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www.sensirion.com Version 1.1 – April 2019 1/14 Datasheet SDP8xx-Digital Digital Differential Pressure Sensor Excellent repeatability, no drift, no offset Extended feature set – smart averaging Calibrated and temperature compensated Product Summary The SDP800 sensor family is Sensirion’s series of digital differential pressure sensors designed for high -volume applications. The sensors measure the pressure of air and non -aggressive gases with superb accuracy and no offset drift. The sensors cover a pressure range of up to ±500 Pa (±2 inch H2O / ±5 mbar) and deliver outstanding accuracy, also at the bottom end of the measuring range. The SDP800 Series features a digital 2-wire I2C interface, which makes it easy to connect directly to a microprocessor. The outstanding performance of these sensors is based on Sensirion’s patented CMOSens® sensor technology, which combines the sensor elemen t, signal processing and digital calibration on a small CMOS chip. The differential pressure is measured by a thermal sensor element using flow -through technology. The well -proven CMOS technology is perfectly suited for high-quality mass production and is the ideal choice for demanding and cost-sensitive OEM applications. Benefits of Sensirion’s CMOSens® Technology High reliability and long-term stability Best signal-to-noise ratio Industry-proven technology with a track record of more than 15 years Designed for mass production High process capability Content
www.sensirion.com Version 1.1 – April 2019 2/14 1. Ordering Information Use the part name and order number shown in the following table when ordering SDP800 series differential pressure sensor. Part name Form Factor Range I2C address Shipping Package Order number SDP800-500Pa Manifold mount 500Pa - bidirectional 0x25 Trays of 80 pieces 1-101551-01 SDP801-500Pa Manifold mount 500Pa - bidirectional 0x26 Trays of 80 pieces 3.000.142 SDP810-500Pa Tube connection 500Pa - bidirectional 0x25 Trays of 80 pieces 1-101532-01 SDP811-500Pa Tube connection 500Pa - bidirectional 0x26 Trays of 80 pieces 3.000.144 SDP800-125Pa Manifold mount 125Pa - bidirectional 0x25 Trays of 80 pieces 1-101599-01 SDP810-125Pa Tube connection 125Pa - bidirectional 0x25 Trays of 80 pieces 1-101597-01 2. Sensor Performance
2.1 Differential Pressure Specification1
Parameter SDP8xx-500Pa SDP8xx-125Pa Measurement range -500 to 500 Pa (-2 to 2 inH2O) -125 to 125 Pa (-0.5 to 0.5 inH2O) Zero point accuracy 2,3 0.1 Pa 0.08 Pa Span accuracy 2,3 3% of reading 3% of reading Zero point repeatability 3 0.05 Pa 0.04 Pa Span repeatability 3 0.5% of reading 0.5% of reading Span shift due to temperature variation < 0.5% of reading per 10°C < 0.5% of reading per 10°C Offset stability < 0.05 Pa/year < 0.05 Pa/year Flow step response time (τ63) < 3ms Resolution 16 bit Calibrated for Air, N2 Media compatibility Air, N2, O2, non-condensing Temperature compensation range -20 °C to +85 °C
2.2 Temperature Specification4
Measurement range -40 °C to +85 °C Resolution 16 bit Accuracy 2 °C (-10 °C to +60 °C) Repeatability 0.1°C 1 Unless otherwise noted, all sensor specifications are valid at 25°C with VDD = 3.3 V and absolute pressure = 966 mbar.
2 Includes repeatability
3 Total accuracy/repeatability is a sum of zero-point and span accuracy/repeatability. 4 The measured temperature is the temperature of the bulk silicon in the sensor. This temperature value is not only depending on the gas temperature, but also on the sensor’s surroundings. Using the signal to measure solely the gas temperature will need special precautions, such as isolating the sensor from external temperate influences.
www.sensirion.com Version 1.1 – April 2019 3/14 3. Specifications
3.1 Electrical Specifications
Parameter Symbol Condition Min. Typ. Max. Units Comments Supply Voltage VDD 2.7 5.5 V Power-up/down level VPOR 2.3 2.5 2.7 V Supply current IDD Measuring 3.8 5.5 mA Idle state 1.1 mA Sleep mode 1 uA
3.2 Timing Specifications
Parameter Symbol Condition Min. Typ. Max. Units Comments Power-up time tPU 25 ms Time to sensor ready Soft reset time tSR 2 ms Time between soft reset command or exit sleep mode and sensor ready I2C SCL frequency fI2C 400 1000 kHz Update rate differential pressure value Continuous mode 1800 2000 2200 Hz Update rate temperature value Continuous mode 112.5 Hz Temperature value is updated at least every 16 pressure values Measurement time Triggered mode 40 45 50 ms
3.3 Mechanical Specifications
Parameter Symbol Condition Min. Typ. Max. Units Comments Allowable overpressure Pmax 1 bar Rated burst pressure Pburst 5 bar Weight W 6 g
3.4 Materials
Wetted materials PBT (polybutylene terephthalate), glass (silicon nitride, silicon oxide), silicon, gold, FR4, silicone as static sealing, epoxy, copper alloy, lead-free solder REACH, RoHS REACH and RoHS compliant
3.5 Absolute Minimum and Maximum Ratings
Supply Voltage VDD -0.3 to 5.5 V Max Voltage on pins (SDA, SCL) -0.3 to VDD+0.3 V Input current on any pin ±70 mA Operating temperature range1 -40 to +85 °C Storage temperature range -40 to +85 °C Max. humidity for long term exposure 40°C dew point ESD HBM (human body model) 2 kV 1 For Air and N2. Long term exposure to (high concentrations of) O2 at high temperatures can reduce the product lifetime
www.sensirion.com Version 1.1 – April 2019 4/14 4. Pin Assignment The pin assignments of the SDP8xx-Digital can be found in Table 1 Pin no. Name Description
1 SCL Serial Clock (I2C Interface)
2 VDD VDD Supply
3 GND Connect to ground
4 SDA Bidirectional Serial Data (I2C Interface)
Table 1: SDP8xx-Digital pin assignment (bottom view). SDA GND VDD SCL
www.sensirion.com Version 1.1 – April 2019 5/14 5. Measurement Modes The SDP8xx-Digital is a highly v ersatile differential pressure sensor and is very flexible regarding the measurement speed. This flexibility not only allows for optimizing the sensor’s performance to a specific application, but also for adapting the sensor to different use cases. For example, in one use case the sensor is de tecting the smallest and fastest changes, whereas at another time the sensor can measure in larger intervals while consuming only little energy.
5.1 Continuous Mode vs Triggered Mode
In continuous mode the sensor is measuring at the highest speed and writes the measurement values to the I2C results buffer, where the I2C master can read out the value when it requires. In triggered mode the sensor is default in an idle state and wakes up when the command is sent. It then powers up the heater and does a measurement. During this time the sensor doesn’t acknowledge any I 2C read header, or stretches the clock when clock stretching is enabled . When the measurement is finished the sensor returns to the idle state and makes the measurement result available to be read out. For more details see chapter 6.3.3. Continuous mode Triggered mode Description Measures continuously Measures once after command is sent Measurement speed and rate Measurement result can be read out continuously and at any time, but not faster than 0.5ms. Measurement result is available in +/ - 45ms after command. Clock stretching is available. Measurement method Sensor configuration is optimized for speed and accuracy. Sensor configuration is optimized for low power consumption. Recommended use Best used where speed and accuracy are most important. Best used where energy consumption is more important than speed.
5.2 Continuous Mode and ‘Average till Read’
In continuous measurement modes a new measurement result is available every 0.5ms. A new value can be read out every 0.5ms. If the ‘average till read’ option is chosen, the sensor averages all values (xi) since last read out, or, when no read has occurred yet, since last start measurement command . This has the benefit that the user can read out the sensor at its own desired speed, without losing information and thus prevents aliasing. During the first 25 ms of averaging the averaged value is obtained as the arithmetic mean. 𝑥̅ = ∑ 𝑥𝑖 𝑁 𝑁 𝑖=1 for 𝑡 < 25 ms When the reading speed is even slower than 25 ms, the sensor will continue to average, but with another algorithm. In this algorithm exponential smoothing is used, with a smoothing factor 𝛼 = 0.05. 𝑆𝑘 = 𝛼 ∙ 𝑥𝑖 + (1 − 𝛼) ∙ 𝑆𝑘−1, 𝑆0 = 𝑥,̅ for 𝑡 > 25 ms Where S0 is the arithmetic value after the first 25 ms. Please refer to relevant literature for more information about exponential smoothing.
5.3 Temperature Compensation Modes and Absolute Pressure Dependency
The SDP8xx is temperature compensated both for differential pressure and for mass flow compensated differential pressure. In use cases where the SDP8xx is used to measure mass flow it is advised to use mass flow temperature compensation. In this case no absolute pressure compensation is required. For more information about temperature and absolute pressure compensation for differential pressure sensors, for example volume flow measurements in bypass, refer to the selection guide in the differential pressure download center on our website.
www.sensirion.com Version 1.1 – April 2019 6/14 6. Digital Interface Description The SDP8xx-digital interface is compatible with the I2C protocol. This chapter describes the command set for SDP8xx-digital. For detailed information about the I2C protocol, please check the document "NXP I2C-bus specification and user manual".
6.1 I2C Addresses
The following table lists the SDP8xx-digital product variants and its I2C addresses. Product Variant I2C address SDP800-500Pa / SDP810-500Pa 0x25 (b 0100101) SDP800-125Pa / SDP810-125Pa 0x25 (b 0100101) SDP801-500Pa / SDP811-500Pa 0x26 (b 0100110) The address is followed by a read or write bit.
6.2 I2C Sequences
The commands are 16 -bit. Data is read from the sensor in multiples of 16 -bit words, each followed by an 8 -bit checksum to ensure communication reliability. I2C master writes 16 bit command I2C master sends read header and receives multiple 16bit words with CRC byte. Dark areas with white text indicate that the sensor controls the SDA (Data) line. I2C sequences can be aborted with a NACK and STOP condition.
6.3 I2C Commands
The command set of the SDP8xx-digital consists of a set of different commands: - Continuous measurement o Start Continuous measurement commands o Stop measurement command - Triggered measurement commands - Soft reset - Entering and exiting sleep mode - Read product identifier and serial number S W ACK I2CAdr[6:0] Cmd[15:8] ACK Cmd[7:0] ACK S R ACK I2CAdr[6:0] Data1[15:8] ACK Data1[7:0] ACK CRC1[7:0] ACK P Data2[15:8] ACK Data2[7:0] ACK CRC2[7:0] ACK P or DataX[15:8] ACK DataX[7:0] ACK CRCX[7:0] ACK P or
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6.3.1 Start Continuous Measurement
The sensor measures both the differential pressure and temperature. Both measurement results can be read out through one single I2C read header. Continuous measurements can be started up in different configurations by a set of commands. Command code (Hex) Temperature compensation Averaging 0x3603 Mass flow Average till read 0x3608 Mass flow None - Update rate 0.5ms 0x3615 Differential pressure Average till read 0x361E Differential pressure None - Update rate 0.5ms After one of the commands has been sent, the chip continuously measures and updates the measurement results. New results can be read continuously with only an I2C read header. The measurement command must only be sent once, if acknowledged. The command must not be resent or other commands must not be sent until the stop measurement command has been issued. After the start measurement command is sent: - the first measurement result is available after 8ms. - small accuracy deviations (few % of reading) can occur during the next 12ms. When no measurement data is yet available the sensor will respond with a NACK to the I 2C read header (I2C address + read bit). Preceding command Consecutive read Description continuous measurement Byte1: DP 8msb Byte2: DP 8lsb Byte3: CRC Byte4: Temp 8msb Byte5: Temp 8lsb Byte6: CRC Byte7: Scale Factor differential pressure 8msb Byte8: Scale Factor differential pressure 8lsb Byte9: CRC After a start continuous measurement commands, the measurement results can be read out. The temperature and scale factor don’t need to be read out (every time). The read sequence can be aborted by a NACK and a STOP condition. The scale factor is for differential pressure in Pascal.
6.3.2 Stop Continuous Measurement
Command Command code (Hex) Description Stop continuous measurement 0x3FF9 This command stops the continuous measurement and puts the sensor in idle mode . It powers off the heater and makes the sensor receptive to another command after 500us. The Stop command is also required when switching between different c ontinuous measurement commands. When the sensor is in continuous measurement mode, the sensor must be stopped before it can accept another command. The only exception is the soft reset command as described in section 6.3.4. In idle mode the sensor will consume less power, but consider the sleep mode for most effective energy saving.
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6.3.3 Triggered Measurement
During a triggered measurement the sensor measures both differential pressure and temperature. The measurement starts directly after the command has been sent. The command needs to be repeated with every measurement. Command code (Hex) Temperature compensation Clock stretching 0x3624 Mass flow 0x3726 Mass flow Yes 0x362F Differential pressure 0x372D Differential pressure Yes During the 45ms that the sensor is measuring, no command can be sent to the sensor. After the 45ms the result can be read out and any command can be sent to the sensor. Monitoring whether or not the sensor is ready with its measurement can be done with the following methods. Method Available Description Clock stretching Only for clock stretching commands The sensor starts the measurement a fter the triggered measurement command with clock stretching. When an I2C read header is sent within 45ms the sensor performs clock stretching after acknowledging the read header. When the sensor has finished the measurement, it makes the result available by releasing the SCL. Polling Only for non-clock stretching commands In this mode the sensor does not acknowledge (NACK) an I2C read header as long as no measurement result is available. When new measurement data is available it can be read out by sending an I 2C read header and reading out the data from the sensor. In the table below the data layout of the results can be found. Preceding command Consecutive read Description Triggered measurement Byte1: DP 8msb Byte2: DP 8lsb Byte3: CRC Byte4: Temp 8msb Byte5: Temp 8lsb Byte6: CRC Byte7: Scale Factor differential pressure 8msb Byte8: Scale Factor differential pressure 8lsb Byte9: CRC After a triggered measurement command , the results can be read out when the sensor is finished with the measurement. The temperature and scale factor don’t ne ed to be read out (every time). The read sequence can be aborted by a NACK and a STOP condition. The scale factor is for differential pressure in Pascal.
6.3.4 Soft Reset
Command I2C address + W bit + command code (Hex) Consecutive read
Description
0x0006 NA This sequence resets the sensor. Note that the I 2C address is 0x00, which is the general call address, and that the command is 8 bit. The reset is implemented according to the I2C specification. After the reset command the sensor will take maximum 2ms to reset. During this time the sensor will not acknowledge its address nor accept commands.
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6.3.5 Entering and Exiting Sleep Mode
In sleep mode the sensor uses the minimum amount of current. The mode can only be entered from idle mode, i.e. when the sensor is not measuring. This mode is particularly useful for battery operated devices. To minimize the current in this mode, the complexity of the sleep mode circuit has been reduced as much as possible, which is mainly reflected by the way the sensor exits the sleep mode. In sleep mode the sensor cannot be soft reset. Command Command code (Hex) Consecutive read Enter Sleep mode 0x3677 NA Triggered mode: the sleep command can be sent after the result have been read out and the sensor is in idle mode. Continuous mode: the sleep command can be sent after a stop continuous measurement command has been issued and the sensor is in idle mode. Exit Sleep mode NA NA The sensor exits the sleep mode and enters the idle mode when it receives the valid I2C address and a write bit (‘0’). Note that the I 2C address is not acknowledged. The sensor should wake up within 2ms. Polling with a write header (I 2C address and a write bit) can be used to check whether the sensor has woken up.
6.3.6 Read Product Identifier
During assembly and start-up of the system, it might be required to check some basic parameters in the sensor - for example to check if the correct sensor is integrated. The product identifier and serial number can be read out after sending a sequence of two commands, both preceded by a start condition. Command Command code Consecutive read Description Read p roduct identifier 0x367C 0xE102 Byte1: Product number [31:24] Byte2: Product number [23:16] Byte3: CRC Byte4: Product number [15:8] Byte5: Product number [7:0] Byte6: CRC Byte7: Serial number [63:56] Byte8: Serial number [55:48] Byte9: CRC Byte10: Serial number [47:40] Byte11: Serial number [39:32] Byte12: CRC Byte13: Serial number [31:24] Byte14: Serial number [23:16] Byte15: CRC Byte16: Serial number [15:8] Byte17: Serial number [7:0] Byte18: CRC Note that both commands need to be preceded with an I2C write header (I2C address + W). The second command returns: - 32 bit unique product and revision number. The number is listed in the table below. Note that the last 8 bits are the revision number and can be subject to change. - 64 bit unique serial number Product Product number SDP800-500Pa 0x03020101 SDP810-500Pa 0x03020A01 SDP801-500Pa 0x03020401 SDP811-500Pa 0x03020D01 SDP800-125Pa 0x03020201 SDP810-125Pa 0x03020B01
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6.4 Checksum Calculation
The checksum byte is generated by a CRC algorithm with the following properties: Property Value Name CRC-8 Protected data read data Width 8 bit Polynomial 0x31 (x8 + x5 + x4 +1) Initialization 0xFF Reflect input False Reflect output False Final XOR 0x00 Example CRC(0xBEEF) = 0x92
6.5 Conversion to Physical Values
Conversion of the differential pressure and temperature sensor signals to a physical value is done with the scale factor.
6.5.1 Scale Factors
Parameter SDP8xx-500Pa SDP8xx-125Pa Differential Pressure (Pascal) 60 Pa-1 240 Pa-1 Differential Pressure (inches H2O) 14’945 (inH2O)-1 59’780 (inH2O)-1 Temperature (°C) 200 °C-1 200 °C-1
6.5.2 Differential Pressure
The digital calibrated differential pressure signal read from the sensor is a signed integer number (two's complement number). The integer value can be converted to the physical value by dividing it by the scale factor. differential pressure = sensor output scale factor
6.5.3 Temperature
The digital calibrated temperature signal read from the sensor is a signed integer number (two's complement number). The integer value can be converted to the physical value by dividing it by the scale factor. temperature in °C = sensor output scale factor
www.sensirion.com Version 1.1 – April 2019 11/14 7. Package Outline
7.1 Dimensions SDP80x – Manifold Connection
Figure 1: SDP80x. All dimensions in mm.
7.2 Dimensions SDP81x – Tube Connection
Figure 2: SDP81x. All dimensions in mm.
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7.3 Footprint
Figure 3: Footprint for PCB mounting (top view = sensor side). All dimensions in mm. A: Overall sensor dimensions B: Holes for additional mounting screws (optional) In case the sensor is not mounted on a PCB and is connected with a cable, the SDP800 series cap is recommended. A B SCL VDD GND SDA
www.sensirion.com Version 1.1 – April 2019 13/14 8. Soldering Standard wave soldering systems may be used for soldering SDP800 series sensors. Reflow soldering is not feasible and may damage the sensor. The sensor ports must be protected from solder splash and flux during soldering. Figure 4 shows an appropriate temperature profile with maximum temperature values. Figure 4: Suitable wave soldering profile. The characteristics of wave soldering machines vary, so any soldering setup must be tested before production use. 9. Shipping Package SDP8xx are shipped in trays of 80pcs. The tray dimension is 355mm x 255mm x 21.5mm. By piling them up, the height per tray can be considered as 19mm.
Revision History
Date Author Version Changes
21.03.2018 ANB V1 Released
02.04.2019 ANB V1.1 Added SDP801-500Pa and SDP811-500Pa product variants, which have I2C address 0x26. 200°C 150°C 100°C 50°C 0°C 250°C Start Flux zone Preheat zone Entrance to solder Wave Exit from solder Wave Solder Wave Peak Temp. Max. 260°C Max 145°C Approx. PCB bottom- side temp. PCB top-side temperature Approx. 1 min (Time in wave < 2 s)
www.sensirion.com Version 1.1 – April 2019 14/14 Important Notices Warning, personal injury Do not use this product as safety or emergency stop devices or in any other application where failure of the product could result in personal injury (including death). Do not use this produc t for applications other than its intended and authorized use. Before installing, handling, using or servicing this product, please consult the datasheet and application notes. Failure to comply with these instructions could result in death or serious injury. If the Buyer shall purchase or use SENSIRION products for any unintended or unauthorized application, Buyer shall defend, indemnify and hold harmless SENSIRION and its officers, employees, subsidiaries, affiliates and distributors against all claims, c osts, damages and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if SENSIRION shall be allegedly negligent with respect to the d esign or the manufacture of the product. ESD Precautions The inherent design of this component causes it to be sensitive to electrostatic discharge (ESD). To prevent ESD -induced damage and/or degradation, take customary and statutory ESD precautions when handling this product. See application note “Handling Instructions” for more information. Warranty SENSIRION warrants solely to the original purchaser of this product for a period of 12 months (one year) from the date of delivery that this product shall be of the quality, material and workmanship defined in SENSIRION’s published specifications of the product. Within such period, if proven to be defective, SENSIRION shall repair and/or replace this product, in SENSIRION’s discretion, free of charge to the Buyer, provided that: notice in writing describing the defects shall be given to SENSIRION within fourteen (14) days after their appearance; such defects shall be found, to SENSIRION’s reasonable satisfaction, to have arisen from SENSIRION’s faulty design, material, or workmanship; the defective product shall be returned to SENSIRION’s factory at the Buyer’s expense; and the warranty period for any repaired or replaced product shall be limited to the unexpired portion of the original period. This warranty does not apply to any equipment which has not been installed and used within the specifications recommended by SENSIRION for the intended and proper use of the equipment. EXCEPT FOR THE WARRANTIES EXPRESSLY SET FORTH HEREIN, SENSIRION MAKES NO WARRANTIES, EITHER EXPRESS OR IMPLIED, WITH RESPECT TO THE PRODUCT. ANY AND ALL WARRANTIES, INCLUDING WITHOUT LIMITATION, WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE EXPRESSLY EXCLUDED AND DECLINED. SENSIRION is only liable for defects of th is product arising under the conditions of operation provided for in the datasheet and proper use of the goods. SENSIRION explicitly disclaims all warranties, express or implied, for any period during which the goods are operated or stored not in accordance with the technical specifications. SENSIRION does not assume any liability arising out of any application or use of any product or circuit and specifically disclaims any and all liability, including without limitation consequential or incidental damages. All operating parameters, including without limitation recommended parameters, must be validated for each customer’s applications by customer’s technical experts. Recommended parameters can and do vary in different applications. SENSIRION reserves the rig ht, without further notice, (i) to change the product specifications and/or the information in this document and (ii) to improve reliability, functions and design of this product. Copyright © 2016-2019, SENSIRION. CMOSens® is a trademark of Sensirion All rights reserved Headquarters and Subsidiaries Sensirion AG Laubisruetistr. 50 CH-8712 Staefa ZH Switzerland phone: +41 44 306 40 00 fax: +41 44 306 40 30 info@sensirion.com www.sensirion.com Sensirion Inc., USA phone: +1 312 690 5858 info-us@sensirion.com www.sensirion.com Sensirion Korea Co. Ltd. phone: +82 31 337 7700~3 info-kr@sensirion.com www.sensirion.co.kr Sensirion Japan Co. Ltd. phone: +81 3 3444 4940 info-jp@sensirion.com www.sensirion.co.jp Sensirion China Co. Ltd. phone: +86 755 8252 1501 info-cn@sensirion.com www.sensirion.com.cn Sensirion Taiwan Co. Ltd phone: +886 3 5506701 info@sensirion.com www.sensirion.com To find your local representative, please visit www.sensirion.com/distributors