[2SMPP-03] Application Note No.MDMK-12-0500 Application Note 01 Usage of Pressure Sensor 2SMPP-03 Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 1 [2SMPP-03] Application Note No.MDMK-12-0500 INDEX 1 OUTLINE ..................................................................................................................................3 2 STRUCTURE OF PRESSURE SENSOR .................................................................................3 3 DIMENSIONS ...........................................................................................................................4 4 PRINCIPAL OF PRESSURE DETECTION ...............................................................................5 5 SPECIFICATIONS OF 2SMPP-03 ............................................................................................7 6 FEATURES OF PRODUCT ......................................................................................................7 7 USAGE .....................................................................................................................................8 7.1 7.2 7.3 CONNECTION METHOD .............................................................................................................8 EXAMPLE OF RECOMMENDED CIRCUIT.....................................................................................10 OUTPUT CHARACTERISTICS 1: BASIC OUTPUT CHARACTERISTICS OF 2SMPP-03 ELEMENTARY SUBSTANCE .....................................................................................................................................11 8 GLOSSARY ............................................................................................................................12 9 WARRANTY AND LIMITED LIABILITY..................................................................................14 10 CONTACT...............................................................................................................................16 11 HISTORY ................................................................................................................................16 Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 2 [2SMPP-03] Application Note No.MDMK-12-0500 1 Outline This document shows an overview of plus an example of a circuit and the recommended connection method to use with the Omron Gauge type pressure sensor (2SMPP-03). 2 Structure of Pressure Sensor Fig.1 shows the structure of 2SMPP-03. Each unit is [mm]. Air inlet hole Stem Lead frame リードフレーム ステム Sensor Chip センサーチップ ワイヤー 9.85mm Fig.a TOP View Cover カバー Lead frame リードフレーム センサーチップ Sensor Chip カバーボンド樹脂 Cover bonding material Wire 8.25mm 4.75mm PP03 1234 Cover カバー ボンディング樹脂 Bonding material ステム Stem ステム Stem Pressure 圧力 ワイヤー Wire Fig.b Inside TOP View Fig.1 Fig.c CROSS Section The structure and parts name of 2SMPP-03 Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 3 [2SMPP-03] Application Note No.MDMK-12-0500 3 Dimensions Fig. 2. shows the outline dimension of 2SMPP-03. Each unit is [mm]. ① Air inlet hole ④ Cavity No. Height of Character 0.4mm The recommended tube inside diameter is 2 mm. Fig. 2 Outline dimension of 2SMPP-03 Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 4 [2SMPP-03] Application Note No.MDMK-12-0500 4 Principal of Pressure detection Omron’s 2SMPP series pressure sensors utilize a piezo-resistive type sensing element. Fig. 3. shows image of overview of Piezo-resistive pressure sensor chip. The diaphragm (blue circle of a Fig. a) is a thin disc, formed on a silicon wafer and deformed by pressure difference between upper and lower. Piezoresistors(green part of Fig. b & Fig. c) are arranged on four points of this thin diaphragm. Aluminum アルミ配線 wire Piezoresistance ピエゾ抵抗 Vout(+) Bonding-Pad ボンディング・パッド Vcc Piezoresistance ピエゾ抵抗 Nsub 1.3mm Contact コンタクト GND Vout(-) 1.3mm Fig. a Top view Pressure 圧力 Fig. b Fig. 3. Null Pressure Fig. c Add Pressure Piezoresistive pressure sensor image and state of change diaphragm Atmospheric pressure (Light blue arrow) pushes down on the diaphragm, and the pressure to be measured (Pink arrow in Fig. c) pushes up from the bottom of the diaphragm. In Fig. b, the target pressure (green arrow) is equal to atmospheric pressure, so it is a condition that does not bend the diaphragm. In Fig. c, the target pressure (Pink arrow) is bigger than atmospheric pressure (Light blue arrow), so the diaphragm is pushed up. Under this condition, the deflection of the diaphragm changes the piezoresistance's value on the upper surface of diaphragm. Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 5 [2SMPP-03] Application Note No.MDMK-12-0500 Fig. 4 shows how to convert from piezoresistance value change to output voltage change. If the pressure applied to the upper and lower diaphragms are balanced, the bridge output voltage V0 is represented by formula 1.1. In theory V0 is zero if R1=R2=R3=R4, as the voltage is generated by a slight variation in manufacturing , and is defined as Voffset . Upon deflection of the diaphragm, pressure equilibrium is broken and each of the resistances of the piezoresistive are changed from R to R ± ⊿ R. Piezoresistive change in the resistance value which is arranged diagonally as shown by the arrows in the figure has the same tendency (increase or decrease). In case of the condition R=R1=R2=R3=R4 formula 1.1 applies, however when the piezoresistive value has changed from R to R ± ⊿ R formula 1.2 applies. This voltage is called the span voltage, by supplying a constant current I, the amount of change can be detected as a voltage V0 resistance value change amount(⊿ R). Since there are manufacturing variations in the piezoresistive R1/R2/R3/R4 as described above, the approximate expression of the span voltage is found in formula 1.3. Icc R1 R1 Bridge output voltage（Vo） R2 R2 ・・・Eq 1. 1 Span Voltage（Vo） Vo R4 R4 ⎛ R ⋅ R − R2 ⋅ R4 ⎞ ⎟⎟ ⋅ I V 0 = ⎜⎜ 1⋅ 3 ⎝ R1 + R 2 + R3 + R 4 ⎠ ⎛ ( R + ⊿R ) ⋅ ( R + ⊿R ) − ( R − ⊿R ) ⋅ ( R − ⊿R ) ⎞ ⎟⎟ ⋅ I V 0 = ⎜⎜ ⎝ ( R + ⊿R ) + ( R − ⊿R ) + ( R + ⊿R ) + ( R − ⊿R ) ⎠ R3 R3 = ⊿R ⋅ I ・・・Eq 1.2 Span Voltage（Vo） V 0 = ⊿R ⋅ I + V offset Fig. 4 ・・・Eq 1.3 Theoretical formula and the electrical equivalent circuit of Piezo-resistive pressure sensor Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 6 [2SMPP-03] Application Note No.MDMK-12-0500 5 Specifications of 2SMPP-03 Table 1 shows the main specifications of 2SMPP-03. Table 1 Specifications of 2SMPP-03 Item Pressure Type Applicable gases Driven method Item Description Gauge Pressure （Note 1） Air （Note 2） Constant Current Supply Min Typ Max Unit Note Pressure Range -50 50 kPa Withstand Pressure -80 120 kPa Supply Current 100 uADC Max Supply Current 200 uADC Ambient Operating Temp -10 100 ℃ Ambient Storage Temp -40 120 ℃ Ambient Operating 10 95 %RH Humidity Ambient Storage Humidity 10 95 %RH Electrical Characteristic（Temperature：23[℃], Drive current：100[uA] Constant current） Item Min Typ Max Unit Bridge Resistance Offset Voltage（Note 1） Span Voltage（Note 1） 18 20 22 kΩ -6.5 -2.5 1.5 mV mV 36.5 42.0 47.5 -48.5 -43.0 -37.5 Non-Linearity（Note 1） %FS（Note 1） 0.3 1.3 -0.3 0.7 Hysteresis（Note 1） %FS（Note 1） -0.2 0.2 -0.2 0.2 Temp influence of Span -1.0 1.0 3.0 -2.0 1.0 4.0 %FS（Note 1） -1.2 0.8 2.8 -1.8 1.2 4.2 %FS（Note 1） Temp influence of Offset -4.0 7.0 -4.0 7.0 （Note 1）：For the meaning of the unit, characteristics, refer to Chapter 8. （Note 2）：Please use dry gases, and avoid dust or corrosive gases. 6 Note at 50[kPa] pressure at -50[kPa] pressure 0～50[kPa] -50～0[kPa] 0～50[kPa] -50～0[kPa] 0[℃](0～50[kPa]) 85[℃]0～50[kPa] 0[℃](-50～0[kPa]) 85[℃](-50～0[kPa]) 0～85[℃]/0～50[kPa] 0～85[℃]/-50～0[kPa] Features of Product As discussed in the section on the principle of pressure sensing, piezoresistive type sensors to minimize the variation in piezoresistive leads to minimization of measurement error. By using CMOS technology which is applied to the production of highly integrated semiconductor, our gauge pressure sensor is able to achieve a good offset voltage, span voltage and temperature variation characteristics. Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 7 [2SMPP-03] Application Note No.MDMK-12-0500 7 Usage 7.1 Connection method As shown in Fig.5, when a constant current of 100uA is provided to the Piezoresistor between terminals 6 and 3. the output voltage, depending on the pressure change, will be output between terminal 1 and 4. Short-circuit terminals 5 and 6 in use and solder terminal 2 to the board, but leave open connection. Refer to the 100uA constant current circuit (Fig. 7) before use. i＝100uA → ５ ６ Constant current source ＋ Ｒ２ ↑ Ｒ１ １ Output Voltage ４ Ｒ３ － Ｒ４ ３ ③ ② ① Pin No. 1 2 3 4 5 6 ④ ⑤ Pin Name Vout(+) No Connect GND Vout(-) N-sub Icc ⑥ Fig. 5 Equivalent Circuit and Connection Diagram of 2SMPP-03 Be sure to check that there is no leak path between each terminal by solder paste before actual use. The desired characteristic may not be achieved if there is the influence of a leak path. Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 8 [2SMPP-03] Application Note No.MDMK-12-0500 Fig.6 shows the recommended mounting pad layout of 2SMPP-03. In order to penetrate the pressure port through the mounting board, through-hole of Φ4.0 mm needs to be made on a mounting board. Through-hole of Φ4.0mm for pressure port. Fig.6 Recommended Mounting PAD Layout of 2SMPP-03 Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 9 [2SMPP-03] Application Note No.MDMK-12-0500 7.2 Example of recommended circuit An example of a recommended circuit is shown in Fig.7. A constant current circuit and an instrumentation amplifier are used with an example of Gain=21. Herein, a power supply voltage is 5 [V]. ○ Calculation of constant current ( R1=40[kΩ] , R2=10[kΩ] ） ⎤ ⎡ 10[kΩ] ⎢5[V ] ⋅ ( 40[kΩ] + 10[kΩ] )⎥ ⎦ => Icc = ⎣ = 100[uA] 10[kΩ] R2 ⎤ ⎡ ⎢VDD ⋅ ( R1 + R 2 )⎥ ⎣ ⎦ Icc = R3 ○ Calculation of Gain ( R4～R5 , R7～R10=10[kΩ] , R6=1[kΩ] ) ⎛ 2 ⋅ 10[kΩ] ⎞ ⎛ 10[kΩ] ⎞ ⎛ 2 ⋅ R5 ⎞ ⎛ R9 ⎞ ⎟⎟ ⋅ ⎜⎜ ⎟⎟ = 21[ratio] Gain = 1 + ⎜ ⎟⋅⎜ ⎟ => Gain = 1 + ⎜⎜ ⎝ R6 ⎠ ⎝ R 4 ⎠ ⎝ 1[kΩ] ⎠ ⎝ 10[kΩ] ⎠ Herein, R4=R8, R5=R7, R9=R10 Then, final output voltage of Vout is defined as Vout = Gain ・Vs. ( Vs is sensor output voltage ) VDD = 5VDC Constant current circuit unit Amplifier circuit unit Pressure Sensor R1 = 40kOhm I s = 100uADC + + R4 = 10kOhm R9 = 10kOhm - - R5 = 10kOhm ⑥ R2 = 10kOhm ④ ① R6 = 1kOhm + Vout R7 = 10kOhm ③ + R8 = 10kOhm R3 = 10kOhm Fig.7 R10 = 10kOhm Reference Input EX) Ref = 1VDC Example of Recommended Circuit Diagram for 2SMPP-03 In such recommended circuit diagram, instrumentation amplifier such as Texas Instruments LMV324 with four operational amplifies can be used for gain adjustment. A metal film resistor with good temperature characteristics should be used for R3. In addition, it is necessary to adjust the Ref voltage value connected to R10 according to the gain to be used. For example, if Gain = 21 then Ref = 1.0 [V], if Gain=201 then Ref = 1.5 [V] would be needed. Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 10 [2SMPP-03] Application Note No.MDMK-12-0500 7.3 Output Characteristics 1: Basic output characteristics of 2SMPP-03 elementary substance Fig.8 shows the output characteristics at room temperature (25deg-C) when applying the pressure from -50 [kPa] to 50 [kPa] at the condition of the constant current 100 uA. Span voltage at positive pressure (0～50[kPa]) is typically 42 [mV],at negative pressure （-50～ 0[kPa]） is typically -43[mV]. Fig.8 Output Characteristic of 2SMPP-03 (raw output voltage between Terminal 1 and 4) Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 11 [2SMPP-03] Application Note No.MDMK-12-0500 8 Glossary z Various pressure and pressure reference name A gauge pressure is a pressure relative to the atmospheric pressure. A gauge pressure which is greater than atmospheric pressure, is called positive pressure. And a gauge pressure which is smaller than atmospheric pressure, is called negative pressure. Absolute Pressure Gauge Pressure Negative Pressure Positive Pressure Differential Pressure Perfect Vacuum Atmosphere ● Reference Pressure z Offset Voltage The output voltage at Null pressure. ( 0[kPa] ). z Span Voltage At positive pressure range (0～50[kPa]) It is calculated by subtracting the output voltage at Null pressure ( 0[kPa] ) from the output voltage at Maximum rating pressure ( 50[kPa] ). At negative pressure range (-50～0[kPa]) It is calculated by subtracting the output voltage at Null pressure ( 0[kPa] ) from the output voltage at Maximum rating pressure ( -50[kPa] ). z Non-Linearity At positive pressure range (0～50[kPa]) The amount of gap from an ideal output straight line and the output voltage at any pressure within the specified range which makes the deviation maximum. An ideal output line is drawn by connecting the points of output voltage at Null pressure ( 0[kPa] ) and at Maximum rating pressure ( 50[kPa] ). %FS notation that is normalized on the Span voltage at the time of 25 deg-C can be used. At negative pressure range (-50～0[kPa]) The amount of gap from an ideal output straight line and the output voltage at any pressure within the specified range which make the deviation maximum. An ideal output line is drawn by connecting the points of output voltage at Null pressure ( 0[kPa] ) and at Maximum rating pressure ( -50[kPa] ). %FS notation that is normalized on the Span voltage at the time of 25 deg-C can be used. z Hysteresis At positive pressure range (0～50[kPa]) The maximum output voltage deviation at any pressure within the specified range when a pressure is repeatedly applied from Null pressure ( 0[kPa] ) to Maximum rating pressure ( 50 [kPa] ). %FS notation that is normalized on the Span voltage at the time of 25 deg-C can be used. At negative pressure range (-50～0[kPa]) The maximum output voltage deviation at any pressure within the specified range when a pressure is repeatedly applied from Null pressure ( 0 [kPa] ) to Maximum rating pressure ( -50 [kPa] ). %FS notation that is normalized on the Span voltage at the time of 25 deg-C can be used. Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 12 [2SMPP-03] Application Note No.MDMK-12-0500 z %FS "Percent Full Scale". Target item and amount of change are normalized on the Span voltage at the time of 25 deg-C. The percentage notation can be used. Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 13 [2SMPP-03] Application Note No.MDMK-12-0500 9 WARRANTY AND LIMITED LIABILITY Thank you for your usage of products of Omron Corporation (“Omron”). Without any special agreements, this Terms and Conditions shall apply to all transactions regardless of who sells. Place an order, accepting this Terms and Conditions. 1. 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All Rights Reserved. 14 [2SMPP-03] Application Note No.MDMK-12-0500 as payment systems (c) Applications in a harsh condition or environment, including, without limitation, outdoor facilities, facilities with potential of chemical contamination or electromagnetic interference, facilities with vibration or impact and facilities on continual operation for a long period (d) Applications under conditions or environment which are not described in this specification (5) Omron Products shown in this catalogue are not intended to be used in automotive applications (including two wheel vehicles). Please DO NOT use the Omron Products in the automotive application. (6)THE PRODUCTS CONTAINED IN THIS CATALOG ARE NOT SAFETY RATED. THEY ARE NOT DESIGNED OR RATED FOR ENSURING SAFETY OF PERSONS, AND SHOULD NOT BE RELIED UPON AS A SAFETY COMPONENT OR PROTECTIVE DEVICE FOR SUCH PURPOSES. Please refer to separate catalogs for OMRON's safety rated products. 4. 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All Rights Reserved. 15 [2SMPP-03] Application Note No.MDMK-12-0500 10 Contact z z OMRON Electronic Components Web http://www.omron.com/ecb/index.html Contact Us For further inquiry such as delivery, price, sample and/or specification, please contact your local agency or Omron sales representative. ¾ Global Sales Office http://www.omron.com/ecb/service/network.html ¾ Mail Contact http://www.omron.com/ecb/contact/index.html ¾ Phone Micro Devices Division Tel: (81) 77-588-9200 686-1 Ichimiyake, Yasu, Shiga, 520-2362 JAPAN Place an order, accepting this Terms and Conditions. http://www.omron.com/ecb/products/order/index.html 11 History Revision Rev 1.0 DATE Oct01, 2013 Note New Released Copyright 2012-2013 OMRON Corporation. All Rights Reserved. 16