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wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 1 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller g eneral d escription the SX9500 is a low-cost, very low power 4-channel capacitive controller that can operate either as a proximity or button sensor. the SX9500 includes sophisticated on- chip auto-calibration circuitry to regularly perfor m sensitivity adjustments, maintaining peak performance over a wi de variation of temperature, humidity and noise enviro nments, providing simplified product development and enhanc ed performance. a dedicated transmit enable (txen) pin is available t o synchronize capacitive measurements for application s that require synchronous detection, enabling very low su pply current and high noise immunity by only measuring proximity when requested. the SX9500 operates directly from an input supply vo ltage of 2.7 to 5.5v, and includes a separate i2c serial bus supply input to enable communication with 1.8 C 5.5 v hosts. the i2c serial communication bus reports pr oximity or touch detection and is used to facilitate parame ter settings adjustment. upon a proximity detection, t he nirq output asserts, enabling the user to either determi ne the relative proximity distance, or simply obtain an in dication of detection. the serial bus can also serve to overwr ite detection thresholds and operational settings in th e event the user wants to change them from their factory pr esets. k ey p roduct f eatures 2.7 C 5.5v input supply voltage capacitive sensor inputs 4 ff capacitance resolution stable proximity & touch sensing with temperature capacitance offset compensation to 30pf active sensor guarding automatic calibration ultra low power consumption: active mode: 170 ua doze mode: 18 ua sleep mode: 2.5 ua 400khz i2c serial interface four programmable i2c sub-addresses input levels compatible with 1.8v host processors open drain nirq interrupt pin three (3) reset sources: por, nrst pin, soft reset -40c to +85c operation compact size: 3 x 3mm thin qfn package pb & halogen free, rohs/weee compliant a pplications notebooks tablets mobile appliances o rdering i nformation semtech p/n package marki ng SX9500iultrt note1 qfn-20 znd8 SX9500evk eval. kit note 1: quantities are ordered in 3k units per reel t ypical a pplication circuit figure 1: typical application circuit
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 2 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller table of contents g eneral d escription .................................................. ................................................... ................... 1 k ey p roduct f eatures ................................................... ................................................... ............... 1 a pplications .................................................. ................................................... .................................. 1 o rdering i nformation ................................................... ................................................... ................ 1 t ypical a pplication circuit .................................................. ................................................... ....... 1 1 g eneral d escription .................................................. ................................................... .......... 5 1.1 pin diagram 5 1.2 marking information 5 1.3 pin identification 6 1.4 acronyms 6 2 e lectrical c haracteristics .................................................. ............................................... 7 2.1 absolute maximum ratings 7 2.2 recommended operating conditions 7 2.3 thermal characteristics 7 electrical specifications 8 3 f unctional description .................................................. ................................................... ... 11 3.1 introduction 11 3.1.1 general 11 3.1.2 parameters and configuration 11 3.1.3 sensor touch/proximity adjustment 11 3.2 scan period 11 3.3 operational modes 12 3.4 configuration 13 3.5 reset 13 3.5.1 power-up 13 3.5.2 nrst 14 3.5.3 software reset 14 3.6 interrupt 15 3.6.1 power-up 15 3.6.2 nirq clearing 15 4 p in descriptions .................................................. ................................................... ................ 16 4.1 introduction 16 4.2 v dd and sv dd 16 4.3 txen 16 4.4 capacitor sensing interface (cs0, cs1, cs2, cs3, cs g) 16 4.5 host interface 16 4.5.1 nirq 16 4.5.2 scl, nrst and txen 17 4.5.3 sda 17 5 d etailed c onfiguration descriptions .................................................. ............................ 18 5.1 introduction 18 5.2 capacitive sensor (cs0, cs1, cs2, cs3) parameters 18 5.2.1 set cps_digital_gain [6:5] (cap sensor gain) 18 5.2.2 set cps_c in r [1:0] (input capacitance range and resolution) 18 5.2.3 set cps_trs [4:0] (detection threshold) 19 5.2.4 set cps_hyst [5:4] (detection hysteresis) 20 5.2.5 set cps_avgdeb[7:6] (average pos/neg debouncing) 20
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 3 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 5.2.6 set cps_avgnegfilt[5:3] & cps_avgposfilt[2:0] (aver age neg/pos filters) 20 5.2.7 set cps_fs[4:3] (sampling frequency) 21 5.2.8 set cps_res[2:0] (resolution factor) 21 5.2.9 set cps_avgtrs[7:0] (averaging threshold) 21 5.3 additional parameter settings 22 5.3.1 set cps_period[6:4] (scan period) 22 5.3.2 set cps_en [3:0] (enable capacitive sensor inputs) 22 5.3.3 set irq_enable [6:3] (enable interrupt sources) 22 6 i2c i nterface .................................................. ................................................... ...................... 23 6.1 i2c write 23 6.2 i2c read 24 6.3 register overview 25 6.4 sensor design 28 7 p ackaging i nformation .................................................. ................................................... ... 29 7.1 package outline drawing 29 7.2 land pattern 30 list of figures figure 1: typical application circuit .................................................. ................................................... ................ 1 figure 2: pin diagram .................................................. ................................................... ........................................ 5 figure 3: qfn marking information .................................................. ................................................... .................. 5 figure 4: i2c start and stop timing .................................................. ................................................... ................ 10 figure 5: i2c data timing .................................................. ................................................... ................................. 10 figure 6 scan period ................................................... ................................................... ....................................... 11 figure 7: power-up vs. nirq .................................................. ................................................... ........................... 13 figure 8: hardware reset .................................................. ................................................... ................................ 14 figure 9: software reset .................................................. ................................................... ................................. 14 figure 10: nirq output simplified diagram .................................................. ................................................... . 16 figure 11: scl/txen/nrst .................................................. ................................................... ............................ 17 figure 12: sda simplified diagram .................................................. ................................................... ................ 17 figure 13: i2c write ................................................... ................................................... ......................................... 23 figure 14: i2c read .................................................. ................................................... .......................................... 24 figure 15: typical touch/proximity capacitive senso r .................................................. .................................. 28 figure 16: package outline drawing .................................................. ................................................... .............. 29 figure 17: package land pattern .................................................. ................................................... ................... 30
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 4 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller list of tables table 1: pin description .................................................. ................................................... .................................... 6 table 2: absolute maximum ratings .................................................. ................................................... ............... 7 table 3: recommended operating conditions .................................................. .................................................. 7 table 4: thermal characteristics .................................................. ................................................... ...................... 7 table 5: electrical characteristics .................................................. ................................................... .................... 9 table 6: i2c timing specification .................................................. ................................................... ................... 10 table 7: i2c sub-address selection ................................................... ................................................... .............. 12 table 8: cps_digital_gain .................................................. ................................................... ............................. 18 table 9: c input range and resolution register .................................................. ............................................... 18 table 10: cap sensor threshold .................................................. ................................................... .................... 19 table 11: cps_hyst .................................................. ................................................... ........................................ 20 table 12: cps_avgdeb .................................................. ................................................... .................................. 20 table 13: sampling frequency control .................................................. ................................................... ......... 21 table 14: cps resolution factor .................................................. ................................................... .................... 21 table 15: scan period, register 0x06 .................................................. ................................................... ............ 22 table 16: register overview .................................................. ................................................... ........................... 28
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 5 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 1 g eneral d escription 1.1 pin diagram figure 2: pin diagram 1.2 marking information znd8 yyww xxxx yyww= date code xxxx = lot number figure 3: qfn marking information
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 6 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 1.3 pin identification pin number name type description 1 csg analog capacitive sensor guard 2 cs3 analog capacitive sensor, 3 3 cs2 analog capacitive sensor, 2 4 cs1 analog capacitive sensor, 1 5 cs0 analog capacitive sensor, 0 6 gnd ground ground 7 nc not used do not connect 8 nc not used do not connect 9 nc not used do not connect 10 nc not used do not connect 11 v dd power SX9500 core power 12 sv dd power host serial port supply voltage. must be less than or equal to v dd . note: during power-up or power-down, sv dd must be less than or equal to v dd 13 nirq digital output interrupt request, active lo w, requires pull-up resistor to sv dd 14 scl digital input i2c clock, requires pull up res istor to sv dd 15 sda digital i/o i2c data, requires pull up resist or to sv dd 16 txen input transmit enable, active high (tie to sv dd if not used). 17 nrst input external reset, active low, requires p ull up resistor to sv dd 18 a1 digital input i2c sub-address, connect to gnd o r v dd 19 a0 digital input i2c sub-address, connect to gnd o r v dd 20 gnd ground ground dap gnd ground exposed pad. connect to ground table 1: pin description 1.4 acronyms dap die attach paddle
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 7 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 2 e lectrical c haracteristics 2.1 absolute maximum ratings stresses above the values listed in absolute maxim um ratings may cause permanent damage to the devic e. this is a stress rating only and functional operation of the device at these, or any other conditions beyond the recommended opera ting conditions, is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability and proper functionality. parameter symbol min max unit supply voltage v dd -0.5 6.0 v sv dd -0.5 6.0 input voltage (non-supply pins) v in -0.5 v dd +0.3 input current (non-supply pins) i in -10 10 ma operating junction temperature t jct -40 125 c reflow temperature t re 260 storage temperature t stor -50 150 esd hbm (human body model, to jesd22-a114) esd hbm 8 kv table 2: absolute maximum ratings 2.2 recommended operating conditions parameter symbol min max unit supply voltage v dd 2.7 5.5 v sv dd 1.65 v dd ambient temperature range t a -40 85 c table 3: recommended operating conditions note: during power-up or power-down, sv dd must be less than or equal to v dd 2.3 thermal characteristics parameter symbol min typical max unit thermal resistance C junction to air (static airflow) q ja 34 c/w table 4: thermal characteristics note: theta ja is calculated from a package in still air, mounted to 3" x 4.5", 4 layer fr4 pcb with thermal vias under exposed pad per jesd51 standards.
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 8 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller electrical specifications all values are valid within the operating condition s unless otherwise specified. parameter symbol conditions min typ max unit current consumption sleep mode i sleep power down, all a nalog circuits shut down. (i2c listening) 2.5 ua doze i doze cps_per io d = 2 00 ms dozeperiod = 2xcps_period cps_fs = 167khz cps_res = medium 18 active i active cps_period = 30ms cps_fs = 167khz cps_res = medium 170 outputs: sda, nirq output current at output low voltage i ol vol = 0.4v 6 ma maximum output low voltage v ol (max) sv dd > 2v 0.4 v sv dd 2v 0.2 x sv dd inputs: scl, sda, txen input logic high v ih 0.8 x sv dd sv dd + 0.3 v input logic low v il -0.3 0.25 x sv dd input leakage current i l cmos input -1 1 ua hysteresis v hys sv dd > 2v 0.05x sv dd v sv dd 2v 0.1x sv dd txen measurements txen actdly delay to when the SX9500 actually begins measure-ments from when txen becomes active 100 s input s : a0, a1 input logic high v ih 0.7 x v dd v dd + 0.3 v input logic low v il -0.3 0.3 x v dd
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 9 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller input: nrst input logic high v ih sv dd > 2v 0.7 x svdd sv dd + 0.3 v sv dd 2v 0.75 x svdd input logic low v il sv dd > 2v 0.6 sv dd 2v 0.3 x sv dd start-up power-up time t por 1 ms nrst nrst minimum pulse width t resetpw 20 ns table 5: electrical characteristics
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 10 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller parameter symbol conditions min typ max unit i2c timing specifications scl clock frequency f scl 400 khz scl low period t low 1.3 us scl high period t high 0.6 data setup time t su;dat 100 data hold time t hd;dat 0 repeated start setup time t su;sta 0.6 start condition hold time t hd;sta 0.6 stop condition setup time t su;sto 0.6 bus free time between stop and start t buf 1.3 input glitch suppression t sp note (1) 50 ns note (1) -- minimum glitch amplitude is 0.7v dd at high level and maximum 0.3v dd at low level. table 6: i2c timing specification note: all timing specifications, refer to figure 4, figu re 5, and table 6 figure 4 : i2c start and stop timing figure 5: i2c data timing
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 11 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 3 f unctional description 3.1 introduction 3.1.1 general the SX9500 is a low-cost, very low-power 4-channel capacitive controller that can operate either as a proximity or button sensor. the SX9500 includes sophisticate d on-chip auto-calibration circuitry to regularly p erform sensitivity adjustments, maintaining peak performan ce over a wide variation of temperature, humidity a nd noise environments, providing simplified product developm ent and enhanced performance. 3.1.2 parameters and configuration the SX9500 allows the user full parameter customiza tion for sensor sensitivity, hysteresis, and detect ion thresholds. if custom parameters are used by the c ustomer, these parameters must be uploaded by the h ost immediately following boot-up or after a reset. 3.1.3 sensor touch/proximity adjustment capacitive touch/proximity detection is directly pr oportional to the SX9500 internal gain and threshol d settings, and external sensor area to optimize proximity dete ction distance. a longer touch/proximity detection range can be accomplished without changing the capacitive sen sor size, by using a high sensitivity setting and/o r lower signal threshold setting for touch/proximity detect ion. 3.2 scan period the scan period determines the minimum touch/proxim ity detection reaction time of the SX9500 and can b e varied by the host from 30ms to approximately 400ms . touch/proximity detection reaction time is propo rtional to the scan period and inversely proportional to power consumption, so longer scan periods corresponds to lower power, but also to longer detection reaction times. the scan period of the SX9500 is defined by two per iods: sensing and idle. during the sensing period, all enabled cs inputs, from cs0 to cs3 are sampled and any detection reported via the i2c bus (via i2c reg ister polling or nirq). the sensing period is variable a nd is proportional to the scan frequency and resolu tion settings in the cap sensing control registers. dur ing the idle period, the SX9500 the analog circuits are placed in standby and the idle timer is initiated. upon e xpiry of the idle timer, a new scan period cycle be gins. cs0a cs0b cs1b cs0a cs0b cs1a figure 6 scan period
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 12 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 3.3 operational modes the SX9500 has four (4) operational modes: active, doze, sleep, and commanded. these modes enable tradeoffs between touch/proximity detection reactio n time and power consumption. active: active mode has the shortest scan periods, with a typical detection reaction time of 30ms. in this m ode, all enabled sensors are scanned and information dat a is processed within this interval. the active sc an period is user configurable and can be extended to a maximum period of 400ms. see cps_period register in sectio n 6.3, (i2c register overview) below. doze: doze mode is by default, enabled in the SX9500. the doze mode period is user configurable (see section 6.3, i2c register overview) and can be used to extend the scan period out to 6.4 seconds for v ery low power consumption applications at the expense of ve ry long detection reaction times (6.4 seconds). in some applications, the detection reaction time n eeds to be fast, but can be slow when detection has not been active for a while. when the SX9500 has not detect ed an object for a specific time, it will automatic ally change modes from active to doze reducing power. this tim e-out period is determined by the cps_dozeperiod which can be configured by the user or turned off ( cps_dozeen) if not required. proximity detection on any sensor will cause the sx 9500 to leave doze mode and re-enter active mode. sleep: sleep mode places the SX9500 in its lowest power m ode, disabling all sensor scanning and setting the idle period to continuous. in this mode, only the i2c serial bus is active. commanded: the commanded mode uses the txen input. the txen input enables the measurement of the capacitive channels when high, likewise when the tx en input is low, the SX9500 is in the sleep mode. specifically, on the rising edge of txen the SX9500 will begin measuring the capacitive channels begin ning with the lowest enabled channel repeating the measuremen t cycle at programmed rates so long as txen remains high. when txen goes low the current measurement s equence will complete and then measurement will cease until the next rising edge of txen.i2c interf ace the i2c serial interface is configured as a slave d evice, operates at speeds up to 400 khz and serves as the sole host interface to the SX9500. the SX9500 has two i/o pins (a0 and a1) that provid es for four possible, user selectable i2c addresses : table 7: i2c sub-address selection a1 a0 address 0 0 0x28 0 1 0x29 1 0 0x2a 1 1 0x2b
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 13 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 3.4 configuration if the application requires customization, the sx95 00 configuration registers can be changed over the i2c bus. some i2c addressable registers are used to read sen sor status and information, while other (configurat ion) registers allow the host to take control of the sx9 500. via the configuration registers, the host can command an operational mode change or modify the active sensor s. these user programmable configuration registers are volatile, therefore during a power-down or reset ev ent, they lose all user programmed content, requiri ng the host to re-write the i2c registers after the event. 3.5 reset a reset to the SX9500 is performed by any one of th e following methods: - power-up - nrst pin - software reset 3.5.1 power-up during a power-up condition, the nirq output is hig h until v dd has met the minimum input voltage requirements and a t por time has expired upon which, nirq asserts to a low condition indicating the SX9500 is initialized. the host is required to perform an i2c read to clea r this nirq status. the SX9500 is then ready for n ormal i2c communication and is operational. figure 7: power-up vs. nirq
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 14 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 3.5.2 nrst when nrst is asserted low and then high, the SX9500 will reset its internal registers and will become active after period, t por . if a hardware reset control output is not availa ble to drive nrst, then this pin must be pulled high to sv dd . figure 8: hardware reset 3.5.3 software reset the host can perform software resets by writing to the i2csoftreset register (see section 6.3 for addi tional information). the nirq output will be asserted low and the host is required to perform an i2c read to clear this nirq status. figure 9: software reset
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 15 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 3.6 interrupt interrupt sources are disabled by default upon powe r-up and resets, and thus must be enabled by the ho st (apart from reset irq). any or all of the following inter rupts can be enabled by writing a 1 into the appr opriate locations within the irqenable register (see sectio n 6.3 for details): touch or proximity detected completed compensation completed conversion the interrupt status can be read from register irqs tat for each of these interrupt sources (see sectio n 6.3 for details). 3.6.1 power-up during initial power-up, the nirq output is high. once the SX9500 internal power-up sequence has comp leted, nirq is asserted low, signaling that the SX9500 is ready. the host must perform a read to irqstat to acknowledge that the status is read and the SX9500 will clear the interrupt and release the nirq line. 3.6.2 nirq clearing the nirq can be asserted in either the active or do ze mode during a scan period. the nirq will be cle ared when the host performs a read of the regirqstat i2c register.
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 16 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 4 p in descriptions 4.1 introduction this section describes the SX9500 pin functionality , pin protection, whether or not the pins are analo g or digital, and if they require pull-up resistors. there is es d protection on all SX9500 i/o. 4.2 v dd and sv dd these are the device supply voltages. v dd is the supply voltage for the internal core and i/ o. sv dd is the supply voltage for the i2c serial interface. note: s vdd must be equal or lower than v dd . 4.3 txen this signal can be used in many applications if a c onversion trigger/enable is needed. this input pin synchronizes the capacitance sensing inputs. when this signal is active, SX9500 immediately performs capacitive measurements. if this input becomes ina ctive during the middle of a measurement, the sx950 0 will complete all remaining measurements and will enter sleep mode until txen goes active again. 4.4 capacitor sensing interface (cs0, cs1, cs2, cs3 , csg) the capacitance sensor input pins cs0, cs1, cs2 and cs3 are connected directly to the capacitor sensin g interface circuitry which converts the sensed capac itance into digital values. the capacitive sensor guard (csg) output provides a guard reference to minimize the parasitic sensor pin capacitances to ground. capacitance sensor pins which are not used must be left open-circuited. additionally, cs pins must be connected directly to the capacitive sensors using a minimum length circuit trace to minimize external noise pick-up. the capacitance sensor and capacitive sensor guard pins are protected from esd events to vdd and groun d. 4.5 host interface the host interface consists of: nirq, nrst, scl, sd a, and txen. these signals are discussed below. 4.5.1 nirq the nirq pin is an open drain output that requires an external pull-up resistor (1..10 kohm). the nir q pin is protected from esd events to svdd and ground. figure 10: nirq output simplified diagram svdd r_ int nirq SX9500 int nirq to host svdd
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 17 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 4.5.2 scl, nrst and txen the scl, nrst and txen pins are high impedance inpu t pins that require an external pull-up resistor (1 ..10 kohm). it is possible to connect nrst and txen hos t output drivers directly without the requirement f or a pull- up resistor if driven from a push-pull host output. these pins are protected from esd events to svdd and ground. figure 11: scl/txen/nrst 4.5.3 sda sda is an i/o pin that requires an external pull-up resistor (1..10 kohm). the sda i/o pin is protect ed to sv dd and ground. figure 12: sda simplified diagram svdd r s cl/txen/nrst from host scl_in/txe n_in/nrst_in svdd svdd r_ sda sda sda_out to/from host sda_in svdd
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 18 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 5 d etailed c onfiguration descriptions 5.1 introduction the SX9500 is a low-cost, very low power 4-channel capacitive controller that can operate either as a proximity or button sensor. it includes sophisticated on-chi p auto-calibration circuitry to regularly perform s ensitivity adjustments, maintaining peak performance over a wi de variation of temperature, humidity and noise environments, providing simplified product developm ent and enhanced performance. the SX9500 comes wit h factory default settings that are appropriate for m ost general applications, however a full complement of registers are accessible to the user to enable application cu stomization and optimization. a dedicated transmit enable (txen) pin is available to synchronize capacitive m easurements and reduce power dissipation for applic ations that require synchronous detection, enabling very l ow supply current and high noise immunity by only m easuring proximity when requested. 5.2 capacitive sensor (cs0, cs1, cs2, cs3) paramete rs the SX9500 sensor has default parameters for the ca pacitive sensors that provides a quick and initial starting point to achieve touch/proximity detection. howeve r, because of unique sensor sizes and sensor locati ons, it is possible to achieve higher and more robust performa nce with minor changes to these default parameters. in general only a few registers require changes to the ir default parameters to achieve improved performan ce. these registers are: 5.2.1 set cps_digital_gain [6:5] (cap sensor gain) the address for the (capacitive) sensor gain is: b its [6:5] provide for four (4) gain settings as sho wn below: bits 6 5 gain 0 0 x 1 0 1 x 2 1 0 x 4 1 1 x 8 table 8: cps_digital_gain 5.2.2 set cps_c in r [1:0] (input capacitance range and resolution) the register for the input capacitance full scale r ange and resolution is: bits [1:0] provide set abi lity over the expected maximum sensed capacitance. a setting of 00 on these bits provides for the largest capacitan ce measurement range, but is not as sensitive for the longest proximity distance, while the setting of 11 provides for the smallest capacitive measurement range, and prov ides the longest proximity distance. the table for this register is shown below: bits 1 0 c input range/resolution 0 0 large 0 1 medium-large 1 0 medium-small 1 1 small table 9: c input range and resolution register
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 19 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 5.2.3 set cps_trs [4:0] ( detection threshold ) this register defines the detection threshold for a ll sensors and the details are shown below. lower thresholds provide longer proximity detection distances but ar e more susceptible to noise, while higher threshold values provide immunity to noise, but results in shorter p roximity detection range. the default value for th is register is [00000]. bits 4 3 2 1 0 threshold value 0 0 0 0 0 0 0 0 0 0 1 20 0 0 0 1 0 40 0 0 0 1 1 60 0 0 1 0 0 80 0 0 1 0 1 100 0 0 1 1 0 120 0 0 1 1 1 140 0 1 0 0 0 160 0 1 0 0 1 180 0 1 0 1 0 200 0 1 0 1 1 220 0 1 1 0 0 240 0 1 1 0 1 260 0 1 1 1 0 280 0 1 1 1 1 300 1 0 0 0 0 350 1 0 0 0 1 400 1 0 0 1 0 450 1 0 0 1 1 500 1 0 1 0 0 600 1 0 1 0 1 700 1 0 1 1 0 800 1 0 1 1 1 900 1 1 0 0 0 1000 1 1 0 0 1 1100 1 1 0 1 0 1200 1 1 0 1 1 1300 1 1 1 0 0 1400 1 1 1 0 1 1500 1 1 1 1 0 1600 1 1 1 1 1 1700 table 10: cap sensor threshold
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 20 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 5.2.4 set cps_hyst [5:4] (detection hysteresis) this register defines the detection hysteresis for all sensors. hysteresis for the capacitive sensors provides an important function in that it keeps the SX9500 from providing oscillating results when detection lev els are close to threshold. the register details are shown below . bits 5 4 detection hysteresis 0 0 32 0 1 64 1 0 128 1 1 256 table 11: cps_hyst 5.2.5 set cps_avgdeb[7:6] (average pos/neg debounci ng) use of debounce in the SX9500 is recommended as it will reduce the effects of extraneous noise for rep orted detection. the SX9500 includes several conditions for debounce: close, far, and data detection. bits 7 6 average pos/neg debouncing 0 0 off 0 1 2 samples 1 0 4 samples 1 1 8 samples table 12: cps_avgdeb 5.2.6 set cps_avgnegfilt[5:3] & cps_avgposfilt[2:0] (average neg/pos filters) the SX9500 includes circuitry to average out the de tected signals. these detected signals can be both positive and negative, and so there are registers to control both the positive and negative averaging filter co efficients. there are eight (8) settings possible in each of th ese filters ranging from off up to highest filterin g. use of these filters is recommended for noisy environment and represents a tradeoff detection response versus false triggering. see cps_avgnegfilt and cps_avgposfilt for register and bit locations.
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 21 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 5.2.7 set cps_fs[4:3] (sampling frequency) the capacitance sampling frequency can be changed i n cps_ctrl2 if the environment is particularly nois y. changing this frequency affects the capacitance sen sing period. it is recommended to use the 167 khz sampling frequency. bits 4 3 sampling frequency 0 0 83 khz 0 1 125 khz 1 0 167 khz 1 1 reserved, do not use table 13: sampling frequency control 5.2.8 set cps_res[2:0] (resolution factor) the cps resolution factor has eight (8) possible se ttings that range from coarsest to very fine that c ontrols the total number of measurements per sensor in a scan p eriod. along with the cps sampling frequency, chan ging this register affects the SX9500 sensing period. t his register is located in cps_ctrl2. bits 2 1 0 resolution 0 0 0 coarsest 0 0 1 very coarse 0 1 0 coarse 0 1 1 medium coarse 1 0 0 medium 1 0 1 fine 1 1 0 very fine 1 1 1 finest table 14: cps resolution factor 5.2.9 set cps_avgtrs[7:0] (averaging threshold) the SX9500 performs averaging on all capacitive mea surements to determine when to perform a calibratio n cycle. the cps_avgtrs register is used to set an 8 -bit positive and negative threshold that determine s when a calibration is internally requested. typically the user would set this register to be between 1000000 0 [7:0] to 11000000 [7:0] which corresponds to ? to ? of the s ystem dynamic range.
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 22 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 5.3 additional parameter settings further application customization is possible to co ntrol scan period, enabled sensors and individual s ensor interrupts are also possible. scan period affects both power dissipation and detection reaction time. 5.3.1 set cps_period[6:4] (scan period) this register controls the scan period of the sx950 0 over a range of 30ms to 400ms. bits 6 5 4 scan period (ms) 0 0 0 30 0 0 1 60 0 1 0 90 0 1 1 120 1 0 0 150 1 0 1 200 1 1 0 300 1 1 1 400 table 15: scan period, register 0x06 5.3.2 set cps_en [3:0] (enable capacitive sensor in puts) if any capacitive sensors are not required, they ca n be disabled in this register. each bit in this r egister corresponds to a specific sensor input. a logic 1 enables the capacitive sensor input, while a logi c 0 disables a capacitive input. cs0 = bit 0 cs1 = bit 1 cs2 = bit 2 cs3 = bit 3 5.3.3 set irq_enable [6:3] (enable interrupt source s) there are a number of interrupt sources that the sx 9500 can report. a logic 1 in the specific locat ion will enable the specific interrupt as shown below. tchirqen [6]: enables the touch/proximity detectio n irq rlsirqen [5]: enables the touch/proxmity no detect irq compdoneirqen [4]: enables the compensation done no tification irq convirqen [3]: enables the conversion completion do ne notification irq
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 23 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 6 i2c i nterface the i2c implemented on the SX9500 is compliant with : - standard (100kb/s) and fast mode (400kb/s) - i2c standard slave mode - 7 bit address (default is 0x28 assuming a1=a0=0). the host can use the i2c to read and write data at any time, and these changes are effective immediate ly. therefore the user should ideally disable the senso r before changing settings, or discard the results while changing (section 3.2). there are four types of i2c registers: - control and status (read). these registers give information about the status of the capacitive sens ors - operation control (read/write). these registers control operating modes. - cap sensor control and parameters (read/write) - cap sensor data read back (read) the i2c can be used to read and write from a start address and then perform read or writes sequentiall y, and the address increments automatically. supported i2c access formats are described in the n ext sections. 6.1 i2c write the format of the i2c write is given in figure 12. after the start condition [s], the slave address ( sa) is sent, followed by an eighth bit (0) indicating a write. the SX9500 then acknowledges [a] that it is being addressed, and the master sends an 8 bit data byte consisting of the SX9500 register address (ra). the slave acknowledges [a] and the master sends the appropria te 8 bit data byte (wd0). again the slave acknowle dges [a]. in case the master needs to write more data, a succeeding 8 bit data byte will follow (wd1), ack nowledged by the slave [a]. this sequence will be repeated u ntil the master terminates the transfer with the st op condition [p]. figure 13: i2c write the register address is incremented automatically w hen successive register data (wd1...wdn) is supplie d by the master.
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 24 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 6.2 i2c read the format of the i2c read is given in figure 13. after the start condition [s], the slave address (s a) is sent, followed by an eighth bit (0) indicating a write. the SX9500 then acknowledges [a] that it is being addressed, and the master responds with an 8-bit data consisti ng of the register address (ra). the slave acknowl edges [a] and the master sends the repeated start conditi on [sr]. once again, the slave address (sa) is sen t, followed by an eighth bit (1) indicating a read. the SX9500 responds with an acknowledge [a] and th e read data byte (rd0). if the master needs to read more data it will acknowledge [a] and the SX9500 will se nd the next read byte (rd1). this sequence can be repeate d until the master terminates with a nack [n] follo wed by a stop [p]. figure 14: i2c read
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 25 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 6.3 register overview add reg acc bits field reset function general control & status 0x00 irqstat r 7 resetirq 1 reset event occurred 6 tchirq 0 sensor detected a touch/proximity 5 rlsirq 0 sensor detected a release condition r/w 4 compdone 0 compensation complete. writing a one in this bit trigs a compensation on all channels r 3 convirq 0 conversion cycle complete 2:1 not used 00 not used 0 txenstat 0 reports txen pad status 0x01 tchcmpstat r 7 tchstat3 0 determines if touch/proximity has been detected on cs3 6 tchstat2 0 determines if touch/proximity has been detected on cs2 5 tchstat1 0 determines if a touch/proximity has been detected on cs1 4 tchstat0 0 determines if a touch/proximity has been detected on cs0 3:0 compstat 1111 specifies which capacitive sensor(s) has a compensation pending general operations c ontrol 0x03 irq_enable r 7 not used 0 not used r/w 6 tchirqen 0 enables the detection irq 5 rlsirqen 0 enables the release irq 4 compdoneirqen 0 enables the compensation irq 3 convirqen 0 enables the conversion irq r 2:0 not used 000 not used cap sensing c ontrol 0x06 cps_ctrl0 r/w 7 not used 0 not used 6:4 cps_period 000 scan period : 000: 30 ms 001: 60 ms 010: 90 ms 011: 120 ms 100: 150 ms 101: 200 ms 110: 300 ms 111 : 400 ms 3:0 cps_en 1111 enables cs0 through cs3 0x07 cps_ctrl1 r/w 7:6 cps_sh 01 cg bias/shield usage. 00 : off, cg high-z (off) 01: on(def.) 10: reserved 11: reserved 5:2 0000 not used r/w 1:0 cps_c in r 00 capacitance range & resolution:
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 26 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 00: large 01: medium large 10: medium small 11: small 0x08 cps_ctrl2 r/w 7 not used 0 not used 6:5 cps_digital_gain 00 set digital gain factor 00: gain = 1 01: gain = 2 10: gain = 4 11: gain = 8 4:3 cps_fs 01 sampling frequency 00: 83 khz 01: 125 khz 10: 167 khz (typical) 11: reserved 2:0 cps_res 000 resolution control 000: coarsest . . 111: finest 0x09 cps_ctrl3 r/w 7 not used 0 not used 6 cps_dozeen 1 enables doze mode 5:4 cps_dozeperiod 00 when doze is enabled, the cap sensing period moves from cps_period to cps_period * : 00: 2* cps_period 10: 8* cps_period 01: 4*cps_period 11: 16*cps_period 3:2 reserved 00 must be 00 1:0 cps_rawfilt 00 raw filter coefficient 00: off 01: low 10: medium 11: high (max filtering) 0x0a cps_ctrl4 r/w 7:0 cps_avgtrs 00000000 average pos/neg threshold = 8 x reg 0x0b cps_ctrl5 r/w 7:6 cps_avgdeb 00 average pos/neg de- bouncer: 00: off 01: 2 samples 10: 4 samples 11: 8 samples 5:3 cps_avgnegfilt 000 average negative filter coefficient : 000: off 001: lowest . . 111: highest (max. filter) 2:0 cps_avgposfilt 000 average positive filter coefficient : 000: off 001: lowest . .. 111: highest (max. filter) 0x0c cps_ctrl6 r/w 7:5 not used 000 not used 4:0 cps_trs 00000 defines the touch/prox
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 27 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller detection threshold for all sensors. see table 10 0x0d cps_ctrl7 r/w 7 cps_cmpautooff 0 disables the automatic compensation trigged by average 6 cps_cmptrg 0 0: compensate channels independently 1: compensate all channels when triggered 5:4 cps_hyst 00 detection hysteresis 00: 32 01: 64 10: 128 11: 256 3:2 cps_clsdeb 00 close debouncer 00: off 01: 2 samples 10: 4 samples 11: 8 samples 1:0 cps_fardeb 00 far debouncer 00: off 01: 2 samples 10: 4 samples 11: 8 samples 0x0e cps_ctrl8 r/w 7:4 cps_stuck 0000 stuck at timeout timer : 0000 : off 00xx: increment every cps_stuck x 64 active frames 01xx: increment every cps_stuck x 128 active frames 1xxx: increment every cps_stuck x 256 active frames 3:0 cps_cmpprd 0000 periodic compensation 0: off else : increment every cps_compprd x 128 active frames sensor r eadback 0x20 cpsrd 7:2 not used 000000 not used r 1:0 cpsrd 00 determines which sensor data will be available in the next reg read. 0x21 usemsb r 7:0 sensusemsb 00000000 provides the useful information for monitoring purposes. signed, 2's complement format 0x22 uselsb r 7:0 sensuselsb 00000000 0x23 avgmsb r 7:0 sensavgmsb 00000000 provides the average information for monitoring purposes. signed, 2's complement format 0x24 avglsb r 7:0 sensavglsb 00000000 0x25 diffmsb r 7:0 sensdiffmsb 00000000 provides the differential information for monitoring purposes. signed, 2's complement format 0x26 difflsb r 7:0 sensdifflsb 00000000 0x27 offmsb r/w 7:0 sensoffmsb 00000000 offset compensation dac code. this is writable to allow forcing some dac 0x28 offlsb r/w 7:0 sensofflsb 00000000
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 28 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller codes. when written, the internal dac code is updated after the write of the lsb reg. msb and lsb regs should be written in sequence. 0x7f i2csoftreset w 7:0 softreset 00000000 write 0xde and reset the chip table 16: register overview 6.4 sensor design this section describes how to properly design capac itive sensors for touch or proximity. sensors can be designed in a variety of shapes depending on the ph ysical requirements of the system, but to achieve o ptimum performance, a careful recognition of the csg betwe en sensors and below must be given in the design. an optimum capacitive sensor should have minimum pa rasitics to both system ground and to the csg. sys tem ground parasitics can be minimized with distance be tween the capacitive sensor and system ground, howe ver csg will be directly adjacent to each sensor as wel l as directly under it (on an adjacent pc board lay er). it is easy to generate a significant capacitance this way and therefore it is recommended to cross-hatch the guard to a large extent. the recommended fill for the cro ss-hatched area is about 20% metal. csx typ, 4 plcs. figure 15: typical touch/proximity capacitive senso r csg csg
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 29 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 7 p ackaging i nformation 7.1 package outline drawing figure 16: package outline drawing
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 30 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller 7.2 land pattern figure 17: package land pattern
wireless & sensing datasheet revision 1.6 june 27, 2012 ? 2012 semtech corpor ation www.semtech.com 31 SX9500 ultra low power, capacitive four (4) - channel proximity/button controller contact information ? semtech 2012 all rights reserved. reproduction in whole or in p art is prohibited without the prior written consent of the copyright owner. the information presented in this document does not form part of any quotation or co ntract, is believed to be accurate and reliable and may be cha nged without notice. no liability will be accepted by the publisher for any consequence of its use. publicat ion thereof does not convey nor imply any license u nder patent or other industrial or intellectual property rights. semtech assumes no responsibility or liab ility whatsoever for any failure or unexpected operation resulting from misuse, neglect improper installatio n, repair or improper handling or unusual physical or electri cal stress including, but not limited to, exposure to parameters beyond the specified maximum ratings or operation outside the specified range. semtech products are not designed, intended, author ized or warranted to be suitable for use in life-support applications, devi ces or systems or other critical applications. inclusion of semtech products in suc h applications is understood to be undertaken solely at the customers own risk. s hould a customer purchase or use semtech products for any such unauthorized applicat ion, the customer shall indemnify and hold semtech and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs damages and attorney fees which could arise. notice: all referenced brands, product names, servi ce names and trademarks are the property of their respective owners. semtech corporation wireless and sensing products division 200 flynn road, camarillo, ca 93012 phone: (805) 498-2111 fax: (805) 498-3804

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