MS5637-02BA03 Low Voltage Barometric Pressure Sensor SPECIFICATIONS QFN package 3 x 3 x 0.9 mm3 High-resolution module, 13 cm Supply voltage: 1.5 to 3.6 V Fast conversion down to 0.5 ms Low power, 0.6 A (standby 0.1 A at 25C) Integrated digital pressure sensor (24 bit ADC) Operating range: 300 to 1200 mbar, -40 to +85 C I2C interface No external components (internal oscillator) The MS5637 is an ultra-compact micro altimeter. It is optimized for altimeter and barometer applications in Smart-phones and Tablet PCs. The altitude resolution at sea level is 13 cm of air. The sensor module includes a high-linearity pressure sensor and an ultra-low power 24 bit ADC with internal factory-calibrated coefficients. It provides a precise digital 24-bit pressure and temperature value and different operation modes that allow the user to optimize for conversion speed and current consumption. A high-resolution temperature output allows the implementation of an altimeter/thermometer function without any additional sensor. The MS5637 can be interfaced to any microcontroller with I2C-bus interface. The communication protocol is simple, without the need of programming internal registers in the device. Small dimensions of 3 x 3 x 0.9 mm 3 allow the integration in mobile devices. This new sensor module generation is based on leading MEMS technology and latest benefits from MEAS Switzerland proven experience and know-how in high volume manufacturing of altimeter modules, which has been widely used for over a decade. The sensing principle employed leads to very low hysteresis and high stability of both pressure and temperature signal. SENSOR SOLUTIONS ///MS5637-02BA03 06/2017 Page 1 MS5637-02BA03 Low Voltage Barometric Pressure Sensor FEATURES FIELD OF APPLICATION Smart-phones Tablet PCs Personal navigation devices TECHNICAL DATA Sensor Performances (VDD = 3 V) Pressure Min Typ Max Unit 2000 mbar Maximum Range 10 ADC 24 0.11 / 0.062/ 0.039 / 0.028 / 0.021 / 0.016 Resolution (1) Error band at 25C, -2 +2 300 to 1200 mbar Error band, -20C to + 85C, -4 +4 300 to 1200 mbar (2) 0.5 / 1.1 / 2.1 / 4.1 / Response time (1) 8.22 / 16.44 Long term stability 1 Temperature Min Range -40 Resolution Typ mbar mbar mbar ms mbar/yr Max Unit +85 C <0.01 Accuracy at 25C bit -1 C +1 C Notes: (1) Oversampling Ratio: 256 / 512 / 1024 / 2048 / 4096 / 8192 (2) With auto-zero at one pressure point FUNCTIONAL BLOCK DIAGRAM VDD SENSOR +IN -IN I2C Bus Interface ADC dig. Filter Sensor Interface IC SGND SDA SCL Memory (PROM) 112 bits GND SENSOR SOLUTIONS /// MS5637-02BA03 06/2017 Page 2 MS5637-02BA03 Low Voltage Barometric Pressure Sensor PERFORMANCE SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS Parameter Supply voltage Storage temperature Overpressure Maximum Soldering Temperature Symbol VDD TS Pmax Conditions Tmax 40 sec max Min. -0.3 -20 Latch up Max. +3.6 +85 Unit V C bar 250 C -2 +2 kV -100 +100 mA Typ. 3.0 +25 20.09 10.05 5.02 2.51 1.26 0.63 1.25 0.01 470 Max. 3.6 +85 Unit V C Typ. 24 16.44 8.22 4.13 2.08 1.06 0.54 Max. 6 Human Body Model JEDEC standard No 78 ESD rating Typ. ELECTRICAL CHARACTERISTICS Parameter Operating Supply voltage Operating Temperature Symbol VDD T Conditions Min. 1.5 -40 OSR Supply current (1 sample per sec.) 8192 4096 2048 1024 512 256 during conversion at 25C (VDD = 3.0 V) from VDD to GND IDD Peak supply current Standby supply current VDD Capacitor 100 A 0.1 mA A nF ANALOG DIGITAL CONVERTER (ADC) Parameter Output Word Symbol Conditions OSR Conversion time SENSOR SOLUTIONS /// MS5637-02BA03 tc Min. 8192 4096 2048 1024 512 256 06/2017 Unit bit ms Page 3 MS5637-02BA03 Low Voltage Barometric Pressure Sensor PERFORMANCE SPECIFICATIONS (CONTINUED) PRESSURE OUTPUT CHARACTERISTICS (VDD = 3.0 V, T = 25 C UNLESS OTHERWISE NOTED) Parameter Operating Pressure Range Extended Pressure Range Conditions Prange Linear Range of Pext ADC Relative Accuracy, autozero at one pressure point (1) 700...1000 mbar at 25C Absolute Accuracy, no autozero 300..1200 mbar at 25C 300..1200mbar, -20..85C OSR Resolution RMS Maximum error with supply voltage Long-term stability Reflow soldering impact Min. 300 Typ. 10 Max. 1200 Unit mbar 2000 mbar 0.1 -2 -4 8192 4096 2048 1024 512 256 VDD = 1.5 V ... 3.6 V IPC/JEDEC J-STD-020C (See application note AN808 on http://meas-spec.com) Recovering time after reflow (2) mbar +2 +4 mbar 0.016 0.021 0.028 0.039 0.062 0.11 mbar 0.5 mbar 1 mbar/yr -1 mbar 3 days (1) Characterized value performed on qualification devices (2) Recovering time at least 66% of the reflow impact TEMPERATURE OUTPUT CHARACTERISTICS (VDD = 3 V, T = 25C UNLESS OTHERWISE NOTED) Parameter Absolute Accuracy Maximum error with supply voltage Conditions at 25C -20..85C Min. -1 -2 VDD = 1.5 V ... 3.6 V OSR Resolution RMS SENSOR SOLUTIONS /// MS5637-02BA03 8192 4096 2048 1024 512 256 06/2017 Typ. Max. +1 +2 Unit C 0.3 C 0.002 0.003 0.004 0.006 0.009 0.012 C Page 4 MS5637-02BA03 Low Voltage Barometric Pressure Sensor PERFORMANCE SPECIFICATIONS (CONTINUED) DIGITAL INPUTS (SDA, SCL) Parameter Serial data clock Input high voltage Input low voltage Input leakage current Input capacitance Symbol SCL VIH VIL Ileak CIN Conditions Symbol VOH VOL CLOAD Conditions Isource = 1 mA Isink = 1 mA Min. Typ. 80% VDD 0% VDD T = 25 C Max. 400 100% VDD 20% VDD 0.1 Unit kHz V V A pF Max. 100% VDD 20% VDD Unit V V pF 6 DIGITAL OUTPUTS (SDA) Parameter Output high voltage Output low voltage Load capacitance SENSOR SOLUTIONS /// MS5637-02BA03 Min. 80% VDD 0% VDD Typ. 16 06/2017 Page 5 MS5637-02BA03 Low Voltage Barometric Pressure Sensor FUNCTIONAL DESCRIPTION VDD SENSOR +IN -IN I2C Bus Interface ADC dig. Filter Sensor Interface IC SGND SDA SCL Memory (PROM) 112 bits GND Figure 1: Block diagram GENERAL The MS5637 consists of a piezo-resistive sensor and a sensor interface integrated circuit. The main function of the MS5637 is to convert the uncompensated analogue output voltage from the piezo-resistive pressure sensor to a 24-bit digital value, as well as providing a 24-bit digital value for the temperature of the sensor. FACTORY CALIBRATION Every module is individually factory calibrated at two temperatures and two pressures. As a result, 6 coefficients necessary to compensate for process variations and temperature variations are calculated and stored in the 112bit PROM of each module. These bits (partitioned into 6 coefficients) must be read by the microcontroller software and used in the program converting D1 and D2 into compensated pressure and temperature values. SERIAL I2C INTERFACE The external microcontroller clocks in the data through the input SCL (Serial CLock) and SDA (Serial DAta). The sensor responds on the same pin SDA which is bidirectional for the I 2C bus interface. So this interface type uses only 2 signal lines and does not require a chip select. Module reference MS563702BA03 SENSOR SOLUTIONS /// MS5637-02BA03 Mode I2C Pins used SDA, SCL 06/2017 Page 6 MS5637-02BA03 Low Voltage Barometric Pressure Sensor PRESSURE AND TEMPERATURE CALCULATION Start Maximum values for calculation results: PMIN = 10mbar PMAX = 2000mbar TMIN = -40C TMAX = 85C TREF = 20C Convert calibration datadata into coefficients (see bit pattern W1 to W4) Read calibration (factory calibrated) from of PROM Recommended variable type Size [1] Value Example / Typical Variable Description | Equation C1 Pressure sensitivity | SENST1 unsigned int 16 16 0 65535 46372 C2 Pressure offset | OFFT1 unsigned int 16 16 0 65535 43981 C3 Temperature coefficient of pressure sensitivity | TCS unsigned int 16 16 0 65535 29059 [bit] min max C4 Temperature coefficient of pressure offset | TCO unsigned int 16 16 0 65535 27842 C5 Reference temperature | TREF unsigned int 16 16 0 65535 31553 C6 Temperature coefficient of the temperature | TEMPSENS unsigned int 16 16 0 65535 28165 Read digitalpressure pressure and and temperature data Read digital temperature data D1 Digital pressure value unsigned int 32 24 0 16777216 6465444 D2 Digital temperature value unsigned int 32 24 0 16777216 8077636 signed int 32 25 -16776960 16777216 68 signed int 32 41 -4000 8500 Calculate temperature [2] dT Difference between actual and reference temperature dT = D2 - TREF = D2 - C5 * 2 8 TEMP Actual temperature (-40...85C with 0.01C resolution) TEMP = 20C + dT * TEMPSENS = 2000 + dT * C6 / 223 2000 = 20.00 C Calculate temperature compensated compensated pressure Calculate temperature pressure OFF Offset at actual temperature [3] OFF = OFFT1 + TCO * dT = C2 * 217 + (C4 * dT ) / 26 signed int 64 41 -17179344900 25769410560 5764707214 SENS Sensitivity at actual temperature [4] SENS = SENST1 + TCS * dT = C1 * 2 16 + (C3 * dT ) / 27 signed int 64 41 -8589672450 12884705280 3039050829 P Temperature compensated pressure (10...1200mbar with 0.01mbar resolution) P = D1 * SENS - OFF = (D1 * SENS / 2 21 - OFF) / 2 15 signed int 32 58 1000 120000 110002 = 1100.02 mbar Display pressure and temperature value Notes [1] [2] [3] [4] Maximal size of intermediate result during evaluation of variable min and max have to be defined min and max have to be defined min and max have to be defined Figure 2: Flow chart for pressure and temperature reading and software compensation. SENSOR SOLUTIONS /// MS5637-02BA03 06/2017 Page 7 MS5637-02BA03 Low Voltage Barometric Pressure Sensor SECOND ORDER TEMPERATURE COMPENSATION In order to obtain best accuracy over temperature range, particularly at low temperature, it is recommended to compensate the non-linearity over the temperature. This can be achieved by correcting the calculated temperature, offset and sensitivity by a second-order correction factor. The second-order factors are calculated as follows: Figure 3: Flow chart for pressure and temperature to the optimum accuracy. SENSOR SOLUTIONS /// MS5637-02BA03 06/2017 Page 8 MS5637-02BA03 Low Voltage Barometric Pressure Sensor I2C INTERFACE COMMANDS The MS5637 has only five basic commands: 1. Reset 2. Read PROM (112 bit of calibration words) 3. D1 conversion 4. D2 conversion 5. Read ADC result (24 bit pressure / temperature) Each I2C communication message starts with the start condition and it is ended with the stop condition. The MS5637 address is 1110110x (write : x=0, read : x=1). Size of each command is 1 byte (8 bits) as described in the table below. After ADC read commands, the device will return 24 bit result and after the PROM read 16 bit results. The address of the PROM is embedded inside of the PROM read command using the a2, a1 and a0 bits. Bit number Bit name Command Reset Convert D1 (OSR=256) Convert D1 (OSR=512) Convert D1 (OSR=1024) Convert D1 (OSR=2048) Convert D1 (OSR=4096) Convert D1 (OSR=8192) Convert D2 (OSR=256) Convert D2 (OSR=512) Convert D2 (OSR=1024) Convert D2 (OSR=2048) Convert D2 (OSR=4096) Convert D2 (OSR=8192) ADC Read PROM Read Command byte 0 1 2 PRO CO M NV 3 Typ 4 5 6 7 Ad2/ Ad1/ Ad0/ Stop Os2 Os1 Os0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 1 1 1 1 1 1 0 0 1 0 0 0 0 1 1 0 0 0 0 1 1 0 Ad2 0 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 hex value 1 0 0 1 1 0 0 0 0 1 1 0 0 0 Ad1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 Ad0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0x1E 0x40 0x42 0x44 0x46 0x48 0x4A 0x50 0x52 0x54 0x56 0x58 0x5A 0x00 0xA0 to 0xAE Figure 4: Command structure SENSOR SOLUTIONS /// MS5637-02BA03 06/2017 Page 9 MS5637-02BA03 Low Voltage Barometric Pressure Sensor RESET SEQUENCE The Reset sequence shall be sent once after power-on to make sure that the calibration PROM gets loaded into the internal register. It can be also used to reset the device PROM from an unknown condition. The reset can be sent at any time. In the event that there is not a successful power on reset this may be caused by the SDA being blocked by the module in the acknowledge state. The only way to get the MS5637 to function is to send several SCLs followed by a reset sequence or to repeat power on reset. 1 1 1 0 1 1 0 0 0 0 0 0 1 1 1 1 0 0 Device Address command S Device Address W A cmd byte A P From Master From Slave S = Start Condition P = Stop Condition W = Write R = Read A = Acknowledge N = Not Acknowledge Figure 5: I2C Reset Command PROM READ SEQUENCE The read command for PROM shall be executed once after reset by the user to read the content of the calibration PROM and to calculate the calibration coefficients. There are in total 7 addresses resulting in a total memory of 112 bit. Addresses contains factory data and the setup, calibration coefficients, the serial code and CRC. The command sequence is 8 bits long with a 16 bit result which is clocked with the MSB first. The PROM Read command consists of two parts. First command sets up the system into PROM read mode. The second part gets the data from the system. 1 1 1 0 1 1 0 0 0 1 0 1 0 0 1 1 0 0 Device Address command S Device Address W A cmd byte A P From Master From Slave S = Start Condition P = Stop Condition W = Write R = Read A = Acknowledge N = Not Acknowledge Figure 6: I2C Command to read memory address= 011 1 1 1 0 1 1 0 1 0 X X X X X X X X 0 X X X X X X X X 0 Device Address data data S Device Address R A Memory bit 15 - 8 A Memory bit 7 - 0 N P From Master From Slave S = Start Condition P = Stop Condition W = Write R = Read A = Acknowledge N = Not Acknowledage Figure 7: I2C answer from MS5637 CONVERSION SEQUENCE The conversion command is used to initiate uncompensated pressure (D1) or uncompensated temperature (D2) conversion. After the conversion, using ADC read command the result is clocked out with the MSB first. If the conversion is not executed before the ADC read command, or the ADC read command is repeated, it will give 0 as the output result. If the ADC read command is sent during conversion the result will be 0, the conversion will not stop and the final result will be wrong. Conversion sequence sent during the already started conversion process will yield incorrect result as well. A conversion can be started by sending the command to MS5637. When command is sent to the system it stays busy until conversion is done. When conversion is finished the data can be accessed by sending a Read command, when an acknowledge is sent from the MS5637, 24 SCL cycles may be sent to receive all result bits. Every 8 bits the system waits for an acknowledge signal. SENSOR SOLUTIONS /// MS5637-02BA03 06/2017 Page 10 MS5637-02BA03 Low Voltage Barometric Pressure Sensor 1 1 1 0 1 1 0 0 0 0 1 0 0 1 0 0 0 0 Device Address command S Device Address W A cmd byte A P From Master From Slave S = Start Condition P = Stop Condition W = Write R = Read A = Acknowledge N = Not Acknowledge Figure 8: I2C command to initiate a pressure conversion (OSR=4096, typ=D1) 1 1 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 Device Address command S Device Address W A cmd byte A P From Master From Slave S = Start Condition P = Stop Condition W = Write R = Read A = Acknowledge N = Not Acknowledge Figure 9: I2C ADC read sequence 1 1 1 0 1 1 0 1 0 X X X X X X X X 0 X X X X X X X X 0 X X X X X X X X 0 Device Address data data data S Device Address R A Data 23-16 A Data 15 - 8 A Data 7 - 0 N P From Master From Slave S = Start Condition P = Stop Condition W = Write R = Read A = Acknowledge N = Not Acknowledge Figure 10: I2C answer from MS5637 SENSOR SOLUTIONS /// MS5637-02BA03 06/2017 Page 11 MS5637-02BA03 Low Voltage Barometric Pressure Sensor CYCLIC REDUNDANCY CHECK (CRC) MS5637 contains a PROM memory with 112-Bit. A 4-bit CRC has been implemented to check the data validity in memory. The C code example below describes the CRC calculation which is stored on DB12 to DB15 in the first PROM word. A d d 0 1 2 3 4 5 6 D B 1 5 D B 1 4 D B 1 3 CRC D B 1 2 D B 1 1 D D D D D D D D D D D B B B B B B B B B B B 1 9 8 7 6 5 4 3 2 1 0 0 Factory defined C1 C2 C3 C4 C5 C6 Figure 11: Memory PROM mapping C Code example for CRC-4 calculation: unsigned char crc4(unsigned int n_prom[]) { int cnt; unsigned int n_rem=0; unsigned char n_bit; // n_prom defined as 8x unsigned int (n_prom[8]) // simple counter // crc reminder n_prom[0]=((n_prom[0]) & 0x0FFF); // CRC byte is replaced by 0 n_prom[7]=0; // Subsidiary value, set to 0 for (cnt = 0; cnt < 16; cnt++) // operation is performed on bytes { // choose LSB or MSB if (cnt%2==1) n_rem ^= (unsigned short) ((n_prom[cnt>>1]) & 0x00FF); else n_rem ^= (unsigned short) (n_prom[cnt>>1]>>8); for (n_bit = 8; n_bit > 0; n_bit--) { if (n_rem & (0x8000)) n_rem = (n_rem << 1) ^ 0x3000; else n_rem = (n_rem << 1); } } n_rem= ((n_rem >> 12) & 0x000F); // final 4-bit reminder is CRC code return (n_rem ^ 0x00); } SENSOR SOLUTIONS /// MS5637-02BA03 06/2017 Page 12 MS5637-02BA03 Low Voltage Barometric Pressure Sensor APPLICATION CIRCUIT The MS5637 is a circuit that can be used in conjunction with a microcontroller in mobile altimeter applications. Figure 12: Typical application circuit SENSOR SOLUTIONS /// MS5637-02BA03 06/2017 Page 13 MS5637-02BA03 Low Voltage Barometric Pressure Sensor PIN CONFIGURATION Pin Name Type Function 1 VDD P Positive supply voltage 2 SDA I/O I2C data 3 SCL I I2C clock 4 GND I Ground DEVICE PACKAGE OUTLINE Notes: (1) Dimensions in mm (2) General tolerance: 0.1 Figure 13: MS5637 package outline SENSOR SOLUTIONS /// MS5637-02BA03 06/2017 Page 14 MS5637-02BA03 Low Voltage Barometric Pressure Sensor RECOMMENDED PAD LAYOUT Pad layout for bottom side of the MS5637 soldered onto printed circuit board. Reserved area: Please do not route tracks between pads Figure 14: MS5637 pad layout SHIPPING PACKAGE SENSOR SOLUTIONS /// MS5637-02BA03 06/2017 Page 15 MS5637-02BA03 Low Voltage Barometric Pressure Sensor MOUNTING AND ASSEMBLY CONSIDERATIONS SOLDERING Please refer to the application note AN808 available on our website for all soldering issues. MOUNTING The MS5637 can be placed with automatic Pick & Place equipment using vacuum nozzles. It will not be damaged by the vacuum. Due to the low stress assembly the sensor does not show pressure hysteresis effects. It is important to solder all contact pads. CONNECTION TO PCB The package outline of the module allows the use of a flexible PCB for interconnection. This can be important for applications in watches and other special devices. CLEANING The MS5637 has been manufactured under clean-room conditions. It is therefore recommended to assemble the sensor under class 10'000 or better conditions. Should this not be possible, it is recommended to protect the sensor opening during assembly from entering particles and dust. To avoid cleaning of the PCB, solder paste of type "noclean" shall be used. Cleaning might damage the sensor! ESD PRECAUTIONS The electrical contact pads are protected against ESD up to 2 kV HBM (human body model). It is therefore essential to ground machines and personnel properly during assembly and handling of the device. The MS5637 is shipped in antistatic transport boxes. Any test adapters or production transport boxes used during the assembly of the sensor shall be of an equivalent antistatic material. DECOUPLING CAPACITOR Particular care must be taken when connecting the device to the power supply. A 100nF minimum ceramic capacitor must be placed as close as possible to the MS5637 VDD pin. This capacitor will stabilize the power supply during data conversion and thus, provide the highest possible accuracy. SENSOR SOLUTIONS /// MS5637-02BA03 06/2017 Page 16 MS5637-02BA03 Low Voltage Barometric Pressure Sensor TYPICAL PERFORMANCE CHARACTERISTICS PRESSURE AND TEMPERATURE ERROR VERSUS PRESSURE AND TEMPERATURE (TYPICAL VALUES) PRESSURE AND TEMPERATURE ERROR VERSUS POWER SUPPLY (TYPICAL VALUES) SENSOR SOLUTIONS /// MS5637-02BA03 06/2017 Page 17 MS5637-02BA03 Low Voltage Barometric Pressure Sensor ORDERING INFORMATION Part Number / Art. Number Product Delivery Form MS563702BA03-50 Micro Altimeter Module 3x3mm Tape & Reel NORTH AMERICA EUROPE ASIA Measurement Specialties, Inc., a TE Connectivity company Tel: 800-522-6752 Email: customercare.frmt@te.com Measurement Specialties (Europe), Ltd., a TE Connectivity Company Tel: 800-440-5100 Email: customercare.bevx@te.com Measurement Specialties (China) Ltd., a TE Connectivity company Tel: 0400-820-6015 Email: customercare.shzn@te.com TE.com/sensorsolutions Measurement Specialties, Inc., a TE Connectivity company. 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