325540009-00

MS5540C Miniature Barometer Module FEATURES   10 - 1100 mbar absolute pressure range 6 coefficients for software compensation stored onchip        Piezoresistive silicon micromachined sensor Integrated miniature pressure sensor 6.2 x 6.4 mm 16 Bit ADC 3-wire serial interface The MS5540C is a SMD-hybrid device including a precision piezoresistive pressure sensor and an ADC-Interface IC. The MS5540C HE is the high endurance version of MS5540C sensor. It is a miniature version of the MS5534C barometer/altimeter module and provides a 16 Bit data word from a pressure and temperature dependent voltage. MS5540C is a low power, low voltage device with automatic power down (ON/OFF) switching. A 3-wire interface is used for all communications with a microcontroller. Compared to MS5534A the pressure range (measurement down to 10 mbar) has been improved. The MS5540C is fully software compatible to the MS5534C and previous versions of MS5540. In addition, the MS5540C is from its outer dimensions compatible to the MS54XX series of pressure sensors. Compared to the previous version the ESD sensitivity level has been improved to 4kV on all pins. The gel protection of the sensor provides a water protection sufficient for 100 m waterproof watches without any additional protection. 1 system clock line (32.768 kHz) Low voltage and low power consumption High Endurance (HE version) APPLICATIONS      Mobile altimeter / barometer systems Weather control systems Adventure or multi-mode watches GPS receivers High endurance pad technology (HE version) SENSOR SOLUTIONS ///MS5540C 06/2017 Page 1 MS5540C Miniature Barometer Module TECHNICAL DATA Sensor Performances (VDD = 3 V) Pressure Min Range Typ 10 Max Unit 1100 mbar ADC 16 bit Resolution Accuracy 0°C to +50°C, 300 to 1000 mbar Accuracy -40°C to +85°C 300 to 1000 mbar 0.1 mbar -1 +1 mbar -2 +5 mbar Response time 35 ms Long term stability -1 mbar/yr Temperature Min Range Resolution Max Unit -40 +85 °C 0.005 0.015 °C -0.8 +0.8 °C Accuracy Typ FUNCTIONAL BLOCK DIAGRAM VDD MCLK Input MUX SENSOR Digital Interface +IN -IN ADC Sensor Interface IC DIN DOUT dig. Filter SCLK Memory (PROM) 64 bits SGND GND SENSOR SOLUTIONS ///MS5540C 08/2017 Page 2 MS5540C Miniature Barometer Module PERFORMANCE SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS Parameter Supply voltage Storage temperature Overpressure Symbol VDD TS P Conditions Ta = 25 °C Min -0.3 -40 Max 4 +85 10 Ta = 25 °C (ISO22810) Unit V °C bar Notes 1 2 NOTES 1) Storage in an environment of dry and non-corrosive gases. 2) The MS5540C is qualified referring to the ISO 22810 standard and can withstand an absolute pressure of 10 bar in salt water or 100 m water respectively. ELECTRICAL CHARACTERISTICS Parameter Symbol Operating pressure range p Supply voltage Supply current, average (1) during conversion (2) standby (no conversion) Current consumption into MCLK (3) Operating temperature range Conversion time External clock signal (4) Duty cycle of MCLK Serial data clock VDD (Ta = 25 °C, VDD = 3.0 V unless noted otherwise) Min Typ Max Unit mbar 10 1100 abs. 2.2 3.0 3.6 V Conditions VDD = 3.0 V Iavg Isc Iss MCLK = 32.768 kHz T tconv MCLK 0.1 µA mA µA 0.5 µA +85 35 35.000 60/40 500 °C ms kHz % kHz 4 1 -40 MCLK = 32.768 kHz 30.000 40/60 SCLK 32.768 50/50 NOTES 1) Under the assumption of one conversion every second. Conversion means either a pressure or a temperature measurement started by a command to the serial interface of MS5540C. 2) During conversion the sensor will be switched on and off in order to reduce power consumption; the total on time within a conversion is about 2 ms. 3) This value can be reduced by switching off MCLK while MS5540C is in standby mode. 4) It is strongly recommended that a crystal oscillator be used because the device is sensitive to clock jitter. A square-wave form of the clock signal is a must. SENSOR SOLUTIONS ///MS5540C 08/2017 Page 3 MS5540C Miniature Barometer Module PERFORMANCE SPECIFICATIONS (CONTINUED) PRESSURE OUTPUT CHARACTERISTICS With the calibration data stored in the interface IC of the MS5540C, the following characteristics can be achieved: Parameter Resolution Absolute Pressure Accuracy Relative Pressure Accuracy Relative Pressure Error over Temperature Long-term Stability Maximum Error over Supply Voltage Conditions Min p =750 .. 1100 mbar Ta = 25°C p =750 .. 1100 mbar Ta = 25°C T = 0 .. +50°C p =300 .. 1000 mbar T = -40 .. +85°C p =300 .. 1000 mbar 12 months VDD = 2.2 .. 3.6 V p = const. (VDD = 3.0 V unless noted otherwise) Typ Max Unit Notes 0.1 mbar 1 -1.5 +1.5 mbar 2, 6 -0.5 +0.5 mbar 3, 6 -1 +1 mbar 4, 6 -2 +5 mbar 4 mbar 5 -1 -1.6 1.6 mbar NOTES 1) A stable pressure reading of the given resolution requires taking the average of 2 to 4 subsequent pressure values due to noise of the ADC. 2) Maximum error of pressure reading over the pressure range. 3) Maximum error of pressure reading over the pressure range after offset adjustment at one pressure point. 4) With the second-order temperature compensation as described in Section "FUNCTION". See next section for typical operating curves. 5) The long-term stability is measured with non-soldered devices. 6) Wet/dry cycle: sensor must be dried typically once a day. TEMPERATURE OUTPUT CHARACTERISTICS This temperature information is not required for most applications, but it is necessary to allow for temperature compensation of the output. Parameter Resolution Conditions Accuracy T = 20 °C T = -40 .. + 85°C Min 0.005 -0.8 -2 Maximum Error over Supply Voltage VDD = 2.2 .. 3.6 V -0.2 (VDD = 3.0 V unless noted otherwise) Typ Max Unit Notes 0.01 0.015 °C 0.8 °C +2 °C 1 +0.2 °C 2 NOTES 1) With the second-order temperature compensation as described in Section "FUNCTION". See next section for typical operating curves. 2) At Ta = 25 °C. SENSOR SOLUTIONS ///MS5540C 08/2017 Page 4 MS5540C Miniature Barometer Module PERFORMANCE SPECIFICATIONS (CONTINUED) DIGITAL INPUTS Parameter Input High Voltage Input Low Voltage Signal Rise Time Signal Fall Time Symbol VIH VIL tr tf Conditions Min 80% VDD 0% VDD Symbol VOH VOL tr tf Conditions Isource = 0.6 mA Isink = 0.6 mA Min 80% VDD 0% VDD (T = -40 °C .. 85 °C, VDD = 2.2 V .. 3.6 V) Typ Max Unit 100% VDD V 20% VDD V 200 ns 200 ns DIGITAL OUTPUTS Parameter Output High Voltage Output Low Voltage Signal Rise Time Signal Fall Time (T = -40 °C .. 85 °C VDD = 2.2 V .. 3.6 V) Typ Max Unit 100% VDD V 20% VDD V 200 ns 200 ns ANALOG DIGITAL CONVERTER (ADC) Parameter Resolution Linear Range Conversion Time INL SENSOR SOLUTIONS ///MS5540C Symbol Conditions Min 4'000 MCLK = 32.768 kHz Within linear range 08/2017 -5 (T = -40 °C .. 85 °C VDD = 2.2 V .. 3.6 V) Typ Max Unit 16 Bit 40'000 LSB 35 ms +5 LSB Page 5 MS5540C Miniature Barometer Module TYPICAL PERFORMANCE CHARACTERISTICS ADC-value D1 vs Pressure (typical) ADC-value D2 vs Temperature (typical) 40000 22000 20000 35000 16000 -40°C 25°C 85°C 14000 12000 ADC-value D2 (LSB) ADC-value D1 (LSB) 18000 30000 25000 10000 20000 8000 15000 6000 0 100 200 300 400 500 600 700 800 900 1000 -40 1100 -20 0 20 40 60 80 Temperature (°C) Pressure (mbar) Pressure Error Accuracy vs temperature (typical) Pressure error vs supply voltage (typical) 18 1 16 0.8 14 0.6 12 10 0.2 0 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 -0.2 1000mbar 800mbar 300mbar Pressure error (mbar) Pressure error (mbar) 0.4 8 Perror(1000,1st order) Perror(1000,2nd order) 6 Perror(800,1st order) 4 Perror(800,2nd order) Perror(300,1st order) 2 Perror(300,2nd order) 0 -0.4 -2 -0.6 -4 -6 -0.8 -8 -40 -1 -20 0 20 40 60 80 Temperature (°C) Voltage (V) Temperature Error Accuracy vs temperature (typical) Temperature error vs supply voltage (typical) 15 0.15 0.1 Temperature error (°C) 0.05 0 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 Temperature error (°C) 10 Temperature error (standard calculation) Temperature error (with 2nd order calculation) 5 -0.05 0 -0.1 -5 -40 -0.15 SENSOR SOLUTIONS ///MS5540C -20 0 20 40 60 80 Temperature (°C) Voltage (V) 08/2017 Page 6 MS5540C Miniature Barometer Module Absolute Pressure Accuracy after Calibration, 2nd order compensation 4 3 Pressure error (mbar) 2 1 85°C 60°C 0 25°C 0°C -40°C -1 -2 -3 -4 0 100 200 300 400 500 600 700 800 900 1000 1100 Pressure (mbar) SENSOR SOLUTIONS ///MS5540C 08/2017 Page 7 MS5540C Miniature Barometer Module FUNCTION GENERAL The MS5540C consists of a piezo-resistive sensor and a sensor interface IC. The main function of the MS5540C is to convert the uncompensated analogue output voltage from the piezo-resistive pressure sensor to a 16-bit digital value, as well as providing a 16-bit digital value for the temperature of the sensor. “D1” “D2” Measured pressure (16-bit) Measured temperature (16-bit) As the output voltage of a pressure sensor is strongly dependent on temperature and process tolerances, it is necessary to compensate for these effects. This compensation procedure must be performed by software using an external microcontroller. D1 D2 Word 1..4 Pressure Calculation in external microcontroller Temperature Sensor For both pressure and temperature measurement the same ADC is used (sigma delta converter): • • for the pressure measurement, the differential output voltage from the pressure sensor is converted for the temperature measurement, the sensor bridge resistor is sensed and converted During both measurements the sensor will only be switched on for a very short time in order to reduce power consumption. As both, the bridge bias and the reference voltage for the ADC are derived from V DD, the digital output data is independent of the supply voltage. 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 64-bit PROM of each module. These 64-bit (partitioned into four words of 16-bit) must be read by the microcontroller software and used in the program converting D1 and D2 into compensated pressure and temperature values. PRESSURE AND TEMPERATURE MEASUREMENT The sequence of reading pressure and temperature as well as of performing the software compensation is depicted in Fig. 3 and Fig. 5. First Word1 to Word4 have to be read through the serial interface. This can be done once after reset of the microcontroller that interfaces to the MS5540C. Next, the compensation coefficients C1 to C6 are extracted using bit-wise logical- and shift-operations (refer to Fig. 4 for the bit-pattern of Word1 to Word4). For the pressure measurement, the microcontroller has to read the 16-bit values for pressure (D1) and temperature (D2) via the serial interface in a loop (for instance every second). Then, the compensated pressure is calculated out of D1, D2 and C1 to C6 according to the algorithm in Fig. 3 (possibly using quadratic temperature compensation according to Fig. 5). All calculations can be performed with signed 16-bit variables. Results of multiplications may be up to 32-bit long (+sign). In the flow according to Fig. 3 a division follows each multiplication. This division can be performed by bit-wise shifting (divisors are to the power of 2). It is ensured that the results of these divisions are less than 65536 (16 bit). For the timing of signals to read out Word1 to Word4, D1, and D2 please refer to the paragraph “Serial Interface". SENSOR SOLUTIONS ///MS5540C 08/2017 Page 8 MS5540C Miniature Barometer Module Basic equations: System initialisation Start Example: Read calibration data (factory calibrated) from PROM of MS5540C Word1 = 46940 Word2 = 40217 Word3 = 25172 Word4 = 47212 Word1, Word2, Word3 and Word4 (4x16 Bit) Convert calibration data into coefficients: (see bit pattern of Word1-Word4) C1: Pressure sensitivity C2: Pressure offset C3: Temperature coefficient of pressure sensitivity C4: Temperature coefficient of pressure offset C5: Reference Temperature C6: Temperature coefficient of the temperature (15 Bit) (12 Bit) (10 Bit) (10 Bit) (11 Bit) (6 Bit) SENST1 OFFT1 TCS TCO Tref TEMPSENS C1 = 23470 C2 = 1324 C3 = 737 C4 = 393 C5 = 628 C6 = 25 (Refer to application note AN516 for limits of coefficients and Pressure and temperature measurement calculated results) Read digital pressure value from MS5540C D1 (16 Bit) D1 = 16460 Read digital temperature value from MS5540C D2 (16 Bit) D2 = 27856 Calculate calibration temperature UT1 = 25248 UT1 = 8*C5+20224 Calculate actual temperature Difference between actual temperature and reference temperature: dT = D2 - UT1 Actual temperature: dT(D2) = D2 - Tref dT TEMP(D2) = 20°+dT(D2)*TEMPSENS TEMP = 391 = 39.1 °C OFF(D2) = OFFT1+TCO*dT(D2) OFF SENS(D2) = SENST1+TCS*dT(D2) SENS = 49923 10 TEMP = 200 + dT*(C6+50)/2 (0.1°C resolution) = 2608 Calculate temperature compensated pressure Offset at actual temperature: OFF = C2*4 + ((C4-512)*dT)/212 Sensitivity at actual temperature: = 5220 SENS = C1 + (C3*dT)/210 + 24576 X = (SENS * (D1-7168))/214 - OFF Temperature compensated pressure: P = X*10/25 + 250*10 (0.1 mbar resolution) P(D1,D2) = D1*SENS(D2)-OFF(D2) X = 23093 P = 9716 = 971.6 mbar Display pressure and temperature value Fig. 3: Flow chart for pressure and temperature reading and software compensation SENSOR SOLUTIONS ///MS5540C 08/2017 Page 9 MS5540C Miniature Barometer Module NOTES 1) Readings of D2 can be done less frequently, but the display will be less stable in this case. 2) For a stable display of 1 mbar resolution, it is recommended to display the average of 8 subsequent pressure values. C1 (15 Bit) C5/I 1 Bit Word1 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 C5/II (10 Bit) Word2 DB9 DB8 DB7 DB6 DB5 DB4 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB5 DB4 DB9 DB8 DB7 DB6 DB5 DB4 DB0 DB10 DB3 DB2 DB1 DB0 DB7 DB6 DB1 DB0 C2/I (6 Bit) DB3 DB2 DB1 DB0 DB11 DB10 C3 (10 Bit) Word4 DB1 C6 (6 Bit) C4 (10 Bit) Word3 DB2 DB9 DB8 C2/II (6-Bit) DB3 DB2 DB1 DB0 DB5 DB4 DB3 DB2 Fig. 4: Arrangement (Bit-pattern) of calibration data in Word1 to Word4 SENSOR SOLUTIONS ///MS5540C 08/2017 Page 10 MS5540C Miniature Barometer Module SECOND-ORDER TEMPERATURE COMPENSATION In order to obtain full temperature accuracy over the whole temperature range, it is recommended to compensate for the non-linearity of the output of the temperature sensor. This can be achieved by correcting the calculated temperature and pressure by a second order correction factor. The second-order factors are calculated as follows: 200 TEMP 450 TEMP < 200 yes yes yes No correction Low Temperatures T2 = 11*(C6+24)*(200 - TEMP)*(200 – TEMP) / 220 P2 = 3 *T2 * (P - 3500)/2 TEMP > 450 14 High Temperatures T2 = 0 T2 = 3*(C6+24)*(450 - TEMP)*(450 – TEMP) / 220 P2 = 0 P2 = T2 * (P - 10000)/213 Calculate pressure and temperature TEMP = TEMP – T2 P = P – P2 Fig. 5: Flow chart for calculating the temperature and pressure to the optimum accuracy. SENSOR SOLUTIONS ///MS5540C 08/2017 Page 11 MS5540C Miniature Barometer Module SERIAL INTERFACE The MS5540C communicates with microprocessors and other digital systems via a 3-wire synchronous serial interface as shown in Fig. 1. The SCLK (Serial clock) signal initiates the communication and synchronizes the data transfer with each bit being sampled by the MS5540C on the rising edge of SCLK and each bit being sent by the MS5540C on the rising edge of SCLK. The data should thus be sampled by the microcontroller on the falling edge of SCLK and sent to the MS5540C with the falling edge of SCLK. The SCLK-signal is generated by the microprocessor’s system. The digital data provided by the MS5540C on the DOUT pin is either the conversion result or the software calibration data. In addition, the signal DOUT (Data out) is also used to indicate the conversion status (conversion-ready signal, see below). The selection of the output data is done by sending the corresponding instruction on the pin DIN (Data input). Following is a list of possible output data instructions:        Conversion start for pressure measurement and ADC-data-out Conversion start for temperature measurement and ADC-data-out Calibration data read-out sequence for Word1 Calibration data read-out sequence for Word2 Calibration data read-out sequence for Word3 Calibration data read-out sequence for Word4 RESET sequence “D1” “D2” (Figure 6a) (Figure 6b) (Figure 6c) (Figure 6d) (Figure 6c) (Figure 6d) (Figure 6e) Every communication starts with an instruction sequence at pin DIN. Fig. 6 shows the timing diagrams for the MS5540C. The device does not need a ‘Chip select’ signal. Instead there is a START sequence (3-Bit high) before each SETUP sequence and STOP sequence (3-Bit low) after each SETUP sequence. The SETUP sequence consists in 4-Bit that select a reading of pressure, temperature or calibration data. In case of pressure- (D1) or temperature- (D2) reading the module acknowledges the start of a conversion by a low to high transition at pin DOUT. Two additional clocks at SCLK are required after the acknowledge signal. Then SCLK is to be held low by the microcontroller until a high to low transition on DOUT indicates the end of the conversion. This signal can be used to create an interrupt in the microcontroller. The microcontroller may now read out the 16 bit word by giving another 17 clocks on the SLCK pin. It is possible to interrupt the data READOUT sequence with a hold of the SCLK signal. It is important to always read out the last conversion result before starting a new conversion. The RESET sequence is special as the module in any state recognizes its unique pattern. By consequence, it can be used to restart if synchronization between the microcontroller and the MS5540C has been lost. This sequence is 21-bit long. The DOUT signal might change during that sequence (see Fig. 6e). It is recommended to send the RESET sequence before each CONVERSION sequence to avoid hanging up the protocol permanently in case of electrical interference. DOUT SCLK Conversion start for pressure measurement and ADC-data-out "D1": end of conversion start of conversion conversion (33ms) ADC-data outMSB DIN DB7 DB6 DB5 DB4 DB3 DB2 DB1 ADC-data outLSB DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 sequence: START+P-measurement Bit0 Bit1 Bit2 Bit3 Bit4 Bit5 Bit6 Bit7 Bit8 Bit9 Start-bit Setup-bits Stop-bit Fig. 6a: D1 ACQUISITION sequence SENSOR SOLUTIONS ///MS5540C 08/2017 Page 12 MS5540C Conversion start for temperature measurement and ADC-data-out "D2": end of conversion conversion (33ms) start of conversion ADC-data outMSB DB7 DB6 DB5 DB4 DB3 DB2 DB1 DIN DOUT SCLK Miniature Barometer Module ADC-data outLSB DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 sequence: START+T-measurement Bit0 Bit1 Bit2 Bit3 Bit4 Bit5 Bit6 Bit7 Bit8 Bit9 Start-bit Setup-bits Stop-bit DIN DOUT SCLK Fig. 6b: D2 ACQUISITION sequence Calibration data re ad out sequence for word 1/ word 3: coefficient-data outMSB DB7 DB6 DB5 DB4 DB3 DB2 DB1 coefficient-data outLSB DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 sequence: coefficient read + address Bit0 Bit1 Bit2 Bit3 Bit4 Bit5 Bit6 Bit7 Bit8 Bit9Bit10Bit11 Start-bit Stop-bit Setup-bits address word 1 address word 3 DIN DOUT SCLK Fig. 6c: Word1, Word3 READING sequence Calibration data re ad out sequence for word 2/ word 4: coefficient-data outMSB DB7 DB6 DB5 DB4 DB3 DB2 DB1 coefficient-data outLSB DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 sequence: coefficient read + address Bit0 Bit1 Bit2 Bit3 Bit4 Bit5 Bit6 Bit7 Bit8 Bit9 Bit1 0Bit1 1 Start-bit Setu p-bits Sto p-bit address word 2 address word 4 DIN DOUT SCLK Fig. 6d: W2, W4 READING sequence RESET - sequence: sequence: RESET Bit0 Bit1 Bit2 Bit3 Bit4 Bit5 Bit6 Bit7 Bit8 Bit9 Bit10Bit11Bit12Bit13Bit14Bit15Bit16Bit17Bit18Bit19Bit20 Fig. 6e: RESET sequence (21 bit) SENSOR SOLUTIONS ///MS5540C 08/2017 Page 13 MS5540C Miniature Barometer Module APPLICATION INFORMATION GENERAL The advantage for this combination of a sensor with a directly adapted integrated circuit is to save other external components and to achieve very low power consumption. The main application field for this system includes portable devices with battery supply, but its high accuracy and resolution make it also suited for industrial and automotive applications. The possibility to compensate the sensor with software allows the user to adapt it to his particular application. Communication between the MS5540C and the widely available microcontrollers is realised over an easy-to-use 3-wire serial interface. Customers may select which microcontroller system to be used, and there are no specific standard interface cells required, which may be of interest for specially designed 4 Bitmicrocontroller applications. CALIBRATION The MS5540C is factory calibrated. The calibration data is stored inside the 64 bit PROM memory. SOLDERING Please refer to the application note AN808 for all soldering issues. HUMIDITY, WATER PROTECTION The version MS5540-CM carries a metal protection cap filled with silicone gel for enhanced protection against humidity. The properties of this gel ensure function of the sensor even when in direct water contact. This feature can be useful for waterproof watches or other applications, where direct water contact cannot be avoided. Nevertheless the user should avoid drying of hard materials like for example salt particles on the silicone gel surface. In this case it is better to rinse with clean water afterwards. Special care has to be taken to not mechanically damage the gel. Damaged gel could lead to air entrapment and consequently to unstable sensor signal, especially if the damage is close to the sensor surface. The metal protection cap is fabricated of special anticorrosive stainless steel in order to avoid any corrosive battery effects inside the final product. The MS5540CM was qualified referring to the ISO Standard 22810 and can withstand a pressure of 10 bar in salt water. For underwater operations as specified in ISO Standard 22810 it is important to seal the sensor with a rubber Oring around the metal cap. Any salt water coming to the contact side (ceramic and pads) of the sensor could lead to permanent damage. LIGHT SENSITIVITY The MS5540C is protected against sunlight by a layer of white gel. It is, however, important to note that the sensor may still be slightly sensitive to sunlight, especially to infrared light sources. This is due to the strong photo effect of silicon. As the effect is reversible there will be no damage, but the user has to take care that in the final product the sensor cannot be exposed to direct light during operation. This can be achieved for instance by placing mechanical parts with holes in such that light cannot pass. CONNECTION TO PCB The package outline of the module allows the use of a flexible PCB to connect it. This can be important for applications in watches and other special devices, and will also reduce mechanical stress on the device. For applications subjected to mechanical shock, it is recommended to enhance the mechanical reliability of the solder junctions by covering the rim or the corners of MS5540C's ceramic substrate with glue or Globtop-like material. SENSOR SOLUTIONS ///MS5540C 08/2017 Page 14 MS5540C Miniature Barometer Module DECOUPLING CAPACITOR Particular care must be taken when connecting the device to power supply. A 47 F tantalum capacitor must be placed as close as possible of the MS5540C's VDD pin. This capacitor will stabilize the power supply during data conversion and thus, provide the highest possible accuracy. APPLICATION EXAMPLE: ALTIMETER SYSTEM USING MS5540C MS5540C is a circuit that can be used in connection with a microcontroller in diving computer applications. It is designed for low-voltage systems with a supply voltage of 3V, particularly in battery applications. The MS5540C is optimised for low current consumption as the AD-converter clock (MCLK) can use the 32.768 kHz frequency of a standard watch crystal, which is supplied in most portable watch systems. For applications in altimeter systems MEAS Switzerland can deliver a simple formula to calculate the altitude, based on a linear interpolation, where the number of interpolation points influences the accuracy of the formula. 3V-Battery LCD-Display VDD XTAL1 32.768 kHz MS5540C VDD 47µF Tantal XTAL2 Keypad MCLK DIN DOUT SCLK GND 4/8bit-Microcontroller GND EEPROM optional Figure 7: Demonstration of MS5540C in a mobile altimeter SENSOR SOLUTIONS ///MS5540C 08/2017 Page 15 MS5540C Miniature Barometer Module PIN CONFIGURATION Fig. 2: Pin configuration of MS5540C Pin Name SCLK GND PV (1) PEN (1) VDD MCLK DIN DOUT Pin 1 2 3 4 5 6 7 8 Type I G N I P I I O Function Serial data clock Ground Negative programming voltage Programming enable Positive supply voltage Master clock (32.768 kHz) Serial data input Serial data output NOTE 1) Pin 3 (PV) and Pin 4 (PEN) are only used by the manufacturer for calibration purposes and should not be connected. RECOMMENDED PAD LAYOUT Pad layout for bottom side of MS5540C soldered onto printed circuit board. Fig. 8: Layout for bottom side SENSOR SOLUTIONS ///MS5540C 08/2017 Page 16 MS5540C Miniature Barometer Module DEVICE PACKAGE OUTLINES Fig. 9: Device package outlines of MS5540-C SENSOR SOLUTIONS ///MS5540C 08/2017 Page 17 MS5540C Miniature Barometer Module SHIPPING PACKAGE Tube Tape & reel SENSOR SOLUTIONS ///MS5540C 08/2017 Page 18 MS5540C Miniature Barometer Module ASSEMBLY MECHANICAL STRESS It is recommended to avoid mechanical stress on the PCB on which the sensor is mounted. The thickness of the PCB should not be below 1.6 mm. A thicker PCB is stiffer creating less stress on the soldering contacts. For applications where mechanical stress cannot be avoided (for example ultrasound welding of the case or thin PCB’s in watches) please fix the sensor with drops of low stress epoxy (for example Hysol FP-4401). MOUNTING The MS5540C 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. Special care has to be taken to not touch the protective gel of the sensor during the assembly. The MS5540C can be mounted with the cap down or the cap looking upwards. In both cases it is important to solder all contact pads. The Pins PEN and PV shall be left open or connected to VDD. Do not connect the Pins PEN and PV to GND! SEALING WITH O-RING In products like outdoor watches the electronics must be protected against direct water or humidity. For those products the MS5540-CM provides the possibility to seal with an O-ring. The protective cap of the MS5540CM is made of special anticorrosive stainless steel with a polished surface. In addition to this the MS5540CM is filled with silicone gel covering the sensor and the bonding wires. The O-ring (or O-rings) shall be placed at the outer diameter of the metal cap. This method avoids mechanical stress because the sensor can move in vertical direction. CLEANING The MS5540C has been manufactured under cleanroom conditions. Each device has been inspected for the homogeneity and the cleanness of the silicone gel. 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 “no-clean” shall be used. Cleaning might damage the sensor! ESD PRECAUTIONS The electrical contact pads are protected against ESD up to 4 kV HBM (human body model). It is therefore essential to ground machines and personal properly during assembly and handling of the device. The MS5540C 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. SENSOR SOLUTIONS ///MS5540C 08/2017 Page 19 MS5540C Miniature Barometer Module ORDERING INFORMATION Part Number 325540009-00 325540009-50 Description MS5540-CM 1BAR White Gel Tube MS5540-CM 1BAR White Gel T&R Delivery Form Tube Tape & Reel TOP-UP 325540009-10 MS5540-01BA 1BAR W Gel P-Caps Tray 325540009-60 MS5540-01BA 1BAR W Gel P-Caps T&R Tape & Reel 325540020-00 MS5540-HE 1BA White Gel HE Tube 325540020-50 MS5540-HE 1BA White Gel HE T&R 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. Measurement Specialties, TE Connectivity, TE Connectivity (logo) and EVERY CONNECTION COUNTS are trademarks. All other logos, products and/or company names referred to herein might be trademarks of their respective owners. The information given herein, including drawings, illustrations and schematics which are intended for illustration purposes only, is believed to be reliable. However, TE Connectivity makes no warranties as to its accuracy or completeness and disclaims any liability in connection with its use. TE Connectivity‘s obligations shall only be as set forth in TE Connectivity‘s Standard Terms and Conditions of Sale for this product and in no case will TE Connectivity be liable for any incidental, indirect or consequential damages arising out of the sale, resale, use or misuse of the product. Users of TE Connectivity products should make their own evaluation to determine the suitability of each such product for the specific application. © 2015 TE Connectivity Ltd. family of companies SENSOR SOLUTIONS ///MS5540C All Rights Reserved. 08/2017 Page 20