Manchester Serial Interface.................................................. 12 Entering Manchester Communication Mode........................ 12 Transaction Types............................................................ 12 Writing to EEPROM......................................................... 12 Manchester Interface Reference........................................ 13 SENT Output Mode.......................................................... 14 Application Information........................................................ 16 Serial Interface Description............................................... 16 Magnetic Target Requirements.......................................... 17 Calculating Target Zero Degree Angle................................ 18 Bypass Pin Usage............................................................ 18 Effect of Orientation on Signal........................................... 20 Linearization.................................................................... 22 Typical Performance Characteristics...................................... 25 Package Outline Drawings................................................... 27 Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 2 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 PINOUT DIAGRAMS AND TERMINAL LIST Terminal List Table Pin Name [1] 14 DGND DGND 1 Pin Number LE-14 LE-24 13 SA0/CS VCC_1 5 5 DGND 3 12 SA1/MOSI VCC_2 - 17 NC 4 11 SCL/SCLK VCC 5 10 SDA/MISO BYP 2 9 SENT NC 6 8 ISEL AGND 7 LE-14 Package (Single SoC) AGND_1 7 3 AGND_2 - 15 BYP_1 2 2 Internal bypass node, connect with bypass capacitor to DGND (die 1). BYP_2 - 14 Internal bypass node, connect with bypass capacitor to DGND (die 2). DGND_1 1, 3, 14 1, 24 DGND_2 - 12,13 ISEL_1 8 18 Selects between I2C operation (set to logic low) or SPI operation (set to logic high) (for SENT/Manchester operation set low) (die 1) ISEL_2 - 6 Selects between I2C operation (set to logic low) or SPI operation (set to logic high) (for SENT/Manchester operation set low) (die 2). NC 4, 6 4, 16 24 DGND_1 DGND_1 1 23 SA0_1/CS_1 BYP_1 2 AGND_1 3 22 SA1_1/MOSI_1 NC 4 21 SCL_1/SCLK_1 VCC_1 5 20 SDA_1/MISO_1 ISEL_2 6 19 SENT_1 SENT_2 7 18 ISEL_1 SDA_2/MISO_2 8 17 VCC_2 SCL_2/SCLK_2 9 16 NC SA1_2/MOSI_2 10 15 AGND_2 SA0_2/CS_2 11 DGND_2 12 _1 SA0_1/CS _2 SA0_2/CS 13 - SA1_1/ MOSI_1 12 Device digital ground terminal. Not Connected; connect to GND for optimal ESD performance. 23 11 I2C: SA0 digital input. Sets slave address bit 0 (LSB) [2]; tie to BYP for 1, tie to DGND for 0. SPI: Chip Select input, active low (die 2). Manchester: LSB of the ID value for Die 2. tie to BYP for 1, to DGND for 0. Must be in I2C operation (ISEL set to a logic low). 22 I2C: SA1 digital input: Sets slave address bit 1 (LSB) [2]; tie to BYP for 1, tie to DGND for 0. SPI: Master Output / Slave Input terminal (die 1). Manchester: MSB of the ID value for Die 1. tie to BYP for 1, to DGND for 0. Must be in I2C operation (ISEL set to a logic low). LE-24 Package (Dual SoC) Device analog ground terminal. I2C: SA0 digital input. Sets slave address bit 0 (LSB) [2]; tie to BYP for 1, tie to DGND for 0. SPI: Chip Select input, active low (die 1). Manchester: LSB of the ID value for Die 1. tie to BYP for 1, to DGND for 0. Must be in I2C operation (ISEL set to a logic low). 14 BYP_2 13 DGND_2 Function Device power supply and input for EEPROM writing pulses. Used to enter/exit Manchester Serial Communication mode; serves as programming data input once mode has been entered. SA1_2/ MOSI_2 - 10 I2C: SA1 digital input: Sets slave address bit 1 (LSB) [2]; tie to BYP for 1, tie to DGND for 0. SPI: Master Output / Slave Input terminal (die 2). Manchester: MSB of the ID value for Die 2. tie to BYP for 1, to DGND for 0. Must be in I2C operation (ISEL set to a logic low). SCL_1/ SCLK_1 11 21 Digital input: Serial clock (I2C: SCL, SPI: SCLK); open drain, pull up externally to 3.3 V (die 1). SCL_2/ SCLK_2 - 9 Digital input: Serial clock (I2C: SCL, SPI: SCLK); open drain, pull up externally to 3.3 V (die 2). SDA_1/ MISO_1 10 20 I2C: Digital data terminal: digital output of evaluated target angle, also programming data input; open drain, pull up externally to 3.3 V (die 1). SPI: Master Input / Slave Output terminal (die 1). SDA_2/ MISO_2 - 8 I2C: Digital data terminal: digital output of evaluated target angle, also programming data input; open drain, pull up externally to 3.3 V (die 2). SPI: Master Input / Slave Output terminal (die 2). SENT_1 9 19 SENT transmission output terminal (die 1); Manchester output in Manchester mode; open drain, pull-up to external supply. SENT_2 - 7 SENT transmission output terminal (die 2); Manchester output in Manchester mode; open drain, pull-up to external supply. [1] The number following the underscore refers to the die number in a dual SOC variant additional information, refer to the Programming Reference addendum, EEPROM Description and Programming section, regarding the INTF register, I2CM field. [2] For Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 3 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 OPERATING CHARACTERISTICS: Valid throughout full operating voltage and ambient temperature ranges, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. [1] Max. Unit [2] 4.5 5 5.5 V ELECTRICAL CHARACTERISTICS Supply Voltage VCC Supply Current VCC Low Flag Threshold ICC - 15 20 mA VCCLOW(TH) 4.4 4.55 4.75 V Supply Zener Clamp Voltage VZSUP IZCC = ICC + 3 mA, TA = 25C 26.5 - - V Reverse Battery Voltage VRCC IRCC = -3 mA, TA = 25C - - -18 V tPO TA = 25C 2 - 40 ms Digital Input High Voltage [3] VIH MOSI, SCLK, CS pins 2.8 - 3.63 V Voltage [3] VIL MOSI, SCLK, CS pins - - 0.5 V VOH MISO pins, TA = 25C 2.93 3.3 3.69 V SPI Output Low Voltage VOL MISO pins SPI Clock Frequency [3] fSCLK MISO pins, CL = 50 pF Power-On Time [3][4] SPI INTERFACE SPECIFICATIONS [5] Digital Input Low SPI Output High Voltage Chip Select to First SCLK Edge [3] Chip Select Idle Time [3] Data Output Valid Time [3] MOSI Setup Time [3] MOSI Hold Time [3] SCLK to CS Hold Time [3] Load Capacitance [3] tCS tCS_IDLE - 0.3 - V 0.1 - 10 MHz Time from CS going low to SCLK falling edge 50 - - ns Time CS must be high between SPI message frames 200 - - ns tDAV Data output valid after SCLK falling edge - 45 - ns tSU Input setup time before SCLK rising edge 10 - - ns tHD Input hold time after SCLK rising edge 50 - - ns tCHD Hold SCLK high time before CS rising edge 5 - - ns Loading on digital output (MISO) pin - - 50 pF CL I2C INTERFACE SPECIFICATIONS (VPU = 3.3 V on SDA and SCL pins) Bus Free Time Between Stop and Start [3] tBUF 1.3 - - s Hold Time Start Condition [3] tHD(STA) 0.6 - - s Setup Time for Repeated Start Condition [3] tSU(STA) 0.6 - - s SCL Low Time [3] tLOW 1.3 - - s SCL High Time [3] tHIGH 0.6 - - s ns Data Setup Time [3] tSU(DAT) 100 - - Data Hold Time [3] tHD(DAT) 0 - 900 ns Setup Time for Stop Condition [3] tSU(STO) 0.6 - - s Logic Input Low Level (SDA and SCL pins) [13] VIL(I2C) - - 0.9 V Logic Input High Level (SDA and SCL pins) VIH(I2C) 2.1 - 3.63 V Continued on the next page... Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 4 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 OPERATING CHARACTERISTICS (continued): Valid throughout full operating voltage and ambient temperature ranges, unless otherwise specified Characteristic I2C Symbol Test Conditions Min. Typ. [1] Max. Unit [2] VIN = 0 V to VCC -1 - 1 A RPU = 1 k, CB = 100 pF, TA = 25C - - 0.6 V INTERFACE SPECIFICATIONS (VPU = 3.3 V on SDA and SCL pins) (continued) Logic Input Current [3] IIN Output Voltage (SDA pin) VOL(I2C) Logic Input Rise Time (SDA and SCL pins) [3] tr(IN) - - 300 ns Logic Input Fall Time (SDA and SCL pins) [3] tf(IN) - - 300 ns SDA Output Rise Time [3] tr(OUT) RPU = 1 k, CB = 100 pF - - 300 ns SDA Output Fall Time [3] tF(OUT) RPU = 1 k, CB = 100 pF - - 300 ns Frequency [13] SCL Clock fCLK - - 400 kHz SDA and SCL Bus Pull-Up Resistor RPU - 1 - k Total Capacitive Load on SDA Line [3] Pull-Up Voltage [3] SENT Interface CB - - 100 pF 2.97 3.3 3.63 V Tick time = 3 s - - 1 ms tSENTMIN Tick time = 0.5 s, 3 data nibbles, SCN, and CRC, nibble length = 27 ticks - 96 - s VSENT(L) 5 k Rpullup 50 k - - 0.10 V Minimum Rpullup = 5 k 0.9 x VS - - V Maximum Rpullup = 50 k 0.7 x VS - - V VPU RPU = 1 k, CB = 100 pF tSENT Specifications [3] SENT Message Duration Minimum Programmable SENT Message Duration SENT Output Signal SENT Trigger Signal Minimum Time Frame for SENT Trigger Signal VSENT(H) VSENTtrig(L) - - 1.4 V VSENTtrig(H) 2.8 - - V Ttrig(MIN) 2 - - s Triggered Delay Time tdSENT From end of trigger pulse to beginning of SENT message frame. TSENT (SENT_MODE 3 and SENT_MODE 4) - 7 - tick Maximum Sink Current ILIMIT Output FET on, TA = 25C - 30 - mA Range of input field - - 1500 G Magnetic Characteristics Magnetic Field [6] B Continued on the next page... Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 5 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 OPERATING CHARACTERISTICS (continued): Valid throughout full operating voltage and ambient temperature ranges, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. [1] Max. Unit [2] - 12 - bit B = 300 G, TA = 25C, ORATE = 0 - 10.8 - bits B 700 G, TA = 25C, ORATE = 0 - 12 - bits ORATE = 0 - 32 - s All linearization and computations disabled, see Figure 1 - 60 - s TA = 25C, ideal magnet alignment, B = 300 G, target rpm = 0, no linearization - 0.5 - degrees TA = 25C, ideal magnet alignment, B = 900 G, target rpm = 0, no linearization - 0.2 - degrees TA = 150C, ideal magnet alignment, B = 300 G, target rpm = 0, no linearization -1.3 - +1.3 degrees TA = 150C, ideal magnet alignment, B = 900 G, target rpm = 0, no linearization - 0.3 - degrees TA = 25C, B = 300 G, no internal filtering, 3 sigma value - 0.6 - degrees TA = 150C, B = 300 G, no internal filtering, 3 sigma value - 0.8 - degrees ANGLE CHARACTERISTICS Output [7] RESANGLE Effective resolution [8] Angle Refresh Rate [9] tANG Response Time [10] Angle tRESPONSE Error [11] ERRANG Angle Noise [11][12] NANG Temperature Drift ANGLEDRIFT TA = 150C, B = 300 G -1.4 1.4 degrees TA = -40C, B = 300 G - 1.2 - degrees - 0.5 - degrees ANGLEDRIFT- B = 300 G, typical maximum drift observed after Angle Drift Over Lifetime LIFE AEC-Q100 qualification testing [1] Typical data is at T = 25C and V A CC = 5 V and it is for design information only. [2] 1 G (gauss) = 0.1 mT (millitesla). [3] Parameters for this characteristic are determined by design. They are not measured at final test. [4] End user can customize what power-on tests are conducted at each power-on that causes a range of power-on times. For more information, see the description of the CFG register. [5] During the power-on phase, the A1335 SPI transactions are not guaranteed. [6] The A1335 operates in Magnetic fields lower than 300 G, but with reduced accuracy and resolution. CVH self-test operation is not guaranteed at field levels above 300 G. [7] RES ANGLE represents the number of bits of data available for reading from the die registers. [8] Effective Resolution is calculated using the formula below: log2(360) - log2 Magnet Position Position 2 t ( ) 1 n Position 1 Response Time n i=1 i where is the Standard Deviation based on thirty measurements taken at each of the 32 angular positions, I = 11.25, 22.5, ... 360. [9] The rate at which a new angle reading is ready. This value varies with the ORATE selection. [10] This value assumes no post-processing and is the response time to read the magnetic position with no further computations. Actual response time is dependent on EEPROM settings. Settings related to filter design, signal path computations, and linearization will increase the response time. [11] Error and noise values are with no further signal processing. Angle Error can be corrected with linearization algorithm, and Angle Noise can be reduced with internal filtering and slower Angle Refresh Rate value. [12] 3 sigma value at 300 G. Operation with a larger magnetic field results in improved noise performance. For 600 G operation, noise reduced by 40-50% vs. 300 G. [13] Parameter is tested at wafer probe only. Sensor Output Output 1 Output 2 t Definition of Response Time Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 6 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 Overview FUNCTIONAL DESCRIPTION The A1335 incorporates a Hall sensor IC that measures the direction of the magnetic field vector through 360 in the x-y plane (parallel to the branded face of the device). The A1335 computes the angle based on the actual physical reading, as well as any internal parameters that have been set by the user. The end user can configure the output dynamic range, output scaling, and filtering. This device is an advanced, programmable internal microprocessor-driven system-on-chip (SoC). It includes a Circular Vertical Hall (CVH) analog front end, a high-speed sampling A-to-D converter, digital filtering, a 32-bit custom microprocessor, a digital control interface capable of supporting I2C, SPI and SENT, and digital output of processed angle data. Advanced linearization, offset, and gain adjustment options are available in the A1335. These options can be configured in onboard EEPROM providing a wide range of sensing solutions in the same device. Device performance can be optimized by enabling individual functions or disabling them in EEPROM to minimize latency. Operation The device is designed to acquire angular position data by sampling a rotating bipolar magnetic target using a multi-segmented circular vertical Hall-effect (CVH) detector. The analog output is processed, and then digitized, and compensated before being loaded into the output register. Refer to Figure 1 for a depiction of the signal process flow described here. * Analog Front End. In this stage, the applied magnetic signal is detected and digitized for more advanced processing. A1 CVH Element. The CVH is the actual magnetic sensing element that measures the direction of the applied magnetic vector. A2 Analog Signal Conditioning. The signal acquired by the CVH is sampled. A3 A-to-D Converter. The analog signal is digitized and handed off to the Digital Front End stage. * Digital Front End. In this preprocessing stage, the digitized signal is conditioned for analysis. D1 Digital Signal Conditioning. The digitized signal is decimated and band pass filtered. D2 Raw Angle Computation. For each sample, the raw angle value is calculated. * Microprocessor. The preprocess signal is subjected to various user-selected computations. The type and selection of computations used involves a trade-off between precision and increased response time in producing the final output. P1 Angle Averaging. The raw angle data is received in a periodic stream, and several samples are accumulated and averaged, based on user-selected output rate. This feature increases the effective resolution of the system. The amount of averaging is determined by the user-programmable ORATE (output rate) field. The user can configure the quantity of averaged samples by powers of two to determine the refresh rate, the rate at which successive averaged angle values are fed into the post-processing stages. The available rates are set as follows: Table 1: Refresh Rates of Averaged Samples ORATE [2:0] Quantity of Samples Averaged Refresh Rate (s) 000 1 32 001 2 64 010 4 128 011 8 256 100 16 512 101 32 1024 110 64 2048 111 128 4096 P1a IIR Filter (Optional). The optional IIR filter can provide more advanced multi-order filtering of the input signal. Filter coefficients can be user-programmed, and the FI bit can be programmed by the user to enable or disable this feature. P2 Angle Compensation. The A1335 is capable of compensating for drift in angle readings that result from changes in the device temperature through the operating ambient temperature range. The device comes from the factory pre-programmed with coefficient settings to allow compensation of linear shifts of angle with temperature. P2a Prelinearization Rotation (Optional, but required if linearization used). The linearization algorithms require input functions that are both continuous and monotonically increasing. The LR bit sets which relative direction of target rotation results in an increasing angle value. The bit must be set such that the input to the linearization algorithm is increasing. Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 7 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 A1 CVH Element A2 Analog Signal Conditioning A3 A to D Converter D1 Digital Signal Conditioning D2 Raw Angle Computation P1 Angle Averaging Analog Front End (Applied Magnetic Signal Detection) Digital Front End (Digital Logic for Processing) Sample Rate (Resolution) (Optional) IR Filter P1a Angle P2 Compensation P2a (Optional) Prelinearization Rotation (Optional) Gain Offset P3 Minimum/ Maximum Angle Check* P4 Gain Adjust* P2b Microprocessor (Angle Processing) (Optional) Harmonic Linearization (Optional) P5 Postlinearization 0 Offset (Optional) P6 Angle Clamping* P4b (Optional) Prelinearization 0 Offset P4a (Optional) Segmented Linearization P4c SRAM EEPROM P5a (Optional) Postlinearization Rotation P7 Angle Rounding to 12 Bits (Optional) Angle Inversion * Short Stroke Applications Only P7a Primary Serial Interface (Optional) Die Adjust Figure 1: Signal Processing Flow (refer by index number to text descriptions) Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 8 A1335 P2b Gain Offset (Optional). Allows zeroing out of the angle prior to applying Gain. Set via the GAIN_OFFSET field. Angle = Angle - GAIN_OFFSET. P3 Minimum/Maximum Angle Check (Short Stroke Applications Only). The device compares the raw angle value to the angle value boundaries set by the user programming the MIN_ ANGLE_S or MAX_ANGLE_S fields. If the angle is excessive, an error flag is set at ERR[AH] (high boundary violation) or ERR[AL] (low boundary violation). This feature is useful for applications that use angle strokes less than 360 degrees (short stroke). (Note: This feature is only active if the Short Stroke bit has been set.) P4 Gain Adjust (Short Stroke Applications Only). This bit adjusts the output dynamic range of the device. For example, if the application only requires 45 degrees of stroke, the user can set this field such that a 45-degree angular change would be distributed across the entire 4095 0 code range. Set using the GAIN field. (Note: This feature is only active if the Short Stroke bit has been set.) P4a Harmonic Linearization (Optional). Applies user-programmed error correction coefficients (set in the LINC registers) to the raw angle measurements. Use the HL bit to enable harmonic linearization. P4b Prelinearization 0 Offset (optional but required if Segmented Linearization is used). The expected angle values should be distributed throughout the input dynamic range to optimize angle post-processing. This is mostly needed for applications that use full 360-degree rotations. This value establishes the position that will correspond to zero error. This value should be set such that the 360 degree range corresponds to the 4095 0 code range. Setting this point is critical if segmented linearization is used. This is required prior to going through linearization, as the compensation requires a continuous input function to operate correctly. Set using the LIN_OFFSET field. Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces P4c Segmented Linearization (Optional). Applies user-programmed error correction coefficients (set in the LINC registers) to the raw angle measurements. Use the SL bit to enable segmented linearization. P5 Postlinearization 0 Offset (Optional). This computation assigns the final angle offset value, to set the low expected angle value to code 0 in the output dynamic range, after all linearization and processing has been completed. Set using the ZERO_OFFSET field. P5a Postlinearization Rotation (Optional). This feature allows the user to chose the polarity of the final angle output, relative to the result of the Prelinearization Rotation direction setting (LR bit, described above). Set using the RO bit. P6 Angle Clamping (Short Stroke Applications Only). The A1335 has the ability to apply digital clamps to the output signal. This feature is most useful for applications that use angle strokes less than 360 degrees. If the output signal exceeds the upper clamp, the output will stay at the clamped value. If the output signal is lower than the lower clamp, the output will stay at the low clamp value. Set using the CLAMP_HI and CLAMP_LO fields. (Note: This feature is only active if the Short Stroke bit has been set.) P7 Angle Rounding to 12 Bits. All of the internal calculations for angle processing in the A1335 take place with 16-bit precision. This step rounds the data into a 12-bit word for output through the Primary Serial Interface. P7a Angle Inversion (Short Stroke Application Only). Rotation within the high and low clamp values. [CLAMP_HI - (Angle - CLAMP_LO)]. (Note: This feature is only active if the Short Stroke bit has been set.) P8 Die Adjust (Optional). Rotates final angle 180 degrees. Used to compensate for the 180 degree offset between die in dual SoC packages. Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 9 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 Diagnostic Features The A1335 was designed with diagnostic requirements in mind and supports many on-chip diagnostics as well as error/status flags, enabling the host microcontroller to assess the operational status of each die. In addition, the A1335 supports three different on-chip userinitiated diagnostics. USER-INITIATED DIAGNOSTICS The following three internal self-tests may be configured to run at power-on, and may also be initiated at any time by the system microcontroller via Extended Access commands through the SPI/I2C interface. A failure of any one of the three self-tests will assert the Self-Test Failure Flag, ST, within the extended error register. The specific failing test can be identified by performing an extended address-read (address 0xFFFC). * CVH Self-Test The CVH self-test is a signal path diagnostic used to verify both analog and digital system integrity. Test execution requires approximately 36 ms, during which time no new angle measurements will be generated by the sensor. The test is implemented by changing the transducer switch configuration from normal mode into a test configuration, allowing a test current to drive the CVHD in place of the magnetic field. By changing the direction of the test current and sequencing different elements within the CVH, the selftest emulates a changing magnetic field angle. The measured angle is monitored to determine a passing or failing device. A failure of the CVH self-test will assert the ST flag. If the self-test was initiated via the Extended Access Command, test results for the individual Hall elements will be stored in the SRAM CmdStatus field (0x00) and the primary serial interface ERD register (0x0E through 0x11). Due to the sensitivity of the self-test, test results are only valid at field levels equal to or less than 300 G and temperatures at or above 25C. * SRAM BIST The SRAM Built-In Self-Test (BIST) verifies proper functionality of the SRAM. The test may be run in either long or short mode, and can be configured to halt on error. A failure of the SRAM BIST will assert the ST flag. When enabled to run on power-up, the short test mode is used, requiring approximately 100 s to complete. For more information on SRAM BIST options, consult the A1335 programming guide. Table 2: Status and Error Flags Fault Condition Description VCC < VCCLOW(TH)(min) Indicates potential for reduced angle accuracy Sensor Response UV error flag is set VCC > 8.8 V Indicates possible system level power supply failure OV error flag is set* Field > MAG_HIGH MAG_HIGH programmable from 0-1240 G in 40 G steps. Monitors Mag Field level in case of mechanical failure MH flag is set Field < MAG_LOW MAG_LOW programmable from 0-620 G in 20 G steps. Monitors Mag Field level in case of mechanical failure ML flag is set -60C > TA > 180C Ambient temperature beyond maximum rating detected TR flag is set Processor Halt Monitors digital logic for proper functionality WT and WC Flags set Single-Bit EEPROM Error (correctable) Detects and corrects a single-bit EEPROM Error ES error flag is set Multi-Bit EEPROM Error (uncorrectable) Detects a multi-bit uncorrectable EEPROM ERROR EU error flag is set Single-Bit SRAM Error (correctable) Detects and corrects a single-bit SRAM Error SS Error flag is set Multi-Bit SRAM Error (uncorrectable) Detects a multi-bit uncorrectable SRAM ERROR SU Error flag is set Angle-Processing Errors New angle measurement did not occur within the maximum time allotted. AT flag is set Angle Out of Range Angle value (prior to scaling by Gain) is outside the range set by MIN_ANGLE and MAX_ANGLE. Short Stroke only. The AL or AH flag is set Loss of VCC Determine if system power was lost. Also detects a reset of the internal microprocessor POR and RC flags are set Self-Test Failure Indicates a failure of one of the three internal self-tests. SRAM BIST, ROM Checksum Verification, and CVH self-test. Tests can be individually configured to run at power-up and may also be user initiated. ST flag set * EEPROM programming pulses result in OV flag assertion. Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 10 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 * ROM Checksum Verification of the ROM checksum may be configured to take place at power-on. In addition, the checksum is continuously recalculated in the background during normal operation (independent of power-on configuration). This test may be initiated at any time by the system microcontroller via an Extended Access Command (0xFFE0). If the self-test was initiated via the Extended Access Command, the failing checksum is stored in the CmdStatus SRAM register (0x00). A bad ROM checksum asserts the Self-Test Failure Flag, ST. LOW VOLTAGE DETECTION In addition to setting the undervoltage (UV) flag, a VCC ramp will also change the state of the output pins (SDA/MISO and SENT) as the part enters and exits the reset condition. This is shown in Figure 2. For more information on diagnostic features and flags, refer to the programmers guide for a more complete description of the available flags and settings. VCC (V) VCC Low Flag Threshold, VCCLOW(TH) 4.4 POR 3.8 3.7 POR UV Error Flag Set UV Error Flag Set State of SDA/MISO and SENT Pins High Impedance Angle Output Accuracy Reduced Accurate Angle Output Angle Output Accuracy Reduced High Impedance t Figure 2: Relationship of VCC and Output Programming Modes The EEPROM can be written through the dedicated I2C or SPI interface pins or via Manchester encoding on the VCC pin, allowing process coefficients to be entered and options selected. (Note: programming EEPROM also requires the VCC line to be pulsed, which could adversely affect other devices if powered from the same line). Certain operating commands also are available by writing directly to SRAM. The EEPROM and SRAM provide parallel data structures for operating parameters. The SRAM provides a rapid test and measurement environment for applica- tion development and bench-testing. The EEPROM provides persistent storage at end of line for final parameters. At Power-on initialization, the EEPROM contents are read into the corresponding SRAM. Provided the Lock Microprocessor [LM] bit within EEPROM is not set, SRAM can be overwritten during operation (Use Caution). The EEPROM is permanently locked by setting the lock EEPROM [LE] bit in the EEPROM. The A1335 EEPROM is programmed via either the I2C, the SPI, or the VCC pin Serial Interface, with additional power provided by pulses on the VCC pin to set the EEPROM bit fields. Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 11 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 MANCHESTER SERIAL INTERFACE To facilitate addressable device programming when using the unidirectional SENT output mode with no need for additional wiring, the A1335 incorporates a serial interface on the VCC line. (Note: The A1335 may be programmed via the SPI or I2C interfaces, with additional wiring connections. For detailed information on part programming, refer to the A1335 programming manual). This interface allows an external controller to read and write registers in the A1335 EEPROM and volatile memory. The device uses a point-to-point communication protocol, based on Manchester encoding per G.E. Thomas (a rising edge indicates a 0 and a falling edge indicates a 1), with address and data transmitted MSB first. The addressable Manchester code implementation uses the logic states of the SA0/SA1 pins to set address values for each die. In this way, individual communication with up to four A1335 die is possible. To prevent any undesired programming of the A1335, the serial interface can be disabled by setting the Disable Manchester bit. With this bit set, the A1335 will ignore any Manchester input on VCC. Entering Manchester Communication Mode Transaction Types As shown in Figure 3, the A1335 receives all commands via the VCC pin, and responds to Read commands via the SENT pin. This implementation of Manchester encoding requires the communication pulses be within a high (VMAN(H)) and low (VMAN(L)) range of voltages on the VCC line. Writing to EEPROM is supported by two high voltage pulses on the VCC line. Each transaction is initiated by a command from the controller; the A1335 does not initiate any transactions. Two commands are recognized by the A1335: Write and Read. Writing to EEPROM When a Write command requires writing to non-volatile EEPROM, after the Write command, the controller must also send two Programming pulses, high-voltage strobes via the VCC pin. These strobes are detected internally, allowing the A1335 to boost the voltage on the EEPROM gates. Refer to the A1335 programming manual for specifics on sensor programming and protocol details. Provided the Disable Manchester bit is not set in EEPROM, the A1335 continuously monitors the VCC line for valid Manchester commands. The part takes no action until a valid Manchester Access Code is received. Write/Read Command Manchester Code There are two special Manchester code commands used to activate or deactivate the serial interface and specify the output format used during Read operations: 1. Manchester Access Code: Enters Manchester Communication Mode; Manchester code output on the SENT pin. A1335 2. Manchester Exit Code; returns the SENT pin to normal (angle data) output format. Once the Manchester Communication Mode is entered, the SENT output pin will cease providing angle data, interrupting any data transmission in progress. ECU VCC SENT Read Manchester Code GND Figure 3: Top-Level Programming Interface Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 12 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 Manchester Interface Reference Table 3: Manchester Interface Protocol Characteristics [1] Characteristics Symbol Note Min. Typ. Max. Unit Defined by the input message bit rate sent from the external controller 4 - 100 kbps INPUT/OUTPUT SIGNAL TIMING Bit Rate Bit Time tBIT Bit Time Error Write Delay errTBIT tWRITE(E) Data bit pulse width at 4 kbps 243 250 257 s Data bit pulse width at 100 kbps 9.5 10 10.5 s Deviation in tBIT during one command frame -11 - +11 % VCC < 6.0 V - - - 1/4 x tbit - 3/4 x tbit s Delay from last bit cell of write command to start of EEPROM programming pulse 40 - - s Required delay from the end of the second EEPROM Program pulse to the leading edge of a following command frame Delay from the trailing edge of a Read tSTART_READ command frame to the leading edge of the Read Acknowledge frame Read Delay EEPROM PROGRAMMING PULSE EEPROM Programming Pulse Setup Time tsPULSE(E) INPUT SIGNAL VOLTAGE Manchester Code High Voltage VMAN(H) Applied to VCC line 7.8 - - V Manchester Code Low Voltage VMAN(L) Applied to VCC line - - 5.7 V Minimum Rpullup = 5 k 0.9 x VS - - V Maximum Rpullup = 50 k 0.7 x VS - - V - - 0.1 V OUTPUT SIGNAL VOLTAGE (Applied on SENT Line) Manchester Code High Voltage VMAN(H) Manchester Code Low Voltage VMAN(L) [1] Determined 5 k Rpullup 50 k by design. Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 13 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces SENT Output Mode The SENT output converts the measured magnetic field angle to a binary value mapped to the Full-Scale Output (FSO) range of 0 to 4095, shown in Figure 4. This data is inserted into a binary pulse message, referred to as a frame, that conforms to the SENT data transmission specification (SAEJ2716 JAN2010). Angle () The SENT frame may be configured via EEPROM. The A1335 may operate in one of three broadly defined SENT modes (see the A1335 programming manual for details on SENT modes and settings). * SAE J2716 SENT: free-streaming SENT frame in accordance with industry specification. Additional programmability allows Tick time adjustment from 0.5 s to 7.9 s. * Triggered SENT (TSENT): User-defined sampling and retrieval. * Shared SENT: Allows multiple devices to share a common SENT line. Devices may either be directly addressed (Addressable SENT or ASENT) or sequentially polled (Sequential SENT or SSENT). 4095 (1111 1111 1111) 2048 (1000 0000 0000) 0000 (0000 0000 0000) SENT Data Value (LSB) A1335 Figure 4: Angle is Represented as a 12-bit Digital Value VCC 5 V Max Sensor ID = 0 Sensor ID = 1 Sensor ID = 2 Host (ECU) Sensor ID = 3 R C Bus Capacitance Figure 5: Allegro's proprietary SENT protocol allows multiple parts to share one common output bus. Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 14 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 The duration of a nibble is denominated in ticks. The period of a tick is set by the SENT_TICK parameter. The duration of the nibble is the sum of the low-voltage interval plus the high-voltage interval. SENT MESSAGE STRUCTURE Data within a SENT message frame is represented as a series of nibbles, with the following characteristics: * Each nibble is an ordered pair of a low-voltage interval followed by a high-voltage interval * The low-voltage interval acts as the delimiting state which acts as a boundary between each nibble. The length of this lowvoltage interval is fixed at 5 ticks. The parts of a SENT message are arranged in the following required sequence (see Figure 7): 1. Synchronization and Calibration: Flags the start of the SENT message. * The high-voltage interval performs the job of the information state and is variable in duration in order to contain the data payload of the nibble 2. Status and Communication Nibble: Provides A1335 status and the optional serial data determined by the setting of the SENT_SERIAL parameter. * The slew rate of the falling edge may be adjusted using the SENT_DRIVER parameter. 4. CRC: Error checking. 3. Data: Angle information and optional data. 5. Pause Pulse (optional): Fill pulse between SENT message frames. 0 5 12 0 Ticks 5 27 Table 4: Nibble Composition and Value Ticks Quantity of Ticks Total Binary (4-bit) Value Decimal Equivalent Value 7 12 0000 0 5 8 13 0001 1 5 9 14 0002 2 Figure 6: General Value Formation for SENT 5 21 26 1110 14 0000 (left), 1111 (right) 5 22 27 1111 15 Message Signal Voltage Message Signal Voltage Low High Interval Interval Low Interval Nibble Data Value = 0000 HighVoltage Interval 5 High Interval Nibble Data Value = 1111 SENT_FIXED SENT_FIXED 56 ticks Nibble Name LowVoltage Interval Synchronization and Calibration SENT_FIXED 12 to 27 ticks Status and Communication 12 to 27 ticks Data 1 (MSB) SENT_FIXED SENT_FIXED SENT_FIXED 12 to 27 ticks 12 to 27 ticks Data 6 CRC Pause Pulse (optional) tSENT Figure 7: General Format for SENT Message Frame Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 15 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 APPLICATION INFORMATION Serial Interface Description The A1335 features I2C-, SPI-, and SENT-compliant interfaces for communication with a host microcontroller, or Master. A basic circuit for configuring the A1335 package is shown in Figure 8. VCC = 5 V VCC 0.1 F 0.1 F BYP A1335 SA1 Host/Master Microprocessor BYP 0.1 F SCLK MOSI A1335 MISO ISEL ISEL AGND AGND DGND DGND DGND SDA (A) Typical A1335 configuration using I2C interface; A1335 set up for serial address 0xC DGND DGND DGND SCL AGND AGND Host/Master Microprocessor 1 k VCC CS SA0 1 k 0.1 F (B) Typical A1335 configuration using SPI interface VCC = 5 V 3.3 V 0.1 F VCC BYP SA0 5 k Host/Master Microprocessor SA1 0.1 F A1335 SENT SCLK AGND AGND MISO ISEL DGND DGND DGND 3.3 V VCC (C) Typical A1335 configuration using SENT interface (SA0/SA1 may be brought to BYP or GND to configure Manchester/Shared SENT address) Figure 8: Typical A1335 configuration Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 16 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 Magnetic Target Requirements There are two main sensing configurations for magnetic angle sensing, on-axis and off-axis. On-axis (end of shaft) refers to when the center axis of a magnet lines up with the center of the sensing element. Off-axis (side shaft) refers to when the angle sensor is mounted along the edge of a magnet. Figure 14 to Figure 17 illustrate on- and off-axis sensing configurations. FIELD STRENGTH The A1335 actively measures and adapts to its magnetic environment. This allows operation throughout a large range of field strengths (recommended range is 300 to 1000 G, operation beyond this range is allowed with no long-term impact). Due to the greater signal-to-noise ratio provided at higher field strengths, performance inherently increases with increasing field strength. Typical angle performance over applied field strength is shown in Figure 9 and Figure 10. Magnetic Material Diameter (mm) Thickness (mm) Neodymium (bonded) 15 4 Neodymium (sintered)* 10 4 Neodymium (sintered) 8 3 Neodymium / SmCo 6 2.5 S N Thickness Diameter *A sintered Neodymium magnet with 10 mm (or greater) diameter and 4 mm thickness is the recommended magnet for redundant applications. 25C 150C 1 14 Recommended Operating Range (300 to 1000 G) 0.5 13 12 11 0 100 10 200 300 400 500 600 700 Field Strength in Gauss 800 900 1000 Figure 9: Typical Maximum Angle Error Over Field Strength Angle Error () Angle Error in Degrees 1.5 Table 5: Target Magnet Parameters 9 8 7 6 5 4 3 2 1 25C 150C 0.9 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Eccentricity of SOC Chip Relative to Magnet Rotation Axis (mm) 0.8 0.7 Noise in Degrees 1 0.6 Figure 11: Simulated Error versus Eccentricity for a 10 mm x 4 mm Neodymium magnet at a 2.7 mm air gap. Recommended Operating Range (300 to 1000 G) 0.5 Typical Systemic Error versus magnet to sensor eccentricity (daxial), Note: "Systemic Error" refers to application errors in alignment and system timing. It does not refer to sensor IC device errors. The data in this graph is simulated with ideal magnetization. 0.4 0.3 0.2 0.1 0 100 200 300 400 500 600 700 Field Strength in Gauss 800 900 1000 Figure 10: Typical One Sigma Angle Noise Over Field Strength Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 17 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 Calculating Target Zero Degree Angle When shipped from the factory, the default angle value when oriented as shown in Figure 12, is approximately 0 (180 on secondary die). In some cases, the end user may want to program an angle offset in the A1335 to compensate for variation in magnetic assemblies, or for applications where absolute system level readings are required. The internal algorithm for computing the output angle is as follows: AngleOUT = AnglepostLin - Zero Offset . (1) The procedure to "zero out" the A1335 is as follows. During final application calibration, position the magnet above the sensor in the required zero-degree position and record the angle reading from the device. Program the Zero Offset field in EEPROM (0x306 bits 12:0) with this value (reference the A1335 programming manual for additional details). It is important to keep in mind that the Zero Offset adjustment occurs after linearization within the A1335's signal path (see Figure 1). As a result, the zero offset adjustment should be done following end-of-line linearization. Bypass Pin Usage The Bypass pin is required for proper device operation and is intended to bypass internal IC nodes of the A1335. A 0.1 F capacitor must be placed in close proximity to the Bypass pin. It is not intended to be used to source external components. Target rotation axis Target poles aligned with A1335 elements Target alignment for default angle setting * Target rotation axis intersects primary die * Primary die 0 default point * Secondary die 180 default point (Example shows element E1 as primary die element E2 as secondary die) S S Pin 1 E1 N E1 N E2 E2 Figure 12: Orientation of Magnet Relative to Primary Die and Secondary Die Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 18 A1335 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces ON-AXIS APPLICATIONS Some common on-axis applications for the device include digital potentiometer, motor sensing, power steering, and throttle sensing. The A1335 is designed to operate with magnets constructed with a variety of magnetic materials, cylindrical geometries, and field strengths, as shown in Table 5. The device has two internal linearization algorithms that can compensate for much of the error due to alignment. Contact Allegro for more detailed information on magnet selection and theoretical error. (a) S N OFF-AXIS APPLICATIONS There are two major challenges with off-axis angle-sensing applications. The first is field strength. All efforts should be conducted to maximize magnetic signal strength as seen by the device. The goal is a minimum of 300 G. Field strength can be maximized by using high-quality magnetic material, and by minimizing the distance between the sensor and the magnet. Another challenge is overcoming the inherent nonlinearity of the magnetic field vector generated at the edge of a magnet. The device has two linearization algorithms that can compensate for much of the geometric error. Harmonic linearization is recommended for off-axis applications. (b) Figure 13: Typical On-Axis (a) and Off-Axis (b) Orientation Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 19 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 Effect of Orientation on Signal +|B| 0G Figure 14: The magnetic field flux lines run between the north pole and south pole of the magnet. The peak flux densities are between the poles. 360 +|B| Detected Rotation Magnetic Flux 0G Zero Crossing 90 180 270 0 360 Figure 15: As the magnet rotates, the Hall element detects the rotating relative polarity of the magnetic field (solid line). When the center of rotation is centered on the Hall element, the magnetic flux amplitude is constant (dashed line). Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 20 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 Hall element Figure 16: Centering the axis of magnet rotation on the Hall element provides the strongest signal in all degrees of rotation. daxial(on-axis) Axis of Rotation daxial(off-axis) AG (off axis) AG (on axis) AG (on axis, centered) Magnetic Flux Lines Figure 17: The magnetic flux density degenerates rapidly away from the plane of peak north-south polarity. When the axis of rotation is placed away from the Hall element, the device must be placed closer to the magnetic poles to maintain an adequate level of flux at the Hall element. Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 21 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 Linearization Magnetic fields are generally not completely linear throughout the full range of target positions. This can be the result of nonuniformities in mechanical motion or of material composition. In some applications, it may be required to apply a mathematical transfer function to the angle that is reported by the A1335. The A1335 has built-in functions for performing linearization on the acquired angle data. It is capable of performing one of two different linearization methods: harmonic linearization and piecewise (segmented) linearization. Segmented linearization breaks up the output dynamic range into 16 equal segments. Each segment is then represented by the equation of a straight line between the two endpoints of the segment. Using this basic principle, it is possible to tailor the output response to compensate for mechanical non-linearity. One example is a fluid level detector in a vehicle fuel tank. Because of requirements to conform the tank and to provide stiffening, fuel tanks often do not have a uniform shape. A level detector with a linear sensor in this application would not correctly indicate the remaining volume of fuel in the tank without some mathematical conversion. Figure 18 graphically illustrates the general concept. Harmonic linearization uses the Fourier series in order to compensate for periodic error components. In the most basic of terms, the Fourier series is used to represent a periodic signal using a Meter and Sender sum of ideal periodic waveforms. The A1335 is capable of using up to 11 Fourier series components to linearize the output transfer function. While it can be used for many applications, harmonic linearization is most useful for 360-degree applications. The error curve for a rotating magnet that is not perfectly aligned will most often have an error waveform that is periodic. This is phenomenon is especially true for systems where the sensor is mounted off-axis relative to the magnet. Figure 19 illustrates this periodic error. An initial set of linearization coefficients is created by characterizing the application experimentally. With all signal processing options configured, the device is used to sense the applied magnetic field at a target zero degrees of rotation reference angle and at regular intervals. For segmented linearization, 16 samples are taken: at nominal zero degrees and every 1/16 interval (22.5) of the full 360 rotational input range. Each angle is read from the ANG[ANGLE] register and recorded. These values are loaded into the Allegro ASEK programming utility for the device, or an equivalent customer software program, to generate coefficients corresponding to the values. The user then uses the software load function to transmit the coefficients to the EEPROM. Each of the coefficient values can be individually overwritten during normal operation by writing directly to the corresponding SRAM. Fill pipe Linear Depth Linearized rate Uniform walls Angled walls Wall stiffener cavities Angled walls, uneven bottom Fuel Volume 0 Figure 18: An integrated vehicle fuel tank has varying volumes according to depth due to structural elements. As shown in the chart, this results in a variable rate of fuel level change, depending on volume at the given depth, and a linearized transfer function can be used against the integral volume. Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 22 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 Figure 19: Correction for Eccentric Orientation daxial daxial = + phase, + amplitude daxial daxial daxial = + phase, + + amplitude daxial daxial = + phase, - amplitude daxial = + phase, - - amplitude 360 n ge t Fu nc tio n 180 n io M ag ne tic In p Li ut ne a riz at In ve rs Ta r io Figure 19a: With the axis of rotation aligned with the Hall element, linearization coefficients are a simple inversion of the input. Detected Angle () 270 90 0 0 Error Correction (V) Figure 19b: Any eccentricity is evaluated as an error. Systematic eccentricity can be factored out by appropriate linearization coefficients. For off-axis applications, the harmonic linearization method is recommended. 90 180 Target Rotational Position () 270 360 +V daxial Correction Corrected Angle Output Inversion Result 0 0 90 180 Device Output Position () 270 360 Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 23 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 HARMONIC COEFFICIENTS The device supports up to 11 harmonics. Each harmonic is characterized by an amplitude and a phase coefficient. To apply harmonic linearization, the device: 1. Calculates the error factors. 2. Applies any programmed offsets. 3. Calculates the linearization factor as: An x sin(n x t + n ) 4095 fun ctio O n ut pu tf un ct io n Interpolated Linear Position (y-axis values represent 16 equal intervals) ut Inp Maximum Full Scale Input io n ct un tf 2432 on cti A -xLIN_3 n t fu u Inp -640 ut pu A xLIN_10 A Coefficients stored in BIN16 0 BIN10 BIN3 BIN2 O BIN1 BIN0 Minimum Full Scale Input Magnetic Input Values (15 x-axis values read and used to calculate coefficients) EEPROM Figure 20: Sample of Linearization Function Transfer Characteristic Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 24 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 TYPICAL PERFORMANCE CHARACTERISTICS 1 0.8 0.6 Angle Error 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1 0 50 100 150 200 250 Encoder Position 300 350 Figure 21: Typical Angle Error versus Encoder Position (300 G, 25C) 2 1.8 1.6 1.6 1.4 1.4 1.2 1.2 1 0.8 0.6 1 0.8 0.6 0.4 0.4 0.2 0.2 0 -40 -20 0 20 40 60 80 Temperature (C) 100 120 140 Figure 22: Peak Angle Error over Temperature (300 G) Mean 3 Sigma 1.8 Drift in Degrees Angle Error in Degrees 2 Mean 3 Sigma 0 -40 -20 0 20 40 60 80 Temperature (C) 100 120 140 Figure 23: Maximum Absolute Drift from 25C Reading (300 G) Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 25 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 1.5 7 Mean 3 Sigma 150C 25C -40C A1335 Noise in degrees 6 Frequency (%) 5 4 3 2 1 0.5 1 0 0 0.5 Noise in degrees 1 0 -40 1.5 Figure 24: Noise Distribution over Temperature (3 Sigma, 300 G) 18 20 Mean 3 Sigma 19 14 18 A1335 ICC in mA 12 Count (%) 0 20 40 60 80 100 120 140 Ambient Temperature in Degrees C Figure 25: Noise Performance over Temperature (3 Sigma, 300 G) 150C 25C -40C 16 -20 10 8 6 17 16 15 4 14 2 13 0 12 13 14 15 16 ICC in mA 17 18 19 Figure 26: ICC Distribution over Temperature (VCC = 5.5 V) 20 12 0 50 100 Ambient Temperature (C) 150 Figure 27: ICC over Temperature (VCC = 5.5 V) Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 26 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 PACKAGE OUTLINE DRAWINGS For Reference Only - Not for Tooling Use (Reference MO-153 AB-1) NOT TO SCALE Dimensions in millimeters Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown 5.00 0.10 1.59 0.45 8 0 D 14 0.65 14 0.20 0.09 1.70 E D 4.40 0.10 6.00 6.40 BSC 0.60 A +0.15 -0.10 1.00 REF 1 2 16X 0.10 1.10 MAX C 0.30 0.19 1 0.25 BSC Branded Face C SEATING PLANE B SEATING PLANE GAUGE PLANE 2 PCB Layout Reference View 0.15 0.00 0.65 BSC A Terminal #1 mark area B Reference land pattern layout (reference IPC7351 TSOP65P640X120-14M); All pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and PCB layout tolerances; when mounting on a multilayer PCB, thermal vias at the exposed thermal pad land can improve thermal dissipation (reference EIA/JEDEC Standard JESD51-5) C Branding scale and appearance at supplier discretion D Hall element, not to scale E Active Area Depth = 0.36 mm (Ref) NNNNNNNNNNNN YYWW LLLLLLLLLLLL 1 C Standard Branding Reference View N = Device part number = Supplier emblem Y = Last two digits of year of manufacture W = Week of manufacture L = Lot number Figure 28: Package LE, 14-Pin TSSOP (Single Die Version) Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 27 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 For Reference Only - Not for Tooling Use (Reference MO-153 AD) Dimensions in millimeters Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown 7.80 0.10 E D 3.40 D 1.00 0.65 0.45 8 0 24 24 0.20 0.09 E2 D D E1 4.40 0.10 6.40 BSC D 2.20 A 1 1.00 REF 1.65 2 0.25 BSC 24X SEATING PLANE 0.10 C 0.30 0.19 6.10 +0.15 0.60 -0.10 0.65 BSC C 1 2 B PCB Layout Reference View SEATING PLANE GAUGE PLANE 1.20 MAX 0.025 0.05 A Terminal #1 mark area B Reference land pattern layout (reference IPC7351 TSOP65P640X120-25M); all pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and PCB layout tolerances; when mounting on a multilayer PCB, thermal vias can improve thermal dissipation (reference EIA/JEDEC Standard JESD51-5) C Branding scale and appearance at supplier discretion D Hall elements (E1, E2), corresponding to respective die; not to scale E Active Area Depth 0.36 mm REF NNNNNNNNNN YYWW LLLLLLLLLL 1 C Standard Branding Reference View N = Device part number = Supplier emblem Y = Last two digits of year of manufacture W = Week of manufacture L = Lot number Figure 29: Package LE, 24-Pin TSSOP (Dual Die Version) Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 28 Precision Hall-Effect Angle Sensor IC with I2C, SPI, and SENT Interfaces A1335 Revision Change - Initial release 1 Updated Angle Characteristics; reduced SENT and Manchester information redundant with A1335 programming guide; added Field Strength section and charts; added on-axis and off-axis figures; corrected CVH location in single-die package outline drawing. 2 Corrected LE-24 Package Outline Drawing dimensions 3 Updated Magnetic Field values in Operating Characteristics table 4 Added description of zero degree position, CS_idle time parameter; CVH self-test operation restricted to field 300 G, temperature 25C; Noise plots and table entry updated with 3 sigma values. Pages Responsible Date All W. Wilkinson September 21, 2015 1, 7, 19, 20, 27 W. Wilkinson December 17, 2015 28 W. Wilkinson April 15, 2016 6 W. Wilkinson July 5, 2016 4, 6, 10, 18, 24, 26 W. Wilkinson July 30, 2018 I2CTM is a trademark of Philips Semiconductors. Copyright (c)2018, Allegro MicroSystems, LLC Allegro MicroSystems, LLC reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current. Allegro's products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro's product can reasonably be expected to cause bodily harm. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use. Copies of this document are considered uncontrolled documents. For the latest version of this document, visit our website: www.allegromicro.com Allegro MicroSystems, LLC 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 29