MS5535B (RoHS*) • • • • • • • • • PRESSURE SENSOR MODULE 0 - 14 bar absolute pressure range 6 coefficients for software compensation stored on-chip Piezoresistive silicon micromachined sensor Integrated miniature pressure sensor 9 x 9 mm 15 Bit ADC 3-wire serial interface 1 system clock line (32.768 kHz) Low voltage and low power consumption RoHS-compatible & Pb-free* DESCRIPTION The MS5535B is a SMD-hybrid device including a piezoresistive pressure sensor and an ADC-Interface IC. It provides a 16 Bit data word from a pressure and temperature dependent voltage. Additionally the module contains 6 readable coefficients for a highly accurate software calibration of the sensor. MS5535B 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 the previous version (MS5535A) the temperature range has been improved (-40 to +125°C. Other improvements concern the ESD sensitivity, current consumption and converter accuracy. FEATURES APPLICATIONS • Supply voltage 2.2 V to 3.6 V • Low supply current • -40°C to +125°C operation temperature • No external components required • 15 Bit ADC resolution pressure measurement and control systems • Mobile water depth measurement systems • Diving computers and divers watches BLOCK DIAGRAM VDD MCLK Input MUX SENSOR +IN -IN Digital Interface ADC Sensor Interface IC SGND DIN DOUT dig. Filter SCLK Memory (PROM) 64 bits GND Fig. 1: Block diagram 5535B. * The European RoHS directive 2002/95/EC (Restriction of the use of certain Hazardous Substances in electrical and electronic equipment) bans the use of lead, mercury, cadmium, hexavalent chromium and polybrominated biphenyls (PBB) or polybrominated diphenyl ethers (PBDE). DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 1 PIN CONFIGURATION Fig. 2: Pin configuration of MS5535B. Pin Name Pin Type Function GND 1 G Ground SCLK 2 I Serial data clock DOUT 3 O Data output DIN 4 I Data input MCLK 5 I Master clock (32.768 kHz) VDD 6 P Positive supply voltage PEN (1) 7 I Programming enable PV (1) 8 N Negative programming voltage NOTE 1) Pin 7 (PEN) and PIN 8 (PV) are only used by the manufacturer for calibration purposes and should not be connected. ABSOLUTE MAXIMUM RATINGS Parameter Supply voltage Storage temperature Overpressure Symbol VDD TS P Conditions o Ta = 25 C Min Max -0.3 -40 4 +125 o Ta = 25 C 30 Unit Notes V C 1 o bar NOTE 1) Storage and operation in an environment of dry and non-corrosive gases. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 2 RECOMMENDED OPERATING CONDITIONS (Ta = 25°C, VDD = 3.0 V unless noted otherwise) Parameter Symbol Conditions Min. Operating pressure range p 0 Supply voltage Supply current, average (1) during conversion (2) standby (no conversion) Current consumption into MCLK (3) Operating temperature range Conversion time VDD 2.2 External clock signal (4) Iavg Isc Iss VDD = 3.0 V 3.0 4 1 MCLK = 32.768 kHz T tconv -40 MCLK = 32.768 kHz MCLK Duty cycle of MCLK Serial data clock Typ. SCLK Max Unit 14 bar abs. 3.6 V 0.1 µA mA µA 0.5 µA +125 °C 35 ms 30.000 32.768 35.000 kHz 40/60 50/50 60/40 % 500 kHz 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 MS5535B. 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 MS5535B 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. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 3 ELECTRICAL CHARACTERISTICS DIGITAL INPUTS (T = -40°C .. 125°C, VDD = 2.2 V .. 3.6 V) Parameter Symbol Conditions Min Typ Max Unit Input High Voltage VIH 80% VDD 100% VDD V Input Low Voltage VIL 0% VDD 20% VDD V Signal Rise Time tr 200 ns Signal Fall Time tf 200 ns DIGITAL OUTPUTS (T = -40°C .. 125°C, VDD = 2.2 V .. 3.6 V) Parameter Symbol Conditions Min Output High Voltage VOH Isource = 0.6 mA Output Low Voltage VOL Isink = 0.6 mA Typ Max Unit 75% VDD 100% VDD V 0% VDD 20% VDD V Signal Rise Time tr 200 ns Signal Fall Time tf 200 ns AD-CONVERTER (T = -40°C .. 125°C, VDD = 2.2 V .. 3.6 V) Parameter Symbol Conditions Min Resolution INL DA5535B_000.doc 00005535838 ECN776 Max 15 Linear Range Conversion Time Typ 0 MCLK = 32.768 kHz Within linear range -4 February 15th, 2006 Unit Bit 40000 LSB 35 ms +4 LSB 4 PRESSURE OUTPUT CHARACTERISTICS With the calibration data stored in the interface IC of the MS5535B the following characteristics can be achieved: (VDD = 3.0 V unless noted otherwise) Parameter Conditions Min p = 0 .. 5 bar p = 0 .. 10 bar p = 0 .. 14 bar p = 0 .. 5 bar p = 0 .. 10 bar p = 0 .. 14 bar p = 0 .. 5 bar p = 0 .. 10 bar p = 0 .. 14 bar -25 -60 -150 -40 -60 -160 -80 -100 -200 Resolution Absolute Pressure Accuracy (Temperature range 0 .. +40°C) Absolute Pressure Accuracy (Temperature range -40 .. +85°C) Absolute Pressure Accuracy (Temperature range -40 .. +125°C) Long-term Stability Maximum Error over Supply Voltage Typ Max 1.2 6 months VDD = 2.2 .. 3.6 V +20 +20 +20 +100 +180 +200 +200 +300 +400 20 -20 +20 Unit Notes mbar 1 mbar 2 mbar 2 mbar 2 mbar 3 mbar/V 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) The long-term stability is measured with non-soldered devices. TEMPERATURE OUTPUT CHARACTERISTICS This temperature information is not required for most applications, but it is necessary to allow for temperature compensation of the pressure output. (VDD = 3.0 V unless noted otherwise) Parameter Conditions Resolution Accuracy Maximum Error over Supply Voltage Min Typ Max Unit 0.005 0.01 0.015 °C T = 20°C -0.8 0.8 °C T = -40 .. +125°C -2 +4 °C VDD = 2.2 .. 3.6 V -0.3 0.3 °C Notes 1 NOTE 1) With the second-order temperature compensation as described in Section “FUNCTION". See next section for typical operating curves. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 5 TYPICAL PERFORMANCE CURVES ADC-value D1 vs Pressure (typical) 30000 ADC-value D1 (LSB) 25000 -40°C 25°C 125°C 20000 15000 10000 0 2000 4000 6000 8000 10000 12000 14000 Pressure (mbar) ADC-value D2 vs Temperature (typical) 45000 40000 ADC-value D2 (LSB) 35000 30000 25000 20000 15000 -40 -20 0 20 40 60 80 100 120 Temperature (°C) DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 6 Absolute Pressure Accuracy after Calibration 250 200 Pressure error (mbar) 150 125°C 100 85°C 60°C 25°C 0°C 50 -40°C 0 0 2000 4000 6000 8000 10000 12000 14000 12000 14000 -50 -100 Pressure (mbar) Absolute Pressure Accuracy (2nd order) after Calibration 40 20 0 0 2000 4000 6000 8000 10000 Pressure error (mbar) -20 125°C -40 85°C 60°C -60 25°C 0°C -80 -40°C -100 -120 -140 -160 Pressure (mbar) DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 7 Pressure Error Accuracy vs temperature (typical) 120 100 Pressure error (mbar) 80 60 Pres. error 4bar (1st order) 40 Pres. error 4bar (2nd order) 20 0 -40 -20 0 20 40 60 80 100 120 -20 -40 Temperature (°C) Temperature Error Accuracy vs temperature (typical) 15 Temperature error (°C) 10 Temperature error (standard calculation) Temperature error (with 2nd order calculation) 5 0 -40 -20 0 20 40 60 80 100 120 -5 Temperature (°C) DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 8 Pressure error vs supply voltage (typical) 8 6 4 Pressure error(mbar) 2 14000mba r 6000mbar 0 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.4 3.6 1000mbar -2 -4 -6 -8 -10 Voltage (V) Temperature error (25°C) vs supply voltage (typical) 0.15 Temperature error (°C) 0.1 0.05 0 2.2 2.4 2.6 2.8 3 3.2 -0.05 -0.1 -0.15 Voltage (V) DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 9 FUNCTION GENERAL The MS5535B consists of a piezoresistive sensor and a sensor interface IC. The main function of the MS5535B is to convert the uncompensated analogue output voltage from the piezoresistive pressure sensor to a 16-Bit digital value, as well as providing a 16-Bit digital value for the temperature of the sensor. • measured pressure (16-Bit) • measured temperature (16-Bit) “D1” “D2” 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 Word1..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 VDD, 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 64Bit 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 the 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 MS5535B. 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 each multiplication is DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 10 followed by a division. 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”. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 11 Basic equations: System initialisation Start Read calibration data (factory calibrated) from PROM of MS5535B Word1 = 18556 Word2 = 49183 Word3 = 22354 Word4 = 28083 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 Pressure and temperature measurement Example: (13 (13 (10 (9 (12 (7 Bit) Bit) Bit) Bit) Bit) Bit) SENST1 OFFT1 TCS TCO T ref TEMPSENS C1 = C2 = C3 = C4 = C5 = C6 = 2319 4864 349 219 2002 51 Read digital pressure value from MS5535B D1 (16 Bit) D1 = 17788 Read digital temperature value from MS5535B D2 (16 Bit) D2 = 26603 Calculate calibration temperature UT1 = 8*C5 + 10000 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 = 243 = 24.3°C OFF(D2) = OFFT1 + TCO*dT(D2) OFF SENS(D2) = SENST1 + TCS * dT(D2) SENS = 4198 11 TEMP = 200 + dT*(C6+100)/2 (0.1°C resolution) = 587 Calculate temperature compensated pressure Offset at actual temperature: 12 OFF = C2 + (C4 - 250)*dT/2 + 10000 Sensitivity at actual temperature: = 14859 SENS = C1/2 + (C3 + 200) )*dT/213 + 3000 Temperature compensated pressure: 12 P = SENS * (D1 - OFF))/2 + 1000 P(D1,D2) = SENS(D2) * (D1 – OFF(D2)) P = 4001 = 4001mbar Display pressure and temperature value Fig. 3: Flow chart for pressure and temperature reading and software compensation. NOTES 1) Readings of D2 can be done less frequently, but the display will be less stable in this case. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 12 2) For a stable display of 0.1 mbar resolution, it is recommended to display the average of 8 subsequent pressure values. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 13 C1 (13 Bit) Word1 DB1 2 DB1 1 DB1 0 DB9 DB8 DB7 DB6 C2/I (3 Bit) DB5 DB4 DB3 DB2 DB1 C2/II (10 Bit) Word2 DB9 DB8 DB7 DB6 DB5 DB4 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB1 1 DB1 0 DB8 DB7 DB6 DB5 DB4 DB1 1 DB10 DB9 DB7 DB6 DB2 DB1 DB0 DB2 DB1 DB0 DB8 C5/II (6 Bit) DB3 DB2 DB1 DB0 DB5 DB4 C4 (9 Bit) Word4 DB1 2 C5/I (6 Bit) C3 (10 Bit) Word3 DB0 DB3 C6 (7 Bit) DB3 DB2 DB1 DB0 DB6 DB5 DB4 DB3 Fig. 4: Arrangement (Bit-pattern) of calibration data in Word1 to Word4. SECOND-ORDER TEMPERATURE COMPENSATION In order to obtain best 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: dT ≥ 0 dT < 0 yes yes Low Temperatures High Temperatures dT2 = dT – (dT/128*dT/128)/2 dT2 = dT – (dT/128*dT/128)/8 Calculate temperature TEMP = (200 + dT2*(C6+100)/2 11) (0.1°C) Fig. 5: Flow chart for calculating the temperature and pressure to the optimum accuracy. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 14 SERIAL INTERFACE The MS5535B 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 synchronises the data transfer with each Bit being sampled by the MS5535B on the rising edge of SCLK and each Bit being sent by the MS5535B 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 MS5535B with the falling edge of SCLK. The SCLK-signal is generated by the microprocessor’s system. The digital data provided by the MS5535B 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 MS5535B. 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 during the last bit of the STOP sequence. 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 16Bit 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. Conversion start for pressure measurement and ADC-data-out "D1": end of conversion st art of conversion conversion (33ms) ADC-dat a outMS B DB7 DB6 DB5 DB4 DB3 DB2 DB1 DIN DOUT SCLK The RESET sequence is special as its unique pattern is recognised by the module in any state. By consequence it can be used to restart if synchronisation between the microcontroller and the MS5535B 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. ADC-dat a outLS B DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 sequence: ST ART +P -measurement Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Bit 9 St art -bit Set up-bit s St op-bit Fig. 6a: D1 ACQUISITION sequence. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 15 end of conversion conversion (33ms) st art of conversion ADC-dat a outMS B DB7 DB6 DB5 DB4 DB3 DB2 DB1 DIN DOUT SCLK Conversion start for temperature measurement and ADC-data-out "D2": ADC-dat a outLS B DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 sequence: ST ART +T -measurement Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Bit 9 St art -bit Set up-bit s St op-bit DIN DOUT SCLK Fig. 6b: D2 ACQUISITION sequence. Calibration data read out sequence for word 1/ word 3: coefficient -dat a outMS B DB7 DB6 DB5 DB4 DB3 DB2 DB1 coefficient -dat a outLS B DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 sequence: coefficient read + address Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Bit 9Bit 10Bit 11 St art -bit St op-bit Set up-bit s address word 1 address word 3 DIN DOUT SCLK Fig. 6c: Word1, Word3 READING sequence. Calibration data read out sequence for word 2/ word 4: coefficient -dat a outMS B DB7 DB6 DB5 DB4 DB3 DB2 DB1 coefficient -dat a outLS B DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 sequence: coefficient read + address Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Bit 9 Bit 10Bit 11 St art -bit Set up-bit s St op-bit address word 2 address word 4 Fig. 6d: W2, W4 READING sequence. DIN DOUT SCLK RESET - sequence: sequence: RESET Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Bit 9 Bit 10Bit 11Bit 12Bit 13Bit 14Bit 15Bit 16Bit 17Bit 18Bit 19Bit 20 Fig. 6e: RESET sequence (21-Bit). DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 16 APPLICATION INFORMATION GENERAL The advantage of combining a pressure sensor with a directly adapted integrated circuit is to save other external components and to achieve a 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 a software allows the user to adapt it to his particular application. Communication between the MS5535B 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 Bit-microcontroller applications. CALIBRATION The MS5535B 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 MS5535BM 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. LIGHT SENSITIVITY The MS5535B is 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 MS5535B' s ceramic substrate with glue or Globtop-like material. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 17 DECOUPLING CAPACITOR Particular care must be taken when connecting the device to power supply. A 47 µF tantalum capacitor must be placed as close as possible of the MS5535B' s VDD pin. This capacitor will stabilise the power supply during data conversion and thus, provide the highest possible accuracy. APPLICATION EXAMPLE: DIVING COMPUTER SYSTEM USING MS5535B MS5535B 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 3 V, particularly in battery applications. The MS5535B 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. 3V-Battery LCD-Display VDD XTAL1 32.768 kHz MS5535 VDD 47uF Tantal XTAL2 Keypad MCLK DIN DOUT SCLK GND 4/8bit-Microcontroller VSS EEPROM optional Figure 7: Demonstration of MS5535B in a diving computer. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 18 DEVICE PACKAGE OUTLINES Fig. 8: Device package outlines of MS5535BM. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 19 RECOMMENDED PAD LAYOUT Pad layout for bottom side of MS5535B soldered onto printed circuit board Pad layout for top side of MS5535B soldered onto printed circuit board DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 20 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 be not below 1.6 mm. A thicker PCB is more stiff 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) at the corners of the sensor as shown below. Fixing with Globtop increases mechanical stability MOUNTING The MS5535B 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 MS5535B 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! Solder at both sides to increase mechanical stability Placement cap down (hole in PCB to fit cap) Placement cap up (rectangular hole in PCB to fit Globtop) SEALING WITH O-RING In products like outdoor watches the electronics must be protected against direct water or humidity. For those products the MS5535BM provides the possibility to seal with an O-ring. The protective cap of the MS5535BM is made of special anticorrosive stainless steel with a polished surface. In addition to this the MS5535BM 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. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 21 CLEANING The MS5535B 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 contacts except programming pads are protected against ESD according to 2 kV HBM (human body model). The PV programming pad is more sensitive due to the nature of the OTP programming cells that store the calibration coefficients. The breakdown voltage of PV is 1 kV. It is therefore essential to ground machines and personal properly during assembly and handling of the device. The MS5535B 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. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 22 ORDERING INFORMATION Product Code MS5535-BM Product Art.-Nr. 14 Pressure Sensor Module with gel 325535001 Package SMD hybrid with solder paste, metal protection cap, silicon gel sensor protection Comments standard version FACTORY CONTACTS Intersema Sensoric SA Ch. Chapons-des-Prés 11 CH-2022 BEVAIX SWITZERLAND Tel. 032 847 9550 Tel. Int. +41 32 847 9550 Telefax +41 32 847 9569 e-mail: http://www.intersema.ch NOTICE Intersema reserves the right to make changes to the products contained in this data sheet in order to improve the design or performance and to supply the best possible products. Intersema assumes no responsibility for the use of any circuits shown in this data sheet, conveys no license under any patent or other rights unless otherwise specified in this data sheet, and makes no claim that the circuits are free from patent infringement. Applications for any devices shown in this data sheet are for illustration only and Intersema makes no claim or warranty that such applications will be suitable for the use specified without further testing or modification. DA5535B_000.doc 00005535838 ECN776 February 15th, 2006 23