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| http://www.wincomtech.com WTC6208ASI WTC6208ASI 8 channels touch sensing button chip specification(v1.8) 1 product introduction ............................. ................................................... ................................................... ........ 3 1.1 brief introduction ............................. ................................................... ................................................... . 3 1.2 technology ..................................... ................................................... ................................................... ... 3 1.3 sensibility adjustment......................... ................................................... ................................................. 4 1.4 csel value and pannel thickness ................ ................................................... ......................................... 4 1.5 the package of WTC6208ASI ..................... ................................................... .................................... 4 2 features and parameters .......................... ................................................... ................................................... ..... 4 2.1 key features ................................... ................................................... ................................................... ... 4 2.1.1 simple application circuit and fewer external components ........................................ ................ 4 2.1.2 high stability............................... ................................................... ............................................. 4 2.1.3 compact keyboard with small space ............ ................................................... ........................... 5 2.1.4 excellent waterproof ......................... ................................................... ....................................... 5 2.1.5 excellent anti-electromagentic interference .. ................................................... .......................... 5 2.1.6 unique wire length self-adjustable technology ................................................... ..................... 5 2.1.7 satisfying the requirements of industrial app lication........................................... ........................ 6 2.2 parameters ..................................... ................................................... ................................................... .... 6 2.2.1 operating voltage ............................ ................................................... ......................................... 6 2.2.2 level of output.............................. ................................................... .......................................... 6 2.2.3 panel (insulated media) thickness ............ ................................................... ............................... 6 2.2.4 effective response time of touch ............. ................................................... ............................. 6 2.2.5 operating temperature ........................ ................................................... ..................................... 6 2.2.6 storage temperature .......................... ................................................... ....................................... 6 3 min applications................................. ................................................... ................................................... .......... 7 4 pin assignment ................................... ................................................... ................................................... .......... 7 5 output output indication ......................... ................................................... ................................................... ..... 8 5.1 the timing sequence chart ...................... ................................................... .............................................. 8 5.2 the truth table of WTC6208ASI .................. ................................................... ........................................ 9 6 typical application circuit...................... ................................................... ................................................... ..... 9
http://www.wincomtech.com WTC6208ASI 6.1 the application circuit ........................ ................................................... ................................................ 9 6.2 the requirement of external components......... ................................................... ................................ 10 7 sensibility setting .............................. ................................................... ................................................... ......... 10 7.1 select a suitable csel......................... ................................................... ................................................ 10 7.2 the area of sense element...................... ................................................... ..............................................11 8 power supply..................................... ................................................... ................................................... ......... 11 8.1 voltage regulator .............................. ................................................... ................................................. 12 8.2 the place of regulator and external components ................................................... ........................ 12 8.3 grounding...................................... ................................................... ................................................... .. 12 8.4 the value of c2 ................................ ................................................... ................................................. 12 8.5 high noise condition ........................... ................................................... .............................................. 12 8.6 power filter ................................... ................................................... ................................................... .. 12 8.7 use +5v power of the main system ............... ................................................... ................................. 13 9 sense element (cap. sensor) used for WTC6208ASI .. ................................................... ............................... 13 9.1 the shape of sense element..................... ................................................... ......................................... 13 9.2 the area of sense element...................... ................................................... .......................................... 14 9.3 the interface must be gapless.................. ................................................... ......................................... 14 9.4 the elastic connection methods................. ................................................... ....................................... 14 10 treatment of vacant sensor channel.............. ................................................... ............................................... 15 11 packing and outline dimensional drawing of wtc62 08asi .............................................. ........................... 15 12 annex............................................. ................................................... ................................................... ............. 17 12.1 appendix 1: attentions of pcb layout .......... ................................................... .................................... 17 12.2 appendix 1: the example operating program of 8 051 and WTC6208ASI interface ....................... ... 20 http://www.wincomtech.com WTC6208ASI WTC6208ASI 8 channels touch sensing button chip specification(v1.8) 1 product introduction 1.1 brief introduction WTC6208ASI is the touch sensing integrated circuit designed to realize the human touch interface. it m ay substitute the mechanical key to achieve the operat or interface with waterproof, dustproof, sealing, s eparation, solid and good-looking performances. one WTC6208ASI can p rovide 3-8 independent keys and the users can use t hem flexibly as per the actual requirements. 1.2 technology WTC6208ASI product applies 16-bit high-precision cd c (capacitor digital converter) to identify the tou ch movement of human fingers via the capacitance chang es on the ic detecting sense element (capacitance s ensor). the data outputted from cdc will be processed by th e built-in risc processor with highly efficient and reliable algorithm, then bcd code output from the ports of WTC6208ASI to indicate the key status . the internal block diagram of WTC6208ASI is shown a s below: http://www.wincomtech.com WTC6208ASI ? 1: internal figure 1:block diagram of WTC6208ASI 1.3 sensibility adjustment the sensibility of all channels may be adjusted by one capacitor csel. 1.4 csel value and pannel thickness by adjusting the capacitance value of csel and the area of sense element properly, WTC6208ASI can apply to the insulation panels with different thickness spanning from 0 to 20mm. 1.5 the package of WTC6208ASI the WTC6208ASI is packaged with the standard 16pi n nsop (150mil). 2 features and parameters 2.1 key features 2.1.1 simple application circuit and fewer external compo nents WTC6208ASI is built in dedicated metrical circuit, self-calibration circuit and risc processor, designed by wincom technology independently, with f ewer external components. 2.1.2 high stability production commissioning-free and excellent long-te rm operation stability its unnecessary to calibrate the system after the sensibility is determined after the capacitor csel value is pre-set. the system can automatically over come the disturbances caused by the electrostatic discharge, electromagnetic interferen ce, temperature variation, humidity and http://www.wincomtech.com WTC6208ASI pollutants piled on the surface, so as to provide s ound precision and operation consistency in various environments. it may be transported for a l ong distance and used in various conditions. the unique compensation algorithm and high-intensit y anti-interference design can ensure the product free from accidental operation in case of l ong-term operation. 2.1.3 compact keyboard with small space the users can use the compact keyboard with small spaces the adjacent key suppression function can prevent t he accidental operation of adjacent keys. the users can use the compact keyboard with fewer space s (space less than 2mm). 2.1.4 excellent waterproof its designed with special waterproof feature. the WTC6208ASI can not only resist splash and water overflow, but also can be used normally after being flooded, different with the general products of other company sold on the market at pre sent, those may be operated accidently upon water splash and overflow and operate slowly after waterlogging, or may be operated accidently after being pressed by fingers. 2.1.5 excellent anti-electromagentic interference it may be used for the home appliance and products applied in general application conditions. the products can be good anti- rf signal interference p erformance even use the one layer pcbs, it can resist the interference of most rf interference sou rce upon the ic, including gsm cell phones. upon application for military purpose and other spe cial case, its recommended to use the two layers pcbs and design it as per the layout require ment offered by this datasheet. 2.1.6 unique wire length self-adjustable technology the identical products sold on the market at presen t are involved with the problems of great discrepancy of induction sensibility as the connect ion line from the sense element to ic pin varies. while the line length self-adjustable feature innov ated by us may automatically correct the discrepancy. the users can obtain the almost consis tent sensibility of all keys on the whole sense panel, without bothering with complicated adjustmen t. http://www.wincomtech.com WTC6208ASI 2.1.7 satisfying the requirements of industrial applicati on the product can provide more reliable performances, more expansive application scope for the users. 2.2 parameters 2.2.1 operating voltage single power 3.3 http://www.wincomtech.com WTC6208ASI effective touch is 1 10 data0 o bcd code data0 output 11 rosc i 10k pull-up resistor 12 vcc i power input 13 data1 o bcd code data1 output 14 data2 o bcd code data2 output 15 sw7 i button(sense element)6 input 16 sw6 i button(sense element)6 input 5 output output indication 5.1 the timing sequence chart when WTC6208ASI judges that any button( sense eleme nts) is touched, it will output a low level signal within 100 ms from out_ flag pin , and the bcd code of touched button will be output from data0,data1,data2 in the same time, host mcu can re ad the bcd code of touched button when out_ flag signal is low. note: out_flag serves as flag of any key is touched , instead of indicating the time of key is touched. the signal of out_flag and the bcd code of touched key will be retained till the finger leaves it, we can just read the bcd code while the out_flag signal is low .the reading program shall be query mode. the timing sequence chart of WTC6208ASI show as be low: the initializing level of output is high figure 3 the timing sequence chart of WTC6208ASI http://www.wincomtech.com WTC6208ASI 5.2 the truth table of WTC6208ASI bcd code output input out_flag data0 data1 data2 initial h h h h touch l l l l sw0 leave h --- --- --- touch l h l l sw1 leave h --- --- --- touch l l h l sw2 leave h --- --- --- touch l h h l sw3 leave h --- --- --- touch l l l h sw4 leave h --- --- --- touch l h l h sw5 leave h --- --- --- touch l l h h sw6 leave h --- --- --- touch l h h h sw7 leave h --- --- --- 6 typical application circuit 6.1 the application circuit the application schematic of WTC6208ASI is very sim ple, with only several resistance and capacitance p arts. the key components are csel and 1k resistor group. the application circuit of WTC6208ASI operating in normal mechanical button mode is shown as below http://www.wincomtech.com WTC6208ASI figure 4: application circuit of WTC6208ASI rp1 and rp2 are the matching resistors, please make sure to put them closer to ic. csel are the 10% dacron capacitor 0.0047uf- 0.022uf or 10% x7r capacitor 0.0047uf- 0.022uf 6.2 the requirement of external components csel is sensibility adjusting capacitor, its requi red to use the terylene capacitor, x7r material surface mount capacitor or npo material surface mount capacitor with the precision of 10% or above for cs el. 1k resistor groups are for impedance matching of each cap. sens or channel. 1k resistance group may provide the bes t and most stable measurement effect for WTC6208ASI. note: ple ase make sure to put csel and matching resistor clo ser to ic as much as possible when pcb layout. 7 sensibility setting with the sensibility setting of WTC6208ASI, the use rs can use the spacer media with various thicknesse s for reliable and flexible touch functions. the sensibility setting of WTC6208ASI is done by selecting csel value. 7.1 select a suitable csel firstly, the users shall select the suitable capaci tor csel pursuant to their actual application. the thicker is the spacer media and the bigger is the capacity of csel, the h igher is the sensibility. generally its recommend ed to select the suitable capacitors between 0.0047uf and 0.022uf, f rom down to up. its recommended to apply terylene http://www.wincomtech.com WTC6208ASI capacitor with the precision of 5% with small tempe rature coefficient for csel, or the terylene capaci tor with the precision of 10%. if surface mounted capacitors are used, please select x7r material surface mount cap acitor or npo material surface mount capacitor with the prec ision of 10% or above for csel. 7.2 the area of sense element increasing the area of sense element may help to im prove the penetrating ability of touch sense. 8 power supply WTC6208ASI is used to measure the tiny change of ca pacitance, requiring small ripples and noise of pow er supply, free from the external strong disturbance o f power supply penetration, especially when its ap plied to induction cooker and microwave furnace, the externa l interference and abrupt change of voltage should be effectively separated. so the power supply is requi red with higher stability. its recommended to appl y the stabilized pressure line composed of 78l05 as shown below. http://www.wincomtech.com WTC6208ASI 12 figure 7: the simple operation circuit with voltage regulator 8.1 voltage regulator when pcb layout, the components of 78l05 power pack age must be put close to vcc pins of WTC6208ASI. 8.2 the place of regulator and external components 78l05, peripheral components and wtc104blsi must be set on the same circuit board collectively, to avo id much noise caused by the extra long power supply li ne. 8.3 grounding the common grounds of components shown in the above figure must be separately connected into an independent group and then connect a separate point to the common ground of whole unit. (the astral on e-point grounding shall be applied.) , 8.4 the value of c2 c2 capacity would impact the discharge time after p ower fail, higher capacity requires longer reset ti me. the values in circles are the recommended values, the users ca n adjust the values as per the different applicatio n purposes. 8.5 high noise condition when the product is applied in the environment with high noise, just avoid to stack the main board wit h high voltage (220v), large current and high frequency op eration and the touch circuit boards. when its ine vitable, just put them far away from the components with high vol tage and large current or add shielding device on t he main board. 8.6 power filter upon pcb typesetting, its recommended to reserve i nductive l1(1mh) bonding pad, which may be not need ed in some special applications. input the power supply o f 78l05, pay attention to the ripples and make sure the wave hollow of ripples not lower than dc 8v. http://www.wincomtech.com WTC6208ASI 13 8.7 use +5v power of the main system if the power supply of touch panel is from main sy stem, just add power filter circuit before the vcc of WTC6208ASI. the requirements for pcb layout are the same with those for the foregoing circuit. the power filter circuit show in the following figu re figure 8: power supply filter circuit the power supplies of analog and digital sections o f circuit shall be separately connected with astral connection method and the sequence of capacitors shall be arra nged as per that shown in the schematic diagram and shall not be arranged randomly. note: this circuit bears sound capacity restricting the p ower noise, but it is apt to generate self-excitati on when its connected to higher load. its recommended that the users shall not connect other loads than touch mod ule or touch chip set. the loads like relays and other ics shall be connected before this circuit, with other filte r voltage regulator added to it. 9 sense element (cap. sensor) used for WTC6208ASI 9.1 the shape of sense element the sense element (cap. sensor)may be the conduc tor in any shapes, but it shall bear some planar ar ea. its recommended to use the round sheet metal or other c onductors whose diameter is above 3mm 3mm. the sense elements usually used include copper foil on pcb, s pring, membrane circuit and ito glass, etc... http://www.wincomtech.com WTC6208ASI figure 9: pcb copper foil sense element the sense elements may be solid or hollow rectangle s, roundness or polygon. 9.2 the area of sense element make sure to keep the area of every sense element the same as much as possible to ensure the consiste nt sensibility. 9.3 the interface must be gapless the air gap between the top surface of sense elemen t and panel back surface will cause the sensibilit y decrease sharply ,so the interface between them must be join ted closely ,make sure no gap between them .the sur faces of sense elements shall be flat, free from any clearan ce with the panel. 9.4 the elastic connection methods commonly used include a to use the sense elements with springs b to make the elastic connection with cylindrical conductive rubber c affix the sense elements with imported high ten acity double sticky tape onto the panel and the dou ble sticky tape shall be not too thick. http://www.wincomtech.com WTC6208ASI figure 10: spring sense element 10 treatment of vacant sensor channel its required to use at least 3 touch keys for WTC6208ASI , otherwise, the modules would not operate normally. when applied in the occasions less than 8 keys, the re would be unoccupied sensor input channels among sw0-sw7. the vacant input channels cannot be suspended , just combine the vacant input channels together and then connect them with a 1k pull high resistor connect to vcc of WTC6208ASI. 11 packing and outline dimensional drawing of wtc6208a si dimensions limeter symbols min nom max a 1.35 1.60 1.75 a1 0.10 0.25 a2 1.45 b 0.33 0.51 c 0.19 0.25 d 9.80 10.00 e 3.80 4.00 http://www.wincomtech.com WTC6208ASI c 1.27 h 5.80 6.20 l 0.40 1.27 0.00 8.00 figure10 WTC6208ASI outline dimensions http://www.wincomtech.com WTC6208ASI 12 annex 12.1 appendix 1: attentions of pcb layout 1: use wtc series of touch chips. upon pcb layout, please put 1k measurement matching resistance group and sensibility adjusting capacitors of csel close to i c as much as possible. 2: upon pcb layout, please make sure the basic bala nced distance from the touch chip to the sense elem ent, shown as below: figure 13: rational pcb layout http://www.wincomtech.com WTC6208ASI figure 14: irrational pcb layout 3: the connection line between the sense element an d touch chip shall be as thin and short as possible . its recommended to apply 5 mil line width as much as po ssible if its allowed by pcb technique. 4: the connection line between the sense element an d touch chip shall not span over the signal wire wi th high distance and high frequency. 5: no other signal wires shall be connected within 0.5mm scope of the connection line between the sens e element and touch chip. 6: if the users apply the copper foil patterns on t he pcb directly as the touch sense element, they sh all use the two layers pcbs. the connection line between the touch chip, sense element and ic pines shall be put on th e back of sense element copper foil (bottom). the sense eleme nt shall be put close to the touch panel. 7: the copper laid on the copper surface of sense e lement shall be done with grid patterns and the are a of copper in the grids shall not exceed 40% of the total area of copper in grids. copper shall be laid with more th an 0.5mm distance from the sense element and touch chip. in principle, if copper is laid on the back of connect ion line between the sense element and ic, just apply the pa tterns in the way as shown in figure 15, and the co pper area shall not exceed 40% of the total area of copper in grids. figure 15: copper pattern on the surface of sense e lement top of pcb bottom of pcb figure 16: grid copper shall be laid outside the ke y sense element on top of pcb figure 17: grid copper shall not be laid underneath the key sense element at the bottom of pcb 8: copper to be laid on the back of sense element c opper (bottom) shall apply the sold copper sheet. b ut copper shall be laid with more than 0.5mm distance from th e sense element and touch chip. the back directly o pposite to the sense element shall be not be laid with copper, any large-area copper foil and other signal wires are not allowed on the back directly opposite to the sense element. 9: apply the connection method for the hole connect ion between the connection line and sense element s hown in http://www.wincomtech.com WTC6208ASI figure 17. figure 18: poor connection figure 19: sound connection figure 20: sound wiring method figure 21: poor wiring method 10: pcb layout example: the copper foil of sense element shall be painted w ith green oil so that copper is not exposed. figure 22: example http://www.wincomtech.com WTC6208ASI 12.2 appendix 1: the example operating program of 8 051 and WTC6208ASI interface the function of example realized by this example pr ocedure is to make 8051 to read the code of touched button of bcd bus of touc h sensing chip, and to display with led. each led would display the status of corr esponding keys. the example operating program of 8051 and wtc6208as i interface #include http://www.wincomtech.com WTC6208ASI #define uint unsigned int //--------------------------------WTC6208ASI interf ace-------------------------------------------- #define daport p1 sbit out_flag = p1^6; sbit out_da2 = p1^2; sbit out_da1 = p1^1; sbit out_da0 = p1^0; //--------------------------------led display inter face--------------------------------------------- sbit led7 = p0^7; sbit led6 = p0^6; sbit led5 = p0^5; sbit led4 = p0^4; sbit led3 = p0^3; sbit led2 = p0^2; sbit led1 = p0^1; sbit led0 = p0^0; //------------------------------------function----- -------------------------------- void delay_loop(uchar i); //delay function void led_on(uchar ledcontroler); // led on void led_off(uchar ledcontroler); //led off //------------------------------------variable defi nition ----------------------------------- uchar getkey; //WTC6208ASI output bcd code uchar temp; //middle variable //------------------------------------------------- ----------------------------------------- // //------------------------------------------------- ----------------------------------------- void main(void) { while(1) { daport = 0xff; if(~out_flag) { //the indicating led on when the b utton is touched getkey = daport; getkey &= 0x07; http://www.wincomtech.com WTC6208ASI led_on(getkey); } else { // the indicating led off after fin ger left the button led_off(getkey); } } } //------------------------------------------------- ---------------------------------------- void delay_loop(uchar i) { while(i) { i--; } } //------------------------------------------------- ----------------------------------------- void led_on(uchar ledcontroler) { switch(ledcontroler) { case 0: led0 = 0; break; case 1: led1 = 0; break; case 2: led2 = 0; break; case 3: led3 = 0; break; case 4: led4 = 0; break; case 5: led5 = 0; break; case 6: led6 = 0; break; case 7: led7 = 0; break; } } //------------------------------------------------- ----------------------------------------- void led_off(uchar ledcontroler) { switch(ledcontroler) { http://www.wincomtech.com WTC6208ASI case 0: led0 = 1; break; case 1: led1 = 1; break; case 2: led2 = 1; break; case 3: led3 = 1; break; case 4: led4 = 1; break; case 5: led5 = 1; break; case 6: led6 = 1; break; case 7: led7 = 1; break; } } address of shenzhen office: flat/rm. 12h, haixia ge, haizhu cheng, chuang ye road, nanshan district, shenzhen, china post code: 518054 tel: 86-755-26406919 13392806258 fax: 86-755-26403148 martin@wincomtech.com , szmartiny@yahoo.com.cn hongkong add.: flat rm m 4/f continental mansion 300kings road, hk. tel: (852) 6949328 end of specification thanks!! http://www.wincomtech.com WTC6208ASI |
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