SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet GENERAL DESCRIPTION KEY PRODUCT FEATURES The SX9300 is the world’s first dual channel capacitive Specific Absorption Rate (SAR) controller that accurately discriminates between an inanimate object and human body proximity. The resulting detection is used in portable electronic devices to reduce and control radio-frequency (RF) emission power in the presence of a human body, enabling significant performance advantages for manufacturers of electronic devices with EMF radiation sources to meet stringent emission regulations' criteria and Specific Absorption Rate (SAR) standards. Operating directly from an input supply voltage of 2.7 to 5.5V, the SX9300 outputs its data via a 1.65 – 5.5V host compatible I2C serial bus. The I2C serial communication bus port is compatible with 1.8V host control to report body detection/proximity and to facilitate parameter settings adjustment. Upon proximity detection, the NIRQ output asserts, enabling the user to either determine the relative proximity distance, or simply obtain an indication of detection. The serial bus can also serve to overwrite detection thresholds and operational settings in the event the user wants to change them from their factory presets. The SX9300 includes an on-chip auto-calibration controller that regularly performs sensitivity adjustments to maintain peak performance over a wide variation of temperature, humidity and noise environments, providing simplified product development and enhanced performance. A dedicated transmit enable (TXEN) pin is available to synchronize proximity measurements to RF transmission, enabling very low supply current and high noise immunity by only measuring proximity when requested. 2.7 – 5.5V Input Supply Voltage Dual SAR Capacitive Sensor Inputs On-Chip SAR Engine For Body versus Inanimate Object Detection Stable Proximity Sensing With Temperature 20mm detection distance Capacitance Offset Compensation to 30pF Active Sensor Guarding Automatic Calibration Ultra Low Power Consumption: Active Mode: Doze Mode: Sleep Mode: 170 uA 18 uA 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 -40°C to +85°C Operation Compact Size: 3 x 3mm Thin QFN package Pb & Halogen Free, RoHS/WEEE compliant APPLICATIONS • • • • • SAR Compliant Systems Notebooks Tablets Mobile Phones Mobile Hot Spots ORDERING INFORMATION Semtech P/N SX9300IULTRT Note1 SX9300EVK Package Marking QFN-20 ZM5C Eval. Kit Note 1: Quantities are ordered in 3K units per Reel TYPICAL APPLICATION CIRCUIT Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 1 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet Table of Contents GENERAL DESCRIPTION ........................................................................................................................ 1 KEY PRODUCT FEATURES..................................................................................................................... 1 APPLICATIONS....................................................................................................................................... 1 ORDERING INFORMATION...................................................................................................................... 1 TYPICAL APPLICATION CIRCUIT ............................................................................................................ 1 GENERAL DESCRIPTION............................................................................................................... 5 1 1.1 1.2 1.3 1.4 2 Pin Diagram Marking information Pin Identification Acronyms 5 5 6 6 ELECTRICAL CHARACTERISTICS ................................................................................................. 7 2.1 2.2 2.3 3 Absolute Maximum Ratings Recommended Operating Conditions Thermal Characteristics 7 7 7 FUNCTIONAL DESCRIPTION ........................................................................................................ 11 3.1 Introduction 3.1.1 General 3.1.2 Parameters and Configuration 3.1.3 Sensor Proximity Adjustment 3.2 Scan Period 3.3 Operational Modes 3.4 I2C interface 3.5 Configuration 3.6 Reset 3.6.1 Power-up 3.6.2 NRST 3.6.3 Software Reset 3.7 Interrupt 3.7.1 Power-up 3.7.2 NIRQ Clearing 4 11 11 11 11 11 12 12 13 13 13 14 14 15 15 15 PIN DESCRIPTIONS ..................................................................................................................... 16 4.1 4.2 4.3 4.4 4.5 5 Introduction VDD and SVDD TXEN Capacitor Sensing Interface (CS0A, CS0B, CS1A, CS1B, CSG) Host Interface 4.5.1 NIRQ 4.5.2 SCL, NRST and TXEN 4.5.3 SDA 16 16 16 16 16 16 17 17 DIFFERENTIAL DETECTION AND SAR COMPLIANCE .................................................................. 18 5.1 5.2 Specific Absorption Rate (SAR) Basics SAR Solution 5.2.1 Set CPS_DEB [5:4] (Debounce) 5.2.2 Set CPS_DELTATRS [3:0] (SAR Delta Detection Threshold) 5.2.3 Set CPS_RATIOTRS [7:0] (SAR Ratio Detection Threshold) 5.2.4 Setting Up The SX9300 To Discriminate Between A Human Body & Inanimate Object Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 2 18 18 18 18 19 19 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 6 DETAILED CONFIGURATION DESCRIPTIONS .............................................................................. 20 6.1 6.2 Introduction Capacitive Sensor (CS0A, CS0B, CS1A, CS1B) Parameters 6.2.1 Set CPS_Digital_GAIN [6:5] (Cap Sensor Gain) 6.2.2 Set CPS_CINR [1:0] (Input Capacitance Range and Resolution) 6.2.3 Set CPS_TRS [4:0] (Detection threshold) 6.2.4 Set CPS_HYST [5:4] (Detection Hysteresis) 6.2.5 Set CPS_AVGDEB[7:6] (Average Pos/Neg Debouncing) 6.2.6 Set CPS_AVGNEGFILT[5:3] & CPS_AVGPOSFILT[2:0] (Average Neg/Pos Filters) 6.2.7 Set CPS_FS[4:3] (Sampling Frequency) 6.2.8 Set CPS_RES[2:0] (Resolution Factor) 6.2.9 Set CPS_AVGTRS[7:0] (Averaging Threshold) 6.3 Additional Parameter Settings 6.3.1 Set CPS_PERIOD[6:4] (Scan Period) 6.3.2 Set CPS_EN [3:0] (Enable Capacitive Sensor Inputs) 6.3.3 Set IRQ_Enable [6:3] (Enable Interrupt Sources) 7 20 20 20 20 21 22 22 22 23 23 23 24 24 24 24 I2C INTERFACE ........................................................................................................................... 25 7.1 7.2 7.3 7.4 8 I2C Write I2C Read Register Overview SAR Sensor Design 25 26 27 31 PACKAGING INFORMATION ........................................................................................................ 32 8.1 8.2 Package Outline Drawing Land Pattern 32 33 LIST OF FIGURES Figure 1: Pin Diagram .............................................................................................................................................5 Figure 2: QFN Marking Information .......................................................................................................................5 Figure 3: I2C Start and Stop timing .....................................................................................................................10 Figure 4: I2C Data timing ......................................................................................................................................10 Figure 5 Scan Period.............................................................................................................................................11 Figure 6: Power-up vs. NIRQ ................................................................................................................................13 Figure 7: Hardware Reset .....................................................................................................................................14 Figure 8: Software Reset ......................................................................................................................................14 Figure 9: NIRQ Output Simplified Diagram ........................................................................................................16 Figure 10: SCL/TXEN/NRST .................................................................................................................................17 Figure 11: SDA Simplified Diagram .....................................................................................................................17 Figure 12: I2C Write...............................................................................................................................................25 Figure 13: I2C Read ...............................................................................................................................................26 Figure 14: Typical SAR Capacitive Sensor .........................................................................................................31 Figure 15: Package Outline Drawing ...................................................................................................................32 Figure 16: Package Land Pattern ........................................................................................................................33 Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 3 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 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: Detection Debounce Control .................................................................................................................18 Table 9: Delta Threshold Selection .....................................................................................................................18 Table 10: CPS_Digital_GAIN ................................................................................................................................20 Table 11: CINPUT Range and Resolution Register ...............................................................................................20 Table 12: Cap Sensor Threshold .........................................................................................................................21 Table 13: CPS_HYST .............................................................................................................................................22 Table 14: CPS_AVGDEB .......................................................................................................................................22 Table 15: Sampling Frequency Control ..............................................................................................................23 Table 16: CPS Resolution Factor.........................................................................................................................23 Table 17: Scan Period ...........................................................................................................................................24 Table 18: Register Overview ................................................................................................................................30 Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 4 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 1 GENERAL DESCRIPTION 1.1 Pin Diagram Figure 1: Pin Diagram 1.2 Marking information ZM5C yyww xxxx yyww= Date Code xxxx = Lot Number Figure 2: QFN Marking Information Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 5 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 1.3 Pin Identification Pin Number Name Type Description 1 CSG Analog Capacitive Sensor Guard 2 CS1B Analog Capacitive Sensor, 1B 3 CS1A Analog Capacitive Sensor, 1A 4 CS0B Analog Capacitive Sensor, 0B 5 CS0A Analog Capacitive Sensor, 0A 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 VDD Power SX9300 Core Power 12 SVDD Power Host serial port supply voltage. Must be less than or equal to VDD. NOTE: During power-up or power-down, SVDD must be less than or equal to VDD 13 NIRQ Digital Output 14 SCL Digital Input I2C Clock, requires pull up resistor to SVDD 15 SDA Digital I/O I2C Data, requires pull up resistor to SVDD 16 TXEN Input Transmit Enable, active HIGH (Tie to SVDD if not used). 17 NRST Input External reset, active LOW, requires pull up resistor to SVDD 18 A1 Digital Input I2C Sub-Address, connect to GND or VDD 19 A0 Digital Input I2C Sub-Address, connect to GND or VDD 20 GND Ground Ground DAP GND Ground Exposed Pad. Connect to Ground Interrupt request, active LOW, requires pull-up resistor to SVDD Table 1: Pin Description 1.4 Acronyms DAP SAR Revision 1.8 Die Attach Paddle Specific Absorption Rate June 27, 2012 © 2012 Semtech Corporation 6 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS 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 and proper functionality. Parameter Symbol MIN MAX VDD -0.5 6.0 SVDD -0.5 6.0 Input voltage (non-supply pins) VIN -0.5 VDD+0.3 Input current (non-supply pins) IIN -10 10 Operating Junction Temperature TJCT -40 125 Reflow temperature TRE Storage temperature TSTOR -50 ESDHBM 8 UNIT Supply Voltage ESD HBM (Human Body model, to JESD22-A114) 260 V mA °C 150 kV Table 2: Absolute Maximum Ratings 2.2 Recommended Operating Conditions Parameter Symbol Supply Voltage Ambient Temperature Range MIN MAX VDD 2.7 5.5 SVDD 1.65 VDD TA -40 85 UNIT V °C Table 3: Recommended Operating Conditions NOTE: During power-up or power-down, SVDD must be less than or equal to VDD 2.3 Thermal Characteristics Parameter Symbol Thermal Resistance – Junction to Air (Static Airflow) MIN θJA Typical MAX 34 UNIT °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. Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 7 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet Electrical Specifications All values are valid within the operating conditions unless otherwise specified. Parameter Symbol Conditions MIN TYP ISLEEP Power down, all analog circuits shut down. (I2C listening) 2.5 Doze IDOZE CPS_PERIOD = 200mS DozePeriod = 2xCps_Period CPS_FS = 167KHz CPS_RES = Medium VDD = 5 volt 18 Active (See Note i) IACTIVE CPS_PERIOD = 30mS CPS_FS = 167kHz CPS_RES = Medium. VDD = 5 volt MAX UNIT Current consumption Sleep Mode uA 170 Outputs: SDA, NIRQ Output Current at Output Low Voltage IOL Maximum Output LOW Voltage VOL(Max) VOL = 0.4V 6 mA SVDD > 2V 0.4 SVDD ≤ 2V 0.2 x SVDD V Inputs: SCL, SDA, TXEN Input logic high VIH 0.8 x SVDD SVDD + 0.3 Input logic low VIL -0.3 0.25 x SVDD Input leakage current IL -1 1 V CMOS input VHYS SVDD> 2V 0.05x SVDD SVDD≤ 2V 0.1x SVDD Hysteresis TXEN measurements TXENACTDLY Delay to when the SX9300 actually begins measurements from when TXEN becomes active uA V µS 100 Input: A0, A1 Input logic high VIH 0.7 x VDD VDD + 0.3 Input logic low VIL -0.3 0.3 x VDD V Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 8 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet Input: NRST Input logic high SVDD> 2V 0.7 x SVDD SVDD ≤ 2V 0.75 x SVDD VIH Input logic low SVDD + 0.3 V SVDD> 2V 0.6 SVDD ≤ 2V 0.3 x SVDD VIL Start-up Power-up time TPOR 1 mS TRESETPW 20 nS NRST NRST minimum pulse width Table 5: Electrical Characteristics Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 9 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet Parameter Symbol Conditions MIN TYP MAX UNIT 400 kHz I2C Timing Specifications SCL clock frequency fSCL SCL low period tLOW 1.3 SCL high period tHIGH 0.6 Data setup time tSU;DAT 100 Data hold time tHD;DAT 0 Repeated start setup time tSU;STA 0.6 Start condition hold time tHD;STA 0.6 Stop condition setup time tSU;STO 0.6 Bus free time between stop and start tBUF 1.3 Input glitch suppression tSP uS Note (1) 50 nS Note (1) -- Minimum glitch amplitude is 0.7VDD at High level and Maximum 0.3VDD at Low level. Table 6: I2C Timing Specification Note: All timing specifications, refer to Figure 3, Figure 4, and Table 6 Figure 3: I2C Start and Stop timing Figure 4: I2C Data timing Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 10 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 3 FUNCTIONAL DESCRIPTION 3.1 3.1.1 Introduction General The SX9300 is the world’s first SAR controller that is designed to detect proximity, differentiating between a human body and an inanimate object. The resulting detection is used in portable electronic devices to reduce and control radio-frequency (RF) emission power in the presence of a human body, enabling significant performance advantages for manufacturers of electronic devices with EMF radiation sources to meet stringent emission regulations' criteria and Specific Absorption Rate (SAR) standards. 3.1.2 Parameters and Configuration The SX9300 allows the user full parameter customization for Sensor sensitivity, hysteresis, and detection thresholds. If custom parameters are used by the customer, these parameters must be uploaded by the host immediately following boot-up or after a reset. 3.1.3 Sensor Proximity Adjustment Capacitive proximity detection is directly proportional to the SX9300 internal gain and threshold settings, and external sensor area to optimize proximity detection distance. A longer Proximity detection range can be accomplished without changing the capacitive sensor size, by using a high sensitivity setting and/or lower signal threshold setting for proximity detection. 3.2 Scan Period The Scan period determines the minimum SAR detection reaction time of the SX9300 and can be varied by the host from 30ms to approximately 400ms. SAR detection reaction time is proportional 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. CS0B CS0A CS1B CS1A CS0B CS0A The Scan period of the SX9300 is defined by two periods: Sensing and Idle. During the Sensing period, all enabled CS inputs, from CS0A to CS1B are sampled and any detection reported via the I2C bus (via I2C register polling or NIRQ). The Sensing period is variable and is proportional to the Scan Frequency and Resolution settings in the Cap Sensing Control Registers. During the Idle period, the SX9300 the analog circuits are placed in standby and the idle timer is initiated. Upon expiry of the idle timer, a new Scan period cycle begins. Figure 5 Scan Period Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 11 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 3.3 Operational Modes The SX9300 has four (4) operational modes: Active, Doze, Sleep, and Commanded. These modes enable tradeoffs between SAR detection reaction time and power consumption. Active: Active mode has the shortest scan periods, with a typical SAR detection reaction time of 30ms. In this mode, all enabled sensors are scanned and information data is processed within this interval. The Active scan period is user configurable and can be extended to a maximum period of 400ms. See CPS_PERIOD register in Section 7.3, (I2C Register Overview) below. Doze: Doze mode is by default, enabled in the SX9300. The Doze mode period is user configurable (see Section 7.3, I2C Register Overview) and can be used to extend the scan period out to 6.4 seconds for very low power consumption applications at the expense of very long SAR detection reaction times (6.4 seconds). In some applications, the SAR detection reaction time needs to be fast, when a human body is present, but can be slow when SAR detection has not been active for a while. When the SX9300 has not detected an object for a specific time, it will automatically change modes from Active to Doze reducing power. This time-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 SX9300 to leave Doze mode and re-enter Active mode. Sleep: Sleep mode places the SX9300 in its lowest power mode, 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 is perhaps the SX9300’s most useful feature. The TXEN input enables the measurement of the SAR channels when HIGH, likewise when the TXEN input is LOW, the SX9300 is in the Sleep mode. Specifically, on the rising edge of TXEN the SX9300 will begin measuring the SAR channels beginning with the lowest enabled channel repeating the measurement cycle at programmed rates (CPS_PERIOD) so long as TXEN remains HIGH. When TXEN goes LOW the current measurement sequence will complete and then measurement will cease until the next rising edge of TXEN. 3.4 I2C interface The I2C serial interface is configured as a slave device, operates at speeds up to 400 kHz and serves as the Host interface to the SX9300. The SX9300 has two I/O pins (A0 and A1) that provides for four possible, user selectable I2C addresses: A1 0 0 1 1 A0 0 1 0 1 Address 0x28 0x29 0x2A 0x2B Table 7: I2C Sub-Address Selection Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 12 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 3.5 Configuration If the application requires customization, the SX9300 configuration registers can be changed over the I2C bus. Some I2C addressable registers are used to read sensor status and information, while other (configuration) registers allow the host to take control of the SX9300. Via the configuration registers, the host can command an operational mode change or modify the active sensors. These user programmable configuration registers are volatile, therefore during a power-down or reset event, they lose all user programmed content, requiring the host to re-write the I2C registers after the event. 3.6 Reset A Reset to the SX9300 is performed by any one of the following methods: - Power-up - NRST pin - Software reset 3.6.1 Power-up During a power-up condition, the NIRQ output is HIGH until VDD has met the minimum input voltage requirements and a TPOR time has expired upon which, NIRQ asserts to a LOW condition indicating the SX9300 is initialized. The Host is required to perform an I2C read to clear this NIRQ status. The SX9300 is then ready for normal I2C communication and is operational. Figure 6: Power-up vs. NIRQ Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 13 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 3.6.2 NRST When NRST is asserted LOW and then HIGH, the SX9300 will reset its internal registers and will become active after period, TPOR. If a hardware reset control output is not available to drive NRST, then this pin must be pulled high to SVDD. Figure 7: Hardware Reset 3.6.3 Software Reset The host can perform software resets by writing to the I2CSoftReset register (see Section 7.3 for additional information). The NIRQ output will be asserted LOW and the Host is required to perform an I2C read to clear this NIRQ status. Figure 8: Software Reset Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 14 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 3.7 Interrupt Interrupt sources are disabled by default upon power-up and resets, and thus must be enabled by the host (apart from RESET IRQ). Any or all of the following interrupts can be enabled by writing a “1” into the appropriate locations within the IRQ_Enable register (see Section 7.3 for details): • Body detected • Completed Compensation • Completed Conversion The interrupt status can be read from register IRQStat for each of these interrupt sources (see Section 7.3 for details). 3.7.1 Power-up During initial power-up, the NIRQ output is HIGH. Once the SX9300 internal power-up sequence has completed, NIRQ is asserted LOW, signaling that the SX9300 is ready. The host must perform a read to IRQStat to acknowledge that the status is read and the SX9300 will clear the interrupt and release the NIRQ line. 3.7.2 NIRQ Clearing The NIRQ can be asserted in either the Active or Doze mode during a scan period. automatically cleared after the Host performs a read of the IRQStat I2C register. Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 15 The NIRQ will be www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 4 PIN DESCRIPTIONS 4.1 Introduction This section describes the SX9300 pin functionality, pin protection, whether or not the pins are analog or digital, and if they require pull-up resistors. There is ESD protection on all SX9300 I/O. 4.2 VDD and SVDD These are the device supply voltages. VDD is the supply voltage for the internal core and I/O. SVDD is the supply voltage for the I2C serial interface. NOTE: SVDD MUST be equal or lower than VDD. 4.3 TXEN This signal can be used in many applications if a conversion trigger/enable is needed. This input pin synchronizes the Capacitance Sensing inputs in systems that need to (for example) transmit RF signals. When this signal is active, SX9300 immediately performs capacitive measurements. If this input becomes inactive during the middle of a measurement, the SX9300 will complete all remaining measurements and will enter sleep mode until TXEN goes active again. 4.4 Capacitor Sensing Interface (CS0A, CS0B, CS1A, CS1B, CSG) The Capacitance Sensor input pins CS0A, CS0B, CS1A and CS1B are connected directly to the Capacitor Sensing Interface circuitry which converts the sensed capacitance 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 GROUND. 4.5 Host Interface The Host Interface consists of: NIRQ, NRST, SCL, SDA, 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 NIRQ pin is protected from ESD events to SVDD and GROUND. SVDD SVDD R_INT NIRQ NIRQ to Host INT SX9300 Figure 9: NIRQ Output Simplified Diagram Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 16 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 4.5.2 SCL, NRST and TXEN The SCL, NRST and TXEN pins are high impedance input pins that require an external pull-up resistor (1..10 kOhm). It is possible to connect NRST and TXEN Host output drivers directly without the requirement for a pullup resistor if driven from a push-pull host output. These pins are protected from ESD events to SVDD and GROUND. SVDD SVDD R SCL_IN/TXEN_IN/NRST_IN From Host SCL/TXEN/NRST Figure 10: 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 protected to SVDD and GROUND. SVDD SVDD R_SDA SDA To/From Host SDA_IN SDA_OUT Figure 11: SDA Simplified Diagram Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 17 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 5 DIFFERENTIAL DETECTION AND SAR COMPLIANCE 5.1 Specific Absorption Rate (SAR) Basics SAR is a measure of the rate at which energy is absorbed by the body when exposed to a radio frequency (RF) electromagnetic field; although, it can also refer to absorption of other forms of energy by tissue, including ultrasound. It is defined as the power absorbed per mass of tissue and has units of watts per kilogram (W/kg). SAR is usually averaged either over the whole body, or over a small sample volume (typically 1g or 10g of tissue). The value cited is then the maximum level measured in the body part studied over the stated volume or mass. The FCC requires that cell phone manufacturers conduct their SAR testing to include the most severe, worstcase (and highest power) operating conditions for all the frequency bands used in the USA for that cell phone. The SAR values recorded on the FCC’s authorization and in the cell phone manual to demonstrate compliance with Commission rules indicate only the highest single measurement taken for each frequency range that the particular model uses. FCC approval means that the device will never exceed the maximum levels of consumer RF exposure permitted by federal guidelines, but it does not indicate the amount of RF exposure consumers experience during normal use of the device. While only the maximum SAR values are used for FCC approval, all test reports submitted by the manufacturer are available in full for public inspection on the Commission’s website. 5.2 SAR Solution A SAR measurement consists of taking two sets of capacitive sensor data. In this case, each sensor must have recognized proximity detection. The two sets of data are then combined within the SX9300 as both a “ratio” of the data and a difference or “delta” of the data. The measured capacitance data can represent a very low level of capacitance. Therefore insuring that the signal is detected for a number of samples will minimize false triggers. The SX9300 includes the ability to “debounce” the detected data for up to 8 samples. 5.2.1 Set CPS_DEB [5:4] (Debounce) The register for the SAR debounce control: Bits [5:4] set the number of debounce samples. BITS 5 4 DEBOUNCE SAMPLES 0 0 1 1 0 1 0 1 None 2 4 8 Table 8: Detection Debounce Control 5.2.2 Set CPS_DELTATRS [3:0] (SAR Delta Detection Threshold) The register for the SAR Delta Threshold Control is at: Bits [3:0] and is used to set Delta Detection Threshold. The Delta measurement is the capacitive difference measurement between the two SAR Sensing Capacitors (Sensor B – Sensor A). Reg value 0000 0001 0010 0011 0100 0101 0110 0111 Threshold Value 0 1 3 5 10 15 20 25 Reg value 1000 1001 1010 1011 1100 1101 1110 1111 Threshold Value 30 35 40 45 50 55 60 70 Table 9: Delta Threshold Selection Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 18 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 5.2.3 Set CPS_RATIOTRS [7:0] (SAR Ratio Detection Threshold) The register for the SAR Ratio Threshold Control is at: 0x10. Bits [7:0] are used to set the SAR RATIO Threshold for the SX9300. The determination of the SAR Ratio Detection Threshold must be determined experimentally, but will be stable for a given design 5.2.4 Setting Up The SX9300 To Discriminate Between A Human Body & Inanimate Object An accurate discrimination between a human body and inanimate object can be obtained using the SX9300. It is important that the sensor pair areas are identical (in area, not necessarily in shape, see Section 7.4 for information as to how to design a successful SAR capacitive sensor). This involves a careful set-up between the following two registers: Delta and Ratio Thresholds. The set-up of these two registers is as follows: With the customer’s system set onto a table, bring a hand to the desired detection distance from the sensor. Set the Delta threshold limit until a “detection” is reported by the SX9300 Set the Ratio threshold limit until a “detection” is reported by the SX9300 Remove the hand and test with a number of inanimate objects to determine if the SX9300 successfully rejects them from reporting. If the SX9300 reports any of them as a “detection”, then raise the Delta threshold limit until it stops being reported and confirm that the human body is still reported (note: you will lose a bit of detection range when you raise threshold limits). If you cannot determine a successful setting that simultaneously rejects inanimate objects and detects a human body, then you must raise the Ratio threshold limit. Repeat 4) until a solution is determined. Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 19 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 6 DETAILED CONFIGURATION DESCRIPTIONS 6.1 Introduction The SX9300 is the first Smart Proximity SAR Compliant sensor that solves the human body versus inanimate object problem that designers of mobile appliances face every day. It requires only small external sensors plus some minor set-up commands to provide a robust SAR solution. The SX9300 comes with factory default settings that are appropriate for most general applications, however a full complement of registers are accessible to the user to enable application customization and optimization. 6.2 Capacitive Sensor (CS0A, CS0B, CS1A, CS1B) Parameters The SX9300 sensor has default parameters for the Capacitive Sensors that provides a quick and initial starting point to achieve SAR compliance. However, because of unique sensor sizes and sensor locations, it is possible to achieve higher and more robust performance with minor changes to these default parameters. In general only a few registers require changes to their default parameters to achieve improved performance. These registers are: 6.2.1 Set CPS_Digital_GAIN [6:5] (Cap Sensor Gain) The address for the (capacitive) sensor gain is: Bits [6:5] provide for four (4) gain settings as shown below: Bits 6 0 0 1 1 5 0 1 0 1 Gain x1 x2 x4 x8 Table 10: CPS_Digital_GAIN 6.2.2 Set CPS_CINR [1:0] (Input Capacitance Range and Resolution) The register for the input capacitance full scale range and resolution is: Bits [1:0] provide set ability over the expected maximum sensed capacitance. A setting of 00 on these bits provides for the largest capacitance 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 provides the longest proximity distance. The table for this register is shown below: Bits 1 0 0 1 1 0 0 1 0 1 CINPUT Range and Resolution Large Medium-Large Medium-Small Small Table 11: CINPUT Range and Resolution Register Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 20 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 6.2.3 Set CPS_TRS [4:0] (Detection threshold) This register defines the detection threshold for all sensors and the details are shown below. Lower thresholds provide longer proximity detection distances but are more susceptible to noise, while higher threshold values provide immunity to noise, but results in shorter proximity detection range. The default value for this register is [00000]. BITS 4 3 2 1 0 THRESHOLD VALUE 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 350 400 450 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 Table 12: Cap Sensor Threshold Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 21 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 6.2.4 Set CPS_HYST [5:4] (Detection Hysteresis) This register defines the detection hysteresis for all sensors. Hysteresis for the SAR sensors provides an important function in that it keeps the SX9300 from providing “oscillating” results when detection levels are close to threshold. The register details are shown below. Bits 5 0 0 1 1 4 0 1 0 1 DETECTION HYSTERESIS 32 64 128 256 Table 13: CPS_HYST 6.2.5 Set CPS_AVGDEB[7:6] (Average Pos/Neg Debouncing) Use of debounce in the SX9300 is recommended as it will reduce the effects of extraneous noise for reported detection. The SX9300 includes several conditions for debounce: Close, Far, and Data Detection. Bits 7 0 0 1 1 6 0 1 0 1 AVERAGE POS/NEG DEBOUNCING OFF 2 Samples 4 Samples 8 Samples Table 14: CPS_AVGDEB 6.2.6 Set CPS_AVGNEGFILT[5:3] & CPS_AVGPOSFILT[2:0] (Average Neg/Pos Filters) The SX9300 includes circuitry to average out the detected signals. These detected signals can be both positive and negative, and so there are registers to control both the positive and negative averaging filter coefficients. There are eight (8) settings possible in each of these filters ranging from OFF up to highest filtering. 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. Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 22 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 6.2.7 Set CPS_FS[4:3] (Sampling Frequency) The capacitance sampling frequency can be changed in CPS_CTRL2 if the environment is particularly noisy. Changing this frequency affects the Capacitance Sensing period. It is recommended to use the 167 kHz sampling frequency. Bits 4 0 0 1 1 3 0 1 0 1 SAMPLING FREQUENCY 83 kHz 125 kHz 167 kHz Reserved, do not use Table 15: Sampling Frequency Control 6.2.8 Set CPS_RES[2:0] (Resolution Factor) The CPS Resolution factor has 8 possible settings that range from coarsest to very fine that controls the total number of measurements per sensor in a Scan Period. Along with the CPS Sampling Frequency, changing this register affects the SX9300 Sensing Period. This register is located in CPS_CTRL2. Bits 1 0 RESOLUTION 1 0 0 1 1 0 0 1 0 1 0 Coarsest Very Coarse Coarse Medium Coarse Medium 1 0 1 Fine 1 1 0 Very Fine 1 1 1 Finest 2 0 0 0 0 Table 16: CPS Resolution Factor 6.2.9 Set CPS_AVGTRS[7:0] (Averaging Threshold) The SX9300 performs averaging on all capacitive measurements to determine when to perform a calibration cycle. The CPS_AVGTRS register is used to set an 8-bit positive and negative threshold that determines when a calibration is internally requested. Typically the user would set this register to be between 10000000 [7:0] to 11000000 [7:0] which corresponds to ½ to ¾ of the system dynamic range. Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 23 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 6.3 Additional Parameter Settings Further application customization is possible to control scan period, enabled sensors and individual sensor interrupts are also possible. Scan period affects both power dissipation and detection reaction time. 6.3.1 Set CPS_PERIOD[6:4] (Scan Period) This register controls the scan period of the SX9300 over a range of 30ms to 400ms. Bits 5 4 Scan PERIOD (ms) 1 0 0 1 1 0 0 1 0 1 0 30 60 90 120 150 1 0 1 200 1 1 0 300 1 1 1 400 6 0 0 0 0 Table 17: Scan Period 6.3.2 Set CPS_EN [3:0] (Enable Capacitive Sensor Inputs) If one set of SAR capacitive sensors is not required, they can be disabled in this register. Each bit in this register corresponds to a specific sensor input. A logic “1” enables the capacitive sensor input, while a logic “0” disables a capacitive input. INPUTS MUST BE DISABLED IN PAIRS. CS0A & CS0B = Bits [1:0] CS1A & CS1B = Bits [3:2] 6.3.3 Set IRQ_Enable [6:3] (Enable Interrupt Sources) There are a number of interrupt sources that the SX9300 can report. A logic “1” in the specific location will enable the specific interrupt as shown below. SARIRQEN [6]: Enables the SAR Proximity Detection IRQ SARRLSIRQEN [5]: Enables the SAR Proximity No Detect IRQ COMPDONEIRQEN [4]: Enables the Compensation Done Notification IRQ CONVIRQEN [3]: Enables the Conversion Completion Done Notification IRQ Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 24 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 7 I2C INTERFACE The I2C implemented on the SX9300 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 immediately. Therefore the user should ideally disable the sensor 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 sensors - 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 sequentially, and the address increments automatically. Supported I2C access formats are described in the next sections. 7.1 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 SX9300 then Acknowledges [A] that it is being addressed, and the Master sends an 8 bit Data Byte consisting of the SX9300 Register Address (RA). The Slave Acknowledges [A] and the master sends the appropriate 8 bit Data Byte (WD0). Again the Slave Acknowledges [A]. In case the master needs to write more data, a succeeding 8 bit Data Byte will follow (WD1), acknowledged by the slave [A]. This sequence will be repeated until the master terminates the transfer with the Stop condition [P]. Figure 12: I2C Write The register address is incremented automatically when successive register data (WD1...WDn) is supplied by the master. Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 25 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 7.2 I2C Read The format of the I2C read is given in Figure 13. After the start condition [S], the slave address (SA) is sent, followed by an eighth bit (‘0’) indicating a Write. The SX9300 then Acknowledges [A] that it is being addressed, and the Master responds with an 8-bit Data consisting of the Register Address (RA). The Slave Acknowledges [A] and the master sends the Repeated Start Condition [Sr]. Once again, the slave address (SA) is sent, followed by an eighth bit (‘1’) indicating a Read. The SX9300 responds with an Acknowledge [A] and the read Data byte (RD0). If the master needs to read more data it will acknowledge [A] and the SX9300 will send the next read byte (RD1). This sequence can be repeated until the master terminates with a NACK [N] followed by a stop [P]. Figure 13: I2C Read Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 26 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 7.3 Register Overview Add Reg General Control & Status 0x00 IRQStat 0x01 TchCmpStat Acc Bits Field R 7 6 5 RESETIRQ TCHIRQ RLSIRQ 1 0 0 R/W 4 COMPDONE 0 R 3 2:1 0 7 CONVIRQ Not Used TXENSTAT SARSTAT3 0 00 0 0 6 SARSTAT2 0 5 SARSTAT1 0 4 SARSTAT0 0 3:0 COMPSTAT 1111 7 6 5 4 Not Used SARIRQEN SARRLSIRQEN COMPDONEIRQEN 3 2:0 CONVIRQEN Not Used 0 000 7 6:4 Not Used CPS_PERIOD 0 000 3:0 CPS_EN 1111 R/W 7:6 CPS_SH 01 R/W 5:2 1:0 CPS_CINR R General Operations Control 0x03 IRQ_Enable R R/W R Cap Sensing Control 0x06 CPS_CTRL0 0x07 CPS_CTRL1 Revision 1.8 June 27, 2012 R/W © 2012 Semtech Corporation 27 Reset 0 0 0 0 0000 00 Function Reset event occurred Sensor proximity detected Sensor detection release condition interrupt Compensation complete. Writing a one in this bit trigs a compensation on all channels Conversion cycle complete Not Used Report TXEN pad status Determines if proximity has been detected for the pair CS1A/CS1B Determines if a human body has been detected for the pair CS1A/CS1B Determines if a proximity has been detected for the pair CS0A/CS0B Determines if a human body has been detected for the pair CS0A/CS0B Specifies which capacitive sensor(s) has a compensation pending Not Used Enables the detection irq Enables the release irq Enables the compensation irq Enables the conversion irq Not Used Not Used 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 Enables CS0A through CS1B CG bias/shield usage. 00 : Off, CG high-Z (off) 01: On(def.) 10: Reserved 11: Reserved Not used Capacitance Range: 00: Large www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 0x08 0x09 CPS_CTRL2 CPS_CTRL3 R/W R/W 7 6:5 Not Used CPS_Digital_GAIN 0 00 4:3 CPS_FS 01 2:0 CPS_RES 000 7 6 5:4 Not Used CPS_DOZEEN CPS_DOZEPERIOD 0 1 00 3:2 1:0 Reserved CPS_RAWFILT 00 00 0x0A CPS_CTRL4 R/W 7:0 CPS_AVGTRS 00000000 0x0B CPS_CTRL5 R/W 7:6 CPS_AVGDEB 00 5:3 CPS_AVGNEGFILT 000 2:0 CPS_AVGPOSFILT 000 7:5 Not Used 000 0x0C CPS_CTRL6 Revision 1.8 June 27, 2012 R/W © 2012 Semtech Corporation 28 01: Medium Large 10: Medium Small 11: Small Not Used Set Digital gain factor 00: Gain = 1 01: Gain = 2 10: Gain = 4 11: Gain = 8 Sampling frequency 00: 83 kHz 01: 125 kHz 10: 167 kHz (Typical) 11: Reserved Resolution Control 000: Coarsest …. 100: Medium …. 111: Finest Not Used Enables doze mode When doze is enabled, the cap sensing period moves from CPS_PERIOD to CPS_PERIOD * : 00: 2*CPS_PERIOD 01: 4* CPS_PERIOD 10: 8*CPS_PERIOD 11: 16*CPS_PERIOD Must be 00 Raw filter coefficient 00: off 01: Low 10: Medium 11: High (Max Filtering) Average pos/neg threshold = 8 x reg Average pos/neg debouncer: 00: off 01: 2 samples 10: 4 samples 11: 8 samples Average negative filter coefficient : 000: off 001: Lowest …. …. 111: Highest (Max. Filter) Average positive filter coefficient : 000: off 001: Lowest .… ….. 111: Highest (Max. Filter) Not Used www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 0x0D 0x0E CPS_CTRL7 CPS_CTRL8 Sensor Readback 0x20 CPSRD 0x21 0x22 0x23 0x24 0x25 0x26 0x27 UseMSB UseLSB AvgMSB AvgLSB DiffMSB DiffLSB OffMSB Revision 1.8 June 27, 2012 4:0 CPS_TRS 7 CPS_CMPAUTOOFF 0 6 CPS_CMPTRG 0 5:4 CPS_HYST 00 3:2 CPS_CLSDEB 00 1:0 CPS_FARDEB 00 7:4 CPS_STUCK 0000 3:0 CPS_CMPPRD 0000 R 7:2 Not Used 000000 00 R 1:0 CPSRD R 7:0 SENSUSEMSB R 7:0 SENSUSELSB R 7:0 SENSAVGMSB R 7:0 SENSAVGLSB R 7:0 SENSDIFFMSB R 7:0 SENSDIFFLSB R/W 7:0 SENSOFFMSB R/W R/W © 2012 Semtech Corporation 29 00000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 Defines the touch/prox detection threshold for all sensors. See Table 12 Disables the automatic compensation trigged by average 0: compensate channels independently 1: compensate all channels when triggered Detection hysteresis 00: 32 01: 64 10: 128 11: 256 Close debouncer 00: off 01: 2 samples 10: 4 samples 11: 8 samples Far debouncer 00: off 01: 2 samples 10: 4 samples 11: 8 samples 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 Periodic compensation 0: off else : increment every CPS_COMPPRD x 128 active frames Not Used Determines which sensor data will be available in the next Reg read. Provides the useful information for monitoring purposes. Signed, 2's complement format Provides the average information for monitoring purposes. Signed, 2's complement format Provides the Diff information for monitoring purposes. Signed, 2's complement format Offset compensation DAC www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 0x28 OffLSB 00000000 R/W 7:0 SENSOFFLSB 0x29 Delta R 3:0 SENSDELTA 0000 0x2A Ratio R 7:0 SENSERATIO 00000000 0x7F I2CSoftReset W 7:0 SOFTRESET 00000000 R/W 7:6 5:4 Not Used CPS_DEB 00 00 3:0 CPS_DELTATRS 0000 7:0 CPS_RATIOTRS 00000000 SAR Mode Registers 0x0F Deb_DeltaTrs 0x10 CPS_RatioTrs R/W code. This is writable to allow forcing some DAC 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. SAR Value Delta (Difference) reading. Signed, 2's complement format (See Register 0x20) Ratio of the SAR values. Unsigned. (See Register 0x20) Write 0xDE and Reset the chip Not Used Data Debouncing associated with detection/release (Useful in a noisy environment): 00: off 01: 2 samples 10: 4 samples 11: 8 samples Defines the delta detection threshold that’s applied to all sensors. See Table 9 Defines the ratio detection threshold applied to all sensors Table 18: Register Overview Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 30 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 7.4 SAR Sensor Design This section describes how to properly design SAR sensors. The SAR sensors for the SX9300 can be designed in a variety of shapes depending on the physical requirements of the system. In the drawing below, the yellow areas represent copper (conductor) and the gray area represents a nonconductor and is the distance r2 – r1 (spacing between the two copper areas). Figure 14: Typical SAR Capacitive Sensor “CSxA” and “CSxB” copper areas refer to the SX9300 sensor inputs. IMPORTANT NOTE: The “A” and “B” sensors cannot be swapped on the SX9300. The outer copper area is always the “A” sensor, and the inner copper area is always the “B” sensor. Also, the area of a CSxB sensor and CSxA sensor must be designed to be nearly equal. The radius “r1” sets the area of SAR sensor CSxB, while the radius “r3 – r2” sets the area of SAR sensor CSxA. For circular capacitive sensors shown above where “r1” is very nearly equal to “r2”, then the area of CSxA is defined by r3 = √2 x r1 This approximation is also true for square type sensors Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 31 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 8 PACKAGING INFORMATION 8.1 Package Outline Drawing Figure 15: Package Outline Drawing Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 32 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet 8.2 Land Pattern Figure 16: Package Land Pattern Revision 1.8 June 27, 2012 © 2012 Semtech Corporation 33 www.semtech.com SX9300 Ultra Low Power, Dual Channel Smart Proximity SAR Compliant Solution WIRELESS & SENSING PRODUCTS Datasheet Semtech 2012 All rights reserved. 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