A1341 High Precision, Programmable Linear Hall Effect Sensor IC with EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization FEATURES AND BENEFITS • Advanced 32-segment output linearization functionality enables high output accuracy and linearity in the presence of non-linear input magnetic fields • Selectable digital SENT (Single Edge Nibble Transmission) or PWM (Pulse Width Modulation) output • SENT output is SAEJ2716 JAN2010 compliant Allegro Proprietary Enhanced Programmable Features • Customer programmable sensitivity offset, bandwidth, output polarity, output clamps, 1st and 2nd order temperature compensation • Simultaneous programming of all parameters for accurate and efficient system optimization • Factory trimmed magnetic input range (coarse sensitivity) and signal offset • Sensitivity temperature coefficient and magnetic offset drift preset at Allegro, for maximum device accuracy without requiring customer temperature testing • Temperature-stable, mechanical stress immune, and extremely low noise device output via proprietary four-phase chopper stabilization and differential circuit design techniques • Diagnostics for open circuit, overvoltage, and undervoltage • Wide ambient temperature range: –40°C to 150°C • Operates with 4.5 to 5.5 V supply voltage Package: 4-pin SIP (suffix KT) 1 mm case thickness DESCRIPTION The A1341 device is a high precision, programmable Hall effect linear sensor integrated circuit (IC) with a configurable pulse width modulated (PWM) or single edge nibble transmission (SENT) output, for both automotive and nonautomotive applications. The signal path of the A1341 provides flexibility through external programming that allows the generation of an accurate, and customized output voltage from a input magnetic signal. The A1341 provides 12 bits of output resolution, and supports a maximum bandwidth of 3 kHz. The BiCMOS, monolithic integrated circuit incorporates a Hall sensor element, precision temperature-compensating circuitry to reduce the intrinsic sensitivity and offset drift of the Hall element, a small-signal high-gain amplifier, proprietary dynamic offset cancellation circuits, and advanced output linearization circuitry. With on-board EEPROM and advanced signal processing functions, the A1341 provides an unmatched level of customer reprogrammable options for characteristics such as gain and offset, bandwidth, output clamps, and output polarity. Multiple input magnetic range and signal offset choices can be preset at the factory In addition, the device supports separate hot and cold, 1st and 2nd order temperature compensation. A key feature of the A1341 is its ability to produce a highly linear device output for nonlinear input magnetic fields. To achieve this, the device divides the output into 32 equal segments and applies a unique linearization coefficient factor to each segment. Linearization coefficients are stored in a look-up table in EEPROM. The A1341 is available in a lead (Pb) free 4-pin single in-line package (KT suffix), with 100% matte tin leadframe plating. Not to scale Analog Subsystem Digital Signal Processing Output Stage ...00110011... Magnetic Signal 12-bit Hall Element Factory Preset Magnetic Range and Signal Offset A to D Conversion Output Bandwidth and Temperature Compensation Sensitivity and Fine Offset Adjustment Linearization Clamps Figure 1: A1341 Signal Processing Path SENT/PWM Output Driver Functions with programmable parameters indicated by double-headed arrows. A1341-DS A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Selection Guide Part Number A1341LKTTN-T Packing* 4000 pieces per 13-in. reel *Contact Allegro™ for additional packing options Table of Contents Specifications Absolute Maximum Ratings Thermal Characteristics Functional Block Diagram Pin-out Diagram and Terminal List Electrical Characteristics Magnetic Characteristics Programmable Characteristics Characteristic Performance Functional Description 3 3 3 4 4 5 6 7 9 12 Signal Processing Parameter Setting 12 Digital Signal Processing 13 Bandwidth Selection 13 Temperature Compensation 13 Sensitivity (Gain) Adjustment 15 Output Fine Offset Adjustment 15 Linearization of Output 15 Output Polarity 16 Output Clamps Setting 16 Output Protocol Selection 16 Protection Features 17 Operating Voltage and Low Voltage Protection17 Open Circuit Detection 17 Typical Application 17 EEPROM Lock Features 18 Memory Locking Mechanisms 18 Programming Serial Interface Transaction Types Writing the Access Code 19 19 19 Writing to EEPROM Reading from EEPROM Error Checking Serial Interface Reference Serial Interface Message Structure 19 20 20 21 22 Linear Output Protocols 27 EEPROM Structure 34 Definitions of Terms 49 Package Outline Drawing 51 PWM Output Mode SENT Output Mode Message Structure Optional Serial Output Protocol Data Nibble Format Pause Pulse Timing Synchronization EEPROM Customer-Programmable Parameter Reference 27 28 28 29 29 29 36 Full Scale (FSI and FSO) 49 Power-On Time (tPO)49 Signal Propagation Delay (tPROP)49 Signal Response Time (tRESP)49 Quiescent Output (QOUT) 49 Quiescent Output Drift through Temperature Range49 Sensitivity (Sens) 49 Sensitivity Drift through Temperature Range 50 Sensitivity Drift Due to Package Hysteresis (ΔSensPKG)50 Linear Sensitivity Error 50 Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 2 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization SPECIFICATIONS Absolute Maximum Ratings Rating Unit Forward Supply Voltage Characteristic Symbol VCC Notes 30 V Reverse Supply Voltage VRCC –20 V Forward Supply Current ICC 30 mA Reverse Supply Current IRCC –30 mA Forward Output Voltage (OUT Pin) VOUT 30 V Reverse Output Voltage (OUT Pin) VROUT –0.5 V ISINK 50 mA EEPROMW(max) 100 cycle –40 to 150 ºC Forward Output Sink Current (OUT Pin) Maximum Number of EEPROM Write Cycles Operating Ambient Temperature TA Maximum Junction Temperature TJ(max) 165 ºC Tstg –65 to 165 ºC Storage Temperature L temperature range Thermal Characteristics may require derating at maximum conditions, see application information Characteristic Symbol Package Thermal Resistance Test Conditions* RθJA 1-layer PCB with copper limited to solder pads Value Unit 174 ºC/W *Additional thermal information available on the Allegro website. Power Dissipation versus Ambient Temperature 1100 Power Dissipation, PD (mW) 1000 900 800 1-layer PCB, Package KT (RθJA = 174 C/W) 700 600 500 400 300 200 100 0 20 40 60 80 100 120 140 160 180 Temperature (°C) Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 3 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 VCC UVLO OVLO Analog Regulator POR Factory Coarse Sensitivity Factory and Magnetic Range Coarse Offset Setting Trim Digital Regulator Clock Generator EEPROM Analog Front End Digital Subsystem ADC Hall Element Serial Decode Anti-Alias Filter Temperature Sensor ADC Precision Reference A/D 12 12 Serial Interface Bandwidth Select Temperature Compensation HV Pulse Master Control Digital Sensitivity and Offset Trim Pulse Detect EEPROM Control Scan/ IDDQ Linearization Clamp SENT/ PWM Driver OUT GND Functional Block Diagram Terminal List Table 1 Number Name 1 VCC Input power supply, use bypass capacitor to connect to ground Function 2 OUT Output pin; EEPROM strobe input 3 NC 4 GND Not connected; connect to GND for optimal ESD performance Device ground 2 3 4 Pin-out Diagram Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 4 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization ELECTRICAL CHARACTERISTICS: valid through full operating temperature range, TA , and supply voltage, VCC , CBYPASS = 10 nF, unless otherwise specified Characteristics Symbol Test Conditions Min. Typ. Max. Unit1 4.5 – 5.5 V General Electrical Characteristics Supply Voltage VCC Supply Current ICC Reverse Supply Current IRCC Supply Zener Clamp Voltage Hall Chopping Frequency3 Low Voltage Detection Threshold Power-On Reset Overvoltage Lockout Threshold SENT Message Duration3 Minimum Programmable SENT Message Duration3 4 – 10 mA VRCC = 20 V – – –5 mA ICC = ICC(max) + 3 mA, TA = 25°C 30 – – V TA = 25°C – 128 – kHz VCC(LVD)LOW LVD_DIS = 0 4.25 4.4 4.55 V VCC(LVD)HIGH LVD_DIS = 0 4.35 4.5 4.7 V PORLOW 3.5 3.7 4.1 V PORHIGH 3.6 3.8 4.15 V OVLO_LO = 1, TA = 25°C 5.6 – – V OVLO_LO = 0, TA = 25°C 18 – – V Tick time = 3 µs – – 1 ms Tick time = 0.25 µs, 3 data nibbles of information, nibble length = 27 ticks – 41 – µs VSAT VCC = 4.5 V, ISINK = 4.6 mA – 0.3 0.45 V VZSUPPLY fC VCC(OV) tSENT tSENTMIN Output Electrical Characteristics Output Saturation Voltage Output Current Limit ILIMIT Output FET on, TA = 25°C 20 35 50 mA Output Zener Clamp Voltage VZOUT TA = 25°C 30 – – V Capacitance3,4 CLOAD OUT to GND – – 10 nF BW = 3000 Hz – 0.5 – ms BW = 1500 Hz – 0.8 – ms BW = 750 Hz – 2 – ms BW = 375 Hz – 3 – ms Output Load Power-On Time5,6 Signal Propagation Delay3,6 Full Scale Output Range3 tPO tPROP FSO BW = 188 Hz – 6 – ms BW = 3000 Hz – 0.35 – ms BW = 1500 Hz – 0.7 – ms BW = 750 Hz – 1.4 – ms BW = 375 Hz – 2.8 – ms BW = 188 Hz – 5.6 – ms PWM_MODE = 1 (PWM mode), CLAMP_HIGH = CLAMP_LOW = 0 (PWM duty cycle) – – 90 %D PWM_MODE = 0 (SENT mode) – – 4095 LSB 11 G (gauss) = 0.1 mT (millitesla). Protection Features section. by design. 4Clarity of a Read Acknowledge message from the device to the controller will be affected by the amount of capacitance and wire inductance on the device output. In such case, it is recommended to slow down the communication speed, and to lower the receiver threshold for reading digital Manchester signal. 5Parameter is verified by lab characterization with a limited amount of samples. 6See Definitions of Terms section. 2See 3Determined Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 5 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization MAGNETIC CHARACTERISTICS: valid through full operating temperature range, TA , and supply voltage, VCC , CBYPASS = 10 nF, unless otherwise specified Characteristics Symbol Test Conditions Factory Programmed Device Values (Before Customer Magnetic Input Signal Range BIN Magnetic Input Signal Offset BINOFFSET Output Sensitivity Sens Quiescent Output OUT(Q) Programming)2,3, Output Clamp Sensitivity Drift Over Temperature4 Output Offset Drift Over Temperature5 DSens DOUT(Q) Max. Unit1,2 – ±500 – G – 0 – %FSI SENS_COARSE = 0, SENS_MULT = 0 SIG_OFFSET = 0 0.097 0.1 0.103 %FSO/G BIN = 0 G, TA = 25°C 49.4 50 50.5 %FSO – 4095 – LSB 94.8 95 95.2 %D – 0 – LSB 4.8 5 5.2 %D TA = –40°C to 25°C – <±0.03 – %/°C TA = 25°C to 150°C – <±0.02 – %/°C TA = –40°C to 25°C – <±0.005 – %/°C TA = 25°C to 150°C – <±0.005 – %/°C PWM_MODE = 1 (PWM mode) (PWM duty cycle) PWM_MODE = 0 (SENT mode) OUTCLP(L) Typ. VCC = 5 V, TA = 25°C SENS_COARSE = 0 PWM_MODE = 0 (SENT mode) OUTCLP(H) Min. PWM_MODE = 1 (PWM mode) (PWM duty cycle) 11 G (gauss) = 0.1 mT (millitesla). 2FSO means Full Scale Output and FSI means Full Scale Input. See Definitions of Terms section. 3Device performance is optimized for the input magnetic range of SENS_COARSE = 0 and input offset of SIG_OFFSET=0. If a different magnetic input range or signal offset is required, please see the tables in the section EEPROM Customer-Programmable Parameter Reference, near the end of this document. 4Does not include drift over lifetime and package hysteresis. 5Offset drifts with temperature changes will be altered from the factory programmed values if Magnetic Input Signal Range is changed. If changes in Magnetic Input Signal Range cannot be avoided because of application requirements, please contact Allegro for detailed information. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 6 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 PROGRAMMABLE CHARACTERISTICS: valid through full operating temperature range, TA , and supply voltage, VCC , CBYPASS = 10 nF, unless otherwise specified Characteristics Internal Bandwidth Symbol Test Conditions Min. Typ. Max. Unit1 – 3 – bit 188 – 3000 Hz TA = 25°C, measured as a percentage of BW – ±5 – % QOUT_FINE – 12 – bit Programming2 Bandwidth Programming Bits BW Bandwidth Programming Range TA = 25°C; for programming values, see BW in EEPROM Structure section Bandwidth Post-Programming Tolerance BW ∆BW Fine Quiescent Output2 FIne Quiescent Output Programming Bits Fine Quiescent Output Programming Range QOUT_FINE TA = 25°C, BIN = 0 G –49 – 49 %FSO Fine Quiescent Output Programming Step Size StepQOUT_ TA = 25°C, BIN = 0 G FINE – 0.0244 – %FSO 0.025 – 0.18 %FSO/G – 12 – bit Output Sensitivity2 Output Sensitivity SENS_OUT TA = 25°C Sensitivity Multiplier Programming Bits SENS_MULT Sensitivity Multipler Programming Range SENS_MULT TA = 25°C 0 – 2 – Sensitivity Multiplier Programming Step Size StepSENS_ TA = 25°C MULT – 0.00048 – – TA = 25°C – 33 – data sampling point LIN_x, programmed with output fitting method – 12 – bit Linearization2 Linearization Positions Linearization Position Coefficient Bits LINPOS_ COEFF Output Polarity Bit LIN_OUTPUT_INVERT – 1 – bit Input Polarity Bit LIN_INPUT_INVERT – 1 – bit Temperature Compensation (TC)2 1st Order Sensitivity TC Programming Bits TC1_SENS_CLD, TA = –40°C – 8 – bit TC1_SENS_HOT, TA = 150°C – 8 – bit – 98 – +291 m%/°C – 1.53 – m%/°C TC2_SENS_CLD, TA = –40°C – 9 – bit TC2_SENS_HOT, TA = 150°C – 9 – bit TC1_SENS_ Typical 1st Order Sensitivity TC Programming Range3 1st Order Sensitivity TC Programming Step Size3 2nd Order Sensitivity TC Programming Bits CLD TC1_ SENS_ HOT StepTC1SENS Continued on the next page… Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 7 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 PROGRAMMABLE CHARACTERISTICS (continued): valid through full operating temperature range, TA , and supply volt- age, VCC , CBYPASS = 10 nF, unless otherwise specified Characteristics Temperature Compensation Symbol (TC)2 Test Conditions Min. Typ. Max. Unit1 –1.53 – 1.53 m%/°C2 – 0.00596 – m%/°C2 – 8 – bit −0.48 − +0.48 G/°C – 0.00381 – G/°C bit (continued) TC2_SENS_ Typical 2nd Order Sensitivity TC Programming Range3,4 CLD TC2_ SENS_ HOT 2nd Order Sensitivity TC Programming StepTC2SENS Step Size3,4 1st Order Magnetic Offset TC Programming Bits Typical 1st Order Magnetic Offset TC Programming Range 1st Order Magnetic Offset TC Step Size TC1_OFFSET TC1_OFFSET SENS_COARSE = 0 StepTC1_ OFFSET Output Clamping Range2 Clamp Programming Bits Output Clamp Programming Range Clamp Programming Step Size CLAMP_HIGH – 6 – CLAMP_LOW – 6 – bit 50.78 – 100 %FSO OUTCLP(H) TA = 25°C, VCC = 5 V OUTCLP(L) TA = 25°C, VCC = 5 V 0 – 49.22 %FSO StepCLP(H) TA = 25°C – 0.78 – %FSO StepCLP(L) TA = 25°C – 0.78 – %FSO Accuracy (After Customer Programming) Linearity Sensitivity Error LinERR – <±1 – % – < ±1 – % Sensitivity Drift Due to Package Hysteresis ∆SensPKG Variation on final programmed Sensitivity value; measured at TA = 25°C after temperature cycling from 25°C to 150°C and back to 25°C Sensitivity Drift Over Lifetime ∆SensLIFE TA = 25°C, shift after AEC Q100 grade 0 qualification testing – ±3 – % Quiescent Output Drift over Lifetime DOUT(Q)LIFE TA = 25°C, shift after AEC Q100 grade 0 qualification testing – <±1 – % SENT Characteristics2 VSENT(L) SENT Output Signal SENT Output Trigger Signal VSENT(H) 10 kΩ ≤ Rpullup ≤ 50 kΩ – – 0.05 V Minimum Rpullup = 10 kΩ 0.9 × VCC – – V Maximum Rpullup = 50 kΩ 0.7 × VCC – – V VSENTtrig(L) – – 1.2 V VSENTtrig(H) 2.8 – – V 11 G (gauss) = 0.1 mT (millitesla). by design. unit m% = 0.001%; for example, 250 m%/°C = 0.025 %/°C = 2.5 × 10–3 /°C. 4The unit m% / C2 means: (10–3 × %) / C2. 2Determined 3The Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 8 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 CHARACTERISTIC PERFORMANCE Average Supply Current (On) versus Temperature 9.0 9.0 8.6 8.6 8.2 TA (°C) -40 7.8 -20 7.4 0 7.0 50 25 75 6.6 100 6.2 125 150 5.8 5.4 5.0 4.0 4.5 5.0 5.5 Supply Current, ICC(av) (mA) Supply Current, ICC(av) (mA) Average Supply Current (On) versus Supply Voltage VCC (V) 8.2 4.5 7.8 5.0 7.4 5.5 7.0 6.6 6.2 5.8 5.4 5.0 -60 6.0 -40 -20 Supply Voltage, VCC (V) Output Saturation Voltage versus Average Supply Voltage 250 TA (°C) -40 -20 200 0 25 50 150 75 100 125 100 150 50 4.5 5.0 5.5 IOUT = 0.45 mA VCC (V) 4.5 5.0 5.5 -40 VCC (V) 5.2 4.5 5.0 5.0 4.8 5.5 4.6 Duty Cycle (%) Duty Cycle (%) 95.6 5.4 40 60 80 100 120 140 160 140 160 4.5 5.0 94.8 5.5 94.6 94.2 120 VCC (V) 95.0 4.2 Ambient Temperature, TA (°C) 20 95.2 94.4 100 0 95.4 4.4 80 -20 Upper Clamp versus Average Temperature 5.6 60 160 Ambient Temperature, TA (°C) 95.8 40 140 50 5.8 20 120 100 96.0 0 100 150 6.0 -20 80 200 0 -60 6.0 Lower Clamp versus Average Temperature -40 60 250 Supply Voltage, VCC (V) 4.0 -60 40 300 IOUT = 0.45 mA 0 4.0 20 Output Saturation Voltage versus Average Temperature Output Saturation Voltage, VSAT (mV) Output Saturation Voltage, ∆VOUT (mV) 300 0 Ambient Temperature, TA (°C) 94.0 -60 -40 -20 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C) Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 9 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 93.0 Average + 3 sigma 0.030 Sensitivity, Sens (m%D/G) Sensitivity Drift, ∆Sens (%/°C) 0.040 Factory Programmed Sensitivity Drift versus Ambient Temperature 0.020 Average 0.010 0 -0.010 Average – 3 sigma -0.020 -0.030 -0.040 -80 ∆TA relative to TA = 25°C -60 -40 -20 0 20 40 60 80 100 120 92.0 91.0 Average + 3 sigma 89.0 Average – 3 sigma 88.0 -40 Factory Programmed Quiescent Voltage Output Drift versus Ambient Temperature 40 60 80 100 120 140 160 50.40 0.002 QVO, VOUT(Q) (%D) Average + 3 sigma 0.004 Average -0 -0.002 -0.004 Average – 3 sigma -0.006 50.30 50.20 50.10 Average Average + 3 sigma 50.00 49.90 Average – 3 sigma 49.80 49.70 40.60 -60 -40 -20 0 20 40 60 80 100 120 49.50 -60 140 -40 -20 Change in Ambient Temperature, ∆TA (°C) 2.0 2.0 Linearity (%) 3.0 Average + 3 sigma Average 0 -1.0 20 40 60 80 100 120 140 160 Negative Linearity versus Ambient Temperature 3.0 1.0 0 Ambient Temperature, TA (°C) Positive Linearity versus Ambient Temperature Linearity (%) 20 50.50 0.006 Average – 3 sigma -2.0 -3.0 -60 0 Factory Programmed Quiescent Voltage Output versus Ambient Temperature 0.008 QVO (m%/°C) -20 Ambient Temperature, TA (°C) Change in Ambient Temperature, ∆TA (°C) -0.008 -80 Average 90.0 87.0 -60 140 Factory Programmed Sensitivity versus Ambient Temperature Average + 3 sigma 1.0 Average 0 Average – 3 sigma -1.0 -2.0 -40 -20 0 20 40 60 80 100 Ambient Temperature, TA (°C) 120 140 160 -3.0 -60 -40 -20 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C) Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 10 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 100 Quiescent Output Duty Cycle QDCDC (%) QOUT_FINE Step Size Duty Cycle (%) 0.025 Quiescent Output Duty Cycle versus QOUT_FINE Code versus Ambient Temperature QOUT_FINE Step Size Duty Cycle versus Ambient Temperature Average + 3 sigma Average Average – 3 sigma 0.024 0.023 0.022 0.021 0.020 0.019 -60 -40 -20 0 20 40 60 80 100 120 140 90 Code 2048 80 70 Code 1024 60 50 Code 0 40 30 20 Code 3072 10 Code 4096 0 -60 160 -40 -20 Ambient Temperature, ∆TA (°C) 50.30 Duty Cycle (%) 0.76 Average Average + 3 sigma 0.70 Average – 3 sigma 0.68 0.66 0 20 40 60 80 100 140 160 120 140 SENS_MULT Minimum SENS_MULT Code 0 SENS_MULT Maximum 49.80 49.50 -60 160 -40 -20 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C) Ambient Temperature, TA (°C) 2.50 120 49.90 46.60 -20 100 50.00 49.70 -40 80 50.10 0.62 0.60 -60 60 50.20 0.64 Sensitivity Multiplication Factor versus Ambient Temperature SENSDC Maximum Multiplier 2.00 SENS_MULT Clamp Step Size Duty Cycle (%) 50.40 0.72 40 50.50 0.78 0.74 20 Quiescent Output Duty Cycle versus SENS_MULT Code versus Ambient Temperature Clamp Step Size Duty Cycle versus Ambient Temperature 0.80 0 Ambient Temperature, ∆TA (°C) 1.50 1.00 0.50 SENSDC Minimum Multiplier 0 -0.50 -60 -40 -20 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C) Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 11 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization FUNCTIONAL DESCRIPTION This section provides descriptions of the operating features and subsystems of the A1341. For more information on specific terms, refer to the Definitions of Terms section. Tables of EEPROM parameter values are provided in the EEPROM Structure section. YAD is the output of the analog subsystem to the A-to-D converter, Signal Processing Parameter Setting BIN is the current magnetic input signal, The A1341 has customer-programmable parameters that allow the user to optimize the signal processing performed by the A1341. Customer-programmable parameters apply to digital signal processing (DSP) stage. Programmed settings are stored in onboard EEPROM. The programming communication protocol is described in the Programming Serial Interface section. SIG_OFFSET the factory-set signal offset, and The initial analog processing is factory programmed to match the application environment in terms of magnetic field range and offset. This allows optimization of the electrical signal presented to the DSP stage: YAD (%FSO) = SENS_COARSE (%FSO/G) × BIN + SIG_OFFSET (%FSI) + QOUT (%FSO) (1) where: SENS_COARSE is the factory-set coarse sensitivity, QOUT is the quiescent voltage output with no factory compensation. The DSP stage provides customer-programmable sensitivity (gain) fine offset adjusting, TC processing, bandwidth, clamp, and linearization selection. Output is a digital voltage signal, proportional to the applied magnetic signal, with customer-selectable formatting: either pulse-wave modulated (PWM) or in the single edge nibble transmission encoding scheme (SENT). The Full Scale Output range is proportional to the Full Scale Input range, but is optimized by customer-programmed parameters. Signal Factory Programmed Magnetic Input Range/ Coarse Sensitivity Factory Programmed Signal Offset Signal Input to A/D Signal Input to Figure 2: Signal Path for Analog Subsystem Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 12 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Digital Signal Processing The digitized analog signal is digitally processed to optimize accuracy and resolution for conversion to the device output stage. An advanced linearization feature also is available. BANDWIDTH SELECTION The 3-dB bandwidth, BW , determines the frequency at which the DSP function imports data from the analog front end A-to-D convertor. It is programmed by setting the BW parameter in EEPROM. The values chosen for BW and RANGE affect the DSP stage output resolution and the Signal Response Time, tRESP . These tradeoffs are represented in the Electrical Characteristics table, above. The device can be compensated internally using the Temperature Compensation (TC) circuitry. TC coefficients can be programmed for Sensitivity and magnetic offset. The effect of temperature is referred to as drift. For magnetic offset, compensation for 1st Order Magnetic Offset TC, TC1_OFFSET , is a linear algorithm accounting for effects of ambient temperature changes during device operation (see Figure 4). It can be programmed using the TC1_OFFSET parameter Table 1: Bandwidth-Related Tradeoffs TEMPERATURE COMPENSATION Bandwidth Selection [Internal Update Rate] (kHz) DSP Output Resolution (bit) Other 11 to 12 3.000 [16.0] 10 to 11 The magnetic properties of materials can be affected by changes in temperature, even within the rated ambient operating temperature range, TA . Any change in the magnetic circuit due to temperature variation causes a proportional change in the device output. Sensitivity Multiplier /Fine QOUT Adjustment TC Codes Applied for TA = 25°C Output Sensitivity and Offset Applied Linearization Linearization Coefficients Applied Clamps Are Set Figure 3: Signal path for digital subsystem Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 13 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization TA Range < 25°C > 25°C 1st Order TC1_SENS_CLD TC1_SENS_HOT 2nd Order TC2_SENS_CLD TC2_SENS_HOT TC 25°C 1_S EN S_C LD Ma TC1_SENS_CLD Code 0 TC1_S EN xC D Min S_CL TC ode 1_S EN S_ H M OT Co ax de TC1_SENS_HOT Code 0 Code TC1_S ENS_H OT Min Code TA EN 25°C S_ CL TC2_SENS_CLD Code 0 NS DM _C LD _H E NS ax C od e T C 2 _S o de Mi n C T C2 _ S E OT x Ma TC2_SENS_HOT Code 0 NS _ HO TM in C e SENS_COARSE_COEF = SENS_COARSE(code 0) / SENS_COARSE(factory code) (sets the factory-programmed sensitivity of the YAD function). FFS od SIG_OFFSET (set to 0) is the factory programmed addition to the magnetic offset parameter (sets the centerpoint of YAD ), and 1_O Table 2: Sensitivity Temperature Compensation options _S ΔTA is the change in ambient temperature from 25°C (for example: at 150°C, ΔTA = 150°C – 25°C = 125°C, or at –40°C, ΔTA = –40°C – 25°C = –65°C), TC e e TA Figure 4: The 1st Order Magnetic Offset Temperature Compensation Coefficient (TC1_OFFSET) is used for linear adjustment of device output for temperature changes. T C2 TC2_SENS is the second-order coefficient: either TC2_SENS_ HOT or TC2_SENS_CLD depending on TA , TC1_OFFSET Code 0 Cod Cod e TC1_SENS is the first-order coefficient: either TC1_SENS_HOT or TC1_SENS_CLD depending on TA , Min ax od YAD is the input from the analog subsystem via the A-to-D converter, ET M ET C where: FFS SE YTC (%FSO) = YAD (%FSO) + [ (TC1_SENS (m%/°C) × ΔTA (°C)) + (TC2_SENS (m%/°C2) × ΔTA2 (°C)) ] × ( YAD (%FSO) – SIG_OFFSET (%FSI) ) + TC1_OFFSET (G/°C) × 0.09 (%FSO/G) × SENS_COARSE_COEF × ΔTA (°C) (2) 1_O 2_ The programmed values set the temperature compensation, YTC, according to the following formula: TC TC Either first-order or second-order, or both TC algorithms can be applied. To apply an algorithm, select non-zero coefficients for the corresponding EEPROM parameters (TC1_SENS_CLD and TC1_SENS_HOT for first-order, TC2_SENS_CLD and TC2_SENS_HOT for second order). If a method should not be used, set the corresponding EEPROM parameter values to zero. If both are selected, the A1341 applies the first-order, and then the second-order algorithm during this stage. QOUT TC1_SENS(m%/C2) Sensitivity drift compensation is customer-programmed (described below), within a framework of programmed temperature compensation. Optional temperature compensation for Sensitivity can be applied using built-in first-order and second-order algorithms. Both approaches adjust the device gain in response to input signal drift by adding or subtracting a value. The coefficients are programmed separately for temperatures above 25°C and below 25°C, as shown in Table 2. The resulting functions are illustrated in Figure 5. TC1_SENS(m%/C2) in a range of ±0.48 G/°C . This compensation is applied in DSP, after bandwidth selection. TC1_OFFSET (G/°C) A1341 TA Figure 5: Sensitivity TC Functions (upper) first order, (lower) second order Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 14 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization SENSITIVITY (GAIN) ADJUSTMENT LINEARIZATION OF OUTPUT Sensitivity is applied in the DSP subsystem, after bandwidth selection and temperature compensation. Note: If Sensitivity must be adjusted more than 20% from the nominal value, please consider switching input magnetic range for the optimization of A-to-D input. Magnetic fields are not always linear throughout the full range of target positions, such as in the case of ring magnet targets rotated in front of a non-back-biased linear Hall sensor IC, shown in Figure 6. The A1341 provides a programmable linearization feature that allows adjustment of the transfer characteristic of the device so that, as the actual position of the target changes, the resulting changes in the applied magnetic field can be output as corresponding linear increments. OUTOUT FINE OFFSET ADJUSTMENT The Fine Offset adjustment is the segment of the DSP signal used to trim the device output, OUT (%FSO). QOUT_FINE is a customer-programmable parameter that sets the Quiescent Output, QOUT , which is device output when there is no significant applied magnetic field. The programmed value sets the DSP output, YDA , taking into account the selected Sensitivity: YDA (%FSO) = SENS_MULT × YTC (%FSO) + QOUT_FINE (%FSO) (3) SENS_OUT (%FSO/G) = SENS_MULT × SENS (%FSO/G) (4) where SENS_MULT is the multiplication factor from 0 to 2. Device Output (%) QOUT_FINE is set as a percentage of OUT . It can be set to add up to 50% of FSO to the output of the DSP stage, or subtract up to 50% of FSO from the DSP output. 100 90 80 70 60 50 40 30 20 10 0 -4 In order to achieve this, an initial set of linearization coefficients has to be created. The user takes 33 samples of BIN: at the start and at every 1/32 interval of the full input range. The user then enters these 33 values into the Allegro ASEK programming utility for the A1341, or an equivalent customer software program, and generates coefficients corresponding to the values. The user then uses the software load function to transmit the coefficients to the EEPROM (LINPOS_COEFF parameter). The user then sets the LIN_TABLE_DONE parameter to 1. When the A1341 is in operation, it applies a built-in algorithm to linearize output based on the stored coefficients. Each of the coefficient values can be individually overwritten during normal operation. Figure 7 shows an example input-output curve. The y axis represents the 32 equal full scale position segments, and the x axis represents the the range of movement. When the A1341 is in operation, it applies a linearization curve built from the 33 coefficients provided by the user. For example, Initial Output Linearized Output -3 -2 -1 0 1 2 3 4 Ring Magnet Rotation (°) Figure 6: Example of Linearization of a Sinusoidal Magnetic Signal Generated by a Rotating Ring Magnet Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 15 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 at position 5 the device originally would output 384 LSB of magnetic field. This 384 LSB is treated as input to the inverse linearization function, after rescaling to the x axis as follows: (384 – 128(offset)) × [32 / (3968(LSBmax) – 128(LSBmin))] + 1 = 3.2 For x = 3.2, the inverse function will give output of 570 LSB which is right on the curve of the linear output signal. OUTPUT POLARITY Device Output Polarity can be changed using the LIN_OUTPUT_INVERT bit set to 1. If the goal is to change output polarity and apply linearization, the output polarity should be changed by setting the gain of the linearization function to 1 (linearization table coefficients are decimal values from 0 to 4096 with steps of 128 codes) and setting the LIN_INPUT_INVERT bit to 1. Then user can collect 33 points for linearization and calculate the coefficients. After the coefficients are loaded into the device, successful linearization will be applied by leaving the LIN_INPUT_INVERT bit set to 1 and setting the LIN_TABLE _DONE bit to 1. OUTPUT CLAMPS SETTING To eliminate the effects of outlier points, the A1341 Clamp Range, OUTCLP , is initially set to 100% of FSO for high clamp and 0% of FSO for low clamp, and can be adjusted using the CLAMP_HIGH and CLAMP_LOW parameters. OUTPUT PROTOCOL SELECTION The A1341 supports a linear voltage output in either PWM or SENT format. The PWM_MODE parameter in EEPROM sets the format. (Output format programming is described in the Linear Output Protocols section.) 4096 3968 3840 3712 3584 3456 Output Signal 3328 3200 Device Digital Output (LSBs) 3072 Input Signal 2944 Linearization Function 2816 2688 2560 2432 2304 2176 2048 1920 1792 1664 (2) Rescaled x = 3.2, yields LSB = 570 1536 1408 1280 1152 1024 896 768 640 (3) Final result is LSB = 570 for the input point 5 512 384 256 (1) x at 5, preprocessing LSB = 384 128 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 Positions Figure 7: Sample of Linearization Function Transfer Characteristic. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 16 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Protection Features OPEN CIRCUIT DETECTION Lockout and clamping features protect the A1341 internal circuitry and prevent spurious output when supply voltage is out of specification. Open circuit detection is also provided. Diagnostic circuitry reuses the output pin (OUT) to provide feedback to the external controller. A sense resistor, ROCD , can be placed between OUT and a separate VBAT reference, as shown in Table 3. OPERATING VOLTAGE AND LOW VOLTAGE DETECTION Typical Application Supply voltage detection features protect the A1341 internal circuitry and prevent spurious output when VCC is out of specification. Diagnostic circuitry reuses the output pin (OUT) to provide feedback to the external controller. The A1341 provides protection for both overvoltage and undervoltage on the supply line. The A1341 has two active circuits to identify when the supply voltage is below the minimum operating level. The internal power-on reset circuitry, POR, controls when an internal reset is triggered. If the supply voltage drops below PORLOW , an internal reset occurs and the output is forced to a high impedance state. When the supply voltage rises above PORHIGH , the device comes out of reset and the output response is dependent on the Low Voltage Detection feature. The Low Voltage Detection, LVD, feature provides feedback to the external controller when VCC is below minimum operating level, but above the POR threshold. This feature is enabled by default and is disabled by setting LVD_DIS to logic 1. When configured for SENT output, if the supply voltage drops below VCC(LVD)LOW , a status bit is set in the SENT message to indicate a low supply voltage condition. When configured for PWM output, if the supply voltage drops below VCC(LVD)LOW , the output is forced to a Logic low state. As the supply voltage rises above VCC(LVD)HIGH , the output returns to normal operating state. The Overvoltage Lockout Threshold, VCC(OV) , is customer programmable to either 6.5 or 19.3 V typical, by setting the OVLO_LO parameter. By default, the part will produce an error at the output if VCC > 19.3 V. Setting OVLO_LO = 1 changes this condition to VCC > 6.5 V. When OVLO_LO = 1, using programming pulses higher than VCC will cause the part to enter in and out of overvoltage lockout mode, causing intermittent errors at the output. This behavior is not fatal, but the output is not valid. If overvoltage conditions are reached, the PWM output will be brought to GND or the SENT_STATUS bits will be set to indicate the condition. Multiple A1341 linear devices can be connected to the external controller as shown in Figure 8. However, EEPROM programming in the A1341 occurs when the external control unit excites the A1341 OUT pin by EEPROM pulses generated by the ECU. Whichever A1341s are excited by EEPROM pulses on their OUT pin will accept commands from the controller. Table 3: Open Circuit Diagnostic Truth Table Node A Node B Node C OUT State Open Closed Closed Closed 0 V to VBAT Open Closed GND/Float Open Open Closed GND/Float Open Closed Open VBAT Closed Open Open VCC Closed Closed Open VCC to VBAT VBAT Referenced VCC A VCC A1341 VBAT B ROCD OUT GND C ECU VCC1 R PULLUP1 VCC 0.01 µF A1341 OUT1 VOUT GND VCC2 R PULLUP2 VCC 0.01 µF A1341 VOUT OUT2 GND Figure 8: Typical Application Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 17 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization EEPROM Lock Features MEMORY LOCKING MECHANISMS The A1341 is equipped with two distinct memory locking mechanisms: Default Lock At power up, all registers of the A1341 are locked by default. EEPROM and volatile memory cannot be read or written. To disable Default Lock, a very specific 30-bit customer access code is written to address 0x24 in less than 70 ms from power-up; see Write Access code. After this, device registers are accessible through the programming interface. If VCC is power cycled, the Default Lock automatically reenables. This ensures that during normal operation, memory content will not be altered due to unwanted glitches on VCC or the output pin. Lock Bit This is used after EEPROM parameters are programmed by the customer. The customer programmable EELOCK feature disables the ability to write to any EEPROM register. This feature takes effect after writing the EELOCK bit and resetting power to the device. This prevents the ability to disable Default Lock using the method described above. Please note that after EELOCK bit is set and VCC pin power cycled, the customer will not have the ability to clear the EELOCK bit or to write any register. Customer will still have ability to read any EEPROM register. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 18 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization PROGRAMMING SERIAL INTERFACE The A1341 incorporates a serial interface that allows an external controller to read and write registers in the A1341 EEPROM and volatile memory. The A1341 uses a point-to-point communication protocol, based on Manchester encoding per G. E. Thomas (a rising edge indicates 0 and a falling edge indicates 1), with address and data transmitted MSB first. Transaction Types Each transaction is initiated by a command from the controller; the A1341 does not initiate any transactions. Two commands are recognized by the A1341: Write and Read. There also are three special function Write commands: Write Access Code, Write Disable Output, and Write Enable Output. One response frame type is generated by the A1341, Read Acknowledge. If the command is Read, the A1341 responds by transmitting the requested data in a Read Acknowledge frame. If the command is any other type, the A1341 does not acknowledge. As shown in Figure 9, The A1341 receives all commands via the VCC pin. It responds to Read commands via the OUT pin. This implementation of Manchester encoding requires the communication pulses be within a high (VMAN(H)) and low (VMAN(L)) range of voltages for the VCC line and the OUT line. The Write command pulses to EEPROM are supported by two high voltage pulses on the OUT line. Writing the Access Code If the external controller will write to or read from the A1341 memory during the current session, it must establish serial communication with the A1341 by sending a Write command including the Access Code within 70 ms after powering up the A1341. If this deadline is missed, all write and read access is disabled until the next power-up. Writing to EEPROM When a Write command requires writing to non-volatile EEPROM (all standard Writes), after the Write command the controller must also send two Programming pulses, well-separated, long high-voltage strobes via the OUT pin. These strobes are detected internally, allowing the A1341 to boost the voltage on the EEPROM gates. The required sequence is shown in Figure 10. Write/Read Command – Manchester Code ECU High Voltage pulses to activate EEPROM cells VCC A1341 GND OUT Read Acknowledge – Manchester Code Figure 9: Top-level Programming Interface Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 19 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 Reading from EEPROM A Read command with the register number is sent from the controller to the A1341. The device responds with a Read Acknowledge frame. Output is automatically disabled after the Read command from the controller is received and output is enabled after a Read Acknowledge command is sent. C0 C1 Input Data C2 Error Checking The serial interface uses a cyclic redundancy check (CRC) for data-bit error checking (synchronization bits are ignored during the check). 1x 0 1x 1 0x 2 1x 3 = x3 + x + 1 Figure 11: CRC Calculation The CRC algorithm is based on the polynomial g(x) = x3 + x + 1 , and the calculation is represented graphically in Figure 11. The trailing 3 bits of a message frame comprise the CRC token. The CRC is initialized at 111. VCC Write Access Command Write Command EEPROM Programming Pulses Write to EEPROM VOUT Write Command tWRITE(E) High Impedance Normal Operation Normal Operation GND <70 ms from power-on VCC Read from EEPROM tsPULSE(E) tWOUT_DIS t tWOUT_EN Read Command Write Access Command <70 ms from power-on VOUT Read Acknowledge Normal Operation Normal Operation GND tSTART_READ tROUT_LOW t tROUT_EN Figure 10: Programming Read and Write Timing Diagrams (see Serial Interface Reference section for definitions) Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 20 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Serial Interface Reference Table 4. Serial Interface Protocol Characteristics1 Characteristics Symbol Note Min. Typ. Max. Unit Customer Access Code should be fully entered in less than tACC , measured from when VCC crosses VCC(UV_high). – – 70 ms Defined by the input message bit rate sent from the external controller 4 – 100 kbps Input/Output Signal Timing Access code Time Out tacc Bit Rate Bit Time Bit Time Error tBIT errTBIT Data bit pulse width at 4 kbps 243 250 257 µs Data bit pulse width at 100 kbps 9.5 10 10.5 µs Deviation in tBIT during one command frame –11 – +11 % – 9 µs – 0.25 × tBIT 60 µs 2 × tBIT – – µs Write Output Disable Delay tWOUT_DIS Required delay from the trailing edge of certain Write command frames to output entering the high impedance state Write Delay tWRITE(E) Required delay from the trailing edge of the second EEPROM Programming pulse to the leading edge of a following command frame Write Output Enable Delay tWOUT_EN Delay from the trailing edge of the final EEPROM programming pulse to output entering the normal operation state – 6 60 µs Read Acknowledge Delay tREAD Required delay from the trailing edge of a Read Acknowledge frame to the leading edge of a following command frame 2 × tBIT – – µs – 45 60 µs 25 µs – 0.25 × tBIT 50 µs – 0.25 × tBIT 150 µs – 0.25 × tBIT µs Time the output is pulled low by device before Read Acknowledge message Read Output Disable Delay tROUT_LOW Read Delay2 Delay from the trailing edge of a Read tSTART_READ command frame to the leading edge of the Read Acknowledge frame Read Output Enable Delay tROUT_EN Required delay from the trailing edge of the final Read Acknowledge pulse to output entering the normal operation state – 45 60 µs Disable Output Delay2 tDIS_OUT Delay from the trailing edge of a Disable Output command frame to the device output going from normal operation to the high impedance state 1 µs – 0.25 × tBIT 5 µs – 0.25 × tBIT 15 µs – 0.25 × tBIT µs Enable Output Delay2 tENB_OUT Delay from the trailing edge of an Enable Output command frame to the device output going from the high impedance state to normal operation 1 µs – 0.25 × tBIT 5 µs – 0.25 × tBIT 15 µs – 0.25 × tBIT µs tsPULSE(E) Delay from last edge of write command to start of EEPROM programming pulse 40 – – μs Applied to VCC line 7.3 – – V Read from OUT line VCC – 0.2 – – V EEPROM Programming Pulse EEPROM Programming Pulse Setup Time Input/Output Signal Voltage Manchester Code High Voltage VMAN(H) Manchester Code Low Voltage VMAN(L) Applied to VCC line – – 5.7 V Read from OUT line – – VSAT V 1Determined by design. 2In the case where a slower baud rate is used, the output responds before the transfer of the last bit in the command message is completed. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 21 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 Serial Interface Message Structure The general format of a command message frame is shown in Figure 12. Note that, in the Manchester coding used, a bit value of 1 is indicated by a falling edge within the bit boundary, and a bit value of zero is indicated by a rising edge within the bit boundary. The bits are described in Table 5. Read/Write Synchronize 0 Memory Address Data 0 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 MSB 0 0 1 1 0 ... CRC 0/1 0/1 0/1 0/1 MSB Manchester Code per G. E. Thomas Bit boundaries Figure 12: General Format for Serial Interface Commands Table 5: Serial Interface Command General Format Bits Parameter Name Values 2 Synchronization 00 Used to identify the beginning of a serial interface command 0 [As required] Write operation 1 [As required] Read operation 1 Read/Write Description 6 Address 0/1 [Read/Write] Register address (volatile memory or EEPROM) Variable Data 0/1 [As required] variable length, for data 3 CRC 0/1 Incorrect value indicates errors Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 22 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization The following command messages can be exchanged between the device and the external controller: • Read • Read Acknowledge • Write • Write Access Code • Write Disable Output • Write Enable Output For EEPROM address information, refer to the EEPROM Structure section. Table 6: Read Function Provides the address in A1341 memory to be accessed to transmit the contents to the external controller in the next Read Acknowledge command. A timely Write Access Code command is required once, at power-up of the A1341. Syntax Sent by the external controller on the A1341 VCC pin. Related Commands Read Acknowledge Read/Write Pulse Sequence Synchronize 0 0 Memory Address CRC 1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 MSB Options None Examples Address in non-volatile memory: 0XXXXX Address in volatile memory: 100100 (Register 0x24) Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 23 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Table 7: Read Acknowledge Function Transmits to the external controller data retrieved from the A1341 memory in response to the most recent Read command. Syntax Sent by the A1341 on the A1341 OUT pin. Sent after a Read command. Related Commands Read Data (30 bits) Synchronize Pulse Sequence 0 CRC 0/1 0/1 0/1 0/1 . . . 0/1 0/1 0/1 0/1 0/1 0 MSB Options If EEPROM Error Checking and Correction (ECC) is not disabled by factory programming, the 6 MSBs are EEPROM data error checking bits. Refer to the EEPROM Structure section for more information. Examples – Table 8: Write Function Transmits to the A1341 data prepared by the external controller. Syntax Sent by the external controller on the A1341 VCC pin. A timely Write Access Code command is required once, at power-up of the A1341. For writing to non-volatile memory. Related Commands Disable Output, Enable Output, Write Access Code Read/Write Synchronize Pulse Sequence 0 0 Data (30 bits) Memory Address 0 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 . . . MSB CRC 0/1 0/1 0/1 0/1 MSB Options – Examples Address in non-volatile memory: 0XXXXX Address in volatile memory: 100100 (Register 0x24) Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 24 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Table 9: Write Access Code Function Transmits the Access Code to the A1341; data prepared by the external controller, but must match the internal 30-bit code in the A1341 memory. Syntax Sent by the external controller on the A1341 VCC pin. Sent within 70 ms of A1341 power-on, and before any other command. Related Commands Read/Write Pulse Sequence 0 0 Data (30 bits) Memory Address Synchronize 0 1 0 0 1 0 0 MSB 1 0 CRC 0 ... 1 0 0 1 MSB Options None Examples Standard Customer Access Code: 0x2781_1F77 to address 0x24 Table 10: Write Disable Output Function Places OUT in a high impedance state. It is not required, but it can be used to disable normal output for longer time than the time that device applies to disable the output after a Read command from the controller. Syntax Sent by the external controller on the A1341 VCC pin. For writing to non-volatile memory. Related Commands Write Enable Output Read/Write Pulse Sequence 0 0 Data (30 bits) Memory Address Synchronize 0 1 MSB Options None Examples 0x10 to address 0x24 0 0 1 0 0 0 ... 0 1 CRC 0 0 0 0 0 1 0 MSB Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 25 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Table 11: Write Enable Output Function Restores normal output from the OUT pin after a high impedance state has been imposed by a Disable Output command. Syntax Sent by the external controller on the A1341 VCC pin. For writing to non-volatile memory: Sent after a Write command and corresponding EEPROM Programming pulses. For reading: Sent after a Read Acknowledge command. Related Commands Write Disable Output Read/Write Pulse Sequence 0 0 Data (30 bits) Memory Address Synchronize 0 1 MSB Options None Examples 0x0 to address 0x24 0 0 1 0 0 0 ... 0 0 CRC 0 0 0 0 0 1 1 MSB Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 26 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization LINEAR OUTPUT PROTOCOLS The operating output of the A1341 is digital voltage signal that transfers information proportionally to the applied magnetic input signal. Two customer-selectable options are provided for output signal formatting: pulse-wave modulated (PWM), and single edge nibble transmission encoding scheme (SENT, SAEJ2716). direct proportion to the applied magnetic field. The PWM output mode is configured by setting the following parameters in EEPROM: • PWM_MODE set to 1 to select the PWM option (for programming parameters, see EEPROM Structure section) PWM Output Mode • FPWM sets the PWM carrier frequency PWM involves converting the output voltage amplitude to a series of constant-frequency binary pulses, with the percentage of the of high portion of the pulse varied in direct proportion to the D = 5% D = 50% D = 95% CLAMP_HIGH Magnetic Signal, BIN (G) PWM Waveform (V) • CALIBRATE_PWM parameter can be set to enable calibration of the output 50% duty cycle level at power-on CLAMP_LOW D0T D1T D2T D3T D4T D5T D6T D7T D8T D9T D10T D(x) = tpulse(x) / Tperiod tpulse(5) Tperiod 0T 1T 2T 3T 4T 5T 6T 7T 8T 9T 10T 11T Time Figure 13: PWM Mode Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 27 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization SENT Output Mode boundary for the nibble; to assign the delimiting state, select a fixed duration for the interval (the SENT_LOVAR parameter selects the interval, and SENT_FIXED sets the duration) The SENT output mode converts the input magnetic signal to a binary value mapped to the Full Scale Output, FSO, range of 0 to 4095, shown in Figure 14. This data is inserted into a binary pulse message, referred to as a frame, that conforms to the SENT data transmission specification (SAEJ2716 JAN2010). Certain parameters for configuration of the SENT messages can be set in EEPROM. • The other interval in the pair becomes the information state and is variable in duration in order to contain the data payload of the nibble The duration of a nibble is denominated in clock ticks. The period of a tick is set by dividing a 4-MHz clock by the value of the SENT_TICK parameter. The duration of the nibble is the sum of the low-voltage interval plus the high-voltage interval. The SENT output mode is configured by setting the following parameters in EEPROM: The nibbles of a SENT message are arranged in the following required sequence (see Figure 15): • PWM_MODE set to 0 (default) to select the SENT option • SENT_x programming parameters (see EEPROM Structure section) 1. Synchronization and Calibration: flags the start of the SENT message MESSAGE STRUCTURE 2. Status and Communication: provides A1341 status and the format of the data A SENT message is a series of nibbles, with the following characteristics: 3. Data: magnetic field and optional data • Each nibble is an ordered pair of a low-voltage interval followed by a high-voltage interval 4. CRC: error checking 5. Pause Pulse (optional): sets timing relative to A1341 updates • Either interval can be the delimiting state, which only sets a Magnetic Signal, BIN (G) 4095 (1111 1111 1111 1111) 2048 (1000 0000 0000 0000) 0000 (0000 0000 0000 0000) SENT Data Value (LSB) A1341 Figure 14: SENT Mode Outputs a Digital Value that can be Read by the External Controller SENT_FIXED SENT_FIXED SENT_FIXED SENT_FIXED SENT_FIXED SENT_FIXED SENT_LOVAR = 0 12 to 27 ticks 56 ticks Nibble Name Synchronization and Calibration 56 ticks SENT_LOVAR = 1 12 to 27 ticks 12 to 27 ticks 12 to 27 ticks Data 1 (MSB) Data 6 CRC 12 to 27 ticks 12 to 27 ticks 12 to 27 ticks Status and Communication 12 to 27 ticks SENT_FIXED SENT_FIXED SENT_FIXED SENT_FIXED Pause Pulse (optional) SENT_FIXED SENT_FIXED tSENT Figure 15: General Format for SENT Message Frame (upper panel) low state fixed, (lower panel) high state fixed Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 28 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization OPTIONAL SERIAL OUTPUT PROTOCOL DATA NIBBLE FORMAT In the Status and Communication section, the data format selection can be: When transmitting normal operation data, information about the magnetic field is embedded in the first three Data nibbles. Each Data nibble consists of 4 bits with values ranging from 0 to 15. In order to present an output with the resolution of 12 bits, 3 Data nibbles are required. The Data nibble containing the MSB of the whole Data section is sent first. • Normal device output (voltage proportional to applied magnetic field) in SENT protocol (SENT_SERIAL = 0). • Augmented data on the magnetic parameters and device settings, in an optional Serial Output protocol (SENT_SERIAL = 1, 2, or 3). Any of these three protocols enables transmission of values from the following EEPROM parameters, in the following order: Table 12: Serial Output Protocols Message ID (4 or 8 bits) Data (8, 12, or 16 bits) 0 Corrected temperature 1 SENS_COARSE 1 SIG_OFFSET 3 QOUT_FINE 4 SENS_MULT 5 CLAMP_HIGH 6 CLAMP_LOW 7 DEVICE_ID (always 134110) □□ Additional Short serial protocol (SENT_SERIAL = 1). Has a message payload of 12 bits: 8 bits are for value data, and 4 bits for the message ID (identification). A total of 16 separate SENT messages are required to transmit the entire data group. □□ Additional Enhanced 16-bit serial protocol (SENT_SERIAL = 2). Has 12 bits for value data, and 4 bits for the message ID. A total of 18 SENT messages are required to transmit the entire data group. □□ Additional Enhanced 24-bit serial protocol (SENT_SERIAL = 3). Has 16 bits for value data, and 8 bits for the message ID. A total of 18 SENT messages are required to transmit the entire data group. Three additional optional Data nibbles can be associated with other parameters, by setting the parameter SENT_DATA: • Counter – Each message frame has a serial number in each Counter nibble • Temperature – Temperature data from the A1341 internal temperature sensor, in two’s complement format, with MSB first: □□ All zeros = 25°C □□ Always is 0.8 LSB/°C except for serial output protocol □□ For serial output protocol, temperature slope = 0.5 LSB/°C. • Inverted – The last nibble in the message frame is the first nibble, inverted (as an additional error check) PAUSE PULSE TIMING SYNCHRONIZATION In the Pause Pulse section, additional time can be added at the end of a SENT message frame to ensure all message frames are of equal length. The SENT_UPDATE parameter selects one of these options: • Allow message frame duration to vary according to the contents; no Pause pulse is applied. (SENT_UPDATE = 0) • The device sends messages with constant duration. If a particular message is shorter, a Pause pulse is inserted with a length that completes the message period. (SENT_UPDATE = 1) • Synchronize the message frame transmission rate with the A1341 internal update rate (set by BW value) by inserting a calculated Pause pulse to complete required period. (SENT_ UPDATE = 2) Figures 16, 17, and 18 show examples of the timing relationship between SENT message Pause pulse configurations and the internal update rate of the A1341. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 29 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization n+1 n+2 n+3 n+4 SENT message 2 SENT message 3 data stat (skipped) sync stat sync CRC data stat sync CRC data stat sync SENT message 1 n+6 (skipped) (skipped) SENT message n+5 CRC n internal update data A1341 SENT message 4 Figure 16: Messages Do not Contain a Pause Pulse (SENT_UPDATE = 0) Messages do not contain a Pause pulse (SENT_UPDATE = 0), so the SENT message frame rate is not constant. The value transmitted in a message is taken from the last internal update ready before the first Data nibble of the message is composed. Therefore, individual internal updates may be skipped or repeated, depending on the BW bandwidth and SENT_TICK time settings. SENT message SENT message 1 SENT message 2 n+6 sync pause n+5 (skipped) CRC CRC data stat sync CRC data stat sync pause n+4 data (skipped) n+3 (skipped) stat n+2 (skipped) sync n+1 pause n internal update SENT message 3 Figure 17: Pause Pulse Used to Extend the Message to Match the Frame Rate (SENT_UPDATE = 1) A constant message frame rate is used, and for each message, a Pause pulse is used to extend the message to match the frame rate (SENT_ UPDATE = 1). Internal updates may be skipped or repeated depending on the BW bandwidth and SENT_TICK time settings. The quantity of skipped or repeated internal updates can vary from message to message. Note: Although the frame transmission rate is constant, discrete SENT messages do not represent equal time interval sampling of the magnetic field. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 30 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization SENT message Panel 18(c): The internal update rate is the same as in panel (b), but the tick duration is reduced slightly. The longest possible SENT message is now synchronized at the internal update rate. Each update is ready before the synchronization nibble is composed, and is transmitted. No updates are skipped. SENT message SENT message 1 data stat sync data stat n+2 CRC pause data n+1 (skipped) sync n sync data SENT message 1 pause CRC data Panel 18(b): The filter bandwidth is reduced by twice relative to the bandwidth in panel (a), which doubles the internal update interval. The longest possible SENT message is now synchronized at two times the internal update rate. The first update is ready before the synchronization nibble is composed, and is transmitted. Two more updates occur before the next SENT message, so only the second update data is included, and the one intervening update is skipped. internal update stat sync CRC pause data stat sync n+1 n+2 SENT message 1 stat Panel 18(a): The longest possible SENT message is synchronized at three times the internal update rate. The first update is ready before the synchronization nibble is composed, and is transmitted. Three more updates occur before the next SENT message, so only the third update data is included, and the two intervening updates are skipped. n n+1 (skipped) SENT message SENT message 1 internal update n stat data sync internal update stat CRC stat SENT message pause n+1 n+2 n+3 (skipped) (skipped) data n sync internal update sync A1341 SENT Panel 18(d): The faster update rate of panel (a) and the shorter tick duration of panel (c) are applied. Because the panel (d) higher bandwidth setting also applies, the overall A1341 response time is faster than that shown in panel (c). However, the panel (c) settings reduce front-end noise better than those of panel (d), because of the lower bandwidth. Figure 18: SENT Message Rate Synchronized with the Internal A1341 Internal Update Rate. For each message, a Pause pulse is used to extend the message to match the internal update rate (SENT_UPDATE = 2). A consistent number of updates are skipped or repeated from message to message. The internal update value transmitted is from the last update ready before the Synchronization and Calibration nibble of the message is composed. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 31 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization The SENT_UPDATE parameter has two other options, which allow direct control of when magnetic field data is sent to the external controller: • Tandem data latching and sending (SENT_UPDATE = 3) • Immediate data latching with a controllable delay before sending (SENT_UPDATE = 4) When SENT_UPDATE = 3 (upper panel in Figure 19), while the A1341 has a Pause pulse on the device output, the controller triggers a latch-and-send sequence by pulling the A1341 output low. When the controller releases the output, the current magnetic field data is latched, and after a delay of tdSENT the latched data is sent to the controller. This option is useful when the controller Controller pulls OUT low requires a prompt response on the current magnetic field. When SENT_UPDATE = 4 (lower panel in Figure 19), while the A1341 has a Pause pulse on the device output, the controller triggers a latch-and-send sequence by pulling the output low. With this option, the current magnetic field data is latched immediately. This allows the controller to postpone receiving the data. When the output is eventually released, the data is sent to the controller after a delay of tdSENT . This option is useful where multiple A1341s are connected to the controller (see Typical Application, Figure 8). All the A1341s can be instructed at the same time to latch magnetic field data, and the controller can then retrieve the data from each A1341 individually. Controller releases OUT; magnetic data latched SENT messages sync pause CRC data stat ... Waiting period, twait sync VOUTx pause tdSENT (6 ticks) Sensor IC starts message containing latched data ... ... (previous message) SENT message Controller pulls OUT low; magnetic data latched Controller releases OUT tdSENT (6 ticks) SENT messages (previous message) sync pause CRC data stat Waiting ... period, twait sync VOUTx pause Sensor IC starts message containing latched data ... ... SENT message Figure 19: Device Output Behavior where Normal Operation Magnetic Field Data is Latched at a Defined Time: (upper panel) if SENT_UPDATE = 3, latched and sent at end of a low pulse, or (lower panel) if SENT_UPDATE = 4, latched at the beginning of a low pulse, but not sent until the end of the pulse. The total delay from the beginning of the low pulse until the data message begins is: twait + tdSENT . Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 32 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 The general format of a command message frame is shown in Figure 15. The individual sections of a SENT message are described in Table 13. Table 13: SENT Message Frame Section Definitions Section Description Synchronization and Calibration Function Syntax Provide the external controller with a detectable start of the message frame. The large quantity of ticks distinguishes this section, for ease of distinction by the external controller. Nibbles: 1 Quantity of ticks: 56 Quantity of bits: 1 Status and Communication Function Syntax Provides the external controller with the status of the A1341 and indicates the format and contents of the Data section. Nibbles: 1 Quantity of ticks: 12 to 27 Quantity of bits: 4 1:0 Device status (set by SENT_STATUS parameter) 3:2 Message serial data protocol (set by SENT_SERIAL parameter) Data Function Syntax Provides the external controller with data selected by the SENT_DATA parameter. Nibbles: 3 to 6 Quantity of ticks: 12 to 27 (each nibble) Quantity of bits: 4 (each nibble) CRC Function Syntax Provides the external controller with cyclic redundancy check (CRC) data for certain error detection routines applied to the Data nibbles and to the Status information. Nibbles: 1 Quantity of ticks: 12 to 27 (each nibble) Quantity of bits: 4 Pause Pulse Function Syntax (Optional) Additional time can be added at the end of a SENT message frame to ensure all message frames are of appropriate length. The SENT_UPDATE parameter sets format. Nibbles: 1 Quantity of ticks: 12 minimum (length determined by SENT_UPDATE option and by the individual structure of each SENT message) Quantity of bits: n.a. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 33 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 EEPROM STRUCTURE Programmable values are stored in an onboard EEPROM, including both volatile and non-volatile registers. Although it is separate from the digital subsystem, it is accessed by the digital subsystem EEPROM Controller module. The EEPROM is organized as 30-bit wide words, and by default each word has 24 data bits and 6 ECC (Error Checking and Correction) check bits, stored as shown in Figure 20. EEPROM Bit Contents 29 28 27 26 25 24 23 22 21 20 19 18 17 D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 16 15 C5 D10 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 D9 D8 D7 D6 D5 D4 C4 D3 D2 D1 C3 D0 C2 C1 C0 Figure 20: EEPROM Word Bit Sequence; C# – Check Bit, D# – Data Bit Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 34 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 Table 14: EEPROM Register Map of Customer-Programmable Parameters Address Bits Parameter Name 0x07 23:21 Reserved 0x07 20:18 OUTDRV_CFG 0x07 17:0 SENTPWM_CFG Description Output Driver Setting SENT and PWM output mode configuration parameters (assignment determined by PWM_MODE bit) 17:11 SENT_TICK Sets Tick Rate Coefficient (PWM_MODE = 0) 10:9 SENT_FIXED Sets Fixed State interval (PWM_MODE = 0) Sets Fixed State Assignment (PWM_MODE = 0) 8 SENT_LOVAR 7:5 SENT_UPDATE 4:3 SENT_DATA DAC profile Sets Pause Pulse and Message Frame Rate (PWM_MODE = 0) Sets Data Nibble Format (PWM_MODE = 0) 2 SENT_STATUS Sets Error Condition (PWM_MODE = 0) 1:0 SENT_SERIAL Sets Message Series Format (PWM_MODE = 0) 3 CALIBRATE_PWM 2:0 FPWM Enables 50% Duty Cycle Calibration (PWM_MODE = 1) 0x08 23:15 TC2_SENS_HOT 2nd Order Sensitivity Temperature Coefficient, ΔT (from 25°C) > 0 Two’s complement 0x08 14:6 TC2_SENS_CLD 2nd Order Sensitivity Temperature Coefficient, ΔT (from 25°C) < 0 Two’s complement 0x08 5:2 SENS_COARSE Factory Trimmed Magnetic Input Signal Range Non-uniform Non-uniform Sets PWM Carrier Frequency (PWM_MODE = 1) 0x08 1:0 Reserved Reserved for system use (bits written here will not affect device operation) 0x09 23:16 TC1_SENS_HOT 1st Order Sensitivity Temperature Coefficient, ΔT (from 25°C) > 0 Non-uniform 0x09 15:8 TC1_SENS_CLD 1st Order Sensitivity Temperature Coefficient, ΔT (from 25°C) < 0 Non-uniform 0x09 7:0 TC1_OFFSET 1st 0x0A 23:12 SCRATCH_C Customer Scratchpad 0x0A 11:0 SENS_MULT Output Sensitivity/ Sensitivity Multiplier 0x0B to 0x1A 23:12 LINPOS_COEFF (LIN_1, LIN_3, ..., LIN_31) Linearization Coefficients (odd-numbered sampling positions) Two’s complement 0x0B to 0x1B 11:0 LINPOS_COEFF (LIN_0, LIN_2, ..., LIN_32) Linearization Coefficients (even-numbered sampling positions) Two’s complement Order Magnetic Offset TC Compensation 0x1B 23 LIN_TABLE_DONE Linearization Coefficients Loaded Flag 0x1B 22 LIN_OUTPUT_INVERT Linearization Output Polarity Inversion 0x1B 21 LIN_INPUT_INVERT 0x1B 20:12 ID 0x1C 23:18 CLAMP_HIGH Clamp Upper Limit 0x1C 17:12 CLAMP_LOW Clamp Lower Limit 0x1C 11 EEPROM_LOCK1 0x1C 10 OVLO_LO Overvoltage Lockout Threshold Low Voltage Detection Disable Two’s complement Linearization Input Polarity Inversion Customer Identification Number Customer EEPROM Lock 0x1C 9 LVD_DIS 0x1C 8:4 SIG_OFFSET Factory Trimmed Magnetic Offset Compensation (Coarse) 0x1C 3 PWM_MODE Normal Operation Output Mode (SENT / PWM) 0x1C 2:0 BW 0x1D 23:12 SCRATCH_C Customer Scratchpad 0x1D 11:0 QOUT_FINE Fine Quiescent Output Duty Cycle Two’s complement Bandwidth Two’s complement 1Customer EEPROM lock allows the customer to lock the EEPROM registers from any further changes for the life of the device. Memory reading is still possible after the EEPROM lock bit is set. In the case that a write command is sent to the device by accident after the EEPROM lock, the device needs to be repowered to be accessible again for memory read. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 35 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 EEPROM Customer-Programmable Parameter Reference Table 15: BW (Register Address: 0x1C, bits 2:0) Function Filter Bandwidth Selects the filter bandwidth (3-dB frequency) for the digitized applied magnetic field signal, applied when passed to the digital system after analog front-end processing. This selection also sets the internal update rate. Syntax Quantity of bits: 3 Related Commands – Code 000 (Default) 001 010 (Same) 011 100 101 110 111 Values Options – Examples – A-to-D Converter Output Rate (Typical) (kHz) Filter 3 dB Bandwidth (Typical) (Hz) 8. 16 8 4 2 1 Factory Use Only Factory Use Only 1500 3000 1500 750 375 188 – – Table 16: CALIBRATE_PWM (Register Address: 0x07, bit 3) Function PWM Calibration Sent at power-on, commands the device to calculate the PWM 50% duty cycle to the centerpoint of the Full Scale Output range. Syntax Quantity of bits: 1 Related Commands PWM_MODE (see EEPROM Structure Section) Values Options None Examples – 0: Disable calibration (Default) 1: Enable calibration Table 17: CLAMP_HIGH (Register Address: 0x1C, bits 23:18) Function Clamp Upper Limit Sets the percentage of the upper half of the Full Scale Output signal passed through at the end of the Digital Signal Processing stage. Syntax Quantity of bits: 6 Related Commands CLAMP_LOW Values 000000: 100%FSO (PWM: 95% maximum duty cycle, SENT: 4095) (Default) 111111: 50.78%FSO (PWM: 50% duty cycle, SENT: 2047) Options The factory-programmed default, OUTCLP(H)init , is used if this parameter is not set. Examples – Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 36 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 Table 18: CLAMP_LOW (Register Address: 0x1C, bits 17:12) Function Clamp Lower Limit Sets the percentage of the lower half of the Full Scale Output signal passed through at the end of the Digital Signal Processing stage. Syntax Quantity of bits: 6 Related Commands CLAMP_HIGH Values Options The factory-programmed default, OUTCLP(L)init , is used if this parameter is not set. Examples – 000000: 0% FSO (PWM: 5% duty cycle, SENT: 0) (Default) 111111: 49.22% FSO (PWM: 50% duty cycle, SENT: 2047) Table 19: EEPROM LOCK: Address 0x1C, bit 11 Function Disables writing into the device memory Syntax Quantity of bits: 1 Related Commands – Values Options Lock bit feature is enabled following a reset of the device power after setting the EEPROM LOCK bit. Examples Refer to Memory Locking Mechanisms section for more information. 0 (default) Default memory lock mechanism 1 Prevents any Read or Write transaction with the device Table 20: Customer_ID (Register Address: 0x1B, bits 20:12) Function Customer Identification Number Available register for identifying the A1341 for multiple-unit applications. Syntax Quantity of bits: 12 Related Commands SCRATCH_C Values Free-form Options – Examples – EEPROM Lock Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 37 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Table 21: FPWM (Register Address: 0x07, bits 2:0) Function PWM Carrier Frequency Sets the carrier frequency for PWM mode normal output (voltage response to applied magnetic field). Selected frequency determines maximum output resolution. Syntax Quantity of bits: 3 Related Commands PWM_MODE (see EEPROM Structure Section) Code 000 (Default) 001 010 011 100 101 110 111 Values Options – Examples – PWM Frequency (Typical) (kHz) Maximum Output Resolution (bits) 0.125 0.25 0.5 1 2 4 0.125 0.125 12 12 12 11 10 9 12 12 Table 22: LIN_INPUT_INVERT (Register Address: 0x1B, bit 21) Function Inverts the polarity of the input signal before it is sent into the linearization block. This setting is effective only if LIN_TABLE_DONE is set to 1. Syntax Quantity of bits: 1 Related Commands LIN_x, LIN_OUTPUT_INVERT Values 0: No inversion of signal before input into the linearization block. (Default) 1: Input signal inverted before it is sent into the linearization block. Options – Examples – Table 23: LIN_OUTPUT_INVERT (Register Address: 0x1B, bit 22) Function Inverts the polarity of the input signal after the linearization block. (Can be used to invert the output polarity without populating the linearization table.) Syntax Quantity of bits: 1 Related Commands LINPOS_COEFF, LIN_INPUT_INVERT Values 0: No inversion of signal after processing in the linearization block. (Default) 1: Input signal inverted after processing in the linearization block. Options – Examples – Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 38 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Table 24: LINPOS_COEFF (LIN_0, LIN_2, ..., LIN_32) (Register Address: 0x0B to 0x1B, bits 11:0) (LIN_1, LIN_3, ..., LIN_31) (Register Address: 0x0B to 0x1A, bits 23:12) Function Linearization Coefficients These addresses are available to store customer-generated and loaded coefficients used for linearization of the temperature-compensated and offset digital signal. Note: These are not used by the device unless the LIN_TABLE_ DONE bit is set. Syntax Quantity of bits: 12 (each) LIN_x corresponds to Input Sample BINx Coefficient data stored in two’s complement format Values must be monotonically increasing Related Commands LIN_INPUT_INVERT, LIN_OUTPUT_INVERT, LIN_TABLE_DONE Values Calculated according to applied magnetic field Output Position (%FSI) EEPROM Address Bits BIN0 100 0x0B 11:00 Input Sample Options Examples Output Position (%FSI) EEPROM Address Bits BIN16 16/32 0x13 11:00 Input Sample BIN1 31/32 0x0B 23:12 BIN17 15/32 0x13 23:12 BIN2 30/32 0x0C 11:00 BIN18 14/32 0x14 11:00 23:12 BIN3 29/32 0x0C 23:12 BIN19 13/32 0x14 BIN4 28/32 0x0D 11:00 BIN20 12/32 0x15 11:00 BIN5 27/32 0x0D 23:12 BIN21 11/32 0x15 23:12 BIN6 26/32 0x0E 11:00 BIN22 10/32 0x16 11:00 BIN7 25/32 0x0E 23:12 BIN23 9/32 0x16 23:12 BIN8 24/32 0x0F 11:00 BIN24 8/32 0x17 11:00 BIN9 23/32 0x0F 23:12 BIN25 7/32 0x17 23:12 BIN10 22/32 0x10 11:00 BIN26 6/32 0x18 11:00 BIN11 21/32 0x10 23:12 BIN27 5/32 0x18 23:12 BIN12 20/32 0x11 11:00 BIN28 4/32 0x19 11:00 BIN13 19/32 0x11 23:12 BIN29 3/32 0x19 23:12 BIN14 18/32 0x12 11:00 BIN30 2/32 0x1A 11:00 BIN15 17/32 0x12 23:12 BIN31 1/32 0x1A 23:12 BIN32 0 0x1B 11:00 – Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 39 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 Table 25: LIN_TABLE_DONE (Register Address: 0x1B, bit 23) Function Linearization Table Loaded Set by the customer to indicate custom coefficients have been loaded (into the LINPOS_COEFF area of EEPROM). When this flag is set, the device uses the customer coefficients for output linearization. Allows correction for targets that generate non-linear magnetic fields. Syntax Quantity of bits: 1 Related Commands LINPOS_COEFF Values Options – Examples – 0: Linearization algorithm applies default coefficients to the processed signal (Default) 1: Linearization algorithm applies customer-loaded coefficients to the processed signal Table 26: LVD_DIS: Address 0x1C bit 9 Function Low Voltage Detection Disable Disable the low voltage detection feature. Syntax Quantity of bits: 1 Related Commands – Values 0: Default, Low Voltage Detection enabled. 1: Low Voltage Detection disabled. Options – Examples – Table 27: OUTDRV_CFG (Register Address: 0x07, bits 20:18) Function Output Signal Configuration Sets configuration of the output signal slew-rate control. Sets the ramp rate on the gate of the output driver, thereby changing slew rate at the output. Syntax Quantity of bits: 3 Related Commands – Fall Time (Typical) (µs) Code 000 (Default) 001 010 011 100 101 110 111 Values Options – Examples – CLOAD = 100 pF CLOAD = 1 nF CLOAD = 10 nF 0.048 0.114. 0.202 0.290 0.760 1.539 3.161 4.819 0.149 0.217 0.309 0.400 0.854 1.555 2.978 4.442 1.324 1.323 1.404 1.492 1.948 2.669 4.118 5.557 Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 40 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 Table 28: OVLO_LO (Register Address: 0x1C, bit 10) Function Overvoltage Lockout Threshold Sets the typical threshold value. Syntax Quantity of bits: 1 Related Commands – Values Options – Examples – 0: 19.3 V typical (Default) 1: 6.5 V typical Table 29: PWM_MODE (Register Address: 0x1C, bit 3) Function Normal Operation Output Mode Changes normal output (voltage response to applied magnetic field) from SENT to PWM. Syntax Quantity of bits: 1 Related Commands CALIBRATE_PWM, FPWM Values Options – Examples – 0: SENT (Default) 1: PWM Table 30: QOUT_FINE (Register Address: 0x1D, bits 11:0) Function Quiescent Output (QOUT) Adjusts the device normal output (digital response to applied magnetic field) to set the baseline output level: for a quiescent applied magnetic field (BIN ≈ 0 G). Syntax Quantity of bits: 12 Code stored in two’s complement format Related Commands SIG_OFFSET Values 0111 1111 1111: +49.98% of output full scale range (Default) 1000 0000 0000: –50% of output full scale range Options The factory-programmed default, QOUT , is used if this parameter is not set. Examples – Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 41 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Table 31: SCRATCH_C (Register Address: 0x1D, bits 23:12) Function Customer Scratchpad For optional customer use in storing values in the device. Syntax Quantity of bits: 12 Two independent locations Related Commands IC Values Free-form field Options – Examples – Table 32: SENS_COARSE (Register Address: 0x08, bits 5:2) Offset drifts with temperature changes will be altered from the factory programmed values after the Coarse Sensitivity is changed. If a change in Coarse Sensitivity is unavoidable, please contact Allegro for detailed information. Function Coarse Sensitivity Sets the nominal (coarse) sensitivity of the device, SENS_COARSE, which can be defined as OUT / ΔBIN . Selection determines the RANGE, the extent of the applied magnetic flux intensity, BIN , sampled for signal processing. (Use SIG_OFFSET to adjust the BIN level at which RANGE is centered.) Syntax Quantity of bits: 4 Related Commands SIG_OFFSET, SENS_MULT Code Values Coarse Sensitivity at VCC = 5 V (Typical) (%FSO/G) RANGE (Typical) (G) 0000 (Default) 0001 0010 0011 0100 0101 0110 0111 0.100 0.333 0.250 0.200 0.167 0.125 0.080 0.067 ±500 ±150 ±200 ±250 ±300 ±400 ±625 ±750 1000 1001 1010 1011 1100 1101 1110 1111 0.057 0.050 0.040 0.033 0.029 0.025 0.5 0.022 ±875 ±1000 ±1250 ±1500 ±1750 ±2000 ±100 ±2250 Options The default, SENS = 0.1%FSO/G for SENS_COARSE and BIN = ±500 G for RANGE are used if this parameter is not set. Output accuracy is reduced with codes 1110 and 1111. Examples To set a sampled BIN range of 500 G, set RANGE = ±250 G (SENS_COARSE = 0011). That would also set Coarse Sensitivity to 0.2%FSO/G (SENS_COARSE = 0011). Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 42 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Table 33: SENS_MULT (Register Address: 0x0A, bits 11:0) Function Sensitivity Multiplier After temperature compensation, establishes the gain of the device in normal output (response to a change in the applied magnetic field) by indicating a multiplier value. Quantity of bits: 12 The SENS_MULT values are mapped to the programming code values as follows: 2.0 Syntax SENS_MULT 1.0 Value 0 0 0x800 0xFFF SENS_MULT Code Related Commands RANGE (SENS_COARSE), TC1_SENS_CLD, TC1_SENS_HOT, TC2_SENS_CLD, TC2_SENS_HOT Values – Options SENS_OUT = SENS_COARSE, that is, SENS_MULT = 1 (code 0) if this parameter is not set. Examples At: RANGE = ±500 G, SENS_COARSE code and available range: 0000: 0.1%FS/G nominal SENS_MULT maximum code gives 0.2%FSO/G nominal Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 43 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Table 34: SENT_DATA (Register Address: 0x07, bits 4:3) Function Data Nibble Format Quantity and contents of Data nibbles in message. (Does not relate to data contained in the Status and Communication nibble.) Syntax Quantity of Bits: 2 Related Commands – Values 0 0: Nibbles 1,2,3: magnetic field data; nibbles 4,5: counter data; nibble 6: inverted nibble 1 (Default) 0 1: Nibbles 1,2,3: magnetic field data; nibbles 4,5: counter data; nibble 6: all zeros 1 0: Nibbles 1,2,3: magnetic field data; nibbles 4,5,6: current temperature data 1 1: Nibbles 1,2,3: magnetic field data (nibbles 4,5,6 skipped) Options – Examples – Table 35: SENT_FIXED (Register Address: 0x07, bits 10:9) Function Fixed Interval Duration Indicates the quantity of ticks in fixed-duration intervals. Syntax Quantity of Bits: 2 Related Commands SENT_LOVAR Values 0 0: 0 1: 1 0: 1 1: 5 ticks (Default) 4 ticks 7 ticks 8 ticks Options SENT_FIXED = 1 ( 4 ticks) does not meet the SENT spec, but is provided for custom fast or improved-EMI communication. Examples – Table 36: SENT_LOVAR (Register Address: 0x07, bit 8) Function State Assignments Assigns fixed duration state (becomes delimiting state; other interval becomes the information state) Syntax Quantity of Bits: 1 Related Commands SENT_FIXED Values 0: Low interval of every nibble is fixed in duration, and the high interval becomes the information state (Default) 1: High interval of every nibble is fixed in duration, and the low interval becomes the information state Options SENT_LOVAR = 0 meets the SENT specification. SENT_LOVAR = 1 does not meet the SENT spec, but is provided for custom improved-EMI communication. For SENT_UPDATE = 3 or 4, the Pause pulse has a fixed low time regardless of the SENT_LOVAR setting. Examples – Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 44 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Table 37: SENT_SERIAL (Register Address: 0x07, bits 1:0) Function Status and Communication Nibble Format Defines values of bits 2 and 3 inside the Status and Communication nibble. Syntax Quantity of Bits: 2 Related Commands – 0 0: Bits 2 and 3 are 0 (Default) 0 1: Bits 2 and 3 are 0 part of the Short Serial protocol: 8-bit value data, 4-bit message ID, 16 SENT frames are required to send an entire serial message 1 0: Bits 2 and 3 are part of the Enhanced 16-bit Serial protocol: 12-bit value data, 4-bit message ID, 18 SENT frames are required to send an entire serial message 1 1: Bits 2 and 3 are part of the Enhanced 24-bit Serial protocol: 16-bit value data, 8-bit message ID, 18 SENT frames are required to send an entire serial message Values Options – Examples – Table 38: SENT_STATUS (Register Address: 0x07, bit 2) Function Error Condition Status Defines values of bits 0 and 1 inside the Status and Communication nibble. Defines data inside the Status and Communication nibble on device error status. Syntax Quantity of Bits: 1 Related Commands SENT_SERIAL Values (SENT_STATUS = 0) 0 0: No error (Default) 0 1: Not used 1 0: Overvoltage condition 1 1: Nonrecoverable EEPROM error, bad Linearization table or other error (SENT_STATUS = 1) 0 0: No error (Default) 0 1: Error condition Options – Examples A Status and Communication nibble value of 0010 indicates an overvoltage condition. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 45 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Table 39: SENT_TICK (Register Address: 0x07, bits 17:11) Function Tick Duration Sets the SENT tick rate coefficient: 4 MHz / SENT_TICK = tick (µs) Syntax Quantity of Bits: 7 Any value from 0 to 127 can be used Related Commands – Values Code PWM Frequency (Typical) (µs) Coefficient (MHz/SENT_TICK) 000 0000 000 0001 000 0010 000 0111 111 1111 111 1110 111 1111 3.0 (Default) 0.25 0.5 0.75 32 31.5 31.75 4/12 4/1 4/2 4/3 4/125 4/126 4/127 Options SENT_TICK = 1 through 11 do not meet the SENT spec, but are provided for custom fast communication. Examples – Table 40: SENT_UPDATE (Register Address: 0x07, bits 7:5) Function Pause Pulse and Frame Rate Pause pulse usage and message frame rate. Syntax Quantity of Bits: 3 Related Commands SENT_LOVAR Values 000: No Pause pulse; new frame immediately follows previous frame (Default) 001: Pause pulse used for minimum constant frame rate (Length of other message sections, plus length of Pause Pulse nibble, is constant. For the maximum message length, Pause pulse information state is the minimum size of 12 ticks.) 010: Pause pulse used for constant frame rate, synchronized with A1341 internal update rate. (Handshaking occurs such that the Synchronization and Calibration nibble starts immediately after the next new data word is ready.) 011: Pause pulse held indefinitely until receipt of trigger pulse (OUT pulled low) from the controller, data latched after output released and message is sent. 100: Pause pulse held indefinitely until receipt of trigger pulse (OUT pulled low) from the controller, data latched immediately and sent when output is released. 101, 110, 111: Same function as 000. Options – Examples – Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 46 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Table 41: SIG_OFFSET (Register Address: 0x1C, bits 8:4) If changing Coarse Magnetic Offset cannot be avoided because of application requirements, please contact Allegro for detailed information. Function Magnetic Offset Compensation (Coarse) Adjusts the center of the selected BIN range (SIG_OFFSET) to adapt to the application magnetic field. Syntax Quantity of bits: 5 Code stored in two’s complement format. Related Commands RANGE, TC1_OFFSET Code Values SIG_OFFSET (% of Full-Scale RANGE) 00000 (Default) 00001 00010 00011 00100 00101 00110 00111 0.00 6.25 12.50 18.75 25.00 31.25 37.50 43.75 01000 01001 01010 01011 01100 01101 01110 01111 50.00 56.25 62.75 68.75 75.00 81.25 87.50 93.75 10000 10001 10010 10011 10100 10101 10110 10111 –100.00 –93.75 –87.50 –81.25 –75.00 –68.75 –62.50 –56.25 11000 11001 11010 11011 11100 11101 11110 11111 –50.00 –43.75 –37.50 –31.25 –25.00 –18.75 –12.50 –6.25 Options The default, QOUT , is used if this parameter is not set. Examples To set the input range from 0 to 1000 G, with a centerpoint at +500 G: 1. Leave SENS_COARSE at 0.1%FSO/G (SENS_COARSE code = 0000). This establishes a full scale input RANGE of 1000 G. 2. The full scale input value, 1000 G, is used as the start point of the offset, so: SIG_Offset = (Centerpoint – Full scale input) / Full scale input = 100 × (500 – 1000) / 1000 = –50% 3. Set the SIG_OFFSET code to 11000 (24), to select SIG_OFFSET = –50%. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 47 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Table 42: TC1_OFFSET (Register Address: 0x09, bits 7:0) Function 1st Order Magnetic Offset Temperature Compensation coefficient Syntax Quantity of bits: 8 Code stored in two’s complement format. Related Commands SIG_OFFSET, TC1_SENS_CLD, TC1_SENS_HOT, TC2_SENS_CLD, TC2_SENS_HOT Values 0000 0000: Default 0111 1111: +0.48 G/°C 1000 0000: –0.48 G/°C Options No fine magnetic offset is applied if this parameter is not set. Examples – Table 43: TC1_SENS_CLD (Register Address: 0x09, bits 15:8) TC1_SENS_HOT (Register Address: 0x09, bits 23:16) Function 1st Order Sensitivity Temperature Coefficient. Specifies a compensation factor for drift in device Sensitivity resulting from changes in ambient temperature during operation. Applies a 1st order, linear compensation algorithm. Two different parameters are set, one for increasing values relative to TA = 25°C, and the other for decreasing values, as follows: • TC1_SENS_HOT: ΔTA (from 25°C) > 0 • TC1_SENS_CLD: ΔTA (from 25°C) < 0 Syntax Quantity of bits: 8 (each parameter) Related Commands SENS_MULT, TC2_SENS_HOT, TC2_SENS_CLD Values 0000 0000: –98 m% / °C 1111 1111: +291 m% / °C Increments (step size) of ±1.53 m% / °C Options Set all bits to 0 if TC1_SENS_HOT and TC1_SENS_CLD are not used. Examples Refer to Temperature Compensation section. Table 44: TC2_SENS_CLD (Register Address: 0x08, bits 14:6) TC2_SENS_HOT (Register Address: 0x08, bits 23:15) Function 2nd Order Sensitivity Temperature Coefficient. Specifies a compensation factor for drift in device Sensitivity resulting from changes in ambient temperature during operation. Applies a 2nd order, quadratic compensation algorithm. Two different parameters are set, one for increasing values relative to TA = 25°C, and the other for decreasing values, as follows: • TC2_SENS_HOT: ΔT (from 25°C) > 0 • TC2_SENS_CLD: ΔT (from 25°C) < 0 Syntax Quantity of bits: 9 (each parameter) Related Commands SENS_MULT, TC1_SENS_HOT, TC1_SENS_CLD Values 0 0000 0000: –1.53 m% / °C 1 1111 1111: +1.53 m% / °C Increments (step size) of ±0.00596 m% / °C Options Set all bits to 0 if TC2_SENS_HOT and TC2_SENS_CLD are not used. Examples Refer to Temperature Compensation section. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 48 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 DEFINITION OF TERMS Full Scale (FSI and FSO) Quiescent Output (QOUT) Full Scale Input, FSI, is the range of the applied magnetic field processed by the device. Full Scale Output, FSO, is the range of output values that device output can have for the applied magnetic field. If device output is configured as PWM, output will be 5% and 95%. If device output is configured as SENT, device output will obtain LSB values from 0 to 4095. See Figure 21. The output value in the quiescent state (when no magnetic field is applied, BIN = 0 G). Power-On Time (tPO) The time required for device output to generate either the first valid output message frame (SENT mode) or the first valid duty cycle (PWM mode), after the power supply has reached its minimum specified operating voltage, VCC(min). When the supply is ramped to its operating voltage, the device requires a finite time to power internal circuits before supplying a valid output value. Signal Propagation Delay (tPROP) The time necessary for the device to respond to an input magnetic change and to create a valid output message. Signal Response Time (tRESP) Typically Signal Response Time is defined as propagation delay plus length of the SENT/PWM message. However if filter bandwidth is chosen such that the corresponding internal output update rate (see BW parameter in EEPROM) is slower than the output digital message length, it might take a couple of output messages to update the user. Output Mode PWM SENT (D %) (LSB) 100 FSO FSI (RANGE) (%) 100 0 50 0 95 1111 1111 1111 1111 50.78 49.22 1000 0000 0000 0000 5 0000 0000 0000 0000 (4095) (2048) (0) B– 0 B+ Applied Magnetic Field, BIN (G) Figure 21: Full Scale Input (FSI) and Full Scale Output (FSO) The central portion of the programmable range for Quiescent Output, QOUT, range lies within the QOUT limits. The Quiescent Output, QOUT , can be customer-programmed around its typical value , which is 0 LSB (SENT mode) or 50% duty cycle (PWM mode). Quiescent Output Drift Through Temperature Range Due to internal component tolerances and thermal considerations, the temperature coefficient used to determine Quiescent Output may drift from its typical initial value, OUT(Q) , when changes occur in the operating ambient temperature, TA. For purposes of specification, the Quiescent Output Drift Through Temperature Range, ΔOUT(Q) , is defined as: ΔOUT(Q) = OUT(Q)TA − OUT(Q)25°C (5) where OUT(Q)TA is the OUT(Q) at a given TA and OUT(Q)25°C is the OUT(Q) at a TA of 25°C. Note that ΔOUT(Q) should be calculated using actual measured values, rather than target values used when programming. The Offset Temperature Coefficient can be seen as representation of the offset drift over temperature in units %/C: ∆OUT(Q) = (OUT(Q)TA – OUT(Q)25°C ) / OUT(Q)25°C ∆TA × 100 (6) where ΔTA = TA – 25°C. Sensitivity (Sens) The proportion of the output voltage to the magnitude of the applied magnetic field. This proportionality is specified as the Sensitivity, Sens (ΔLSB/G for SENT mode, ΔD/G for PWM mode), and is effectively the gain of the device. An individual A1341 device may be unipolar, and respond to the presence of either a south (positive) polarity magnetic field, or a north (negative) polarity magnetic field (but not both). Or it may be bipolar, and respond to both polarities. If responsive to a south field, a south field opposite and perpendicular to the branded face of the package will increase the output from its quiescent value toward the maximum output limit. If responsive to a north field, a north field opposite and perpendicular to the branded face of the Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 49 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization package will decrease the output from its quiescent value. purposes of specification, the Sensitivity Drift Due to Package Hysteresis, is defined as: For bipolar configurations, Sensitivity is defined as: Sens = OUT(BPOS) – OUT(BNEG) BPOS – BNEG , (7) and for unipolar configurations (south field responsive) as: Sens = OUT(BPOS) – OUT(Q) BPOS , (8) where BPOS and BNEG are two magnetic fields with the indicated opposite polarities. Sensitivity Drift Through Temperature Range Due to internal component tolerances and thermal considerations, the temperature coefficient used to determine Sensitivity may drift from its typical initial value, SensTCinit , and the expected value after customer programming (EEPROM parameters TC1_ SENS_CLD, TC1_SENS_HOT, TC2_SENS_CLD, TC2_SENS_ HOT) when changes occur in the operating ambient temperature, TA. For purposes of specification, the Sensitivity Drift Through Temperature Range, ∆SensTC , is defined as: ∆SensTC = SensTA – SensEXPECTED(TA) SensEXPECTED(TA) × 100 (%) . (9) where SensTA is the actual Sens at the current ambient temperature, and SensEXPECTED(TA) is the Sens calculated based on programmed parameters. Sensitivity Temperature Coefficient can be seen as a representation of the Sensitivity drift in %/°C when a temperature divider, ∆T = TA – 25°C, is inserted into equation 9. Sensitivity Drift Due to Package Hysteresis (∆SensPKG) Package stress and relaxation can cause the device sensitivity at TA = 25°C to change during and after temperature cycling. For ∆SensPKG = Sens(25°C)2 – Sens(25°C)1 Sens(25°C)1 × 100 (%) (10) where Sens(25°C)1 is the programmed value of Sensitivity at TA = 25°C, and Sens(25°C)2 is the value of Sensitivity at TA = 25°C, after temperature cycling. Linearity Sensitivity Error The A1341 is designed to provide a linear output in response to a ramping applied magnetic field. Consider two magnetic field strengths, B1 and B2. Ideally, the sensitivity of a device is the same for both field strengths, for a given supply voltage and temperature. Linearity error is present when there is a difference between the sensitivities measured at B1 and B2. Linearity Error is calculated separately for the positive (LinERRPOS ) and negative (LinERRNEG ) applied magnetic fields. Linearity error is measured and defined as: SensBx SensBx/2 × 100 (%) Sens–Bx LinERRNEG = 1– Sens –Bx/2 where: × 100 (%) LinERRPOS = 1– SensBx = |OUT(Bx) – OUT(Q)| Bx (11) (12) and BX and –BX are positive and negative magnetic fields Final Linearity Sensitivity Error (LinERR) is the maximum value of the absolute positive and absolute negative linearization errors. Note that unipolar devices only have positive linearity error (LinERRPOS). Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 50 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization A1341 PACKAGE OUTLINE DRAWING For Reference Only - Not for Tooling Use (Reference DWG-9202) Dimensions in millimeters - NOT TO SCALE Dimensions exclusive of mold flash, gate burs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown B 10° 5.21 +0.08 –0.05 1.00 +0.08 –0.05 E 2.60 F 1.00 F Mold Ejector Pin Indent +0.08 3.43 –0.05 F 0.89 MAX 1 2 3 Branded Face 4 A 0.54 REF NNNN YYWW 0.41 +0.08 0.20 –0.05 +0.08 –0.05 D 12.14 ±0.05 1.27 NOM N = Device part number Y = Last two digits of year of manufacture W = Week of manufacture 0.54 REF 0.89 MAX 1.50 +0.08 –0.05 D +0.08 5.21 –0.05 Standard Branding Reference View A Dambar removal protrusion (16X) B Gate and tie burr area C Branding scale and appearance at supplier discretion D Thermoplastic Molded Lead Bar for alignment during shipment E Active Area Depth, 0.37 mm REF F Hall element, not to scale +0.08 1.00 –0.05 Package KT, 4-Pin SIP Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 51 A1341 High Precision, Programmable Linear Hall Effect Sensor IC With EEPROM, SENT and PWM Output Protocols, and Advanced Output Linearization Revision History Revision Revision Date – November 13, 2014 Description of Revision Initial Release Copyright ©2012-2014, Allegro MicroSystems, LLC Allegro MicroSystems, LLC reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current. Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use. For the latest version of this document, visit our website: www.allegromicro.com Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 52