SM324-10E

TMR Smart Magnetometer SM324-10E Ultraprecise TMR Smart Magnetometer Features Can detect magnets more than 50 mm away In-plane sensitivity—more usable us than Hall sensors Internal temperature compensation I²C field measurement plus on/off digital output Ultraminiature 2.5 x 2.5 x 0.8 0. mm TDFN6 package • • • • • Key Specifications 0 to ±20 Oe (0 to ±2m T) magnetic field operating range Ultra-accurate— ±0.3% of full scale at 25 °C 1.5 mA typical ical supply current 300 samples/second −40 °C to +125 °C operating range • • • • • Block Diagram DSP Core TMR Sensor Element ADC Temperature Sensor SCL SDA Applications • Proximity sensors • Noncontact current sensing • Automotive applications • Robotics • Internet of Things (IoT) end d nodes Description The SM324 Smart Magnetometer provides ultraprecise magnetic field measurements. Digital The sensor combines an ultraprecise precise Tunneling Output Magnetoresistance (TMR) sensor element with sophisticated digital signal processing. The digital signal processing improves accuracy and allows applicationapplication specific calibration. Calibration coefficients are stored in an internal nonvolatile memory. Unlike awkward, old-fashioned fashioned Hall-effect Hall sensors, TMR is sensitive in-plane for optimal current sensing and easy mechanical interfaces. TMR also provides more sensitivity, higher precision, and lower noise than Hall. An I²C C interface provides data as well as a programming interface. A digital output provides precise, programmable magnetic thresholds. Designed for harsh industrial or automotive environments, the SM324 has robust ESD protection and full −40 °C to +125 °C operating temperature range. 1 NVE Corporation 11409 Valley View Road, Eden Prairie irie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www. w.nve.com ©NVE Corporation TMR Smart Magnetometer Absolute Maximum Ratings Parameter Supply voltage Input/ Output voltages (SCL, SDA, Digital Out) Storage temperature ESD (Human Body Model) Applied magnetic field Min. −0.4 −0.5 −50 4000 Max. 3.63 VDD+0.5 130 Unlimited Units Volts Volts °C Volts Oe 2 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Operating Specifications Parameter Operating temperature Supply voltage Supply current (VDD = 3.3 V) Power-Up and Power-Down Power-on reset low voltage Power down time (duration below VBOR) Power-on reset rising slope Symbol TMIN; TMAX VDD Min. −40 1.68 Max. 125 3.6 2.5 250 750 Units °C V mA nA nA 0.2 V µs V/ms tST1 1 ms tST2 2.5 ms tWU1 0.5 ms tWU2 2 ms 1.5 20 50 IDD VBOR tBOR SRVDD Typ. 0 3 10 Start-up time Wake-up time Internal Temperature Sensor Temperature resolution Magnetic Measurements Operating magnetic field strength Conversion rate TRES H fCON 0.003 300 ±0.3 ±1 0.1 24 Accuracy Hysteresis Output resolution Digital Output S/s Sink current Source current Low-level analog output voltage High-level analog output voltage Nonvolatile Memory Write time Endurance Thermal Characteristics Junction-to-ambient thermal resistance Package power dissipation I²C Interface ISOURCE ISINK VOL VOH 10 10 mA mA mV V θJA Data transfer rate DR Bus voltage Low level input threshold voltage High level input threshold voltage Low level output current Capacitive load I/O capacitance VBUS VIL VIH IOL CB CI/O 50 VDD 16 320 500 400 k 3 During repeated 0xAA commands VDD = 3.3V VOL< 0.5V; VOH > 2.8V IL = −50 μA IL = 50 μA msec cycles °C/W mW 3.4 M 3 0.8 25°C TMIN to TMAX TMIN to TMAX %FS bits 300 5 10000 TMIN to TMAX %FS fUPDATE 1000 VDD ramp time to active communication VDD ramp time to active operation Idle to active communication Idle to active operation Oe S/s Update rate 0 VDD−0.05 Active; TMIN to TMAX Idle Mode; ≤ 85°C Idle Mode; ≤ 125°C °K/LSB 20 270 Test Condition VDD + 0.5 2.2 mA 400 10 Baud Standard mode I²C fast mode V V V VOL=0.4V pF pF 3 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer SM324 Overview The SM324 is a non-contact magnetometer designed for proximity or current sensing. The heart of the SM324 is a unique tunneling magnetoresistance (TMR) sensor, which yields negligible hysteresis of less than 0.1%, or 0.04 Oe / 4 µT from −40°C to 125°C. Factory calibration for gain and offset, plus temperature correction and digital linearization provide extraordinary accuracy of ±0.3% of full scale. Combined with a high-sensitivity TMR element, absolute accuracy is 0.12 Oe / 12 µT at 25°C, or 0.4 Oe / 40 µT from −40°C to 125°C. With a tiny 2.5 by 2.5 mm TDFN package and typical 1.5 mA active supply current and 50 nA idle current, the SM324 is also the smallest, lowest-power magnetometer in its class. SM324 Operation A block diagram is shown below: Nonvolatile Memory Temperature comp. and Calibration 2nd-Order Linearization TMR Sensor Element 18-bit ADC Temperature Sensor Controller Digital Core Comparator SCL SDA DOUT Figure 1. Detailed block diagram. A robust 18-bit ADC, second-order linearization, and temperature compensation provide ultra-precise magnetic field measurements. The digital core provides three bytes (24 bits) of mathematical precision. Two outputs are available: an industry-standard I²C output for interfacing directly to microcontrollers and FPGAs, and a simple digital output for threshold detection of proximity, fault, overcurrent, and saturating magnetic fields. Several other parameters can be programmed into the SM324 through the I²C interface. 4 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer User Defined Memory Twenty-six 16-bit blocks of nonvolatile memory are available for part identification or general purpose use. This number can be overwritten if needed. Note that the nonvolatile memory is subject to endurance limitations and should only be used for occasionally updated data. Sensor Offset The sensor core of the SM324 is factory calibrated for highest accuracy, and a programmable three-byte parameter, OFFS, is available for user adjustments to environments with non-zero magnetic fields. OFFS has a sign/magnitude form where the mostsignificant bit is the sign (1 = negative), and the range is ±50% of the ±20 Oe (±2 mT) full-scale range. Internal Temperature Sensor The SM324 utilizes an internal temperature sensor for compensation. The thermometer is factory calibrated and a userprogrammable three-byte variable, TEMP, is available for additional temperature offset calibration. Similar to the OFFS parameter, TEMP has a sign/magnitude form where the most-significant bit is the sign (1 = negative), and the range is ±50% of the 165°C full-scale temperature range. Digital Output for Threshold Detection The SM324 has a programmable digital output that can be configured for threshold detection. The output is push-pull CMOS, and can source or sink up to 10 mA. Digital Output Parameters The output is programmable using two 24-bit threshold parameters (THRSH1 and THRSH2). THRSH1 and THRSH2 are unsigned integers, each representing 0 to 100% of full scale, where 50% is zero field, 0 is the negative end of the range ( −20 Oe / −2 mT), and 0xFFFFFF is the positive high end of the range (+20 Oe / +2 mT). Digital Threshold Updating DOUT updates automatically with each sample in the Cyclic Mode, although the refresh rate is limited to eight samples per second in that mode. In normal mode, DOUT updates with each I²C data request, so the sensor must be connected to a I²C Master continuously requesting data for the output to be usable. Digital Threshold Modes The digital output can be programmed as a high-field, low field, or window comparator. The output can also be reversed with a two-bit parameter, so either a high-field or low-field output can be generated. The figures below show the outputs for the three comparator modes as set by the CONFIG parameter. Digital Output Digital Output On On Off Off Field Field THRSH1 THRSH1 Fig. 2a. Normal mode (CONFIG = 01 bin). Fig. 2b. Inverted mode (CONFIG = 10 bin). 5 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Digital Output Digital Output On Off On On Off Off Field THRSH1 THRSH2 Field THRSH2 Fig. 2c. Window mode (CONFIG=11 bin; THRSH2>THRSH1). THRSH1 Fig. 2d. Inverted window mode (CONFIG=11; THRSH1>THRSH2). These graphs are with respect to magnetic field, with zero field at the y-axis intercept in the center of the x-axis. The I²C output is unsigned, with zero field corresponding to 50%. The Digital Threshold Modes are summarized in the following table: CONFIG (bin) 01 10 11 DOUT 0: Measurement < THRSH1 1: Measurement > THRSH1 0: Measurement > THRSH1 1: Measurement < THRSH1 Output determined by threshold settings. If THRSH1 > THRSH2 1: Measurement > THRSH1 OR Measurement < THRSH2 0: THRSH1 > Measurement > THRSH2 If THRSH2 > THRSH1 1: THRSH1 < Measurement < THRSH2 0: Measurement > THRSH2 OR Measurement < THRSH1 Table 1. Digital Output (DOUT) Threshold Configuration The Window mode (CONFIG = 11) can be used to provide a response independent of polarity. For example, the default settings of CONFIG = 11, THRSH1 = 75% (0xC00000), and THRSH2 = 25% (0x400000) cause DOUT to be high if the field magnitude is more than 10 Oe / 1 mT (i.e., greater than +10 Oe or less than −10 Oe) as shown in the following diagram: Digital Output On On Off Field TRSH2 TRSH1 Fig. 2e. Default DOUT configuration (CONFIG=11; THRSH1=75%; THRSH2=25%; for omnipolar DOUT). 6 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Directions of Sensitivity The diagrams below show two permanent magnet orientations that will activate the sensor in the direction of sensitivity: Figure 3. Magnetic orientation. Unlike Hall effect or other sensors, TMR sensors are sensitive to fields in the plane of the package, which is more convenient. The axis of sensitivity is in the pin 2 to pin 5 sensor axis, which is ideal for position sensing, or for current sensing since a currentsensing trace can be run under the sensor without crossing the pins. Position Sensing A typical proximity sensor using an SM324-10E sensor and magnet is shown below. With a 4 Oe (0.4 mT) operate point, the sensor actuates with a rare-earth magnet at more than 50 mm (two inches) from the sensor: AG035-06 circuit board SM324 sensor Magnet Figure 4. The SM324-10E sensor can be activated by a magnet more than 50 mm away. Thresholds even lower than 4 Oe can be programmed for the SM324-10E, although care must be taken to account for the earth’s magnetic field, which is approximately 0.5 Oe or 50 µT. Typical magnetic operate distances are illustrated below for an inexpensive ceramic disk magnet: 7 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer 20 Field (Oe) 15 10 5 0 0 10 20 Distance (mm) 30 40 Figure 5. Field vs. distance from the center of the sensor (NVE part number 12216; ferrite magnet; d=6 mm; t=4 mm; C1/Y10T; Ms=Br=2175 G). Larger and stronger magnets allow farther operate and release distances. For more calculations, use our axial disc magnetic field versus distance Web application at: www.nve.com/spec/calculators.php#tabs-Axial-Disc-Magnet-Field. 8 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Current Sensing In a typical current sensor configuration, a magnetic field provided by an off-chip current strap produces a magnetic field in the plane of the sensor. The digital output can be used for current threshold detection or overcurrent protection. Typical current sensing configurations are shown below: Figure 6a. 0.05" (1.3 mm) trace (0 – 5 A typ.). Figure 6b. Five turns of 0.0055" (0.14 mm) trace (0 – 1 A typ.). For the geometry shown below and narrow traces, the magnetic field generate can be approximated by Ampere’s law: Sensor Circuit Board d Current Trace w Figure 7. The geometry of current-sensing over a circuit board trace. H = 2I d [“H” in oersteds, “I” in amps, and “d” in millimeters] For traces on the top side of the board, “d” is simply the distance of the sensor element from the bottom of the package, which is 0.5 millimeters. Traces on the top side of the board are typically used for currents of five amps or less. Large traces on the bottom side of the PCB can be used for currents of more than five amps. More precise calculations can be made by breaking the trace into a finite element array of thin traces, and calculating the field from each array element. We have a free, Web-based application with a finite-element model to estimate magnetic fields and sensor outputs in this application: www.nve.com/spec/calculators.php#tabs-Current-Sensing 9 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Power-Up and Initialization Parts power in the “normal” (single-reading) mode. In this mode, the sensor output and DOUT are updated when data is requested via I²C, so the sensor should be connected to a I²C Master continuously requesting data. If the “cyclic” mode (DOUT automatically updated) is desired, it should be invoked with the appropriate I²C commands. Parameters such as I²C address, temperature and field offsets, digital output thresholds and configuration are stored in nonvolatile memory and retain their state through power cycle unless they are deliberately changed. As specified in “Operating Specifications—Power-Up and Power-Down,” a reasonably fast supply rise time is necessary to guarantee a power-on reset. DOUT Update Modes Two operational modes are available with the SM324. The “normal” mode allows the user to update DOUT and retrieve a single sensor reading via I²C. The part returns to a low-power idle state when communication is complete. The Cyclic Mode automatically updates the sensor read buffer and DOUT at a programmed interval. Field and temperature can be read via I²C during cyclic mode, and such reads update the measurements and DOUT. Note that the minimum Cyclic Mode Interval is 125 ms, so without I²C data reads, DOUT is only updated a maximum of eight times per second in Cyclic Mode. Although data can be read, parameters cannot read or written in Cyclic Mode. The DOUT mode can be set via I²C (see Table 2 below), and the cyclic interval is programmed using the CINT parameter (see Table 3): Command Read User Memory Write User Memory Checksum Single Measurement Cyclic Measurement Command Value (hex) 0x20-0x38 0x60-0x78 0x90 0xAA 0xAB 2x Oversample Measure 0xAC 4x Oversample Measure 0xAD 8x Oversample Measure 0xAE 16x Oversample Measure 0xAF Cyclic Measure Stop 0xBF Notes 16-bit user defined data 16-bit user defined data Perform memory update to CHECKSUM. 24-bit field plus 24-bit temperature measurement Cyclic 24-bit field and temperature measurements Complete 2x full continuous measurements and compute average values Complete 4x full continuous measurements and compute average values Complete 8x full continuous measurements and compute average values Complete 16x full continuous measurements and compute average values Stops cyclic measurements Table 2. SM324 command options. Parameter Value (binary) 000 001 010 011 100 101 110 111 Cyclic Mode Update Interval Not assigned 125 msec 250 msec 500 msec 1000 msec 2000 msec 4000 msec Not assigned Table 3. CINT (Cyclic Interval) parameter values. 10 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Sensor Measurements and Offsets Field and Temperature Measurements The sensor provides field and temperature measurements with each reading. The measurements are 24-bit unsigned integers. 0x000000 represents the minimum value, which is −20 Oe / −2 mT for field and −40°C for temperature. 0xFFFFFF represents full scale, which is +20 Oe / +2 mT for field and +125°C for temperature. Saturation and Overflow All measurements responses start with a status byte followed by the data. Bit 0 of the status byte indicates the sensor is saturated because field is too high for an accurate measurement. In this case, Bit 0 of the status byte will be set and the field measurement will remain at or near 0xFFFFFF. Offsets Temperature and field offsets are factory calibrated, but can be reprogrammed if necessary. Offsets are in 24-bit sign/magnitude format, where the most significant bit (bit 23) is the sign (0 = positive; 1 = negative), and bits 22:0 are the magnitude. The offset range is ±50% of full-scale, where field full-scale is ±20 Oe / ±2 mT; and temperature full-scale is 165°C. Measurements and offsets are illustrated below: 224 24 ld Fi e wit h fse Of t Digital Output Digital Output 2 ld Fi e Te -20 0 Field (Oe) 0 -40 +20 rat ure Tem ra pe tu r ffse t e TEMP Offset OFFS (offset) 0 e mp hO wit -25 Fig. 8a. Sensor output versus field. 0 25 50 Temperature (°C) 75 100 Fig. 8b. Sensor output versus temperature. 11 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation 125 TMR Smart Magnetometer I²C Interface The I²C interface is an industry standard full-duplex 400 kHz connection with the sensor as the slave to an external master such as a microcontroller. Consistent with industry practice, SDA and SCL are open-drain, and pull up resistors to VDD are normally needed. The SDA / SCL pins should not be left floating for proper power-up/operation. A schematic of a typical microcontroller interface is show in the Applications section. I²C Address The SM324 has a seven-bit address, which can be defined in the nonvolatile memory with the I²CADD parameter. Allowable I²C addresses are 8 to 127. Addresses 4 to 7 are reserved for I²C High-Speed Mode. The factory default I²C Slave Address is 16 (0x10 hex). A power cycle is required for a device to respond to an I²CADD change. Data Format Each command follows the sequence shown below. All I²C read responses start with a status byte followed by the data. The data depends on the previous commands. Only the number of bytes that are needed for the command must be sent. An exception is the I²C High-Speed Mode where three bytes must always be sent. After the execution of a command, the expected data can be read or if no data is returned by the command, the next command can be sent. You can read the same data more than once if the read request is repeated. Command or I²C Memory Write Sequence S Addr W A Command A S Addr W A Command A S Addr W A Memory Address A P Data [15:8] Data [15:8] Data [7:0] A A Data [7:0] A A P P Read Sequence Following AAHEX Command S Addr R A Status A Field [23:16] A Field [15:8] A Field [7:0] A Temp [23:16] A Temp [15:8] A Temp [7:0] N Read Sequence Following 2-byte Memory Write Command S Addr R A Status A Data [15:8] A Data [7:0] N P Key: S/P: Start/Stop A/N: Acknowledge / Not Acknowledge R/W: Read (1) / Write (0) 12 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation P TMR Smart Magnetometer Status Byte A read status can be executed at any time with the following command sequence: S Addr R A Status N P The status byte contains the following bits: Bit Meaning 7 0 6 Voltage OK? 5 Busy? 4, 3 00 2 Memory Error? 1 0 0 Saturation? Voltage check (bit 6): “1” if the sensor is properly powered;“0” if the supply voltage is out of range and data may be unreliable. Busy indication (bit 5): “1” if the device is busy, which indicates that the data for the last command is not available yet. No new commands are processed if the device is busy. Note that the device is always busy if the cyclic measurement operation has been started. Memory integrity/error flag (bit 2): Indicates the checksum test failed. The bit is calculated only on power-up, so a newly-written CHECKSUM will only be used for verification after the next power-on reset. Also, the CHECKSUM is only recalculated on request (a 0x90 command), so the flag will indicate an error if the memory is changed without requesting a CHECKSUM recalculation. Saturation (bit 0): “1” if the last sensor measurement indicates the sensor is saturated. 13 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Memory Register The SM324 uses an internal nonvolatile memory to enable user programmable parameters such as I²C address, temperature and field offsets, digital output thresholds and configuration parameter, and cyclic mode interval. Each register is 16 bits and is written using the scheme described in the I²C interface section. The memory address and number of bits for each parameter are also provided. Memory address bit 6 is a write bit, so writing to nonvolatile memory uses an address 0x40 higher than the address for reading. Table 4 summarizes programmable parameters: Parameter Device Identifiers Symbol User Memory I²C Address I²CADD Offsets Temperature Offset (lower 16 bits) Temperature Offset (sign bit + upper 7 bits) Field Offset (lower 16 bits) Field Offset (sign bit + upper 7 bits) Read Address (hex) Write Address (hex) 00-01; 20-38 40-41; 60-78 [15:0] -- -- 0x02 0x42 [6:0] 0x10 16 dec 0x18 0x58 [15:0] 0x19 0x59 [15:8] 0x17 0x57 [15:0] 0x19 0x59 [7:0] Default Hex Value Bits Notes Changes requires a power cycle. Sign/Magnitude format; most significant bit is sign (1=negative); bits 22:0 are magnitude (±50% of full scale); full scale field = ±20 Oe; full scale temp. = 165°C. TEMP Factory Calibrated OFFS Mode Parameters Cyclic Interval CINT Digital Output Configuration Threshold 1 (LSB) Threshold 1 (MSB) Threshold 2 (LSB) Threshold 2 (MSB) Threshold Configuration THRSH1 THRSH2 CONFIG 0x02 0x42 [14:12] 000BIN 0 0x13 0x15 0x14 0x15 0x02 0x53 0x55 0x54 0x55 0x42 [15:0] [7:0] [15:0] [15:8] [8:7] 0x0000 0xC0 0x0000 0x40 11BIN 10 Oe / 1 mT −10 Oe / −1 mT 3 Time between automatic measurements (= 2 CINT-4 sec.; see Table 3). Unsigned (0–100% of full scale) (See Table 1) Table 4. SM324 programmable parameters. 14 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Supply Decoupling VDD should be bypassed with a 1 nF (0.001 µF) capacitor placed as close as possible to the supply and ground pins. A larger capacitor is not required and could interfere with power-up timing. Typical Circuit A typical microcontroller interface is shown below: 1.8 - 3.6V SM324-10E VDD VDD SDA SDA SCL SCL DOUT 1k LE D 3 CVDD GND Microcontroller 1 nF GND R 5 Figure 9. Typical microcontroller interface. The SM324 is configured as a Slave and the microcontroller should be configured as the Master. The SM324 I²C interface is compatible with 1.8 to five-volt nominal microcontrollers. The SM324 SDA and SCL lines are open-drain, so the microcontroller’s internal pull-up resistor should be activated in software. If external pull-ups are used with different power supplies, they should be connected to the lower supply voltage, which is usually the sensor (Slave) supply. VDD should be bypassed with a 1 nF (0.001 µF) capacitor placed as close as possible to the VDD and GND pins. A LED can be used to indicate the digital output. The digital output can source or sink 10 mA. The appropriate series resistor depends on the supply voltage and LED type, and of course the LED cannot be operated at the low end of the sensor supply voltage range, such as 1.8 volts. 15 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Illustrative Microcontroller Code The following pseudocode illustrates a typical I²C read of the sensor output, as well as memory read and memory write. Actual implementation is, of course, hardware dependent. //================== Read 24-bit magnetic field and temperature ================== // Command Request I2C_Start() I2C_Write( 0x20 ) I2C_ReadACK() I2C_Write( 0xAA ) I2C_ReadACK() I2C_Stop() // // // // // // Send start Write I2C target address (16) with read/write bit set to write (0) Read ACK(acknowledge) from target Write command(0xAA = read magnetic field and temperature) Read ACK from target Send stop // Read data I2C_Start() // I2C_Write (0x21) // I2C_ReadACK() // I2C_Read( &status_byte ) // I2C_SendACK() // I2C_Read(&field_bits_23_16)// I2C_SendACK() // I2C_Read(&field_bits_15_8) // I2C_SendACK() // I2C_Read(&field_bits_7_0) // I2C_SendACK() // I2C_Read(&temp_bits_23_16) // I2C_SendACK() // I2C_Read(&temp_bits_15_8) // I2C_SendACK() // I2C_Read(&temp_bits_7_0) // I2C_SendNACK() // I2C_Stop() // Send start Write I2C target address (16) with read/write bit set to read (1) Read ACK from target Read status byte Send ACK Read magnetic field bits 23:16 Send ACK Read magnetic field bits 15:8 Send ACK Read magnetic field bits 7:0 Send ACK Read temperature bits 23:16 Send ACK Read temperature bits 15:8 Send ACK Read temperature bits 7:0 Send NACK (not acknowledged) Send stop Status byte interpretation: Bit 7: Not used - always 0 Bit 6: Powered - always 1 Bit 5: Busy - 0=measurement complete, 1=measurement in progress Bit 4: Not used - always 0 Bit 3: Not used - always 0 Bit 2: Memory error - 0=checksum matches memory contents, 1=checksum does not match Bit 1: Not used - always 0 Bit 0: Saturation - 0=OK, 1=Sensor saturation (i.e. field is too strong) Common status bytes: 0x40 = Measurement successful. 0x44 = Measurement successful but checksum doesn't match memory contents (send 0x90 to reset checksum) 0x60 = Measurement not yet complete. Repeat read command. 0x41 = Measurement complete but not valid because sensor is saturated. 16 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer //================== Read from memory register 0 I2C_Start() I2C_Write( 0x20 ) I2C_ReadACK() I2C_Write( 0x00 ) I2C_ReadACK() I2C_Stop() // // // // // // ================== // Command request Send start Write target I2C address (16) with read/write bit set to write (0) Read ACK(acknowledge) from target Write command (0x00 = read memory address 0) Read ACK from target Send stop // Read data I2C_Start() // I2C_Write (0x21) // I2C_ReadACK() // I2C_Read( &status_byte ) // I2C_SendACK() // I2C_Read( &data_bits_15_8 )// I2C_SendACK() // I2C_Read( &data_bits_7:0 ) // I2C_SendNACK() // I2C_Stop() // Send start Write target I2C address (16) with read/write bit set to read (1) Read ACK from target Read status byte Send ACK Read contents of memory (bits 15:8) Send ACK Read contents of memory (bits 7:0) Send NACK (not acknowledged) Send stop //================== Write value 0x1234 to memory register 0 request I2C_Start() I2C_Write( 0x20 I2C_ReadACK() I2C_Write( 0x40 I2C_ReadACK() I2C_Write( 0x12 I2C_ReadACK() I2C_Write( 0x34 I2C_ReadACK() I2C_Stop() ) ) ) ) // // // // // // // // // // ================== // Command Send start Write target I2C address (16) with read/write bit set to write (0) Read ACK(acknowledge) from target Write command (0x40 = write to memory address 0) Read ACK from target Write bits 15:8 of 0x1234 Read ACK from target Write bits 7:0 of 0x1234 Read ACK from target Send stop 17 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Evaluation Support Breakout Board The AG960-07E breakout board provides easy connections to an SM324-10E sensor with a six pin connector. It also has a recommended 1 nF bypass capacitor: NVE Figure 10. AG960-07E breakout board (actual size) 0.5" x 0.6" (12 mm x 15 mm) Evaluation Kit This board includes an SM324-10E Smart Magnetometer, a microcontroller that interfaces to the SM324 via I²C, and interfaces to a PC via USB. The sensor can be activated with a magnet or an on-board current trace. A Windows-based user interface provides two-way communication with the sensor to display the sensor outputs and allowing field calibration. Microcontroller I/O connector NVE Isolator USB UART DOUT LED SM324-10 sensor USB connector SM 324 Current trace (0 to ±5A) USB active LED USB/ext. power selector External Power DC-DC convertor Ready 3.3V Busy LEDs regulator Figure 11. AG951-07E: SM324-10E Smart Magnetometer Evaluation Kit board (actual size). Socket Board The AG954-07E provides a TDFN6 socket for easy interface to smart sensors such as the SM324-10E without soldering: Figure 12. AG954-07E: TDFN socket board 1.5" x 2" (38 mm x 50 mm)(actual size) 18 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer 2.5 x 2.5 mm TDFN6 Package (approx. 15x actual size) 2.00 ± 0.05 0.80 MAX. 6 4 6 1.30±0.05 2.50±0.10 4 Magnetic Sensitivity Axis C0.10 PIN 1 ID 1 1 3 3 0.30±0.05 (6X) 2.50 ± 0.10 0.0-0.05 0.30±0.05 0.65 TYP. (4X) 1.30 REF (2X) 0.20 REF Pin 1 2 3 4 5 6 Symbol VDD GND DOUT SCL SDA NC Description Power Supply (bypass with a 1 nF capacitor) Ground / VSS Digital Output (push-pull CMOS output) I²C Clock (input) I²C Data (bidirectional/open drain) Not internally connected RoHS COMPLIANT Notes: • Dimensions in millimeters. • Soldering profile per JEDEC J-STD-020C, MSL 1. 19 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Ordering Information SM324 - 10E TR13 Product Family SM = Smart Magnetometer Precision 3 = 3-Byte resolution; TMR Sensor Element Magnetic Orientation 2 = Cross-axis (sensitive to a field vector in the pin 2 to pin 5 direction) Field Range 4 = 20 Oe / 2 mT Magnetic Field Range Part Package 10E = RoHS-Compliant 2.5 x 2.5 mm TDFN6 Package Bulk Packaging TR13 = 13'' Tape and Reel Bulk Packaging 20 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Revision History SB-00-077 Rev. D August 2019 Change • Added SI units (mT or µT) where appropriate throughout. • Added diagram showing magnetic orientations (Figure 3; p. 7). • Added Evaluation Support section with Breakout Board, Evaluation Kit, and Socket Board (p. 17). SB-00-077 Rev. C April 2019 Change • Added “Illustrative Microcontroller Code” section (pp. 15 - 16). SB-00-077 Rev. B February 2019 Change • Added “Power-Up and Initialization” section and clarified Cyclic Mode (p. 9). • Added charts showing field and temperature outputs (p. 10). • More detailed descriptions of bit/byte concatenation (p. 11). • Clearer Table 4 memory map; merged Table 5 into Table 4 (p. 13). • Clarified direction of sensitivity (p. 15). • Corrected minor specification inconsistencies. SB-00-077 Rev. A September 2018 Change • Dropped “Preliminary” designation. • Misc. style changes. • Dropped fax number. SB-00-077-PRELIM2 August 2018 Change • Dropped “Product Preview” designation. • Added 25°C accuracy specification. • Added hysteresis specification. • Misc. minor changes. SB-00-077-PRELIM July 2018 Change • Initial preliminary release. 21 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer Datasheet Limitations The information and data provided in datasheets shall define the specification of the product as agreed between NVE and its customer, unless NVE and customer have explicitly agreed otherwise in writing. All specifications are based on NVE test protocols. In no event however, shall an agreement be valid in which the NVE product is deemed to offer functions and qualities beyond those described in the datasheet. Limited Warranty and Liability Information in this document is believed to be accurate and reliable. However, NVE does not give any representations or warranties, expressed or implied, as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information. In no event shall NVE be liable for any indirect, incidental, punitive, special or consequential damages (including, without limitation, lost profits, lost savings, business interruption, costs related to the removal or replacement of any products or rework charges) whether or not such damages are based on tort (including negligence), warranty, breach of contract or any other legal theory. Right to Make Changes NVE reserves the right to make changes to information published in this document including, without limitation, specifications and product descriptions at any time and without notice. This document supersedes and replaces all information supplied prior to its publication. Use in Life-Critical or Safety-Critical Applications Unless NVE and a customer explicitly agree otherwise in writing, NVE products are not designed, authorized or warranted to be suitable for use in life support, life-critical or safety-critical devices or equipment. NVE accepts no liability for inclusion or use of NVE products in such applications and such inclusion or use is at the customer’s own risk. Should the customer use NVE products for such application whether authorized by NVE or not, the customer shall indemnify and hold NVE harmless against all claims and damages. Applications Applications described in this datasheet are illustrative only. NVE makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification. Customers are responsible for the design and operation of their applications and products using NVE products, and NVE accepts no liability for any assistance with applications or customer product design. It is customer’s sole responsibility to determine whether the NVE product is suitable and fit for the customer’s applications and products planned, as well as for the planned application and use of customer’s third party customers. Customers should provide appropriate design and operating safeguards to minimize the risks associated with their applications and products. NVE does not accept any liability related to any default, damage, costs or problem which is based on any weakness or default in the customer’s applications or products, or the application or use by customer’s third party customers. The customer is responsible for all necessary testing for the customer’s applications and products using NVE products in order to avoid a default of the applications and the products or of the application or use by customer’s third party customers. NVE accepts no liability in this respect. Limiting Values Stress above one or more limiting values (as defined in the Absolute Maximum Ratings System of IEC 60134) will cause permanent damage to the device. Limiting values are stress ratings only and operation of the device at these or any other conditions above those given in the recommended operating conditions of the datasheet is not warranted. Constant or repeated exposure to limiting values will permanently and irreversibly affect the quality and reliability of the device. Terms and Conditions of Sale In case an individual agreement is concluded only the terms and conditions of the respective agreement shall apply. NVE hereby expressly objects to applying the customer’s general terms and conditions with regard to the purchase of NVE products by customer. No Offer to Sell or License Nothing in this document may be interpreted or construed as an offer to sell products that is open for acceptance or the grant, conveyance or implication of any license under any copyrights, patents or other industrial or intellectual property rights. Export Control This document as well as the items described herein may be subject to export control regulations. Export might require a prior authorization from national authorities. Automotive Qualified Products Unless the datasheet expressly states that a specific NVE product is automotive qualified, the product is not suitable for automotive use. It is neither qualified nor tested in accordance with automotive testing or application requirements. NVE accepts no liability for inclusion or use of non-automotive qualified products in automotive equipment or applications. In the event that customer uses the product for design-in and use in automotive applications to automotive specifications and standards, customer (a) shall use the product without NVE’s warranty of the product for such automotive applications, use and specifications, and (b) whenever customer uses the product for automotive applications beyond NVE’s specifications such use shall be solely at customer’s own risk, and (c) customer fully indemnifies NVE for any liability, damages or failed product claims resulting from customer design and use of the product for automotive applications beyond NVE’s standard warranty and NVE’s product specifications. 22 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation TMR Smart Magnetometer An ISO 9001 Certified Company NVE Corporation 11409 Valley View Road Eden Prairie, MN 55344-3617 USA Telephone: (952) 829-9217 www.nve.com e-mail: sensor-info@nve.com ©NVE Corporation All rights are reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. SB-00-077_SM324_revD August 2019 23 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 sensor-apps@nve.com www.nve.com ©NVE Corporation