SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET -----4 KEY PRODUCT FEATURES GENERAL DESCRIPTION The SX8652 is a very low power, high reliability controller for 4-wire and 5-wire resistive touch screens used in PDAs, portable instruments and point-of-sales terminal applications. It features a wide input supply range from 1.65V to 3.7V and low power modes to preserve current when the screen is unintentionally touched. To compute touch screen X-Y coordinates and touch pressure with precision, a low power 12-bit analog-digital converter is activated with the possibility to enable on-chip data averaging processing algorithms to reduce host activity and suppress system noise. The touch screen controller inputs have been specially designed to provide robust on-chip ESD protection of up to 15kV in both HBM and Contact Discharge, and eliminates the need for external protection devices. The SX8652 is controlled by a high speed SPITM serial interface. The SX8652 is available in a 4.0 mm x 3.0 mm 14-DFN package and a 1.5 mm x 2.0 mm wafer level chip scale package (WLCSP) for space conscience applications. APPLICATIONS DSC, DVR, Cell Phones PDA, Pagers Point-of-Sales Terminals Touch-Screen Monitors ORDERING INFORMATION Part Number Package (Dimension in mm) Marking SX8652ICSTRT1 12 - Ball WLCSP (1.5x2.0) FG97 SX8652IWLTRT1 14 - Lead DFN (4.0x 3.0) FG97 Extremely Low Power Consumption: 23uA@1.8V 8kSPS Superior On-chip ESD Protection 15kV HBM (X+,X-,Y+,Y-) 2kV CDM 25kV Air Gap Discharge 15kV Contact Discharge 300V MM Single 1.65V to 3.7V Supply/Reference 4-Wire or 5-Wire Resistive Touch Screen Interface Integrated Preprocessing Block to Reduce Host Loading and Bus Activity Four User Programmable Operation Modes provides Flexibility to address Different Application Needs Manual, Automatic, Pen Detect, Pen Trigger Low Noise Ratiometric Conversion Throughput: 5000 (X-Y) coordinates/second (c/s) with 7Sample Averaging Low Power Shut-Down Mode < 1uA Hardware & Software reset Precision, High Speed 12-bit SAR ADC Operating At 74k SPS SPITM Serial Interface Touch Pressure Measurement (4-Wire) Auxiliary Input (4-Wire) For Alternate ADC Input or Start of Conversion Trigger -40C to +85C operation Pb-Free, Halogen Free, RoHS/WEEE compliant product Windows CE 6.0, Linux Driver Support Available Packages: 14-LD (4.0 mm x 3.0 mm) DFN 12-Ball (1.5 mm x 2.0 mm) WLCSP 1. 3000 Units / reel VDD S X 865 2 VDD C o ntrol N IR Q A U X /W IP E R N R S T (D FN only) POR T o the touch screen SPI X + /B R Y + /TR Touch S creen Interface S C LK ref+ X -/TL Y -/B L V ref NCS OSC in A D C out ref- D igital Filter T o the H o st DOUT D IN GND Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 1 www.semtech.com SX8652 ADVANCED COMMUNICATIONS & SENSING DATASHEET Table of contents Section 1. 2. 3. 4. 5. Page General Description ................................................................................................................................................. 4 1.1. DFN Pinout Diagram and Marking Information (Top View).............................................................................. 4 1.2. WLCSP Pinout Diagram and Marking Information (Top View) ........................................................................ 4 1.3. Pin Description................................................................................................................................................. 5 1.4. Simplified Block Diagram ................................................................................................................................. 5 Electrical Characteristics ......................................................................................................................................... 6 2.1. Absolute Maximum Ratings ............................................................................................................................. 6 2.2. Recommended Operating Conditions.............................................................................................................. 6 2.3. Thermal Characteristics ................................................................................................................................... 6 2.4. Electrical Specifications ................................................................................................................................... 7 2.5. Host Interface Specifications ........................................................................................................................... 9 2.6. Host Interface Timing Waveforms.................................................................................................................... 9 Functional Description ........................................................................................................................................... 10 3.1. General Introduction ..................................................................................................................................... 10 3.2. Device Interface and ESD protection............................................................................................................. 11 3.2.1. Touchscreen interface............................................................................................................................. 11 3.2.2. Host Interface and Control Pins .............................................................................................................. 11 4-wire Touch Screen Detailed Description ............................................................................................................ 12 4.1. Touch Screen Operation................................................................................................................................ 12 4.2. Coordinates Measurement............................................................................................................................. 12 4.3. Pressure Measurement.................................................................................................................................. 13 4.4. Pen Detection ................................................................................................................................................ 13 5-wire Touch Screen Detailed Description ............................................................................................................ 14 5.1. Touch Screen Operation................................................................................................................................ 14 5.2. Coordinates Measurement............................................................................................................................. 14 5.3. Pen Detection ................................................................................................................................................ 14 6. Data Processing .................................................................................................................................................... 15 7. Power-Up, Reset ................................................................................................................................................... 15 8. Modes of Operation ............................................................................................................................................... 15 9. 8.1. MANual Mode ................................................................................................................................................ 16 8.2. AUTOmatic mode .......................................................................................................................................... 16 8.3. PENDET Mode .............................................................................................................................................. 17 8.4. PENTRIG Mode ............................................................................................................................................. 17 Host Interface ........................................................................................................................................................ 19 9.1. SPI Read/Write Registers .............................................................................................................................. 19 9.2. SPI Reading Channel Data............................................................................................................................ 19 9.3. SPI Host Commands ..................................................................................................................................... 20 9.4. SPI implementation and multiple Read/Write ................................................................................................ 20 9.5. Invalid Qualified Data..................................................................................................................................... 21 Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 2 www.semtech.com SX8652 ADVANCED COMMUNICATIONS & SENSING DATASHEET Table of contents Section 10. Page 9.6. Register Map................................................................................................................................................. 22 9.7. SX8652 register ............................................................................................................................................ 23 Application Information ......................................................................................................................................... 24 10.1. Acquisition Setup ........................................................................................................................................... 24 10.2. Channel Selection.......................................................................................................................................... 24 10.3. Noise Reduction............................................................................................................................................. 24 10.3.1. POWDLY................................................................................................................................................. 24 10.3.2. SETDLY .................................................................................................................................................. 25 10.4. AUX Input - 4-wire touchscreen only ............................................................................................................. 25 10.5. Interrupt Generation....................................................................................................................................... 25 10.6. Coordinate Throughput Rate ......................................................................................................................... 25 10.6.1. SPI Communication Time ....................................................................................................................... 25 10.6.2. Conversion Time ..................................................................................................................................... 26 10.7. ESD event...................................................................................................................................................... 26 11. Packaging Information ........................................................................................................................................... 27 11.1. DFN Package................................................................................................................................................. 27 11.2. WLCSP Package ........................................................................................................................................... 28 Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 3 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 1. General Description 1.1. DFN Pinout Diagram and Marking Information (Top View) 1 14 (NC) VDD 2 13 NRST X+/BR 3 12 NCS Y+/TR 4 11 NIRQ X-/TL 5 10 DOUT Y-/BL 6 9 DIN GND 7 8 SCLK 15 PIN 1 IDENTIFIER FG97 YYWW XXXXX AUX/ WIPER Figure 1. SX8652 DFN Top View, Pad on Bottom Side YYWW: date code XXXXX: Lot Number 1.2. WLCSP Pinout Diagram and Marking Information (Top View) X+/BR Y+/TR X-/TL Y-/BL FG97 YYWW XXXXXX 3 VDD NCS DIN GND AUX/WIPER # NIRQ DOUT SCLK A B C D 2 1 BALL A1 IDENTIFIER Figure 2. SX8652 WLCSP Top View, Solder Bumps on Bottom Side YYWW: date code XXXXX: Lot Number Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 4 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 1.3. Pin Description Pin Number # Name Type Description DFN WLCSP 1 A1 AUX/WIPER Digital Input / Analog Input Conversion Synchronization (4-wire) or Analog Auxiliary Input (4-wire) / Wiper Input (5-wire) 2 A2 VDD Power Input Input power supply, connect to a 0.1uF capacitor to GND 3 A3 X+/BR Analog IO X+ Right electrode (4-wire) / Bottom Right (5-wire) channel 4 B3 Y+/TR Analog IO Y+ Top electrode (4-wire) /Top Right (5-wire) channel 5 C3 X-/TL Analog IO X- Left electrode (4-wire) /Top Left (5-wire) channel 6 D3 Y-/BL Analog IO Y- Bottom electrode (4-wire) /Bottom Left (5-wire) channel 7 D2 GND Ground Ground 8 D1 SCLK Digital Input SPI Serial Clock Input 9 C2 DIN Digital Output SPI Serial Data Input 10 C1 DOUT Digital Output SPI Serial Data Output 11 B1 NIRQ Digital Output, open drain Interrupt Request Output, Active low, Need external pull-up 12 B2 NCS Digital Input SPI Chip Select Input, Active low 13 - NRST Digital Input DFN package only, Reset Input, Active low, Internal pull-up resistor 14 - (NC) 15 - GND Not Connected Power input Backside Ground Table 1. Pin description 1.4. Simplified Block Diagram The SX8652 simplified block diagram is shown in Figure 3. VDD SX8652 VDD Control NIRQ AUX/WIPER NRST (DFN only) POR To the touch screen SPI X+/BR Y+/TR Touch Screen Interface X-/TL Y-/BL Vref NCS OSC SCLK ref+ in ADC out ref- Digital Filter To the Host DOUT DIN GND Figure 3. Simplified block diagram of the SX8652 Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 5 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 2. Electrical Characteristics 2.1. Absolute Maximum Ratings Stresses above the values listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these, or any other conditions beyond the "Recommended Operating Conditions", is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Parameter Symbol Min. Max. Unit Supply Voltage VDDABS -0.5 3.9 V Input voltage (non-supply pins) VIN -0.5 3.9 V Input current (non-supply pins) IIN 10 mA Operating Junction Temperature TJCT 125 C Reflow temperature TRE 260 C Storage temperature TSTOR 150 C ESD HBM (Human Body Model) ESD (Contact Discharge) 15(i) kV 8(ii) kV ESDHBM2 2 kV ESDCD 15 kV ILU 100 mA High ESD pins: X+/BR, X-/TL, Y+/TR, Y-/BL, Aux/Wiper ESDHBM1 All pins except high ESD pins High ESD pins: X+/BR, X-/TL, Y+/TR, Y-/BL, Aux/Wiper Latchup(iii) -50 Table 2. Absolute Maximum Ratings (i) Tested to TLP (10A) (ii) Tested to JEDEC standard JESD22-A114 (iii) Tested to JEDEC standard JESD78 2.2. Recommended Operating Conditions Parameter Supply Voltage Ambient Temperature Range Symbol Min. Max Unit VDD 1.65V 3.7 V TA -40 85 C Min. Max Unit Table 3. Recommended Operating Conditions 2.3. Thermal Characteristics Symbol Parameter Thermal Resistance with DFN package - Junction to Ambient (iii) JA 39 C/W Thermal Resistance with WLCSP package - Junction to Ambient (iii) JA 65 C/W Table 4. Thermal Characteristics (iii) 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 (if applicable) per JESD51 standards. Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 6 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 2.4. Electrical Specifications All values are valid within the recommended operating conditions unless otherwise specified. Symbol Parameter Conditions Min. Typ Max Unit Current consumption Mode = MANUAL Ipwd Converter stopped, pen detection off, SPI listening, OSC stopped 0.4 1 uA Mode = PENDET Ipndt Converter stopped, pen detection activated, device generates interrupt upon detection, SPI listening, OSC stopped 0.4 1 uA Mode =PENTRIG Ipntr Converter stopped, pen detection activated, device starts conversion upon pen detection. SPI listening, OSC stopped 0.4 1 uA Mode=AUTO Iauto Converter stopped, pen detection off, SPI listening, OSC on, timer on 1.5 Operation @8kSPS, VDD=1.8V Iopl 23 50 uA Operation @42kSPS, VDD=3.3V Ioph 105 140 uA uA Digital I/O High-level input voltage VIH 0.8VDD VDD+0.2 V Low-level input voltage VIL VSS-0.3 0.2VDD V VHysLow VDD > 2V 0.05 VDD V VHysHigh VDD < 2V 0.1 VDD V Output Logic High VOH IOH>-2mA 0.8VDD Output Logic Low VOL IOL<2mA 0 Input leakage current LI CMOS input High ESD Input - Output capacitance CX+/BR ,CX-/TL ,CY+/TR , CY-/BL, CAUX 50 pF Input - Output capacitance CNRST , CNIRQ ,CNCS ,CDIN , CDOUT, CSCLK 5 pF Hysteresis 0.4 V 1 uA Table 5. Electrical Specifications Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 7 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET Symbol Parameter Conditions Min. Typ Max Unit 1 ms Startup Power-up time tpor Time between rising edge VDD and rising NIRQ ADC Resolution Ares Offset Aoff Gain error Age Differential Non Linearity Integral Non Linearity 12 bits 1 LSB 0.5 LSB Adnl 1 LSB Ainl 1.5 LSB 5 Ohm At full scale Resistors X+, X-, Y+, Y- resistance Rchn Touch Pad Biasing Resistance Pen detect resistance RPNDT_00 RPNDT = 0 100 kOhm RPNDT_01 RPNDT = 1 200 kOhm RPNDT_10 RPNDT = 2 50 kOhm RPNDT_11 RPNDT = 3 25 kOhm 0.1 uF External components Capacitor between VDD, GND recommendations Cvdd Type 0402, tolerance +/-50% Table 5. Electrical Specifications Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 8 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 2.5. Host Interface Specifications Parameter Symbol Condition Min Typ Max Unit 5000 60 kHz % SPI TIMING SPECIFICATIONS (i) SCLK Clock Frequency Duty Cycle fSCLK duty 40 NCS edge to first SCLK "" TCSS 50 NCS edge to DOUT Low TDCD SCLK High Pulse Width TCKH 80 SCLK Low Pulse Width TCKL 80 Data Setup Time TDS 40 Data Valid to SCLK Hold Time TDH 70 Data Output Delay after SCLK "" TDOD NCS "" to SCLK Ignored TCSI NCS "" to DOUT Hi-Z state TCCZ NCS Hold Time TCSW 100 ns 70 50 90 150 (i) All timing specifications refer to voltage levels (50% VDD, VOH, VOL) defined in Table 6 unless otherwise mentioned. Table 6. Host Interface Specifications 2.6. Host Interface Timing Waveforms tCSW CSN 50%VDD tCSS tCKL tDOD tCKH tCSI 50%VDD SCLK tDH tDS DIN 50%VDD tDCD tCCZ DOUT D11 VOH VOL Figure 4. SPI Timing Waveform Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 9 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 3. Functional Description 3.1. General Introduction This section provides an overview of the SX8652 architecture, device pinout and a typical application. The SX8652 is designed for 4-wire and 5-wire resistive touch screen applications. The touch screen or touch panel is the resistive sensor and can be activated by either a finger or stylus. When the top layer is pressed, it makes contact with the bottom sheet and the touch location can be measured. As shown in Figure 5 with a 4-wire panel, the touch screen coordinates and touch pressure are converted into SPI format by the SX8652 for transfer to the host. The auxiliary input can be used to convert with 12-bit resolution any analog input in the supply range. It can also serves as an external synchronisation input to trig the touchscreen acquisition as described in the Application Information section. VDD SX8652 VDD HOST Control 4-wire touchscreen NIRQ INT AUX/WIPER NRST (DFN only) X-/TL Y+/TR SPI Touch Screen Interface CS OSC SCLK ref+ Y-/BL X+/BR DIO NCS in ADC out ref- Vref Digital Filter SCLK DOUT MISO DIN SPI Interface POR MOSI GND Figure 5. SX8652 with a 4-wire touch screen A 5-wire touchscreen application is shown in Figure 6. The 5-wire top sheet acts as a voltage measuring probe. The measurement accuracy is not affected by damage on this sheet and consequently the reliability is improved but the touch pressure can not be calculated. 5-wire touchscreen VDD SX8653 VDD HOST Control NIRQ INT AUX/WIPER Y+/TR SPI Touch Screen Interface OSC SCLK ref+ X+/BR Vref Y-/BL NCS in ADC out ref- Digital Filter DOUT DIN DIO CS SCLK MISO SPI Interface NRST (DFN only) POR X-/TL MOSI GND Figure 6. SX8652 with a 5-wire touch screen Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 10 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 3.2. Device Interface and ESD protection The touch screen controller inputs have been specially designed to provide robust on-chip ESD protection of up to 15kV in both HBM and Contact Discharge. 3.2.1. Touchscreen interface The X+/BR, X-/TL, Y+/TR,Y-/BL, AUX/WIPER are the pins dedicated for the touchscreen interface. It provides the voltage sequence in order to obtain the coordinates and pressure measurement. The five pins are connected to BR, TL, TR, BL, WIPER on a 5-wire touchscreen. They are the electrodes on the 4 corners of the bottom layer of the touchscreen plus the electrode on the top layer. On a 4-wire touchscreen, only 4 electrodes are used: X+,X-,Y+,Y-. The AUX pin is not needed and therefore can be used to convert an analog signal (range GND - VDD) into 12-bit digital value. The touchscreen interface pins are the most exposed pins for an ESD event. As shown in Figure 7, theses pins have internal ESD protection to GROUND and VDD. 3.2.2. Host Interface and Control Pins The SX8652 is a slave device configured via the SPI interface. NIRQ provides an interrupt to the host processor when a pen is detected or when channel data is available. The NIRQ pin is an active low, open drain output to facilitate interfacing to different supply voltages and thus requires an external pull-up resistor (1-10 kOhm). The host can reset the chip via the SPI interface or with the dedicated pin NRST. The NRST pin is an active low input that provides a hardware reset. An internal pull-up enables the interfacing with devices at different supply voltage. NRST and NIRQ pins are protected to GROUND. VDD Power M anagem ent GND X + /B R R chn X -/T L R chn Y + /T R R chn Y - /B L AUX/ W ip e r R chn Touch S c re e n D r iv e r s In te rfa c e MUX A D C NRST C o n tr o l D a t a P r o c e s s in g SPI N IR Q DIN DOUT SCLK NCS Figure 7. ESD protection Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 11 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 4. 4-wire Touch Screen Detailed Description 4.1. Touch Screen Operation A 4-wire resistive touch screen consists of two resistive sheets separated by an insulator (Figure 4.2). t Y ec el Y+ Y+ tro Contact point R3 with the top conductive sheet de shee c tiv e u d n co T op Y+ s Rytot Bo Y- m tto X+ R4 co nd X- t uc e iv e sh et X e le es c tro d YTop conductive sheet before the stylus contact YTop conductive sheet after the stylus contact Figure 8. 4-wire Touch Screen When a pressure is applied on the top sheet with a stylus for example, a connection with the lower sheet is made. The contact point split the Rxtot bottom resistance in the vertical axis into two resistances R1 and R2. In the same way, the Rytot resistance in the horizontal axis of the top sheet is divided into two resistances R3 and R4. Rxtot = R1 + R2 Rytot = R3 + R4 The touchscreen controller imposes a voltage level on X or Y electrodes allowing the detection of the contact position. 4.2. Coordinates Measurement During the touch, the top and bottom touchscreen layers are connected. The resistance between the two sheets is RT. A current coming from the reference voltage goes from X+ to X- to perform the X coordinate measurement. Figure 9 shows the measurement schematics. X+ Y+ R1 + R3 + ADC - Xpos RT Vref - Since the ADC had a high input impedance, no current flows through RT and R3. The positive ADC input is biased with a voltage created by the R1, R2 voltage divider. R2 X- R4 Y- The conversion with the 12 bit ADC gives the X location. Figure 9. Abscissa (X) coordinates measurement R2 Xpos = 4095 -------------------R1 + R2 The Y coordinate is measured in a similar fashion with the measurement setup given in Table 7. R4 Ypos = 4095 -------------------R3 + R4 Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 12 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 4.3. Pressure Measurement The 4-wire touchscreen allows pressure measurement. The contact resistance between the two sheets are a function of the pressure applied on the top sheet. Indeed, the a low pressure applied with the finger will create a small contact area. With a greater pressure, the contact area will be bigger and the RT resistance smaller. The RT contact resistance is therefore an indication of the applied pressure. RT is deducted from Z1 and Z2 measurement. The measurement setup given in Table 7 allows to find Z1 and Z2. R4 z1 = 4095 --------------------------------R1 + R4 + R T R4 + Rt z2 = 4095 --------------------------------R1 + R4 + R T Arranging Z1 and Z2 with Rxtot and Rytot allows the computation of RT. An alternative calculation method is using Xpos and Ypos. Ypos R T = Rytot ------------ 4095 Rytot Y pos R T = ------------------------------- 4095 z2 ----- - 1 z1 4095Xpos ----------- 1 - Rxtot 1 - ------------z1 4095 Measurement Vref + Vref- ADC + X X+ X- Y+ Y Y+ Y- X+ Z1 X+ Y- Y+ Z2 X+ Y- X- Table 7. Measurement setup 4.4. Pen Detection The pen detection circuitry is used to detect a user action on the touchscreen. The contact between the two layers generates an interrupt or starts an acquisition sequence. Doing a pen detection prior to conversion avoids feeding the host with dummy data and saves power. If the touchscreen is powered between X+ and Y- through a resistor RPNDT, no current will flow so long as pressure is not applied to the surface (see Figure 10). When a pressure is applied, a current path is created and brings X+ to the level defined by the resistive divider determined by RPNDT and the sum of R1, RT and R4. RPNDT Y+ + Vref - X+ R3 RT R1 R4 R2 Y- Sb Q Rb Q IRQ X- Internal logic Figure 10. 4-wire pen detection circuitry RPNDT should be set to the greatest value of 200 kOhm for optimal detection (see Table 15). Increasing PowDly settings can also improve the detection on panel with high resistance. The pen detection will set the PENIRQ bit of the RegStat register. The PENIRQ bit will be cleared and the NIRQ will be deasserted as soon as the host reads the status register. In PENDET mode, the pen detection will set NIRQ low. Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 13 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 5. 5-wire Touch Screen Detailed Description 5.1. Touch Screen Operation As the 4-wire, the 5-wire resistive touch screen consists of two resistive sheets separated by an insulator (Figure 11). The main difference is that the 4 wires are connected on the 4 corners of the bottom conductive sheet. They are referred as Top Left, Top Right, Bottom Left, Bottom Right. Top W ip e The fifth wire is embedded in the top sheet and is used for sensing the electrode voltage and is referred as the wiper. cond u c ti v e e she t TR r a t io a r is L in e a t t e r n p TL n BR BL B o tt o m u c ti cond ee ve sh t Figure 11. 5-wire touchscreen 5.2. Coordinates Measurement When the electrodes TL is connected with BL and TR with BR, they form with the linearization pattern 2 electrodes bars which are very similar to the X electrodes in a 4-wire touchscreen. In the same way, the association of TL with TR and BL with BR create Y electrodes. The four corners are therefore able to produce voltage gradients in the horizontal and vertical axis. The wiper is connected to the high input impedance of the ADC. When a pressure is applied on the top sheet, the contact point split the bottom sheet resistance into R1 and R2 on the X axis and R3 and R4 on the Y axis. The X and Y position converted by the 12-bit ADC gives the following result. R2 Xpos = 4095 -------------------R1 + R2 R4 Ypos = 4095 -------------------R3 + R4 5.3. Pen Detection The BR pin is connected to the positive pin of the reference voltage through RPNDT. The wiper panel is grounded at the AUX/WIPER pin to provide the grounding path for a screen touch event. The BR pin is monitored to detect voltage drop. When a pressure is applied on the top surface, a current path is created between the two layers and the PENIRQ bit of the RegStat register will be set. RPNDT should be set to the greatest value of 200 kOhm for optimal detection (see Table 15). Increasing PowDly settings can also improve the detection on panel with high resistance. In PENDET mode, the pen detection will set NIRQ low. R PNDT BR + Vref - Bottom layer Sb R1 Rb Top layer AUX/ WIPER Q - Q Internal logic Figure 12. 5-wire pen detection circuitry Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 14 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 6. Data Processing The SX8652 offers 4 types of data processing which allows the user to make trade-offs between data throughput, power consumption and noise rejection. The parameter FILT is used to select the filter order Nfilt as seen in Table 8. The sn samples from the ADC can be averaged. The processed cn 12-bit value is then send through the SPI bus. The noise rejection will be improved with a high order to the detriment of the power consumption. The K coefficient in Table 8 is a filter constant. Its value is K=4079/4095. FILT Nfilt Explanation 0 1 No average 1 3 3 ADC samples are averaged 2 5 5 ADC samples are averaged 3 7 7 ADC samples are sorted and the 3 center samples are averaged Processing sn = cn 1 s n = --- K ( c n + c n - 1 + c n - 2 ) 3 1 s n = --- K ( c n + c n - 1 + c n - 2 + c n - 3 + c n - 4 ) 5 c max1 c max2 c a c b c c c min1 c min2 1 s n = --- K ( c a + c b + c c ) 3 Table 8. Filter order 7. Power-Up, Reset During power-up, NIRQ pin is kept low, the POR reset all registers and states of the SX8652. The SX8652 is not accessible and SPI communications are ignored. As soon as NIRQ rises, the SX8652 is in manual mode with only the SPI peripheral enabled to minimize power consumption. The host can reset the SX8652 by setting the NRST pin low or via the SPI bus. Writing the code 0xDE to the register RegSoftReset reset the circuit. When NRST is driven LOW by the host, NIRQ will be driven low by the SX8652. After the reset NIRQ will be released by the SX8652. voltage VDD VDD/2 time voltage t POR NIRQ time Figure 13. Power-up, NIRQ 8. Modes of Operation The SX8652 has four operation modes that are configured using the SPI commands as defined in Table 13 and Table 15. These 4 modes are: manual (command `MANAUTO' and RATE=0), automatic (command `MANAUTO' and RATE>0), pen detect (command `PENDET'), pen trigger mode (command `PENTRG'). Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 15 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET In the PENDET mode the pen detection is activated. The SX8652 will generate an interrupt (NIRQ) upon pen detection and set the PENIRQ bit in the SPI status register. To quit the PENDET mode the host needs to configure the manual mode. In the PENTRG mode the pen detection is activated and a channel conversion will start after the detection of a pen. The SX8652 will generate an interrupt (NIRQ) upon pen detection and set the CONVIRQ bit in the SPI status register. To quit the PENTRIG mode the host needs to configure the manual mode. The PENTRG mode offers the best compromise between power consumption and coordinate throughput. 8.1. MANual Mode In manual mode (RATE=0), the host sequences all the actions by the SPI commands described in Table 9. When a command is received, the SX8652 executes the associated task and waits for the next command. Command Action Select and bias a channel Wait for the programmed settling time (POWDLY) CONVERT(CHAN) Start conversion Select and bias a channel SELECT(CHAN) Table 9. CONVERT and SELECT command The channel can be biased for an arbitrary amount of time by first sending a SELECT command and then a CONVERT command once the settling time requirement is met. The SELECT command can be omitted if the large range of POWDLY settings cover the requirements. In the latter case, the CONVERT command alone is enough to perform an acquisition. With CHAN=SEQ, multiple channels are sampled. This requires programming the POWDLY field in register RegCTRL0. The selected channel will be powered during POWDLY before a conversion is started. The channel bias is automatically removed after the conversion has completed. 8.2. AUTOmatic mode In automatic mode (RATE > 0), SX8652 start the acquisition when a touch is detected. It converts all the channels selected with RegChnMsk and set NIRQ low when it is finished. After the host has read the channels, if CONDIRQ=1 and the touch is detected again, the SX8652 starts a new conversion cycle. To not loose data, the SX8652 does not begin conversion before the host read all the channels. We can define the time ts between the start of the conversion and the end of the channels reading by the host. The rate programmed is achieved if ts<1/RATE otherwise the new rate is 1/ts. When the control CONDIRQ bit (see register RegStat Table 15) is set to `1' then the interrupts will only be generated if the pen detect occurred. This result in a regular interrupt stream, as long as the host performs the read channel commands, and the screen is touched. When the screen is not touched, interrupts does not occur. If the control CONDIRQ bit is cleared to `0', the interrupts will be always generated. In case there is no pen detected on the screen then the coordinate data will be qualified as invalid, see section [9.5]. This result in a regular interrupt stream as long as the host performs the read channel commands, This working is illustrated in Figure 16. Figure 14 shows the SPI working in automatic mode with CONDIRQ=1. After the first sentence send through the SPI to make the initialization, traffic is reduced as only reads are required. Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 16 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET The processing time is the necessary time for the SX8652 to makes the pen detection, the settling time (POWDLY) and the conversion of the selected channels. This time increases with the number of channel selected and the filter used. NIRQ interrupt signal notifies the host when the conversions are done. TOUCH NIRQ CS DIN DOUT The host just need to read the channels data to release the interrupt. Read Channel Data CMD Processing time Data from SX8652 Time is 1/ RATE Figure 14. SPI working in AUTO mode 8.3. PENDET Mode The PENDET mode can be used if the host only needs to know if the screen has been touched or not and take from that information further actions. When pen detect circuitry is triggered the interrupt signal NIRQ will be generated and the status register bit `PENIRQ' will be set. The bit is cleared by reading the status register RegStat. The PENDET working is illustrated in Figure 16. 8.4. PENTRIG Mode The PENTRIG mode offers the best compromise between power consumption and coordinate throughput. In this mode the SX8652 will wait until a pen is detected on the screen and then starts the coordinate conversions. The host will be signaled only when the screen is touched and coordinates are available. The flowchart is describes in Figure 16. The coordinate rate in pen trigger mode is determined by the speed of the host reading the channels and the conversion times of the channels. The host performs the minimum number of SPI commands in this mode. The host has to wait for the NIRQ interrupt to make the acquisition of the data. TOUCH NIRQ CS DIN DOUT Read Channel Data CMD Data from SX8652 Conversion time The SPI working is illustrated in Figure 15. Figure 15. SPI working in PENTRIG mode Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 17 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET yes AUTO MODE PENDET MODE CONDIRQ=1 ? Touch Detected ? PENTRIG MODE no no yes yes Touch Detected ? Touch Detected ? Set interrupt NIRQ=0 Start channel conversion no RegStat read yes Set timer=RATE Start timer Start channel conversion Release Interrupt NIRQ=1 All conversion finished Set interrupt NIRQ=0 All channel data read All conversion finished Release Interrupt NIRQ=1 Set interrupt NIRQ=0 All channel data read Release Interrupt NIRQ=1 Timer expire Figure 16. AUTO, PENDET and PENTRIG Mode Flowchart Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 18 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 9. Host Interface The host interfaced is composed of a SPI bus. It performs the read/ write operations on the registers and channels data. 9.1. SPI Read/Write Registers The WRITE command allows the host to write a single or multiple registers in the SX8652. The host can read single or multiple registers from the SX8652 by the READ command. This is defined in Table 10. W/R command name CR(7:0) 4 3 Function 7 6 5 WRITE(RA) 0 0 0 RA(4:0) Write register (see Table 14 for RA) READ(RA) 0 1 0 RA(4:0) Read register (see Table 14 for RA) Table 10. 2 1 0 W/R commands 9.2. SPI Reading Channel Data Five channels can be sampled by the SX8652: X, Y, Z1, Z2 and AUX. They are defined in Table 12. They can be converted in sequence with the RegChanMsk register. The READCHAN command allows the host to read the data obtained after the channels conversion and processing. W/R command name READCHAN 7 6 5 CR(7:0) 4 3 2 1 0 0 0 1 x x x x Table 11. Channel x Function Read data from channel Read Channels Data CHAN(2:0) 2 1 0 Function X 0 0 0 X channel Y 0 0 1 Y channel Z1 0 1 0 First channel for pressure measurement Z2 0 1 1 Second channel for pressure measurement Auxiliary channel AUX 1 0 0 reserved 1 0 1 reserved 1 1 0 SEQ 1 1 1 Channel sequentially selected from RegChanMsk register, (see Table 15) Table 12. Channel definition The channel data are 12-bit of unsigned format which corresponds to integers between 0 and 4095. This is send on two bytes, MSB first then LSB. A mask with the value 0x0FFF (4095) must be done to filter the four first unknown bit. When a channel data has been transmitted, the next one is sent in the successive order: X,Y, Z1, Z2 and AUX. If a channel has not been converted, the data is not transmitted. When the channel data buffer gets empty, the data will carry an invalid data as explained in the channel data format. Remark: After a conversion sequence, it is possible to read only one time the same channel. Example: the SX8652 is set to convert X and Y. The value 0xC0 is set in RegChanMsk. The first byte read after the READCHAN command will be X(MSB), then X(LSB), Y(MSB) and at the end Y(LSB). If the host carry on the reading, it will get invalid data. Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 19 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 9.3. SPI Host Commands .The host can issue commands to change the operation mode or perform manual actions as defined in Table 13. command name 7 6 5 CR(7:0) 4 3 SELECT(CHAN) 1 0 0 0 x CONVERT(CHAN) 1 0 0 1 x MANAUTO 1 0 1 1 x Function 2 1 0 CHAN(2:0) Bias channel (see Table 12 for CHAN) CHAN(2:0) x x Bias channel (see Table 12 for CHAN) x Enter manual or automatic mode. PENDET 1 1 0 0 x x x x Enter pen detect mode. PENTRG 1 1 1 0 x x x x Enter pen trigger mode. Table 13. Host Commands 9.4. SPI implementation and multiple Read/Write The SPI implemented on the SX8652 is set to the common setting CPOL=0 and CPHA=0 which means data are sampled on the rising edge of the clock, and shifted on the falling one. The default state of the clock when NCS gets asserted is low. If a host send a command while the system is busy, the command is discarded. The SPI protocol is designed to be able to do multiple read/write during a transaction. During one single operation, as long as NCS stay asserted, the register address is automatically increased to allow sequential read/write (or sequential retrieval of data). Between each different operation though (READ/WRITE/READCHAN), the communication should be restarted. This is described in Figure 17. Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 20 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET Writing Register NCS Single Write Multiple Write SCLK DIN RA[4:0] 0 0 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 DOUT Reading Register NCS Single Read Multiple Read SCLK DIN RA[4:0] 0 1 0 DOUT 7 6 5 4 3 2 1 0 Reading Channel Data NCS 7 6 5 4 3 2 1 0 Single Read Multiple Read SCLK DIN 0 0 1 DOUT 11 10 9 8 7 6 5 4 3 2 1 0 11 10 9 8 7 6 5 4 3 2 1 0 Other command NCS SCLK DIN Unknown bit CMD Single access DOUT Multiple access Figure 17. Data channel format 9.5. Invalid Qualified Data The SX8652 returns 0xFFFF data in case of invalid qualified data. This occurs: When the SX8652 has read all the channel data in the FIFO When a conversion is done without a pen being detected. Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 21 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 9.6. Register Map Register Address RA(4:0) Register Description 0 0000 RegCtrl0 Write, Read 0 0001 RegCtrl1 Write, Read 0 0010 RegCtrl2 Write, Read 0 0100 RegChanMsk Write, Read 0 0101 RegStat Read 1 1111 RegSoftReset Write Table 14. Register address The details of the registers are described in the next sections. Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 22 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 9.7. SX8652 register Register Bit Default Description Set rate in coordinates per sec (cps) ( 20%) If RATE =0: Manual mode. if RATE >0: Automatic mode 7:4 0000 RATE RegCtrl0 0000: Timer disabled -Manual mode 0001: 10 cps 0010: 20 cps 0011: 40 cps 0100: 60 cps 0101: 80 cps 0110: 100 cps 0111: 200 cps 1000: 300 cps 1001: 400 cps 1010: 500 cps 1011: 1k cps 1100: 2k cps 1101: 3k cps 1110: 4k cps 1111: 5k cps Conversion (or first conversion when filtering is enabled) settling time ( 10%) 3:0 7:6 0000 00 POWDLY AUXAQC 0000: Immediate (0.5 us) 0001: 1.1 us 0010: 2.2 us 0011: 4.4 us 0100: 8.9 us 0101: 17.8 us 0110: 35.5 us 0111: 71.0 us 1000: 0.14 ms 1001: 0.28 ms 1010: 0.57 ms 1011: 1.14 ms 1100: 2.27 ms 1101: 4.55 ms 1110: 9.09 ms 1111: 18.19 ms 00: AUX is used as an analog input (4wire only) 01: On rising AUX edge, wait POWDLY and start acquisition 10: On falling AUX edge, wait POWDLY and start acquisition 11: On rising and falling AUX edges, wait POWDLY and start acquisition The AUX trigger works only in manual mode with 4-wire touchscreen 5 1 CONDIRQ Enable conditional interrupts 0: interrupt always generated at end of conversion cycle. If no pen is detected the data is set to `invalid qualified'. 4 0 SCREEN Select the type of screen: 0: 4-wire 1: 5 -wire 10: 50 kOhm 11: 25 kOhm RegCtrl1 RegCtrl2 1: interrupt generated when pen detect is successful 3:2 00 RPDNT Select the Pen Detect Resistor 00: 100 kOhm 01: 200 kOhm 1:0 00 FILT Digital filter control 00: Disable 01: 3 sample averaging 10: 5 sample averaging 11: 7 sample acquisition, sort, average 3 middle samples 7:4 0 reserved Settling time while filtering ( 10%) 0000: Immediate (0.5 us) 0001: 1.1 us 0010: 2.2 us 0011: 4.4 us 0100: 8.9 us 0101: 17.8 us 0110: 35.5 us 0111: 71.0 us 1000: 0.14 ms 1001: 0.28 ms 1010: 0.57 ms 1011: 1.14 ms 1100: 2.27 ms 1101: 4.55 ms 1110: 9.09 ms 1111: 18.19 ms 3:0 0000 SETDLY Table 15. SX8652 Register Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 23 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET Register Bit Default RegChanMsk Description 7 1 XCONV 0: no sample 1: Sample X channel 6 1 YCONV 0: no sample 1: Sample Y channel 5 0 Z1CONV 0: no sample 1: Sample Z1 channel 4 0 Z2CONV 0: no sample 1: Sample Z2 channel 3 0 AUXCONV 0: no sample 1: Sample AUX channel 0 0 reserved 0 0 reserved 0 0 reserved Host writing to this register is ignored. RegStat RegSoftReset 7 0 CONVIRQ 0: no IRQ pending 1: Conversion sequence finished IRQ is cleared by the channel data read command 6 0 PENIRQ Operational in pen detect mode 0: no IRQ pending 1: Pen detected IRQ pending IRQ is cleared by the RegStat reading 5 1 RSTEVENT A reset event has occurred 4:0 00000 7:0 0x00 reserved Writing 0xDE to this register reset the SX8652 Any other data will not affect the SX8652 Table 15. SX8652 Register 10. Application Information This section describes in more detail application oriented data. 10.1. Acquisition Setup Prior to an acquisition, the SX8652 can be setup by writing the control registers. Registers are written by issuing the register write command. They can be read by issuing the read command. Please refer to the section [9.7]. 10.2. Channel Selection The SX8652 can be setup to start a single channel conversion or to convert several channels in sequence. For a single conversion, the channel to be converted is determined from the CHAN(2:0) field in the command word (defined in Table 12). Several channels defined in RegChanMsk can be acquired sequentially by setting the CHAN(2:0) field to SEQ. The channels will be sampled in the order X, Y, Z1, Z2, AUX. 10.3. Noise Reduction A noisy environment can decrease the performance of the controller. For example, an LCD display located just under the touch screen can adds a lot of noise on the high impedance A/D converter inputs. 10.3.1. POWDLY In order to perform correct coordinates acquisition properly, some time must be given for the touch screen to reach a proper level. It is a function of the PCB trace resistance connecting the SX8652 to the touchscreen and also the Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 24 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET capacitance of the touchscreen. We can define tau as the RC time constant. POWDLY duration should be programmed to 10 tau to reach 12 bit accuracy. Adding a capacitor from the touch screen drivers to ground is a solution to minimize external noise but it increases settling time and consequently the power consumption. 10.3.2. SETDLY A best method to filter noise is described in section [6] (Data processing). When filtering is enabled, the channel will be biased initially during a time of POWDLY for the first conversion. The parameter SETDLY sets the settling time between the subsequent conversions in a filter set. In most applications, SETDLY can be set to 0. In applications with a high tau and where accuracy of 1LSB is required SETDLY should be increased. 10.4. AUX Input - 4-wire touchscreen only The AUX input can be used to sample an analog signal in the range 0-VDD. For system supply by battery, the battery voltage can be monitored for example. The conversion is done in sequence with the touchscreen acquisition therefore the sample rate is defined with RegCtrl0 in AUTO mode. The AUX pin can also triggered conversions. A rising edge, a falling edge or both applied on the AUX pin can trigger the conversion. This is defined by AUXACQ in RegCtrl1. This method can be used to sample touchscreen when there is noise-free periods. 10.5. Interrupt Generation An interrupt (NIRQ=0) will be generated: During the power-up phase or after a reset After a touch on the panel being detected in PENDET mode. PENIRQ (bit [6] of RegStat) will be set at the same time. After completion of a conversion in MANUAL, PENTRIG or AUTO mode. CONVIRQ (bit [7] of RegStat) will be set at the same time. The NIRQ will be released and pulled high(NIRQ=1) by the external pull-up resistor: When the power-up phase is finished When the host read all channels data that were previously converted by the SX8652 in MANUAL, PENTRIG or AUTO mode. CONVIRQ will be cleared at the same time. When the host read the status register in PENDET mode. PENIRQ, will be cleared at the same time. An active NIRQ (low) needs to be cleared before any new conversions will occur. 10.6. Coordinate Throughput Rate The coordinate throughput rate depends on the following factors: The SPI communication time: Tcom The conversion time: Tconv 1 The coordinate rate is the frequency to get the X, Y, Z1 and Z2 coordinate: CoordRate = ------------------------------T com + T conv 10.6.1. SPI Communication Time The minimum time to read the channel data in PENTRIG mode is: T com = ( 8 + 16 x N chan ) x T SPI The highest throughput will be obtained with a SPI frequency of 5MHz when the host read the channel data as quickly as possible after the NIRQ falling edge. Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 25 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 10.6.2. Conversion Time The maximum possible throughput can be estimated with the following equation T conv = 47 T osc + N chan [ POWDLY + SETDLY ( N filt - 1 ) + T osc ( 21N filt + 1 ) ] with: Nfilt = {1,3,5,7} based on the order defined for the filter FILT (see Figure 8). Nchan = {1,2,3,4,5} based on the number of channels defined in RegChanMsk POWDLY = 0.5us to 18.19ms, settling time as defined in RegCtrl0 SETDLY = 0.5us to 18.19ms, settling time when filtering as defined in RegCtrl2 Tosc is the oscillator period (555ns +/- 15%) Table 16 gives some examples of Coordinate Rate and Sample Rate for various setting in PENTRIG mode. Nch [1..5 ] Nfilt [1 3 5 7] PowDly [uS] SetDly [uS] 2 1 0.5 - 2 3 71 4 3 140 Tconv [uS] Tcomm [uS] CoordRate [kSPS] 51 8 16.7 0.5 190 8 5.0 0.5 740 14 1.3 Table 16. Coordinate throughput examples 10.7. ESD event In case of ESD event, the chip may reset to protect its internal circuitry. The bit RSTEVENT indicates that a reset event has occurs. ESD event may trig the pen detection circuitry. In this case wrong data will be send to the host. To detect this false coordinates on 4-wire touchscreen, Z1 and Z2 can be read. The conditions Z1<LowThreshold and Z2>HighThreshold indicate an ESD event. The values LowThreshold and HighThreshold are given for indication only on the table below and should be fine tune according to the system. LowThreshold HighThreshold 10 4070 Table 17. Threshold to detect false coordinates Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 26 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 11. Packaging Information 11.1. DFN Package A B D DIMENSIONS MILLIMETERS MIN NOM MAX DIM PIN1 INDICATOR (LASER MARK) A A1 A2 b D D1 E E1 e L N aaa bbb E A SEATING PLANE aaa C A1 A2 0.80 0.70 0.00 0.02 0.05 - (0.20) 0.18 0.25 0.30 3.90 4.00 4.10 3.05 3.20 3.30 2.90 3.00 3.10 1.55 1.70 1.80 0.50 BSC 0.30 0.40 0.50 14 0.08 0.10 C LxN D1 1 2 E/2 E1 N bxN e bbb C A B D/2 NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS. Figure 18. DFN Package Outline Drawing DIMENSIONS DIM C G H K P X Y Z MILLIMETERS (2.90) 2.20 1.70 3.30 0.50 0.30 0.70 3.60 NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 3. THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD SHALL BE CONNECTED TO A SYSTEM GROUND PLANE. FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR FUNCTIONAL PERFORMANCE OF THE DEVICE. Figure 19. DFN Package Land Pattern Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 27 www.semtech.com SX8652 15kV ESD Low Power 4-Wire / 5-Wire Resistive Touchscreen Controller with SPI Interface ADVANCED COMMUNICATIONS & SENSING DATASHEET 11.2. WLCSP Package B 1.50.10 A INDEX AREA A1 CORNER 2.00.10 0.10 C 0.625 Max. 0.250.02 SEATING PLANE C 1.00 0.08 C 0.50 D 0.50 C 1.50 B 0.25 A 1 2 3 12X O0.3150.03 0.05 C A B NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS Figure 20. WLCSP Package Outline Drawing 1.00 0.50 0.50 0.25 1.50 12X O0.25 NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS 2. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. Figure 21. WLCSP Land Pattern of WLCSP Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 28 www.semtech.com SX8652 DATASHEET ADVANCED COMMUNICATIONS & SENSING (c) S e m te c h 2 0 1 0 A ll rig h ts re s e rv e d . R e p ro d u c tio n in w h o le o r in p a rt is p ro h ib ite d w ith o u t th e p rio r w ritte n c o n s e n t o f th e c o p y rig h t o w n e r. T h e in fo rm a tio n p re s e n te d in th is d o c u m e n t d o e s n o t fo rm p a rt o f a n y q u o ta tio n o r c o n tra c t, is b e lie v e d to b e a c c u ra te a n d re lia b le a n d m a y b e c h a n g e d w ith o u t n o tic e . N o lia b ility w ill b e a c c e p te d b y th e p u b lis h e r fo r a n y c o n s e q u e n c e o f its u s e . P u b lic a tio n th e re o f d o e s n o t c o n v e y n o r im p ly a n y lic e n s e u n d e r p a te n t o r o th e r in d u s tria l o r in te lle c tu a l p ro p e rty rig h ts . S e m te c h a s s u m e s n o re s p o n s ib ility o r lia b ility w h a ts o e v e r fo r a n y fa ilu re o r u n e x p e c te d o p e ra tio n re s u ltin g fro m m is u s e , n e g le c t im p ro p e r in s ta lla tio n , re p a ir o r im p ro p e r h a n d lin g o r u n u s u a l p h y s ic a l o r e le c tric a l s tre s s in c lu d in g , b u t n o t lim ite d to , e x p o s u re to p a ra m e te rs b e y o n d th e s p e c ifie d m a x im u m ra tin g s o r o p e ra tio n o u ts id e th e s p e c ifie d ra n g e . S E M T E C H P R O D U C T S A R E N O T D E S IG N E D , IN T E N D E D , A U T H O R IZ E D O R W A R R A N T E D T O B E S U IT A B L E F O R U S E IN L IF E -S U P P O R T A P P L IC A T IO N S , D E V IC E S O R S Y S T E M S O R O T H E R C R IT IC A L A P P L IC A T IO N S . IN C L U S IO N O F S E M T E C H P R O D U C T S IN S U C H A P P L IC A T IO N S IS U N D E R S T O O D T O B E U N D E R T A K E N S O L E L Y A T T H E C U S T O M E R 'S O W N R IS K . S h o u ld a c u s to m e r p u rc h a s e o r u s e S e m te c h p ro d u c ts fo r a n y s u c h u n a u th o riz e d a p p lic a tio n , th e c u s to m e r s h a ll in d e m n ify a n d h o ld S e m te c h a n d its o ffic e rs , e m p lo y e e s , s u b s id ia rie s , a ffilia te s , a n d d is trib u to rs h a rm le s s a g a in s t a ll c la im s , c o s ts d a m a g e s a n d a tto rn e y fe e s w h ic h c o u ld a ris e . A ll re fe re n c e d b ra n d s , p ro d u c t n a m e s , s e rv ic e n a m e s a n d tra d e m a rk s a re th e p ro p e rty o f th e ir re s p e c tiv e o w n e rs . Contact information Semtech Corporation Advanced Communications & Sensing Products E-mail: sales@semtech.comacsupport@semtech.comInternet: http://www.semtech.com USA 200 Flynn Road, Camarillo, CA 93012-8790. Tel: +1 805 498 2111 Fax: +1 805 498 3804 FAR EAST 12F, No. 89 Sec. 5, Nanking E. Road, Taipei, 105, TWN, R.O.C. Tel: +886 2 2748 3380 Fax: +886 2 2748 3390 EUROPE Semtech Ltd., Units 2 & 3, Park Court, Premier Way, Abbey Park Industrial Estate, Romsey, Hampshire, SO51 9DN. Tel: +44 (0)1794 527 600 Fax: +44 (0)1794 527 601 ISO9001 CERTIFIED Revision V1.7/October 2010 (c)2010 Semtech Corp. Page 29 www.semtech.com