AS5145

Data Sheet AS5145/AS5145A/AS5145B 1 2 - B i t P r o g r a m m a b l e M a g n etic R otary Enco der 1 General Description The AS5145 is a contact less magnetic rotary encoder for accurate angular measurement over a full turn of 360 degrees. It is a system-on-chip, combining integrated Hall elements, analog front end and digital signal processing in a single device. To measure the angle, only a simple two-pole magnet, rotating over the center of the chip, is required. The magnet may be placed above or below the IC. The absolute angle measurement provides instant indication of the magnet’s angular position with a resolution of 0.0879º = 4096 positions per revolution. This digital data is available as a serial bit stream and as a PWM signal. An internal voltage regulator allows the AS5145 to operate at either 3.3V or 5V supplies. Three incremental outputs Quadrature A/B (10 or 12 bit) and Index output signal (preprogrammed versions available AS5145A for 10 bit and AS5145B for 12 bit) User programmable zero position Failure detection mode for magnet placement, monitoring, and loss of power supply Red-Yellow-Green indicators display placement of magnet in Zaxis Serial read-out of multiple interconnected AS5145 devices using Daisy Chain mode Tolerant to magnet misalignment and gap variations Wide temperature range: - 40ºC to +150ºC Fully automotive qualified to AEC-Q100, grade 0 Small Pb-free package: SSOP 16 (5.3mm x 6.2mm) 2 Key Features Contact less high resolution rotational position encoding over a full turn of 360 degrees Two digital 12 bit absolute outputs: - Serial interface - Pulse width modulated (PWM) output 3 Applications The device is ideal for industrial applications like contactless rotary position sensing and robotics; automotive applications like steering wheel position sensing, transmission gearbox encoder, head light position control, torque sensing, valve position sensing and replacement of high end potentiometers. Figure 1. AS5145 Automotive Rotary Encoder IC VDD3V3 VDD5V MagINCn MagDECn PWM Interface Sin Hall Array & Front end Amplifier Cos DSP Ang Absolute Interface (SSI) DO CSn CLK OTP Register Mux Mode_Index PDIO Incremental Interface DTEST1_A DTEST2_B PWM LDO 3.3V Mag AS5145 www.austriamicrosystems.com/AS5145 Revision 1.10 1 - 36 AS5145 Data Sheet - C o n t e n t s Contents 1 General Description .................................................................................................................................................................. 2 Key Features............................................................................................................................................................................. 3 Applications............................................................................................................................................................................... 4 Pin Assignments ....................................................................................................................................................................... 4.1 Pin Descriptions.................................................................................................................................................................................... 1 1 1 4 4 5 Absolute Maximum Ratings ...................................................................................................................................................... 6 Electrical Characteristics........................................................................................................................................................... 6.1 Magnetic Input Specification................................................................................................................................................................. 6.2 System Specifications .......................................................................................................................................................................... 6 7 8 9 7 Timing Characteristics ............................................................................................................................................................ 8 Detailed Description................................................................................................................................................................ 8.1 Mode_Index Pin.................................................................................................................................................................................. 8.1.1 8.1.2 8.1.3 8.1.4 8.1.5 Synchronous Serial Interface (SSI) ........................................................................................................................................... Incremental Mode ...................................................................................................................................................................... Sync Mode................................................................................................................................................................................. Sin/Cosine Mode ....................................................................................................................................................................... Daisy Chain Mode ..................................................................................................................................................................... 11 12 12 13 14 16 16 16 17 18 8.2 Pulse Width Modulation (PWM) Output.............................................................................................................................................. 8.3 Analog Output..................................................................................................................................................................................... 8.2.1 Changing the PWM Frequency.................................................................................................................................................. 18 9 Application Information ........................................................................................................................................................... 9.1 Programming the AS5145 .................................................................................................................................................................. 9.1.1 9.1.2 9.1.3 9.1.4 9.1.5 9.1.6 9.1.7 19 19 Zero Position Programming ....................................................................................................................................................... 19 OTP Memory Assignment.......................................................................................................................................................... 20 User Selectable Settings ........................................................................................................................................................... 20 OTP Default Setting................................................................................................................................................................... 21 Redundancy ............................................................................................................................................................................... 21 Redundant Programming Option ............................................................................................................................................... 22 OTP Register Entry and Exit Condition ..................................................................................................................................... 22 23 23 24 9.2 Alignment Mode.................................................................................................................................................................................. 9.3 3.3V / 5V Operation ............................................................................................................................................................................ 9.4 Selecting Proper Magnet .................................................................................................................................................................... 9.4.1 Physical Placement of the Magnet ............................................................................................................................................ 25 9.4.2 Magnet Placement..................................................................................................................................................................... 26 9.5 Simulation Modeling ........................................................................................................................................................................... 9.6 Failure Diagnostics ............................................................................................................................................................................. 26 27 9.6.1 Magnetic Field Strength Diagnosis ............................................................................................................................................ 27 9.6.2 Power Supply Failure Detection ................................................................................................................................................ 27 9.7 Angular Output Tolerances ................................................................................................................................................................. 9.7.1 9.7.2 9.7.3 9.7.4 9.7.5 9.7.6 Accuracy .................................................................................................................................................................................... Transition Noise......................................................................................................................................................................... High Speed Operation ............................................................................................................................................................... Propagation Delays ................................................................................................................................................................... Internal Timing Tolerance .......................................................................................................................................................... Temperature .............................................................................................................................................................................. 27 27 29 29 29 30 30 www.austriamicrosystems.com/AS5145 Revision 1.10 2 - 36 AS5145 Data Sheet - C o n t e n t s 9.7.7 Accuracy over Temperature ...................................................................................................................................................... 30 9.8 AS5145 Differences to AS5045.......................................................................................................................................................... 30 10 Package Drawings and Markings ......................................................................................................................................... 10.1 Recommended PCB Footprint.......................................................................................................................................................... 32 33 11 Ordering Information ............................................................................................................................................................. 35 www.austriamicrosystems.com/AS5145 Revision 1.10 3 - 36 AS5145 Data Sheet - P i n A s s i g n m e n t s 4 Pin Assignments Figure 2. Pin Assignments (Top View) MagINCn MagDECn DTest1_A DTest1_B NC Mode_Index VSS PDIO 1 2 3 16 15 14 VDD5V VDD3V3 NC NC PWM CSn CLK DO AS5145 4 5 6 7 8 13 12 11 10 9 4.1 Pin Descriptions The following SSOP16 shows the description of each pin of the standard SSOP16 package (Shrink Small Outline Package, 16 leads, body size: 5.3mm x 6.2mmm; (see Figure 2). Table 1. Pin Descriptions Pin Number 1 2 3 4 5 6 7 8 9 10 11 12 13 Pin Name MagINCn MagDECn DTest1_A DTest2_B NC Mode_Index VSS PDIO DO CLK CSn PWM NC Description Magnet Field Magnitude INCrease; active low, indicates a distance reduction between the magnet and the device surface. (see Table 9) Magnet Field Magnitude DECrease; active low, indicates a distance increase between the device and the magnet. (see Table 9) Test output in default mode Test output in default mode Must be left unconnected Select between slow (open, low: VSS) and fast (high) mode. Internal pull-down resistor (~10kΩ). Negative Supply Voltage (GND) OTP Programming Input and Data Input for Daisy Chain mode. Internal pull-down resistor (~74kΩ). Connect to VSS if not used Data Output of Synchronous Serial Interface Clock Input of Synchronous Serial Interface; Schmitt-Trigger input Chip Select, active low; Schmitt-Trigger input, internal pull-up resistor (~50kΩ) Pulse Width Modulation of approximately. 244Hz; 1µs/step (optional 122Hz; 2µs/step) Must be left unconnected www.austriamicrosystems.com/AS5145 Revision 1.10 4 - 36 AS5145 Data Sheet - P i n A s s i g n m e n t s Table 1. Pin Descriptions Pin Number 14 15 16 Pin Name NC VDD3V3 VDD5V Must be left unconnected 3V-Regulator Output, internally regulated from VDD5V. Connect to VDD5V for 3V supply voltage. Do not load externally. Positive Supply Voltage, 3.0 to 5.5 V Description Pin 1 and 2 are the magnetic field change indicators, MagINCn and MagDECn (magnetic field strength increase or decrease through variation of the distance between the magnet and the device). These outputs can be used to detect the valid magnetic field range. Furthermore those indicators can also be used for contact-less push-button functionality. Pin 3 and 4 are multi function pins for sync mode, sin/cosine mode and incremental mode. Pin 6 Mode_Index allows switching between filtered (slow) and unfiltered (fast mode). In incremental mode, the pin changes from input to output and provides the index pulse information. A change of the Mode during operation is not allowed. The setup must be constant during power up and during operation. Pins 7, 15, and 16 are supply pins, pins 5, 13, and 14 are for internal use and must not be connected. Pin 8 (PDIO) is used to program the zero-position into the OTP(see page 19). This pin is also used as digital input to shift serial data through the device in Daisy Chain configuration, (see page 14). Pin 11 Chip Select (CSn; active low) selects a device within a network of AS5145 encoders and initiates serial data transfer. A logic high at CSn puts the data output pin (DO) to tri-state and terminates serial data transfer. This pin is also used for alignment mode (see Alignment Mode on page 23) and programming mode (see Programming the AS5145 on page 19). Pin 12 allows a single wire output of the 12-bit absolute position value. The value is encoded into a pulse width modulated signal with 1µs pulse width per step (1µs to 4096µs over a full turn). By using an external low pass filter, the digital PWM signal is converted into an analog voltage, e.g. for making a direct replacement of potentiometers possible. www.austriamicrosystems.com/AS5145 Revision 1.10 5 - 36 AS5145 Data Sheet - A b s o l u t e M a x i m u m R a t i n g s 5 Absolute Maximum Ratings Stresses beyond those listed in Table 2 may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in Section 6 Electrical Characteristics on page 7 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 2. Absolute Maximum Ratings Parameter DC supply voltage at pin VDD5V DC supply voltage at pin VDD3V3 Input pin voltage Input current (latchup immunity) Electrostatic discharge Storage temperature -55 -0.3 -100 Min -0.3 Max 7 5 VDD5V +0.3 100 ±2 125 Units V V V mA kV ºC Except VDD3V3 Norm: EIA/JESD78 Class II Level A Norm: JESD22-A114E Min – 67ºF; Max +257ºF The reflow peak soldering temperature (body temperature) specified is in accordance with IPC/JEDEC J-STD-020C “Moisture/Reflow Sensitivity Classification for NonHermetic Solid State Surface Mount Devices”. The lead finish for Pb-free leaded packages is matte tin (100% Sn). Comments Package Body temperature 260 ºC Humidity non-condensing 5 85 % www.austriamicrosystems.com/AS5145 Revision 1.10 6 - 36 AS5145 Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s 6 Electrical Characteristics TAMB = -40 to +150ºC, VDD5V = 3.0-3.6V (3V operation) VDD5V = 4.5-5.5V (5V operation) unless otherwise noted. Table 3. Electrical Characteristics Symbol Operating Conditions TAMB Isupp VDD5V VDD3V3 VDD5V VDD3V3 VON Voff Ambient temperature Supply current Supply voltage at pin VDD5V Voltage regulator output voltage at pin VDD3V3 Supply voltage at pin VDD5V Supply voltage at pin VDD3V3 Power-on reset thresholds On voltage; 300mV typ. hysteresis Power-on reset thresholds Off voltage; 300mV typ. hysteresis Programming voltage Programming voltage off level Programming current 5V Operation 3.3V Operation (pin VDD5V and VDD3V3 connected) 4.5 3.0 3.0 3.0 1,37 DC supply voltage 3.3V (VDD3V3) 1.08 1.9 2.6 -40 16 5.0 3.3 3.3 3.3 2.2 +150 21 5.5 3.6 3.6 3.6 2.9 V V V ºC mA Parameter Condition Min Typ Max Unit Programming Conditions VPROG VProgOff IPROG d Voltage applied during programming Line must be discharged to this level Current during programming 10µA max. current @ 100mV 2mA max. current @ 100mV 3.3 0 3.6 1 100 V V mA Ω Ω Rprogramme Programmed fuse resistance (log 1) Runprogram med 100k 50 ∞ 100 Unprogrammed fuse resistance (log 0) DC Characteristics CMOS Schmitt-Trigger Inputs: CLK, CSn (CSn = Internal Pull-up) VIH VIL VIon- VIoff ILEAK IiL High level input voltage Low level input voltage Schmitt Trigger hysteresis Input leakage current Pull-up low level input current CLK only CSn only, VDD5V: 5.0V 1 -1 -30 0.7 * VDD5V During programming 3.3 1 -100 Normal operation 0.7 * VDD5V 0.3 * VDD5V V V V µA DC Characteristics CMOS / Program Input: PDIO VIH VPROG VIL IiL IOZ VOL 1 High level input voltage High level input voltage Low level input voltage High level input current VDD5V: 5.5V VDD5V 3.6 0.3 * VDD5V V V V µA 30 100 DC Characteristics CMOS Output Open Drain: MagINCn, MagDECn Open drain leakage current Low level output voltage 1 VSS + 0.4 µA V www.austriamicrosystems.com/AS5145 Revision 1.10 7 - 36 AS5145 Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s Table 3. Electrical Characteristics Symbol IO Parameter Output current Condition VDD5V: 4.5V VDD5V: 3V VDD5V – 0.5 VSS +0.4 VDD5V: 4.5V VDD5V: 3V VDD5V – 0.5 VSS +0.4 VDD5V: 4.5V VDD5V: 3V VDD5V – 0.5 VSS +0.4 VDD5V: 4.5V VDD5V: 3V 4 2 1 4 2 4 2 Min Typ Max 4 2 Unit mA DC Characteristics CMOS Output: PWM VOH VOL IO High level output voltage Low level output voltage Output current V V mA DC Characteristics CMOS Output: A, B, Index VOH VOL IO High level output voltage Low level output voltage Output current V V mA DC Characteristics Tri-state CMOS Output: DO VOH VOL IO IOZ High level output voltage Low level output voltage Output current Tri-state leakage current V V mA µA 1. Either with 3.3V or 5V supply. 6.1 Magnetic Input Specification TAMB = -40 to +150°C, VDD5V = 3.0 to 3.6V (3V operation) VDD5V = 4.5 to 5.5V (5V operation) unless otherwise noted. Two-pole cylindrical diametrically magnetized source: Table 4. Magnetic Input Specification Symbol dmag tmag Bpk Boff Parameter Diameter Thickness Magnetic input field amplitude Magnetic offset Field non-linearity fmag_abs Input frequency (rotational speed of magnet) Condition Recommended magnet: Ø 6mm x 2.5mm for cylindrical magnets Required vertical component of the magnetic field strength on the die’s surface, measured along a concentric circle with a radius of 1.1mm Constant magnetic stray field Including offset gradient 153 rpm @ 4096 positions/rev; fast mode 38 rpm @ 4096 positions/rev; slow mode Min 4 2.5 45 75 ± 10 5 2.54 0.63 Typ 6 Max Unit mm mm mT mT % Hz www.austriamicrosystems.com/AS5145 Revision 1.10 8 - 36 AS5145 Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s Table 4. Magnetic Input Specification Symbol Disp Ecc Parameter Displacement radius Eccentricity Recommended magnet material and temperature drift Condition Max. offset between defined device center and magnet axis (see Figure 19) Eccentricity of magnet center to rotational axis NdFeB (Neodymium Iron Boron) SmCo (Samarium Cobalt) -0.12 -0.035 Min Typ Max 0.25 100 Unit mm µm %/K 6.2 System Specifications TAMB = -40 to +150°C, VDD5V = 3.0 to 3.6V (3V operation) VDD5V = 4.5 to 5.5V (5V operation) unless otherwise noted. Table 5. Input Specification Symbol RES INLopt Parameter Resolution Integral non-linearity (optimum) Condition 0.088 deg Maximum error with respect to the best line fit. Centered magnet without calibration, TAMB =25 ºC. Maximum error with respect to the best line fit. Centered magnet without calibration, TAMB = -40 to +150ºC Best line fit = (Errmax – Errmin) / 2 Over displacement tolerance with 6mm diameter magnet, without calibration, TAMB = -40 to +150ºC 12bit, no missing codes 1 sigma, fast mode (MODE = 1) TN Transition noise 1 sigma, slow mode (MODE = 0 or open) Fast mode (Mode = 1); Until status bit OCF = 1 Slow mode (Mode = 0 or open); Until OCF = 1 Fast mode (MODE = 1) Slow mode (MODE = 0 or open) TAMB = 25ºC, slow mode (MODE=0 or open) TAMB = -40 to +150ºC, slow mode (MODE=0 or open) TAMB = 25ºC, fast mode (MODE = 1) TAMB = -40 to +150ºC, fast mode (MODE=1) Max. clock frequency to read out serial data 2.48 2.35 9.90 9.38 2.61 2.61 10.42 10.42 Min Typ Max 12 ± 0.5 Unit bit deg INLtemp Integral non-linearity (optimum) ± 0.9 deg INL DNL Integral non-linearity Differential non-linearity ± 1.4 ± 0.044 0.06 0.03 20 deg deg Deg RMS tPwrUp Power-up time ms 80 96 384 2.74 kHz 2.87 10.94 kHz 11.46 1 MHz µs tdelay System propagation delay absolute output : delay of ADC, DSP and absolute interface Internal sampling rate for absolute output: fS fS Internal sampling rate for absolute output Read-out frequency CLK/SEL www.austriamicrosystems.com/AS5145 Revision 1.10 9 - 36 AS5145 Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s Figure 3. Integral and Differential Non-Linearity Example 1023 α 10bit code Actual curve 2 1 0 1023 TN DNL+1LSB INL 0.35° 512 Ideal curve 512 0 0° 180° 360 ° α [degrees] Integral Non-Linearity (INL) is the maximum deviation between actual position and indicated position. Differential Non-Linearity (DNL) is the maximum deviation of the step length from one position to the next. Transition Noise (TN) is the repeatability of an indicated position. www.austriamicrosystems.com/AS5145 Revision 1.10 10 - 36 AS5145 Data Sheet - T i m i n g C h a r a c t e r i s t i c s 7 Timing Characteristics TAMB = -40 to +150 ºC, VDD5V = 3.0 to 3.6V (3V operation) VDD5V = 4.5 to 5.5V (5V operation), unless otherwise noted. Table 6. Timing Characteristics Symbol Parameter Conditions Time between falling edge of CSn and data output activated Time between falling edge of CSn and first falling edge of CLK Rising edge of CLK shifts out one bit at a time Time between rising edge of CLK and data output valid After the last bit DO changes back to “tristate” CSn =high; To initiate read-out of next angular position Clock frequency to read out serial data Signal period = 4098µs ±10% at TAMB = -40 to +150ºC Position 0d; angle 0 degree Position 4098d; angle 359.91 degrees Time to prog. a singe fuse bit Time to charge the cap after tPROG Data can be loaded at n x 2µs Read the data from the latch Write the data to the latch 500 >0 1 500 500 413 100 Min Typ Max Units Synchronous Serial Interface (SSI) tDOactive tCLKFE TCLK/2 tDOvalid tDOtristate tCSn fCLK Data output activated (logic high) First data shifted to output register Start of data output Data output valid Data output tri-state Pulse width of CSn Read-out frequency 100 ns ns ns ns ns ns MHz Pulse Width Modulation Output fPWM PWMIN PWMAX Programming Conditions tPROG tCHARGE fLOAD fREAD fWRITE Programming time per bit Refresh time per bit LOAD frequency READ frequency WRITE frequency 10 1 500 2.5 2.5 20 µs µs kHz MHz MHz PWM frequency Minimum pulse width Maximum pulse width 220 0.90 3686 224 1 4096 268 1.10 4506 Hz µs µs www.austriamicrosystems.com/AS5145 Revision 1.10 11 - 36 AS5145 Data Sheet - D e t a i l e d D e s c r i p t i o n 8 Detailed Description The AS5145 is manufactured in a CMOS standard process and uses a spinning current Hall technology for sensing the magnetic field distribution across the surface of the chip. The integrated Hall elements are placed around the center of the device and deliver a voltage representation of the magnetic field at the surface of the IC. Through Sigma-Delta Analog / Digital Conversion and Digital Signal-Processing (DSP) algorithms, the AS5145 provides accurate high-resolution absolute angular position information. For this purpose a Coordinate Rotation Digital Computer (CORDIC) calculates the angle and the magnitude of the Hall array signals. The DSP is also used to provide digital information at the outputs MagINCn and MagDECn that indicate movements of the used magnet towards or away from the device’s surface. A small low cost diametrically magnetized (two-pole) standard magnet provides the angular position information (see Figure 18). The AS5145 senses the orientation of the magnetic field and calculates a 12-bit binary code. This code can be accessed via a Synchronous Serial Interface (SSI). In addition, an absolute angular representation is given by a Pulse Width Modulated signal at pin 12 (PWM). This PWM signal output also allows the generation of a direct proportional analog voltage, by using an external Low-Pass-Filter. The AS5145 is tolerant to magnet misalignment and magnetic stray fields due to differential measurement technique and Hall sensor conditioning circuitry. Figure 4. Typical Arrangement of AS5145 and Magnet 8.1 Mode_Index Pin The Mode_Index pin activates or deactivates an internal filter, that is used to reduce the analog output noise. Activating the filter (Mode pin = LOW or open) provides a reduced output noise of 0.03º rms. At the same time, the output delay is increased to 384µs. This mode is recommended for high precision, low speed applications. Deactivating the filter (Mode pin = HIGH) reduces the output delay to 96µs and provides an output noise of 0.06º rms. This mode is recommended for higher speed applications. Setup the Mode pin affects the following parameters: Table 7. Slow and fast mode parameters Parameter Sampling rate Transition noise (1 sigma) Output delay Maximum speed @ 4096 samples/rev Maximum speed @ 1024 samples/rev Maximum speed @ 256 samples/rev Maximum speed @ 64 samples/rev Slow Mode (mode= low or open) 2.61 kHz (384 µs) ≤ 0.03º rms 384µs 38 rpm 153 rpm 610 rpm 2441 rpm Fast Mode (mode=high, VDD= 5V) 10.42 kHz (96µs) ≤ 0.06º rms 96µs 153 rpm 610 rpm 2441 rpm 9766 rpm Note: A change of the Mode during operation is not allowed. The setup must be constant during power up and during operation. www.austriamicrosystems.com/AS5145 Revision 1.10 12 - 36 AS5145 Data Sheet - D e t a i l e d D e s c r i p t i o n 8.1.1 Synchronous Serial Interface (SSI) Figure 5. Synchronous Serial Interface with Absolute Angular Position Data CSn tCLK FE CLK TCLK/2 1 18 tCSn 8 tCLK FE 1 DO tDO active D11 D10 D9 tDO valid D8 D7 D6 D5 D4 D3 D2 D1 D0 OCF COF LIN Mag Mag Even INC DEC PAR tDO Tristate D11 Angular Position Data Status Bits If CSn changes to logic low, Data Out (DO) will change from high impedance (tri-state) to logic high and the read-out will be initiated. After a minimum time tCLK FE, data is latched into the output shift register with the first falling edge of CLK. Each subsequent rising CLK edge shifts out one bit of data. The serial word contains 18 bits, the first 12 bits are the angular information D[11:0], the subsequent 6 bits contain system information, about the validity of data such as OCF, COF, LIN, Parity and Magnetic Field status (increase/decrease). A subsequent measurement is initiated by a “high” pulse at CSn with a minimum duration of tCSn. Data Content D11:D0 absolute angular position data (MSB is clocked out first) OCF (Offset Compensation Finished), logic high indicates the finished Offset Compensation Algorithm COF (Cordic Overflow), logic high indicates an out of range error in the CORDIC part. When this bit is set, the data at D11:D0 is invalid. The absolute output maintains the last valid angular value. This alarm may be resolved by bringing the magnet within the X-Y-Z tolerance limits. LIN (Linearity Alarm), logic high indicates that the input field generates a critical output linearity. When this bit is set, the data at D11:D0 may still be used, but can contain invalid data. This warning may be resolved by bringing the magnet within the X-Y-Z tolerance limits. Even Parity bit for transmission error detection of bits 1…17 (D11…D0, OCF, COF, LIN, MagINC, MagDEC) Placing the magnet above the chip, angular values increase in clockwise direction by default. Data D11:D0 is valid, when the status bits have the following configurations: Table 8. Status Bit Outputs OCF COF LIN Mag INC 0 1 0 0 0 1 1 Note: MagInc=MagDec=1 is only recommended in YELLOW mode (see Table 9) Mag DEC 0 1 0 1 Even checksum of bits 1:15 Parity www.austriamicrosystems.com/AS5145 Revision 1.10 13 - 36 AS5145 Data Sheet - D e t a i l e d D e s c r i p t i o n Z-axis Range Indication (Push Button Feature, Red/Yellow/Green Indicator). The AS5145 provides several options of detecting movement and distance of the magnet in the Z-direction. Signal indicators MagINCn and MagDECn are available both as hardware pins (pins #1 and 2) and as status bits in the serial data stream (see Figure 5). In the default state, the status bits MagINC, MagDec and pins MagINCn, MagDECn have the following function: Table 9. Magnetic Field Strength Red-Yellow-Green Indicator Status Bits Mac INC 0 1 1 Mag DEC 0 1 1 All other combinations LIN 0 0 1 Hardware Pins Mac INCn Mag DECn Off On On n/a Off Off On n/a OPT: Mag CompEn = 1 (Red-Yellow-Green) Description No distance change Magnetic input field OK (GREEN range, ~45…75mT) YELLOW range: magnetic field is ~ 25…45mT or ~75…135mT. The AS5145 may still be operated in this range, but with slightly reduced accuracy. RED range: magnetic field is ~~135mT. It is still possible to operate the AS5145 in the red range, but not recommended. Not available Note: Pin 1 (MagINCn) and pin 2 (MagDECn) are active low via open drain output and require an external pull-up resistor. If the magnetic field is in range, both outputs are turned off. The two pins may also be combined with a single pull-up resistor. In this case, the signal is high when the magnetic field is in range. It is low in all other cases (see Table 9). 8.1.2 Incremental Mode The AS5145 has an internal interpolator block. This function is used if the input magnetic field is to fast and a code position is missing. In this case an interpolation is done. With the OTP bits OutputMd0 and OutputMd1 a specific mode can be selected. For the available pre-programmed incremental versions (10bit and 12bit), these bits are set during test at austriamicrosystems. These settings are permanent and can not be recovered. A change of the incremental mode (WRITE command) during operation could cause problems. A power-on-reset in between is recommended. During operation in incremental mode it is recommended setting CSn = High, to disable the SSI-Interface. Table 10. Incremental Resolution Output Md1 Output Md0 DTest1_A and DTest2_B Pulses Mode Description AS5145 function DTEST1_A and DTEST2_B are not used. The Mode_Index pin is used for selection of the decimation rate (low speed/high speed). DTEST1_A and DTEST2_B are used as A and B signal. In this mode the Mode_Index Pin is switched from input to output and will be the Index Pin. The decimation rate is set to 64 (fast mode) and cannot be changed from external. In this mode a control signal is switched to DTEST1_A and DTEST2_B. Resolution Index Width Default mode 0 0 10 bit Incremental mode (low DNL) 12 bit Incremental mode (high DNL) Sync mode 0 1 10 256 1/3 LSB 1 0 12 1024 1 1 www.austriamicrosystems.com/AS5145 Revision 1.10 14 - 36 AS5145 Data Sheet - D e t a i l e d D e s c r i p t i o n Incremental Power-up Lock Option. After power-up, the incremental outputs can optionally be locked or unlocked, depending on the status of the CSn pin: CSn = low at power-up: CSn has an internal pull-up resistor and must be externally pulled low ( R ext ≤ 5k Ω ). If Csn is low at power-up, the incremental outputs (A, B, Index) will be high until the internal offset compensation is finished. This unique state (A=B=Index = high) may be used as an indicator for the external controller to shorten the waiting time at power-up. Instead of waiting for the specified maximum power up-time (0), the controller can start requesting data from the AS5145 as soon as the state (A=B=Index = high) is cleared. CSn = high or open at power-up: In this mode, the incremental outputs (A, B, Index) will remain at logic high state, until CSn goes low or a low pulse is applied at CSn. This mode allows intentional disabling of the incremental outputs until, for example the system microcontroller is ready to receive data. Figure 6. Incremental Output ClockWise D Test1_A Programmed Zero Position Counter ClockWise D Test2_B Mode_Index 1 LSB 3 LSB The hysteresis trimming is done at the final test (factory trimming) and set to 4 LSB, related to a 12 bit number. Incremental Output Hysteresis. To avoid flickering incremental outputs at a stationary magnet position, a hysteresis is introduced. In case of a rotational direction change, the incremental outputs have a hysteresis of 4 LSB. Regardless of the programmed incremental resolution, the hysteresis of 4 LSB always corresponds to the highest resolution of 12 bit. In absolute terms, the hysteresis is set to 0.35 degrees for all resolutions. For constant rotational directions, every magnet position change is indicated at the incremental outputs (see Figure 7). For example, if the magnet turns clockwise from position “x+3“ to “x+4“, the incremental output would also indicate this position accordingly. A change of the magnet’s rotational direction back to position “x+3“ means that the incremental output still remains unchanged for the duration of 4 LSB, until position “x+2“is reached. Following this direction, the incremental outputs will again be updated with every change of the magnet position. Figure 7. Hysteresis Window for Incremental Outputs Incremental Output Indication X +6 X +5 X +4 X +3 X +2 X +1 X X Hysteresis : 0.35° X +1 X +2 X +3 X +4 X +5 X +6 Clockwise Direction Magnet Position Counterclockwise Direction www.austriamicrosystems.com/AS5145 Revision 1.10 15 - 36 AS5145 Data Sheet - D e t a i l e d D e s c r i p t i o n Incremental Output Validity. During power on the incremental output is kept stable high until the offset compensation is finished and the CSn is low (internal Pull Up) the first time. In quadrature mode A = B = Index = high indicates an invalid output. If the interpolator recognizes a difference larger than 128 steps between two samples it holds the last valid state. The interpolator synchronizes up again with the next valid difference. This avoids undefined output burst, e.g. if no magnet is present. 8.1.3 Sync Mode This mode is used to synchronize the external electronic with the AS5145. In this mode two signals are provided at the pins DTEST1_A and DTEST2_B. By setting of Md0=1 and Md1=1 in the OTP register, the Sync Mode will be activated. Figure 8. DTest1_A and DTest2_B 400µs (100µs) DTest1_A DTest1_B Every rising edge at DTEST1_A indicates that new data in the device is available. With this signal it is possible to trigger an external customer Microcontroller (interrupt) and start the SSI readout. DTEST2_B indicates the phase of available data. 8.1.4 Sin/Cosine Mode This mode can be enabled by setting the OTP Factory-bit FS2. If this mode is activated the 16 bit sinus and 16 bit cosines digital data of both channels will be switched out. Due to the high resolution of 16 bits of the data stream an accurate calculation can be done externally. In this mode the open drain outputs of DTEST1_A and DTEST2_B are switched to push-pull mode. At Pin MagDECn the clock impulse, at Pin MagINCn the Enable pulse will be switched out. The Pin PWM indicates, which phase of signal is being presented. The mode isn’t available in the default mode. 8.1.5 Daisy Chain Mode The Daisy Chain mode allows connection of several AS5145s in series, while still keeping just one digital input for data transfer (see “Data IN” in Figure 9). This mode is accomplished by connecting the data output (DO; pin 9) to the data input (PDIO; pin 8) of the subsequent device. The serial data of all connected devices is read from the DO pin of the first device in the chain. The length of the serial bit stream increases with every connected device, it is n * (18+1) bits: n= number of devices. e.g. 38 bit for two devices, 57 bit for three devices, etc. The last data bit of the first device (Parity) is followed by a dummy bit and the first data bit of the second device (D11), etc. (see Figure 10). Figure 9. Daisy Chain Hardware Configuration µC Data IN AS5145 1 Device DO PDIO st AS5145 2 DO nd Device PDIO AS5145 last Device DO PDIO CSn CLK CLK CSn CLK CSn CLK CSn www.austriamicrosystems.com/AS5145 Revision 1.10 16 - 36 AS5145 Data Sheet - D e t a i l e d D e s c r i p t i o n Figure 10. Daisy Chain Mode Data Transfer CSn tCLK FE TCLK/2 1 8 18 D 1 2 3 CLK DO tDO active D11 tDO valid D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 OCF COF LIN Mag Mag Even INC DEC PAR D11 D10 D9 Angular Position Data 1 Device st Status Bits Angular Position Data 2 Device nd 8.2 Pulse Width Modulation (PWM) Output The AS5145 provides a pulse width modulated output (PWM), whose duty cycle is proportional to the measured angle. For angle position 0 to 4094 t on ⋅ 4098 Position = ------------------------ – 1 ( t on + t off ) Examples: 1. An angle position of 180° will generate a pulse width ton = 2049µs and a pause toff of 2049 µs resulting in Position = 2048 after the calculation: 2049 * 4098 / (2049 + 2049) -1 = 2048 2. An angle position of 359.8° will generate a pulse width ton = 4095µs and a pause toff of 3 µs resulting in Position = 4094 after the calculation: 4095 * 4098 / (4095 + 3) -1 = 4094 Exception: 1. An angle position of 359.9° will generate a pulse width ton = 4097µs and a pause toff of 1 µs resulting in Position = 4096 after the calculation: 4097 * 4098 / (4097 + 1) -1 = 4096 The PWM frequency is internally trimmed to an accuracy of ±5% (±10% over full temperature range). This tolerance can be cancelled by measuring the complete duty cycle as shown above. Figure 11. PWM Output Signal (EQ 1) Angle PWMIN 0 deg (Pos 0) 1µs PWMAX 359.91 deg (Pos 4095) 4098µs 4097µs 1/fPWM www.austriamicrosystems.com/AS5145 Revision 1.10 17 - 36 AS5145 Data Sheet - D e t a i l e d D e s c r i p t i o n 8.2.1 Changing the PWM Frequency The PWM frequency of the AS5145 can be divided by two by setting a bit (PWMhalfEN) in the OTP register (see Programming the AS5145 on page 19). With PWMhalfEN = 0 the PWM timing is as shown in Table 11: Table 11. PWM Signal Parameters (Default mode) Symbol fPWM PWMIN PWMAX Parameter PWM frequency MIN pulse width MAX pulse width Typ 244 1 4097 Unit Hz µs µs Note Signal period: 4097µs - Position 0d - Angle 0 deg - Position 4095d - Angle 359.91 deg When PWMhalfEN = 1, the PWM timing is as shown in Table 12: Table 12. PWM Signal Parameters with Half Frequency (OTP option) Symbol fPWM PWMIN PWMAX Parameter PWM frequency MIN pulse width MAX pulse width Typ 122 2 8194 Unit Hz µs µs Note Signal period: 8194µs - Position 0d - Angle 0 deg - Position 4095d - Angle 359.91 deg 8.3 Analog Output An analog output can be generated by averaging the PWM signal, using an external active or passive low pass filter. The analog output voltage is proportional to the angle: 0º= 0V; 360º = VDD5V. Using this method, the AS5145 can be used as direct replacement of potentiometers. Figure 12. Figure 11: Simple 2nd Order Passive RC Low Pass Filter Pin12 PWM R1 R2 analog out VDD C1 C2 0V Pin7 VSS 0º 360º Figure 11 shows an example of a simple passive low pass filter to generate the analog output. R1,R2 ≥ 10kΩ C1,C2 ≥ 2.2µF / 6V (EQ 2) R1 should be greater than or equal to 4k7 to avoid loading of the PWM output. Larger values of Rx and Cx will provide better filtering and less ripple, but will also slow down the response time. www.austriamicrosystems.com/AS5145 Revision 1.10 18 - 36 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9 Application Information The benefits of AS5145 are as follows: Complete system-on-chip Flexible system solution provides absolute and PWM outputs simultaneously Ideal for applications in harsh environments due to contactless position sensing No calibration required No temperature compensation necessary 9.1 Programming the AS5145 After power-on, programming the AS5145 is enabled with the rising edge of CSn with PDIO = high and CLK = low. The AS5145 programming is a one-time-programming (OTP) method, based on poly silicon fuses. The advantage of this method is that a programming voltage of only 3.3V to 3.6V is required for programming (either with 3.3V or 5V supply). The OTP consists of 52 bits, of which 21 bits are available for user programming. The remaining 31 bits contain factory settings and a unique chip identifier (Chip-ID). A single OTP cell can be programmed only once. Per default, the cell is “0”; a programmed cell will contain a “1”. While it is not possible to reset a programmed bit from “1” to “0”, multiple OTP writes are possible, as long as only unprogrammed “0”-bits are programmed to “1”. Independent of the OTP programming, it is possible to overwrite the OTP register temporarily with an OTP write command at any time. This setting will be cleared and overwritten with the hard programmed OTP settings at each power-up sequence or by a LOAD operation. Use application note AN514X_10 to get more information about the programming options. The OTP memory can be accessed in the following ways: Load Operation: The Load operation reads the OTP fuses and loads the contents into the OTP register. A Load operation is automatically executed after each power-on-reset. Write Operation: The Write operation allows a temporary modification of the OTP register. It does not program the OTP. This operation can be invoked multiple times and will remain set while the chip is supplied with power and while the OTP register is not modified with another Write or Load operation. Read Operation: The Read operation reads the contents of the OTP register, for example to verify a Write command or to read the OTP memory after a Load command. Program Operation: The Program operation writes the contents of the OTP register permanently into the OTP ROM. Analog Readback Operation: The Analog Readback operation allows a quantifiable verification of the programming. For each programmed or unprogrammed bit, there is a representative analog value (in essence, a resistor value) that is read to verify whether a bit has been successfully programmed or not. 9.1.1 Zero Position Programming Zero position programming is an OTP option that simplifies assembly of a system, as the magnet does not need to be manually adjusted to the mechanical zero position. Once the assembly is completed, the mechanical and electrical zero positions can be matched by software. Any position within a full turn can be defined as the permanent new zero position. For zero position programming, the magnet is turned to the mechanical zero position (e.g. the “off”-position of a rotary switch) and the actual angular value is read. This value is written into the OTP register bits Z35:Z46 (see Figure 13). Note: The zero position value may also be modified before programming, e.g. to program an electrical zero position that is 180º (half turn) from the mechanical zero position, just add 2048 to the value read at the mechanical zero position and program the new value into the OTP register. www.austriamicrosystems.com/AS5145 Revision 1.10 19 - 36 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9.1.2 OTP Memory Assignment Bit 51 50 49 48 47 46 : 35 34 33 : 29 28 27 26 25 24 23 : 20 19 18 17 16 : 0 Symbol mbit1 PWMhalfEN_Index width MagCompEn pwmDIS Output Md0 Output Md1 Z0 : Z11 CCW RA0 : RA4 FS 0 FS 1 FS 2 FS 4 FS 5 : FS 8 FS 9 FS 10 ChipID0 ChipID1 : ChipID17 mbit0 Factory Bit 0 18 bit Chip ID ID Section 20 - 36 Factory Section FS 3 Factory Bit Redundancy Address Direction 12 bit Zero Position Function Factory Bit 1 PMW frequency Index pulse width Alarm mode (programmed by austriamicrosystems to 1) Disable PWM Customer Section Default, 10 bit inc, 12 bit inc Sync mode Table 13. OTP Bit Assignment 9.1.3 User Selectable Settings The AS5145 allows programming of the following user selectable options: - PWMhalfEN_Indexwidth: Setting this bit, the PWM pulse will be divided by 2, in case of quadrature incremental mode A/B/Index setting of Index impulse width from 1 LSB to 3LSB - Output Md0: Setting this bit enables sync- or 10bit incrememantal mode (see Table 10). - Output Md1: Setting this bit enables sync- or 12bit incrememantal mode (see Table 10). - Z [11:0]: Programmable Zero / Index Position www.austriamicrosystems.com/AS5145 Revision 1.10 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n - CCW: Counter Clockwise Bit ccw=0 – angular value increases in clockwise direction ccw=1 – angular value increases in counterclockwise direction - RA [4:0]: Redundant Address: an OTP bit location addressed by this address is always set to “1” independent of the corresponding original OTP bit setting 9.1.4 - OTP Default Setting Output Md0, Output MD1: 00= Default mode Z0 to Z11: 00 = no programmed zero position CCW: 0 = clockwise operation RA4 to RA0:0 = no OTP bit is selected MagCompEN: 1 = The green/yellow Mode is enabled The AS5145 can also be operated without programming. The default, un-programmed setting is: 9.1.5 Redundancy For a better programming reliability a redundancy is implemented. In case when the programming of one bit failed this function can be used. With an address RA(4:0) one bit can be selected and programmed. Table 14. Redundancy Addressing PWMhalfEN_Indexwidth MagCompEN Output Md0 Output Md1 pwmDIS Address Z0 Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 Z9 Z10 Z11 00000 00001 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 01111 10000 10001 10010 10101 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 www.austriamicrosystems.com/AS5145 Revision 1.10 21 - 36 CCW 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9.1.6 Redundant Programming Option In addition to the regular programming, a redundant programming option is available. This option allows that one selectable OTP bit can be set to “1” (programmed state) by writing the location of that bit into a 5-bit address decoder. This address can be stored in bits RA4..RA0 in the OTP user settings. Example: setting RA4…0 to “00001” will select bit 51 = PWhalfEN_Indexwidth, “00010” selects bit 50 = MagCompEN, “10010” selects bit 34 =CCW, etc. 9.1.7 OTP Register Entry and Exit Condition Figure 13. OTP Access Timing Diagram Setup Condition OTP Access CSn PDIO CLK Operation Mode Selection Exit Condition To avoid accidental modification of the OTP during normal operation, each OTP access (Load, Write, Read, Program) requires a defined entry and exit procedure, using the CSn, PDIO and CLK signals as shown in Figure 13. Figure 14. OTP Programming Connection AS5145 Demoboard For programming, keep these 6 wires as short as possible! max. length = 2 inches (5cm) 1 MagINCn DTest1_A VDD5V 16 VDD3V3 15 NC 14 NC 13 PWM CSn CLK DO 12 11 10 9 2.2µF 2 MagDECn 3 4 DTest2_B 5 6 7 10n 3V3 7 6 5 4 3 2 1 22k *see Text PROG CSN DO CLK 5VUSB VDD3V3 VSS NC µC Mode_Index VSS 8 PDIO AS5145 Cap only required for OTP programming GND www.austriamicrosystems.com/AS5145 Revision 1.10 USB connect to USB interface on PC 3 VPROG 2 + 1 10µF VSS GND 3.3 … 4.6 V only required for OTP programming IC1 22 - 36 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9.2 Alignment Mode The alignment mode simplifies centering the magnet over the center of the chip to gain maximum accuracy. Alignment mode can be enabled with the falling edge of CSn while PDIO = logic high (see Figure 15). The Data bits D11-D0 of the SSI change to a 12-bit displacement amplitude output. A high value indicates large X or Y displacement, but also higher absolute magnetic field strength. The magnet is properly aligned, when the difference between highest and lowest value over one full turn is at a minimum. Under normal conditions, a properly aligned magnet will result in a reading of less than 128 over a full turn. The MagINCn and MagDECn indicators will be = 1 when the alignment mode reading is < 128. At the same time, both hardware pins MagINCn (#1) and MagDECn (#2) will be pulled to VSS. A properly aligned magnet will therefore produce a MagINCn = MagDECn = 1 signal throughout a full 360º turn of the magnet. Stronger magnets or short gaps between magnet and IC may show values larger than 128. These magnets are still properly aligned as long as the difference between highest and lowest value over one full turn is at a minimum. The Alignment mode can be reset to normal operation by a power-on-reset (disconnect / re-connect power supply) or by a falling edge on CSn with PDIO = low. Figure 15. Enabling the Alignment Mode PDIO CSn AlignMode enable Read-out via SSI 2µs min. 2µs min. Figure 16. Exiting Alignment Mode PDIO CSn exit AlignMode Read-out via SSI 9.3 3.3V / 5V Operation The AS5145 operates either at 3.3V ±10% or at 5V ±10%. This is made possible by an internal 3.3V Low-Dropout (LDO) Voltage regulator. The internal supply voltage is always taken from the output of the LDO, meaning that the internal blocks are always operating at 3.3V. For 3.3V operation, the LDO must be bypassed by connecting VDD3V3 with VDD5V (see Figure 17). For 5V operation, the 5V supply is connected to pin VDD5V, while VDD3V3 (LDO output) must be buffered by a 1...10µF capacitor, which is supposed to be placed close to the supply pin (see Figure 17) with recommended 2.2µF). Note: The VDD3V3 output is intended for internal use only It must not be loaded with an external load. The output voltage of the digital interface I/O’s corresponds to the voltage at pin VDD5V, as the I/O buffers are supplied from this pin. www.austriamicrosystems.com/AS5145 Revision 1.10 23 - 36 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n Figure 17. Connections for 5V / 3.3V Supply Voltages 5V Operation 2.2µF VDD3V3 100nF VDD5V LDO Internal VDD DO + 4.5 - 5.5V I N T E R F A C E PWM CLK CSn + 3.3V Operation VDD3V3 100nF VDD5V LDO Internal VDD DO 3.0 - 3.6V I N T E R F A C E PWM CLK CSn - VSS PDIO VSS PDIO A buffer capacitor of 100nF is recommended in both cases close to pin VDD 5V. Note that pin VDD 3V3 must always be buffered by a capacitor. It must not be left floating, as this may cause an instable internal 3.3V supply voltage which may lead to larger than normal jitter of the measured angle. 9.4 Selecting Proper Magnet Typically the magnet should be 6mm in diameter and 2.5mm in height. Magnetic materials such as rare earth AlNiCo/SmCo5 or NdFeB are recommended. The magnetic field strength perpendicular to the die surface has to be in the range of ±45mT…±75mT (peak). The magnet’s field strength should be verified using a gauss-meter. The magnetic field Bv at a given distance, along a concentric circle with a radius of 1.1mm (R1), should be in the range of ±45mT…±75mT(see Figure 18). www.austriamicrosystems.com/AS5145 Revision 1.10 24 - 36 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n Figure 18. Typical Magnet (6x3mm) and Magnetic Field Distribution typ. 6mm diameter N S Magnet axis R1 Magnet axis Vertical field component R1 concentric circle; radius 1.1mm Vertical field component Bv (45…75mT) 0 360 360 9.4.1 Physical Placement of the Magnet The best linearity can be achieved by placing the center of the magnet exactly over the defined center of the chip as shown in the drawing below: Figure 19. Defined Chip Center and Magnet Displacement Radius 3.9mm 3.9mm 1 2.433mm Defined center Rd 2.433mm Area of recommended maximum magnet misalignment www.austriamicrosystems.com/AS5145 Revision 1.10 25 - 36 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9.4.2 Magnet Placement The magnet’s center axis should be aligned within a displacement radius Rd of 0.25mm from the defined center of the IC. The magnet may be placed below or above the device. The distance should be chosen such that the magnetic field on the die surface is within the specified limits (see Figure 19). The typical distance “z” between the magnet and the package surface is 0.5mm to 1.5mm, provided the use of the recommended magnet material and dimensions (6mm x 3mm). Larger distances are possible, as long as the required magnetic field strength stays within the defined limits. However, a magnetic field outside the specified range may still produce usable results, but the out-of-range condition will be indicated by MagINCn (pin 1) and MagDECn (pin 2), (see Table 1). Figure 20. Vertical Placement of the Magnet N S N Die surface Package surface Z 0.576mm ± 0.1mm 1.282mm ± 0.15mm 9.5 Simulation Modeling Figure 21. Arrangement of Hall Sensor Array on Chip (principle) 3.9mm±0.235mm 1 2.433mm ±0.235mm X1 Y1 X2 Y2 AS5145 die Center of die Radius of circular Hall sensor A diametrically magnetized permanent magnet is placed above or below the surface of the AS5145. The chip uses an array of Hall sensors to sample the vertical vector of a magnetic field distributed across the device package surface. The area of magnetic sensitivity is a circular locus of 1.1mm radius with respect to the center of the die. The Hall sensors in the area of magnetic sensitivity are grouped and configured such that orthogonally related components of the magnetic fields are sampled differentially. The differential signal Y1-Y2 will give a sine vector of the magnetic field. The differential signal X1-X2 will give an orthogonally related cosine vector of the magnetic field. www.austriamicrosystems.com/AS5145 Revision 1.10 26 - 36 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n The angular displacement (Q) of the magnetic source with reference to the Hall sensor array may then be modelled by: (Y1 – Y2) Θ = arctan ------------------------ ± 0.5º ( X1 – X2 ) (EQ 3) The ±0.5º angular error assumes a magnet optimally aligned over the center of the die and is a result of gain mismatch errors of the AS5145. Placement tolerances of the die within the package are ±0.235mm in X and Y direction, using a reference point of the edge of pin #1 (see Figure 21). In order to neglect the influence of external disturbing magnetic fields, a robust differential sampling and ratio metric calculation algorithm has been implemented. The differential sampling of the sine and cosine vectors removes any common mode error due to DC components introduced by the magnetic source itself or external disturbing magnetic fields. A ratio metric division of the sine and cosine vectors removes the need for an accurate absolute magnitude of the magnetic field and thus accurate Z-axis alignment of the magnetic source. The recommended differential input range of the magnetic field strength (B(X1-X2), B(Y1-Y2)) is ±75mT at the surface of the die. In addition to this range, an additional offset of ±5mT, caused by unwanted external stray fields is allowed. The chip will continue to operate, but with degraded output linearity, if the signal field strength is outside the recommended range. Too strong magnetic fields will introduce errors due to saturation effects in the internal preamplifiers. Too weak magnetic fields will introduce errors due to noise becoming more dominant. 9.6 Failure Diagnostics The AS5145 also offers several diagnostic and failure detection features: 9.6.1 Magnetic Field Strength Diagnosis By software: the MagINC and MagDEC status bits will both be high when the magnetic field is out of range. By hardware: Pins #1 (MagINCn) and #2 (MagDECn) are open-drain outputs and will both be turned on (= low with external pull-up resistor) when the magnetic field is out of range. If only one of the outputs are low, the magnet is either moving towards the chip (MagINCn) or away from the chip (MagDECn). 9.6.2 Power Supply Failure Detection By software: If the power supply to the AS5145 is interrupted, the digital data read by the SSI will be all “0”s. Data is only valid, when bit OCF is high, hence a data stream with all “0”s is invalid. To ensure adequate low levels in the failure case, a pull-down resistor (~10kΩ) should be added between pin DIO and VSS at the receiving side. By hardware: The MagINCn and MagDECn pins are open drain outputs and require external pull-up resistors. In normal operation, these pins are high ohmic and the outputs are high (see Table 9). In a failure case, either when the magnetic field is out of range of the power supply is missing, these outputs will become low. To ensure adequate low levels in case of a broken power supply to the AS5145, the pull-up resistors (~10kΩ) from each pin must be connected to the positive supply at pin 16 (VDD5V). By hardware: PWM output: The PWM output is a constant stream of pulses with 1kHz repetition frequency. In case of power loss, these pulses are missing. 9.7 Angular Output Tolerances 9.7.1 Accuracy Accuracy is defined as the error between measured angle and actual angle. It is influenced by several factors: - The non-linearity of the analog-digital converters - Internal gain and mismatch errors - Non-linearity due to misalignment of the magnet As a sum of all these errors, the accuracy with centered magnet = (Errmax – Errmin)/2 is specified as better than ±0.5 degrees @ 25ºC (see Figure 23). Misalignment of the magnet further reduces the accuracy. Figure 22 shows an example of a 3D-graph displaying non-linearity over XYmisalignment. The center of the square XY-area corresponds to a centered magnet (see dot in the center of the graph). The X- and Y- axis extends to a misalignment of ±1mm in both directions. The total misalignment area of the graph covers a square of 2x2mm (79x79mil) with a step size of 100µm. For each misalignment step, the measurement as shown in Figure 23 is repeated and the accuracy (Errmax – Errmin)/2 (e.g. 0.25º in Figure 23) is entered as the Z-axis in the 3D-graph. www.austriamicrosystems.com/AS5145 Revision 1.10 27 - 36 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n Figure 22. Example of Linearity Error Over XY Misalignment 6 5 4 °3 2 1 0 1000 800 600 400 800 500 200 -100 -400 200 0 -700 -200 -400 -600 -1000 -800 -1000 x y The maximum non-linearity error on this example is better than ±1 degree (inner circle) over a misalignment radius of ~0.7mm. For volume production, the placement tolerance of the IC within the package (±0.235mm) must also be taken into account. The total nonlinearity error over process tolerances, temperature and a misalignment circle radius of 0.25mm is specified better than ±1.4 degrees. The magnet used for this measurement was a cylindrical NdFeB (Bomatec® BMN-35H) magnet with 6mm diameter and 2.5mm in height. Figure 23. Example of Linearity Error Over 360º 0.5 0.4 0.3 0.2 0.1 0 - 0.1 - 0.2 - 0.3 - 0.4 - 0.5 1 55 109 163 217 271 325 379 433 487 541 595 649 703 757 811 865 919 973 transition noise Err max Err min www.austriamicrosystems.com/AS5145 Revision 1.10 28 - 36 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9.7.2 Transition Noise Transition noise is defined as the jitter in the transition between two steps. Due to the nature of the measurement principle (Hall sensors + Preamplifier + ADC), there is always a certain degree of noise involved. This transition noise voltage results in an angular transition noise at the outputs. It is specified as 0.06 degrees rms (1 sigma)x1 in fast mode (pin MODE = high) and 0.03 degrees rms (1 sigma)x1 in slow mode (pin MODE = low or open). This is the repeatability of an indicated angle at a given mechanical position. The transition noise has different implications on the type of output that is used: Absolute output; SSI interface: The transition noise of the absolute output can be reduced by the user by implementing averaging of readings. An averaging of 4 readings will reduce the transition noise by 6dB or 50%, e.g. from 0.03ºrms to 0.015ºrms (1 sigma) in slow mode. PWM interface: If the PWM interface is used as an analog output by adding a low pass filter, the transition noise can be reduced by lowering the cutoff frequency of the filter. If the PWM interface is used as a digital interface with a counter at the receiving side, the transition noise may again be reduced by averaging of readings. Incremental mode: In incremental mode, the transition noise influences the period, width and phase shift of the output signals A, B and Index. However, the algorithm used to generate the incremental outputs guarantees no missing or additional pulses even at high speeds (up to 30.000 rpm and higher). Note: Statistically, 1 sigma represents 68.27% of readings and 3 sigma represents 99.73% of readings. 9.7.3 High Speed Operation Sampling Rate: The AS5145 samples the angular value at a rate of 2.61k (slow mode) or 10.42k (fast mode, selectable by pin MODE) samples per second. Consequently, the absolute outputs are updated each 384µs (96µs in fast mode). At a stationary position of the magnet, the sampling rate creates no additional error. Absolute Mode: At a sampling rate of 2.6kHz/10.4kHz, the number of samples (n) per turn for a magnet rotating at high speed can be calculated by nslowmode = nfastmode = 60 ---------------------------------rpm ⋅ ( 384 )μ s 60 -------------------------rmp ⋅ 96 μ s (EQ 4) (EQ 5) The upper speed limit in slow mode is ~6.000rpm and ~30.000rpm in fast mode. The only restriction at high speed is that there will be fewer samples per revolution as the speed increases (see Table 7). Regardless of the rotational speed, the absolute angular value is always sampled at the highest resolution of 12 bit. Incremental Mode: Incremental encoders are usually required to produce no missing pulses up to several thousand rpm’s. Therefore, the AS5145 has a built-in interpolator, which ensures that there are no missing pulses at the incremental outputs for rotational speeds of up to 30,000 rpm, even at the highest resolution of 12 bits (4096 pulses per revolution). 9.7.4 Propagation Delays The propagation delay is the delay between the time that the sample is taken until it is converted and available as angular data. This delay is 96µs in fast mode and 384µs in slow mode. Using the SSI interface for absolute data transmission, an additional delay must be considered, caused by the asynchronous sampling (0 … 1/ fsample) and the time it takes the external control unit to read and process the angular data from the chip (maximum clock rate = 1MHz, number of bits per reading = 18). Angular Error Caused by Propagation Delay. A rotating magnet will cause an angular error caused by the output propagation delay. This error increases linearly with speed: esampling = rpm * 6 * prop.delay Where: esampling = angular error [º] rpm = rotating speed [rpm] prop.delay = propagation delay [seconds] Note: Since the propagation delay is known, it can be automatically compensated by the control unit processing the data from the AS5145. (EQ 6) www.austriamicrosystems.com/AS5145 Revision 1.10 29 - 36 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9.7.5 Internal Timing Tolerance The AS5145 does not require an external ceramic resonator or quartz. All internal clock timings for the AS5145 are generated by an on-chip RC oscillator. This oscillator is factory trimmed to ±5% accuracy at room temperature (±10% over full temperature range). This tolerance influences the ADC sampling rate and the pulse width of the PWM output: - Absolute output; SSI interface: A new angular value is updated every 96µs (typ) in fast mode and every 384µs (typ) in slow mode. - PWM output: A new angular value is updated every 384µs (typ). The PWM pulse timings Ton and Toff also have the same tolerance as the internal oscillator. If only the PWM pulse width Ton is used to measure the angle, the resulting value also has this timing tolerance. However, this tolerance can be cancelled by measuring both Ton and Toff and calculating the angle from the duty cycle (see Pulse Width Modulation (PWM) Output on page 17) t on ⋅ 4097 Position = ------------------------ – 1 ( t on + t off ) (EQ 7) 9.7.6 Temperature Magnetic Temperature Coefficient. One of the major benefits of the AS5145 compared to linear Hall sensors is that it is much less sensitive to temperature. While linear Hall sensors require a compensation of the magnet’s temperature coefficients, the AS5145 automatically compensates for the varying magnetic field strength over temperature. The magnet’s temperature drift does not need to be considered, as the AS5145 operates with magnetic field strengths from ±45…±75mT. Example: A NdFeB magnet has a field strength of 75mT @ –40ºC and a temperature coefficient of -0.12% per Kelvin. The temperature change is from -40º to +125º = 165K.The magnetic field change is: 165 x -0.12% = -19.8%, which corresponds to 75mT at -40ºC and 60mT at 125ºC. The AS5145 can compensate for this temperature related field strength change automatically, no user adjustment is required. 9.7.7 Accuracy over Temperature The influence of temperature in the absolute accuracy is very low. While the accuracy is less than or equal to ±0.5º at room temperature, it may increase to less then or equal to ±0.9º due to increasing noise at high temperatures. Timing Tolerance over Temperature. The internal RC oscillator is factory trimmed to ±5%. Over temperature, this tolerance may increase to ±10%. Generally, the timing tolerance has no influence in the accuracy or resolution of the system, as it is used mainly for internal clock generation. The only concern to the user is the width of the PWM output pulse, which relates directly to the timing tolerance of the internal oscillator. This influence however can be cancelled by measuring the complete PWM duty cycle instead of just the PWM pulse. 9.8 AS5145 Differences to AS5045 All parameters are according to AS5045 data sheet except for the parameters shown below: Table 15. Difference Between AS5145 and AS5045 Building Block Resolution Ambient temperature range Data length AS5145 12bits, 0.088º/step -40ºC to +150ºC read: 18bits (12bits data + 6 bits status) OTP write: 18 bits (12 bits zero position + 6 bits mode selection) MagINCn, MagDECn: same feature as AS5045, indicator red-yellow-green magnetic range Pin3 (DTest1_A); Pin 4 (DTest2_B); Pin 6 (Mode_Index) 2x1024 ppr (12-bit) 2x256 ppr low-jitter (10-bit) MODE_Index pin, switch between fast and slow mode. In case of incremental mode is this pin an output the fast mode is setup in this case. AS5045 12bits, 0.088º/step -40ºC to +125ºC read: 18bits (12bits data + 6 bits status) OTP write: 18 bits (12 bits zero position + 6 bits mode selection) MagINCn, MagDECn Pins 1 and 2 Incremental encoder Not used Pin 3: not used Pin 4: not used Pin 6 MODE pin, switch between fast and slow mode www.austriamicrosystems.com/AS5145 Revision 1.10 30 - 36 AS5145 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n Table 15. Difference Between AS5145 and AS5045 Building Block Pin 12 Sampling frequency Propagation delay Transition noise (rms; 1sigma) OTP programming options AS5145 PWM output: frequency selectable by OTP: 1µs / step, 4096 steps per revolution, f=244Hz 2µs/ step, 4096 steps per revolution, f=122Hz selectable by MODE input pin: 2.5kHz, 10,4kHz 384µs (slow mode) 96µs (fast mode) 0.03 degrees max. (slow mode) 0.06 degrees max. (fast mode) PPTRIM; programming voltage 3.3V – 3.6V 70ºC; 52-bit serial data protocol; CSn, PDIO and CLK AS5045 PWM output: frequency selectable by OTP: 1µs / step, 4096 steps per revolution, f=244Hz 2µs / step, 4096 steps per revolution, f=122Hz selectable by MODE input pin: 2.5kHz, 10,4kHz 384µs (slow mode) 96µs (fast mode) 0.03 degrees max. (slow mode) 0.06 degrees max. (fast mode) EasyZap; programming voltage 7.3V – 7.5V; Csn; Prog and CLK; 16-bit (32-bit) serial data protocol; www.austriamicrosystems.com/AS5145 Revision 1.10 31 - 36 AS5145 Data Sheet - P a c k a g e D r a w i n g s a n d M a r k i n g s 10 Package Drawings and Markings The device is available in SSOP 16 (5.3mm x 6.2mm). Figure 24. Package Drawings AYWWIZZ AS5145 Table 16. Package Dimensions Symbol A A1 A2 b c D E E1 e K L 0º 0.63 mm Min 1.73 0.05 1.68 0.25 0.09 6.07 7.65 5.2 Typ 1.86 0.13 1.73 0.315 6.20 7.8 5.3 0.65 0.75 8º 0.95 Max 1.99 0.21 1.78 0.38 0.20 6.33 7.9 5.38 www.austriamicrosystems.com/AS5145 Revision 1.10 32 - 36 AS5145 Data Sheet - P a c k a g e D r a w i n g s a n d M a r k i n g s 10.1 Recommended PCB Footprint Figure 25. PCB Footprint Table 17. Recommended Footprint Data Symbol A B C D E mm 9.02 6.16 0.46 0.65 5.01 www.austriamicrosystems.com/AS5145 Revision 1.10 33 - 36 AS5145 Data Sheet - R e v i s i o n H i s t o r y Revision History Table 18. Revision History Revision Number 1.1 Date May 30, 2008 July 23, 2008 July 25, 2008 apg Owner Description Changed the temperature to 150ºC across the datasheet. Added Key Feature: Fully automotive qualified to AEC-Q100, grade 0 Changed the values in Table 10 for 10bit and 12 bit incremental mode Inserted 10kΩ for pin 6 in Table 1 changed values for fmag_abs in Table 4 Made changes to Incremental Mode on page 14. 1.2 August 24, 2008 rfu Removed quadrature from Figure 6. Inserted Incremental Output Hysteresis on page 15 and Figure . Modified the typ value of all in Table 11. changed the values in equation2 (page 18) Modified Applications 1.3 August 27, 2008 rfu Removed table Magnetic field strength variation indicator and modified Table 9 cell headings Changed angle position values in Pulse Width Modulation (PWM) Output on page 17 and also update Table 6 for the same. Changed the value of tDOvalid in Table 6 apg February 16, 2009 1.4 Changed the value of PWMIN, PWMAX in Table 6 Updated Figure 14 with 2.2µF capacitor without polarity Updated Figure 17 with 2.2µF instead of 2.2µF....10µF Changed key feature: Added pre-programmed versions available February 18, 2009 mub Removed 10 bit from pin descriptions for pin 12 on page 4 Deleted Min value for tDOvalid in Table 6 updated ordering information February 22, 2009 1.5 1.6 1.7 1.8 1.9 1.10 August 12, 2009 Sep 29, 2009 Nov 05, 2009 Dec 04, 2009 apg rfu July 15, 2009 apg rfu Changed the Max value of tDOvalid in Table 6 to 413 Added “AS5145-I10/AS5145-I12” to the header Made some sentence corrections and spelling mistakes Updated Incremental Mode on page 14 with new information. Added a note to the ordering information Updated Figure 13 Added Incremental Power-up Lock Option on page 15 Timing Characteristics (page 11) - Updated the parameter ‘PWM Frequency’ (fPWM) Updated section Internal Timing Tolerance (page 30) September 29, 2008 February 13, 2009 apg www.austriamicrosystems.com/AS5145 Revision 1.10 34 - 36 AS5145 Data Sheet - O r d e r i n g I n f o r m a t i o n 11 Ordering Information The devices are available as the standard products shown in Table 19. Table 19. Ordering Information Ordering Code AS5145-HSSU AS5145-HSST AS5145A-HSSU AS5145B-HSSU 1 Description 12-Bit Programmable Magnetic Rotary Encoder 12-Bit Programmable Magnetic Rotary Encoder Pre-programmed 10 bit incremental Pre-programmed 12 bit incremental Delivery Form Tubes Tape & Reel Tubes Tubes Package SSOP 16 (5.3mm x 6.2mm) SSOP 16 (5.3mm x 6.2mm) SSOP 16 (5.3mm x 6.2mm) SSOP 16 (5.3mm x 6.2mm) 1. The pre-programmed devices AS5145A-HSSU and AS5145B-HSSU are available on request. Note: All products are RoHS compliant and Pb-free. Buy our products or get free samples online at ICdirect: http://www.austriamicrosystems.com/ICdirect For further information and requests, please contact us mailto:sales@austriamicrosystems.com or find your local distributor at http://www.austriamicrosystems.com/distributor www.austriamicrosystems.com/AS5145 Revision 1.10 35 - 36 AS5145 Data Sheet - C o p y r i g h t s Copyrights Copyright © 1997-2009, austriamicrosystems AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. All products and companies mentioned are trademarks or registered trademarks of their respective companies. Disclaimer Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for each application. 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Contact Information Headquarters austriamicrosystems AG Tobelbaderstrasse 30 A-8141 Unterpremstaetten, Austria Tel: +43 (0) 3136 500 0 Fax: +43 (0) 3136 525 01 For Sales Offices, Distributors and Representatives, please visit: http://www.austriamicrosystems.com/contact www.austriamicrosystems.com/AS5145 Revision 1.10 36 - 36