A S5 04 5B 12-Bit Programmable Magnetic Position Sensor 1 General Description Two digital 12-bit absolute outputs: The AS5045B is a contact less magnetic position sensor 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. - Serial interface - Pulse width modulated (PWM) output Quadrature A/B/I output 12-bit User programmable zero position To measure the angle, only a simple two-pole magnet, rotating over the center of the chip, is required. The magnet can 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. Failure detection mode for magnet placement, monitoring, and loss of power supply Red-Yellow-Green indicators display placement of magnet in Z- axis Serial read-out of multiple interconnected AS5045B devices using Daisy Chain mode Tolerant to magnet misalignment and gap variations An internal voltage regulator allows the AS5045B to operate at either 3.3V or 5V supplies. Wide temperature range: - 40ºC to +125ºC Small Pb-free package: SSOP 16 (5.3mm x 6.2mm) 3 Applications 2 Key Features Contact less high resolution rotary position sensor over a full turn of 360 degrees The device is ideal for industrial applications like automatic or elevator doors, robotics, motor control and optical encoder replacement. Figure 1. Blockdiagram Rotary Position Sensor IC VDD3V3 MagINCn VDD5V MagDECn LDO 3.3V PWM Interface Sin Hall Array & Frontend Amplifier Cos PWM Ang ATAN (Cordic) Mag Absolute Interface (SSI) DO CSn CLK OTP Register PDIO A AS5045B Incremental Interface B I www.ams.com Revision 1.0 1 - 33 AS5045B Datasheet - C o n t e n t s Contents 1 General Description .................................................................................................................................................................. 1 2 Key Features............................................................................................................................................................................. 1 3 Applications............................................................................................................................................................................... 1 4 Pin Assignments ....................................................................................................................................................................... 3 4.1 Pin Descriptions.................................................................................................................................................................................... 3 5 Absolute Maximum Ratings ...................................................................................................................................................... 5 6 Electrical Characteristics........................................................................................................................................................... 6 6.1 Magnetic Input Specification................................................................................................................................................................. 7 6.2 System Specifications .......................................................................................................................................................................... 8 7 Timing Characteristics ............................................................................................................................................................ 10 8 Detailed Description................................................................................................................................................................ 11 8.1 Synchronous Serial Interface (SSI) .................................................................................................................................................... 11 8.2 Incremental Mode............................................................................................................................................................................... 13 8.3 Daisy Chain Mode .............................................................................................................................................................................. 14 8.4 Pulse Width Modulation (PWM) Output.............................................................................................................................................. 15 8.4.1 Changing the PWM Frequency.................................................................................................................................................. 16 8.5 Analog Output..................................................................................................................................................................................... 9 Application Information ........................................................................................................................................................... 17 9.1 Programming the AS5045B................................................................................................................................................................ 9.1.1 9.1.2 9.1.3 9.1.4 9.1.5 9.1.6 9.1.7 16 Zero Position Programming ....................................................................................................................................................... OTP Memory Assignment.......................................................................................................................................................... User Selectable Settings ........................................................................................................................................................... OTP Default Setting................................................................................................................................................................... Redundancy............................................................................................................................................................................... Redundant Programming Option ............................................................................................................................................... OTP Register Entry and Exit Condition ..................................................................................................................................... 9.2 Alignment Mode.................................................................................................................................................................................. 17 17 18 18 19 19 20 20 21 9.3 3.3V / 5V Operation ............................................................................................................................................................................ 22 9.4 Selecting Proper Magnet .................................................................................................................................................................... 22 9.4.1 Physical Placement of the Magnet ............................................................................................................................................ 23 9.4.2 Magnet Placement..................................................................................................................................................................... 24 9.5 Failure Diagnostics ............................................................................................................................................................................. 24 9.5.1 Magnetic Field Strength Diagnosis ............................................................................................................................................ 24 9.5.2 Power Supply Failure Detection ................................................................................................................................................ 24 9.6 Angular Output Tolerances ................................................................................................................................................................. 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.6.7 Accuracy .................................................................................................................................................................................... Transition Noise......................................................................................................................................................................... High Speed Operation ............................................................................................................................................................... Propagation Delays ................................................................................................................................................................... Internal Timing Tolerance .......................................................................................................................................................... Temperature .............................................................................................................................................................................. Accuracy over Temperature ...................................................................................................................................................... 10 Package Drawings and Markings ......................................................................................................................................... www.ams.com Revision 1.0 24 26 26 26 27 27 27 28 10.1 Recommended PCB Footprint.......................................................................................................................................................... 11 Ordering Information ............................................................................................................................................................. 24 30 32 2 - 33 AS5045B Datasheet - P i n A s s i g n m e n t s 4 Pin Assignments Figure 2. Pin Assignments (Top View) 1 16 VDD5V MagDECn 2 15 VDD3V3 A 3 14 NC B 4 13 NC NC 5 12 PWM I 6 11 CSn VSS 7 10 CLK PDIO 8 9 DO AS5045B MagINCn 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 Name Pin Number MagINCn 1 MagDECn 2 A 3 B 4 NC 5 - I 6 Digital output VSS 7 Supply pin PDIO 8 OTP Programming Input and Data Input for Daisy Chain mode. Pin Digital input pull-down has an internal pull-down resistor (74kΩ). Connect this pin to VSS if programming is not required. DO 9 Digital output/ tri-state Data Output of Synchronous Serial Interface CLK 10 Digital input, Schmitt- Clock Input of Synchronous Serial Interface; Schmitt-Trigger input Trigger input www.ams.com Pin Type Digital output open drain Digital output Description Magnet Field Magnitude Increase. Active low. Indicates a distance reduction between the magnet and the device surface. (see Table 8) Magnet Field Magnitude Decrease. Active low. Indicates a distance increase between the device and the magnet. (see Table 8) Quadrature output A (1024 Pulses) Quadrature output B (1024 Pulses) Must be left unconnected Index signal for the quadrature output. Negative Supply Voltage (GND) Revision 1.0 3 - 33 AS5045B Datasheet - P i n A s s i g n m e n t s Table 1. Pin Descriptions Pin Name Pin Number Pin Type Description CSn 11 PWM 12 Digital output Pulse Width Modulation NC 13 - Must be left unconnected NC 14 - Must be left unconnected VDD3V3 15 Supply pin 3V-Regulator Output, internally regulated from VDD5V. Connect to VDD5V for 3V supply voltage. Do not load externally. VDD5V 16 Supply pin Positive Supply Voltage, 3.0V to 5.5V Digital input pullChip Select. Active low. Schmitt-Trigger input, internal pull-up resistor down, Schmitt-Trigger (50kΩ) input 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 used for incremental angle information in 12-bit quadrature signal format. Pin 6 Index output used for incremental angle information. (Zero position reference). 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 17). This pin is also used as digital input to shift serial data through the device in Daisy Chain configuration, (see page 13). Pin 11 Chip Select (CSn; active low) selects a device within a network of AS5045Bs 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 21) and programming mode (see Programming the AS5045B on page 17). 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.ams.com Revision 1.0 4 - 33 AS5045B Datasheet - 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 6 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 2. Absolute Maximum Ratings Parameter Min Max Units -0.3 7 V 5 V Comments Electrical Parameters DC supply voltage at pin VDD5V DC supply voltage at pin VDD3V3 Input pin voltage -0.3 VDD5V +0.3 V Except VDD3V3 Input current (latchup immunity) -100 100 mA Norm: EIA/JESD78 Class II Level A ±2 kV Norm: JESD22-A114E 150 ºC Min -67ºF; Max +302ºF 260 ºC The reflow peak soldering temperature (body temperature) specified is in accordance with IPC/ JEDEC J-STD-020 “Moisture/Reflow Sensitivity Classification for Non-Hermetic Solid State Surface Mount Devices”. The lead finish for Pb-free leaded packages is matte tin (100% Sn). 85 % Electrostatic Discharge Electrostatic discharge Temperature Ranges and Storage Conditions Storage temperature -55 Package Body temperature Humidity non-condensing Moisture Sensitive Level (MSL) www.ams.com 5 3 Represents a maximum floor time of 168h Revision 1.0 5 - 33 AS5045B Datasheet - 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 +125ºC, VDD5V = 3.0-3.6V (3V operation) VDD5V = 4.5-5.5V (5V operation) unless otherwise noted. Also valid for version I. Table 3. Electrical Characteristics Symbol Parameter Condition Min TAMB Ambient temperature Version I -40 Isupp Supply current VDD5V Supply voltage at pin VDD5V Typ Max Unit +125 ºC 16 21 mA 4.5 5.0 5.5 3.0 3.3 3.6 3.0 3.3 3.6 3.0 3.3 3.6 1,37 2.2 2.9 1.08 1.9 2.6 Operating Conditions VDD3V3 Voltage regulator output voltage at pin VDD3V3 5V Operation VDD5V Supply voltage at pin VDD5V VDD3V3 Supply voltage at pin VDD3V3 3.3V Operation (pin VDD5V and VDD3V3 connected) VON Power-on reset thresholds On voltage; 300mV typ. hysteresis Power-on reset thresholds Off voltage; 300mV typ. hysteresis Voff DC supply voltage 3.3V (VDD3V3) V V V Programming Conditions VPROG Programming voltage Voltage applied during programming 3.3 3.6 V VProgOff Programming voltage off level Line must be discharged to this level 0 1 V IPROG Programming current Current during programming 100 mA Rprogramme Programmed fuse resistance (log 1) 10µA max. current @ 100mV 100k ∞ Ω Unprogrammed fuse resistance (log 0) 2mA max. current @ 100mV 50 100 Ω d Runprogram med DC Characteristics CMOS Schmitt-Trigger Inputs: CLK, CSn (CSn = Internal Pull-up) 0.7 * VDD5V VIH High level input voltage VIL Low level input voltage VIon- VIoff Schmitt Trigger hysteresis ILEAK Input leakage current CLK only -1 1 IiL Pull-up low level input current CSn only, VDD5V: 5.0V -30 -100 0.7 * VDD5V VDD5V V 3.3 3.6 V 0.3 * VDD5V V 100 µA Normal operation V 0.3 * VDD5V 1 V V µA DC Characteristics CMOS / Program Input: PDIO VIH High level input voltage 1 VPROG High level input voltage VIL Low level input voltage IiL High level input current During programming VDD5V: 5.5V 30 DC Characteristics CMOS Output Open Drain: MagINCn, MagDECn IOZ Open drain leakage current 1 µA VOL Low level output voltage VSS + 0.4 V www.ams.com Revision 1.0 6 - 33 AS5045B Datasheet - 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 Parameter IO Output current Condition Min Typ Max VDD5V: 4.5V 4 VDD5V: 3V 2 Unit mA DC Characteristics CMOS Output: PWM VOH High level output voltage VOL Low level output voltage IO Output current VDD5V – 0.5 V VSS +0.4 VDD5V: 4.5V 4 VDD5V: 3V 2 V mA DC Characteristics CMOS Output: A, B, Index VOH High level output voltage VOL Low level output voltage IO Output current VDD5V – 0.5 V VSS +0.4 VDD5V: 4.5V 4 VDD5V: 3V 2 V mA DC Characteristics Tri-state CMOS Output: DO VOH High level output voltage VOL Low level output voltage IO Output current IOZ Tri-state leakage current VDD5V – 0.5 V VSS +0.4 VDD5V: 4.5V 4 VDD5V: 3V 2 1 V mA µA 1. Either with 3.3V or 5V supply. 6.1 Magnetic Input Specification TAMB = -40 to +125°C, VDD5V = 3.0 to 3.6V (3V operation) VDD5V = 4.5 to 5.5V (5V operation) unless otherwise noted. Also valid for version I. Two-pole cylindrical diametrically magnetized source: Table 4. Magnetic Input Specification Symbol Parameter Condition Min Typ dmag Diameter 4 6 tmag Thickness Recommended magnet: Ø 6mm x 2.5mm for cylindrical magnets Bpk Magnetic input field amplitude Required vertical component of the magnetic field strength on the die’s surface, measured along a concentric circle with a radius of 1.1mm Boff Magnetic offset fmag_abs Disp www.ams.com Max mm 2.5 mm 75 mT Constant magnetic stray field ± 10 mT Input frequency (rotational speed of magnet) 153 rpm @ 4096 positions/rev 2.54 Hz Displacement radius Max. offset between defined device center and magnet axis (see Figure 17) 0.25 mm Revision 1.0 45 Unit 7 - 33 AS5045B Datasheet - 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 Parameter Condition Min Typ Ecc Eccentricity Eccentricity of magnet center to rotational axis Recommended magnet material and temperature drift NdFeB (Neodymium Iron Boron) -0.12 SmCo (Samarium Cobalt) -0.035 Max Unit 100 µm %/K 6.2 System Specifications TAMB = -40 to +125°C, VDD5V = 3.0 to 3.6V (3V operation) VDD5V = 4.5 to 5.5V (5V operation) unless otherwise noted. Also valid for version I. Table 5. Input Specification Symbol Parameter Condition RES Resolution INLopt INLtemp Max Unit 0.088 deg 12 bit Integral non-linearity (optimum) Maximum error with respect to the best line fit. Centered magnet without calibration, TAMB =25 ºC. ± 0.5 deg Integral non-linearity (optimum) Maximum error with respect to the best line fit. Centered magnet without calibration, TAMB = -40 to +125ºC ± 0.9 deg INL Integral non-linearity Best line fit = (Errmax – Errmin) / 2 Over displacement tolerance with 6mm diameter magnet, without calibration, TAMB = -40 to +125ºC ± 1.4 deg DNL Differential non-linearity 12-bit, no missing codes ± 0.044 deg TN Transition noise 1 sigma 0.06 Deg RMS tPwrUp Power-up time Until status bit OCF = 1 20 ms tdelay System propagation delay absolute output : delay of ADC, DSP and absolute interface 96 µs tdelayINC System propagation delay incremental output 192 µs fS Internal sampling rate for absolute output 11.46 kHz CLK/SEL Read-out frequency 1 MHz www.ams.com Min 9.38 Max. clock frequency to read out serial data Revision 1.0 Typ 10.42 8 - 33 AS5045B Datasheet - 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 4095 α 12bit code 4095 Actual curve 2 TN DNL+1LSB 1 0 Ideal curve INL 0.09° 2048 2048 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.ams.com Revision 1.0 9 - 33 AS5045B Datasheet - 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 +125 ºC, VDD5V = 3.0 to 3.6V (3V operation) VDD5V = 4.5 to 5.5V (5V operation), unless otherwise noted. Also valid for version I. Table 6. Timing Characteristics Symbol Parameter Conditions Min Typ Max Units 100 ns Synchronous Serial Interface (SSI) tDOactive Data output activated (logic high) Time between falling edge of CSn and data output activated tCLKFE First data shifted to output register Time between falling edge of CSn and first falling edge of CLK 500 ns TCLK/2 Start of data output Rising edge of CLK shifts out one bit at a time 500 ns tDOvalid Data output valid Time between rising edge of CLK and data output valid 413 ns tDOtristate Data output tri-state After the last bit DO changes back to “tristate” 100 ns tCSn Pulse width of CSn CSn =high; To initiate read-out of next angular position 500 fCLK Read-out frequency Clock frequency to read out serial data >0 ns 1 MHz Pulse Width Modulation Output fPWM PWM frequency Signal period = 4098µs ±10% at TAMB = -40 to +125ºC 220 244 268 Hz PWMIN Minimum pulse width Position 0d; angle 0 degree 0.90 1 1.10 µs PWMAX Maximum pulse width Position 4098d; angle 359.91 degrees 3686 4096 4506 µs tPROG Programming time per bit Time to prog. a single fuse bit 10 20 µs tCHARGE Refresh time per bit Time to charge the cap after tPROG 1 fLOAD LOAD frequency Data can be loaded at n x 2µs 500 kHz fREAD READ frequency Read the data from the latch 2.5 MHz fWRITE WRITE frequency Write the data to the latch 2.5 MHz Programming Conditions www.ams.com Revision 1.0 µs 10 - 33 AS5045B Datasheet - D e t a i l e d D e s c r i p t i o n 8 Detailed Description The AS5045B 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 AS5045B provides accurate highresolution 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 16). The AS5045B 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 AS5045B is tolerant to magnet misalignment and magnetic stray fields due to differential measurement technique and Hall sensor conditioning circuitry. Figure 4. Typical Arrangement of AS5045B and Magnet 8.1 Synchronous Serial Interface (SSI) Figure 5. Synchronous Serial Interface with Absolute Angular Position Data TCLK/2 CSn tCSn tCLK FE tCLK FE 1 CLK D11 DO D10 D9 D8 D7 D6 D5 1 18 8 D4 D3 D2 D1 D0 OCF COF LIN Mag Mag Even INC DEC PAR D11 tDO valid tDO active www.ams.com Angular Position Data Status Bits Revision 1.0 tDO Tristate 11 - 33 AS5045B Datasheet - D e t a i l e d D e s c r i p t i o n 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 can 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 can still be used, but can contain invalid data. This warning can 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 7. Status Bit Outputs OCF COF 1 LIN 0 Mag INC Mag DEC 0 0 0 1 1 0 1 1 0 Parity Even checksum of bits 1:15 Note: MagInc=MagDec=1 is only recommended in YELLOW mode (see Table 8) Z-axis Range Indication (Push Button Feature, Red/Yellow/Green Indicator). The AS5045B 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 8. Magnetic Field Strength Red-Yellow-Green Indicator Status Bits Hardware Pins OTP: Mag CompEn = 1 (Red-Yellow-Green) Mac INCn Mag DECn Description Mac INC Mag DEC LIN 0 0 0 Off Off No distance change Magnetic input field OK (GREEN range, ~45…75mT) 1 1 0 On Off YELLOW range: magnetic field is ~ 25…45mT or ~75…135mT. The AS5045B can still be operated in this range, but with slightly reduced accuracy. 1 1 1 On On RED range: magnetic field is ~<25mT or >~135mT. It is still possible to operate the AS5045B in the red range, but not recommended. n/a n/a Not available All other combinations 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. www.ams.com Revision 1.0 12 - 33 AS5045B Datasheet - D e t a i l e d D e s c r i p t i o n The two pins can 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 8). 8.2 Incremental Mode The AS5045B 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. 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: ext ≤ 5kΩ ). 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) can 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 AS5045B as soon as the state (A=B=Index = high) is cleared. CSn = low at power-up: CSn has an internal pull-up resistor and must be externally pulled low ( R 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 Programmed Zero Position Counter ClockWise A B 1 LSB I 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. www.ams.com Revision 1.0 13 - 33 AS5045B Datasheet - D e t a i l e d D e s c r i p t i o n Figure 7. Hysteresis Window for Incremental Outputs Incremental Output Indication Hysteresis : 0.35° X +6 X +5 X +4 X +3 X +2 X +1 X X Magnet Position X +1 X +2 X +3 X +4 X +5 X +6 Clockwise Direction Counterclockwise Direction 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. 8.3 Daisy Chain Mode The Daisy Chain mode allows connection of several AS5045Bs in series, while still keeping just one digital input for data transfer (see “Data IN” in Figure 8). 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 9). Figure 8. Daisy Chain Hardware Configuration AS5045B µC st 1 Device Data IN DO CSn PDIO CLK AS5045B 2 nd DO CSn Device PDIO CLK AS5045B last Device DO CSn PDIO CLK CLK CSn www.ams.com Revision 1.0 14 - 33 AS5045B Datasheet - D e t a i l e d D e s c r i p t i o n Figure 9. Daisy Chain Mode Data Transfer CSn tCLK FE TCLK/2 1 CLK D11 DO tDO active 18 8 D10 tDO valid D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 OCF COF LIN Mag Mag Even INC DEC PAR Status Bits Angular Position Data D 1 2 3 D11 D10 D9 Angular Position Data nd st 2 Device 1 Device 8.4 Pulse Width Modulation (PWM) Output The AS5045B 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 ) (EQ 1) 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 10. PWM Output Signal Angle PWMIN 0 deg (Pos 0) 1µs 4098µs PWMAX 359.91 deg (Pos 4095) 4097µs 1/fPWM www.ams.com Revision 1.0 15 - 33 AS5045B Datasheet - D e t a i l e d D e s c r i p t i o n 8.4.1 Changing the PWM Frequency The PWM frequency of the AS5045B can be divided by two by setting a bit (PWMhalfEN) in the OTP register (see Programming the AS5045B on page 17). With PWMhalfEN = 0 the PWM timing is as shown in Table 9: Table 9. PWM Signal Parameters (Default mode) Symbol Parameter Typ Unit Note fPWM PWM frequency 244 Hz Signal period: 4097µs PWMIN MIN pulse width 1 µs - Position 0d - Angle 0 deg PWMAX MAX pulse width 4097 µs - Position 4095d - Angle 359.91 deg When PWMhalfEN = 1, the PWM timing is as shown in Table 10: Table 10. PWM Signal Parameters with Half Frequency (OTP option) Symbol Parameter Typ Unit Note fPWM PWM frequency 122 Hz Signal period: 8194µs PWMIN MIN pulse width 2 µs - Position 0d - Angle 0 deg PWMAX MAX pulse width 8194 µs - Position 4095d - Angle 359.91 deg 8.5 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 AS5045B can be used as direct replacement of potentiometers. Figure 11. Simple 2nd Order Passive RC Low Pass Filter Pin12 R2 R1 analog out PWM VDD C1 C2 0V Pin7 0º 360º VSS Figure 10 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.ams.com Revision 1.0 16 - 33 AS5045B Datasheet - 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 AS5045B 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 AS5045B After power-on, programming the AS5045B is enabled with the rising edge of CSn with PDIO = high and CLK = low. The AS5045B 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 pro- grammed 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 12). Note: The zero position value can 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.ams.com Revision 1.0 17 - 33 AS5045B Datasheet - 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 Symbol Function mbit1 Factory Bit 1 51 PWMhalfEN_Index width PMW frequency Index pulse width 50 MagCompEn Alarm mode (programmed by ams to 1) 49 pwmDIS Disable PWM 48 Reserved 47 Reserved 12 bit inc. (programmed by ams) bit 47 to 1, bit 48 to 0 46 Z0 : : 35 Z11 34 CCW 33 RA0 : : 29 RA4 28 FS 0 27 FS 1 26 FS 2 25 FS 3 24 FS 4 23 FS 5 : : 20 FS 8 19 FS 9 18 FS 10 17 ChipID0 16 ChipID1 : : 0 ChipID17 12-bit Zero Position Direction Factory Bit 18-bit Chip ID mbit0 9.1.3 Factory Section Redundancy Address ID Section Bit Customer Section Table 11. OTP Bit Assignment Factory Bit 0 User Selectable Settings The AS5045B 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 - Z [11:0]: Programmable Zero / Index Position www.ams.com Revision 1.0 18 - 33 AS5045B Datasheet - 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 The AS5045B can also be operated without programming. The default, un-programmed setting is: - 9.1.5 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 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. 0 0 00001 1 0 0 00010 0 1 0 00011 0 0 00100 0 0 Z0 Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 Z9 Z10 Z11 CCW pwmDIS 0 Reserved MagCompEN 00000 Reserved Address PWMhalfEN_Indexwidth Table 12. Redundancy Addressing 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00101 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 00110 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 00111 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 01000 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 01001 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 01010 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 01011 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 01100 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 01101 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 01110 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 01111 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 10000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 10001 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 10010 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 10101 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 www.ams.com Revision 1.0 19 - 33 AS5045B Datasheet - 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 For timing options, refer to Programming the AS5045B (page 17). Figure 12. OTP Access Timing Diagram OTP Access Setup Condition CSn PDIO CLK Exit Condition Operation Mode Selection 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 12. www.ams.com Revision 1.0 20 - 33 AS5045B Datasheet - 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 13). 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 will 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 13. Enabling the Alignment Mode PDIO CSn 2µs min. AlignMode enable Read-out via SSI exit AlignMode Read-out via SSI 2µs min. Figure 14. Exiting Alignment Mode PDIO CSn www.ams.com Revision 1.0 21 - 33 AS5045B Datasheet - A p p l i c a t i o n I n f o r m a t i o n 9.3 3.3V / 5V Operation The AS5045B 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 15). 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 15) 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. Figure 15. Connections for 5V / 3.3V Supply Voltages 5V Operation 3.3V Operation 2.2 ... 10µF VDD3V3 VDD3V3 100nF VDD5V 100nF LDO Internal VDD VDD5V LDO Internal VDD DO DO 4.5 - 5.5V VSS I N T E R F A C E PWM + - - + CLK 3.0 - 3.6V CSn PDIO VSS I N T E R F A C E PWM CLK CSn 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 can lead to larger than normal jitter of the measured angle. 9.4 Selecting Proper Magnet Typically the magnet is 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 is verified using a gauss-meter. The magnetic field Bv at a given distance, along a concentric circle with a radius of 1.1mm (R1) is in the range of ±45mT…±75mT(see Figure 16). www.ams.com Revision 1.0 22 - 33 AS5045B Datasheet - A p p l i c a t i o n I n f o r m a t i o n Figure 16. Typical Magnet (6x3mm) and Magnetic Field Distribution typ. 6mm diameter N S Magnet axis Magnet axis R1 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 17. Defined Chip Center and Magnet Displacement Radius 3.9mm 3.9mm 2.4325mm 1 Defined center 2.4325mm Rd www.ams.com Area of recommended maximum magnet misalignment Revision 1.0 23 - 33 AS5045B Datasheet - 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 must be aligned within a displacement radius Rd of 0.25mm from the defined center of the IC. The magnet can be placed below or above the device. The distance can be chosen such that the magnetic field on the die surface is within the specified limits (see Figure 17). 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. A magnetic field outside the specified range still can be detected by the chip. But the out-of-range condition will be indicated by MagINCn (pin 1) and MagDECn (pin 2), (see Table 1). 9.5 Failure Diagnostics The AS5045B also offers several diagnostic and failure detection features: 9.5.1 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). 9.5.2 Power Supply Failure Detection By software: If the power supply to the AS5045B 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) must 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 8). 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 AS5045B, 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. 9.6 Angular Output Tolerances 9.6.1 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 19). Misalignment of the magnet further reduces the accuracy. Figure 18 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 19 is repeated and the accuracy (Errmax – Errmin)/2 (e.g. 0.25º in Figure 19) is entered as the Z-axis in the 3D-graph. www.ams.com Revision 1.0 24 - 33 AS5045B Datasheet - A p p l i c a t i o n I n f o r m a t i o n Figure 18. Example of Linearity Error Over XY Misalignment 6 5 4 ° 3 800 500 2 200 1 -100 x -400 -700 -1000 -1000 -800 -600 y -400 -200 0 200 400 600 800 1000 0 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 19. Example of Linearity Error Over 360º 0.5 0.4 0.3 0.2 transition noise 0.1 Err max 0 -0.1 1 55 109 163 217 271 325 379 433 487 541 595 649 703 757 811 865 919 973 Err min -0.2 -0.3 -0.4 -0.5 www.ams.com Revision 1.0 25 - 33 AS5045B Datasheet - A p p l i c a t i o n I n f o r m a t i o n 9.6.2 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. 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: 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 can be further 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 15,000 rpm and higher). Note: Statistically, 1 sigma represents 68.27% of readings and 3 sigma represents 99.73% of readings. 9.6.3 High Speed Operation Sampling Rate: The AS5045B samples the angular value at a rate of 10.42k samples per second. Consequently, the absolute outputs are updated each 96µs. At a stationary position of the magnet, the sampling rate creates no additional error. Absolute Mode: At a sampling rate of 10.4kHz, the number of samples (n) per turn for a magnet rotating at high speed can be calculated by n= 60 -------------------------rmp ⋅ 96μs (EQ 3) The upper speed limit is ~30,000 rpm. 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. Therefore, the AS5045B has a built-in interpolator, which ensures that there are no missing pulses at the incremental outputs for rotational speeds of up to 15,000 rpm, even at the highest resolution of 12 bits (4096 pulses per revolution). 9.6.4 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. 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 (EQ 4) 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 AS5045B. 9.6.5 Internal Timing Tolerance The AS5045B does not require an external ceramic resonator or quartz. All internal clock timings for the AS5045B 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). - PWM output: A new angular value is updated every 96µs (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 Mod- www.ams.com Revision 1.0 26 - 33 AS5045B Datasheet - A p p l i c a t i o n I n f o r m a t i o n ulation (PWM) Output on page 15) 9.6.6 Temperature Magnetic Temperature Coefficient. One of the major benefits of the AS5045B 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 AS5045B automatically compensates for the varying magnetic field strength over temperature. The magnet’s temperature drift does not need to be considered, as the AS5045B 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 AS5045B can compensate for this temperature related field strength change automatically, no user adjustment is required. 9.6.7 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 can increase to less than 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 can 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. www.ams.com Revision 1.0 27 - 33 AS5045B Datasheet - 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 20. Package Drawings and Dimensions Symbol A A1 A2 b c D E E1 e L L1 L2 R Θ N Min 1.73 0.05 1.68 0.22 0.09 5.90 7.40 5.00 0.55 0.09 0º Nom 1.86 0.13 1.73 0.315 0.17 6.20 7.80 5.30 0.65 BSC 0.75 1.25 REF 0.25 BSC 4º 16 Max 1.99 0.21 1.78 0.38 0.25 6.50 8.20 5.60 0.95 8º Notes: 1. Dimensions and tolerancing conform to ASME Y14.5M-1994. 2. All dimensions are in millimeters. Angles are in degrees. Marking: YYWWMZZ. YY WW M ZZ Last two digits of the manufacturing year Manufacturing week Plant identifier Assembly traceability code www.ams.com Revision 1.0 28 - 33 AS5045B Datasheet - 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 Figure 21. Vertical Cross Section of SSOP-16 Notes: 1. All dimensions in mm. www.ams.com Revision 1.0 29 - 33 AS5045B Datasheet - 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 22. PCB Footprint Recommended Footprint Data Symbol mm A 9.02 B 6.16 C 0.46 D 0.65 E 5.01 www.ams.com Revision 1.0 30 - 33 AS5045B Datasheet - R e v i s i o n H i s t o r y Revision History Revision Date Owner Description 1.0 03 July, 2013 mub Initial Revision www.ams.com Revision 1.0 31 - 33 AS5045B Datasheet - 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 13. Table 13. Ordering Information Ordering Code Description Delivery Form AS5045B-ASST Pre-programmed 12-bit incremental (125 °C) Tape&Reel (13”) AS5045B-ASSM Pre-programmed 12-bit incremental (125 °C) Tape&Reel (7”) Package SSOP 16 (5.3mm x 6.2mm) Note: All products are RoHS compliant and ams green. Buy our products or get free samples online at www.ams.com/ICdirect Technical Support is available at www.ams.com/Technical-Support For further information and requests, email us at [email protected] (or) find your local distributor at www.ams.com/distributor www.ams.com Revision 1.0 32 - 33 AS5045B Datasheet - C o p y r i g h t s Copyrights Copyright © 1997-2013, ams 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 ams AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. ams 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. ams 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 ams 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 ams AG for each application. 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Contact Information Headquarters ams AG Tobelbaderstrasse 30 A-8141 Unterpremstaetten, Austria Tel Fax : +43 (0) 3136 500 0 : +43 (0) 3136 525 01 For Sales Offices, Distributors and Representatives, please visit: http://www.ams.com/contact www.ams.com Revision 1.0 33 - 33