UM10370 User Manual for the PCF8883 Evaluation Kit OM11055
Contents
1. eene 10 8 1 D finitiolis iii Hire Aide eet 10 8 2 Disclaimers ssssssssseeneeeee 10 8 3 Trademarks iiie cederet reete dens 10 9 ena 11 founded by Please be aware that important notices concerning this document and the product s described herein have been included in the section Legal information NXP B V 2009 All rights reserved For more information please visit http www nxp com For sales office addresses email to salesaddresses nxp com Date of release 2 December 2009 Document identifier UM10370 2 Mouser Electronics Authorized Distributor Click to View Pricing Inventory Delivery amp Lifecycle Information NXP OM11055 5982. PCF8883 board and the other end into a PC or a USB power adapter Alternatively a 9V battery can be used The capacitive proximity sensor is now active 2 With no jumpers on J9 timed mode touching the sense plate CP1 will turn on the green output LED LD1 for about two seconds Please read this manual completely for configuration options and modes UM10370_2 NXP B V 2009 All rights reserved User manual Rev 02 2 December 2009 3 of 11 NXP Semiconductors U M1 0370 PCF8883 Evaluation Kit OM11055 3 Board description and layout Below the top view of the board is shown Option to connect an external sense plate PCF8883 High impedance op amp 0Y1 Sensor output connections Output LED LD1 Setting of output time Mini USB connector for power Setting of switch mode Push button toggle or pulse l B Optional header to select sense plate defaults to CP1 PCF8883 EVAL BOARD Four sense plates selected by J6 Fig 1 Top view of the PCF8883 evaluation board The lower halve is dominated by four sensor areas of different size The actual circuit is on the upper halve of the board Arrows indicate the parts of interest which are described more in detail in subsequent sections 3 1 Setting the PCF8883 operation modes The OM11055 allows the user to set one of three output switching behaviour modes using jumper J9 Refer to Fig 2 a With no jumper on J9 the PCF8883 will
3. and therefore such inclusion and or use is for the customer s own risk Applications Applications that are described herein for any of these products are for illustrative purposes only NXP Semiconductors makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification Export control This document as well as the item s described herein may be subject to export control regulations Export might require a prior authorization from national authorities 8 3 Trademarks Notice All referenced brands product names service names and trademarks are property of their respective owners NXP B V 2009 All rights reserved User manual Rev 02 2 December 2009 10 of 11 NXP Semiconductors UM10370 PCF8883 Evaluation Kit OM11055 9 Contents 1 Introd ction eee 3 2 Quick slart eco renoaaino nior nns eura 3 3 Board description and layout 4 3 1 Setting the PCF8883 operation modes 4 4 User configurable settings 4 1 Sensor plate selection sssss 4 2 Sensitivity settings 4 3 Power supply options 4 4 High impedance op amp 5 Sensor adjustment 6 Board schematic eesuusss T References and resource URLs 8 8 Legal information
4. UM10370 User Manual for the PCF8883 Evaluation Kit OM11055 Rev 02 2 December 2009 User manual Document information Info Content Keywords Capacitive switch sensor proximity switch PCF8883 OM11055 PCF8883 evaluation board Abstract The OM11055 is a PCF8883 evaluation board which can be used to demonstrate and evaluate the PCF8883 capacitive proximity switch The PCB is designed to make it easy to adjust the switch s sensitivity The board can be powered using a Mini USB cable or a 9V battery founded by Philips NXP Semiconductors UM10370 Revision history PCF8883 Evaluation Kit OM11055 Rev Date 02 20091202 01 20090731 Description Fully updated version to reflect the change of the evaluation kit Revision 1 was written for the preliminary evaluation board which was marked MA142_EVALBOARD BRD Revision 2 is valid for the new evaluation kit OM11055 not marked as such on the board Initial release Contact information For additional information please visit http www nxp com For sales office addresses please send an email to salesaddresses nxp com UM10370 2 NXP B V 2009 All rights reserved User manual Rev 02 2 December 2009 2 of 11 NXP Semiconductors U M1 0370 PCF8883 Evaluation Kit OM11055 1 Introduction This user manual describes the OM11055 evaluation kit This board was developed in order to provide a tool for application engineers and d
5. d to the input pin which is marked In this case do not jumper any pins on J6 Cut trace under J6 to disable CP1 User can now add an 8pin header and Jumper at J6 to select sensor plates CP1 to CP4 Or User can connect external sensor at J14 amp J18 using coax cable Fig 3 Sensor plate selection UM10370 2 NXP B V 2009 All rights reserved User manual Rev 02 2 December 2009 5 of 11 NXP Semiconductors U M1 0370 UM10370_2 PCF8883 Evaluation Kit OM11055 The size and form of the sensor plate can be varied to obtain optimal switching behaviour or to shape the sensor for a given application The following figure shows some creative examples of how the switch can be used with sensors of various size and shape J 2 a Area b Strip c Wire open d Wire loop e Solid body Fig 4 Examples of sensor areas and shapes 4 2 Sensitivity settings The OM11055 board allows for easy modifications to the circuit to change the switch s sensitivity It can be difficult to remove and install surface mount capacitors and resistors without damaging the board Therefore the OM11055 board includes holes to add conventional through hole passive components which enable quick evaluation of different values To remove the SMD components R1 and C1 from the circuit cut the trace shorts on the underside of the PCB at J4 and J5 Refer to the PCF8883 datasheet and the application no
6. evelopment engineers wishing to try and evaluate the single channel PCF8883 capacitive proximity switch A LED displays the status of the switch test points facilitate measurements of important signals The desired capacitive sensor area can vary in terms of material form size and switching distance Each particular switch configuration demands a suitable electrical circuit for the input signal This board allows to easily change the input circuit and the two capacitors which define the sensitivity and reaction speed of the sensor in a typical application This offers the opportunity to rapidly evaluate many possible switching configurations Features e Simple demonstration of the single channel PCF8883 capacitive proximity switch e Jumper to select one of the three possible switch modes of the PCF8883 e Evaluate different sensor sizes four different sensor plates included on the board or off board user defined sensors e Two power supply options via USB cable or a 9V battery Provisions for through hole components allowing them to be easily changed Contents of the kit One PCF8883 evaluation board One 3 ft USB A B Mini Cable e All documentation is available from the NXP website http www standardics nxp com support boards pcf8883 2 Quick start The OM11055 is an evaluation board for the single channel PCF8883 capacitive proximity switch 1 Apply power to the board by connecting the supplied mini USB cable to the
7. hts reserved User manual Rev 02 2 December 2009 7 of 11 NXP Semiconductors U M1 0370 PCF8883 Evaluation Kit OM11055 Table 1 Optimizing step by step Step Component 1 Cin Cr 2 Rs 3 Rc 4 Copc 5 Cerin Description Min Typ Max Cin is the total input capacitance Csensor Ccable Cr Cr should 10 pF 30 pF 60 pF be chosen such that Cin is about 30 pF This can be checked by measuring the voltage over Ccpc which should then be about 1 2 Vpp Rs and Cr form a low pass filter The typical values are likely to be 68kO correct for most applications This resistance compensates large input capacitances long coaxial 5 kO 39ko 50kQ cable larger sensor plate area Smaller resistor values should be used with larger input capacitances Ccpc determines the sensitivity of the sensor If the sensitivity is 90 nF 470 nF 2500 nF increased the possibility of incorrect switching due to interfering electrical fields is also increased This parameter has a strong influence on the switching characteristic Ccu determines the internal sampling frequency and therefore the 0 pF 22 pF 100 nF reaction time of the switch Smaller values of Cern correspond to shorter reaction times Shorter reaction times lead to increased current consumption 6 Board schematic On the next page the schematic of the Rev A OM11055 PCB is shown Revision A is identified by the fact that there is no revision number on
8. internal review and subject to formal approval which may result in modifications or additions NXP Semiconductors does not give any representations or warranties as to the accuracy or completeness of information included herein and shall have no liability for the consequences of use of such information 8 2 Disclaimers General Information in this document is believed to be accurate and reliable However NXP Semiconductors does not give any representations or warranties expressed or implied as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information Right to make changes NXP Semiconductors reserves the right to make changes to information published in this document including without limitation specifications and product descriptions at any time and without notice This document supersedes and replaces all information supplied prior to the publication hereof Suitability for use NXP Semiconductors products are not designed authorized or warranted to be suitable for use in medical military aircraft space or life support equipment nor in applications where failure or malfunction of a NXP Semiconductors product can reasonably be expected UM10370_2 to result in personal injury death or severe property or environmental damage NXP Semiconductors accepts no liability for inclusion and or use of NXP Semiconductors products in such equipment or applications
9. operate in pulse mode The output is activated for a defined time at each capacitive event This defined time is determined by C5 b With the jumper across the TOG and TIM pins the PCF8883 will operate in toggle mode touch on touch off c With the jumper across the SW and TIM pins the PCF8883 will operate in momentary switch mode push button The output is active as long as the capacitive event lasts UM10370 2 NXP B V 2009 All rights reserved User manual Rev 02 2 December 2009 4 of 11 NXP Semiconductors U M1 0370 PCF8883 Evaluation Kit OM11055 Fig 2 Selection of operating mode using jumper J9 4 User configurable settings The OM11055 kit allows the user to configure the PCF8883 sensor for evaluation in a specific application 4 1 Sensor plate selection The OM11055 board includes four sensor plates on the board itself and provisions to connect the PCF8883 to an external sensor The board connects CP1 to the PCF8883 by default To enable the other sensor options 1 Cut the trace that shorts J6 pins 1 amp 2 on the underside of the board 2 Solder in a user supplied 8 pin header 0 1 pitch at J6 3 To select sensor plate CP4 connect a user supplied jumper across J6 pins 7 amp 8 to select CP3 jumper pins 5 amp 6 of J6 etc To use an off board sensing plate connect the plate at J14 amp J18 using coax cable The coaxial shield must be connecte
10. r to op amp U2 jumper J12 before connecting the input to pin CPC of the PCF8883 J16 Reversing this sequence could result in a CMOS latch up Remark 2 The capacitor Ccec must be a good quality X7R type to minimize charge leakage 5 Sensor adjustment It is recommended to start the evaluation of the application using the pre assembled components on the board since these have typical values and were tuned for use with the default connected sensor plate CP1 This should give an adequate response in most cases In cases where the switch does not respond or responds unreliably it is likely that the input capacitance exceeds the specified input range The voltage measured on Cerc via testpoint TP2 should ideally be approximately 7 Vppneg note V Vppnga which is half the internally regulated supply voltage not V2 Vpp The bias point can be optimized by first changing Cr and possibly also Rc according to step 1 in the 5 step table below Once the switch works properly further optimizations can be done by adjusting Ccec and Cun Details concerning optimization of the biasing are given in application note AN10832 The circuit has three parameters that influence the switching behaviour These are listed below in order of their influence e Switch sensitivity set by Ccec e Calibration of the total capacitance on the sensor input using resistor Rc and capacitor Cr e Switching speed set by Coin UM10370 2 NXP B V 2009 All rig
11. te AN10832 for details on adjusting the sensitivity Cut trace under J5 to disable C1 Cut trace under J4 to disable R1 Fig 5 Traces to be cut for sensitivity setting adjustment NXP B V 2009 All rights reserved User manual Rev 02 2 December 2009 6 of 11 NXP Semiconductors U M1 0370 PCF8883 Evaluation Kit OM11055 4 3 Power supply options Power to the OM11055 PCB can be supplied using a mini USB cable provided or a 9V battery The 9V battery connector can be removed and a user provided power supply could be connected at JP3 amp JP4 for evaluation of a specific application Using an external power supply also allows for easy measuring of the power consumption Warning There is no protection against reverse polarity of the external power supply 4 4 High impedance op amp A high input impedance rail to rail input and output op amp U2 is included on the board to measure the voltage at the CPC pin of the PCF8883 A capacitor is connected between pin CPC and Vss The value of this capacitor is used to adjust the sensitivity of the switch Since this is a very high impedance node measuring directly with a probe would disturb the control loop Therefore this voltage buffer has been included on the board By default this op amp is not connected as it would add to power consumption measurements To enable U2 install two pin headers and jumpers at J12 and J16 Remark 1 Always first provide powe
12. the PCB The schematic is also available as a separate PDF document on our website Make sure to check our website periodically for updates T References and resource URLs UM10370 2 The documents below provide further useful information 1 PCF8883 product datasheet 2 AN10832 PCF8883 capacitive proximity switch with auto calibration Table 2 Resource URLs Item Resource Description and location 1 OM11055 eval kit Includes document package This dociment e Board schematic and BOM e Links to datasheets and application notes e Location http www standardics nxp com support boards PCF8883 2 PCF8883 webpage Links to the datasheets and application notes http www nxp com pip PCF8883_1 html NXP B V 2009 All rights reserved User manual Rev 02 2 December 2009 8 of 11 Z 0 0LAn jenuew Jes 6002 1equie eg Z c0 9H VDDREG O Oros Jo e io SW 9V BATTERY OFF BOARD jp VDO E NXP SEMICONDUCTORS o aja tile CAP PROXIMITY SENSOR EVAL BOARD Size Document Number Re PCFB8883 1 D e iday July 31 2009 She Fig 6 Schematic of OM11055 pamasa syfu Ily 6002 8 dXN LLJO6 SJOJONPUODIWISS dXN SSOLLINO 104 uonenje 3 88849d OZEOLINN NXP Semiconductors UM10370 8 Legal information PCF8883 Evaluation Kit OM11055 8 1 Definitions Draft The document is a draft version only The content is still under
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