IQS227AS-00000000-TSR

Azoteq IQ Switch® ProxSense® Series IQS227AS/B DATASHEET Single channel capacitive proximity and touch controller The IQS227AS/B ProxSense® IC is a fully integrated Self Capacitive sensor with dual outputs (Touch and Proximity outputs). Features > > > > > > > > Sub 2.5µA in Low Power Mode while sensing Proximity Automatic Tuning Implementation (ATI) - Automatic tuning of sense electrode Internal Capacitor Implementation (ICI) – reference capacitor on-chip Supply voltage: 1.8V to 3.6V Minimum external components Data streaming option RoHS2 Advanced on-chip digital signal processing Compliant User selectable (OTP): 4 Power Modes IO sink / source Time-out for stuck key Output mode (Direct / Latch / Toggle) Proximity and Touch Button sensitivity Applications > > > > > > > > > > > > LCD, Plasma & LED TVs GSM cellular telephones – On ear detection / touch keys LED flashlights or headlamps White goods and appliances Office equipment, toys, sanitary ware Flame proof, hazardous environment Human Interface Devices Proximity detection enables backlighting activation Wake-up from standby applications Replacement for electromechanical switches Find-In-The-Dark (FITD) applications Automotive: Door pocket lighting, electric window control GUI trigger on Proximity detected. Available options TA TSOT23-6 WLCSP-8 DFN-6 -20°C to 85°C IQS227AS - - -40°C to 85°C IQS227B IQS227B IQS227B Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS227AS/B Datasheet Revision 1.40 Page 1 of 37 October 2021 IQ Switch® ProxSense® Series Azoteq Contents IQS227AS/B DATASHEET................................................................................................................................ 1 1 OVERVIEW ..................................................................................................................................................... 5 1.1 APPLICABILITY ............................................................................................................................................ 5 1.2 ANALOGUE FUNCTIONALITY ......................................................................................................................... 5 2 PACKAGING AND PIN-OUT .......................................................................................................................... 6 2.1 IQS227AS/B.............................................................................................................................................. 6 2.1.1 TSOT23-6 Pin-out ............................................................................................................................. 6 2.1.2 WLCSP-8 Pin-out .............................................................................................................................. 7 2.1.3 DFN-6 Pin-out ................................................................................................................................... 8 2.2 SCHEMATIC................................................................................................................................................. 9 2.2.1 TSOT23-6 .......................................................................................................................................... 9 2.2.2 WLCSP-8........................................................................................................................................... 9 2.2.3 DFN-6 .............................................................................................................................................. 10 3 USER CONFIGURABLE OPTIONS ............................................................................................................. 11 3.1 CONFIGURING OF DEVICES ........................................................................................................................ 11 4 MEASURING CAPACITANCE USING THE CHARGE TRANSFER METHOD .......................................... 14 5 DESCRIPTIONS OF USER OPTIONS ......................................................................................................... 14 5.1 PROXIMITY / TOUCH SENSOR ..................................................................................................................... 15 5.2 LOGIC SELECT FOR OUTPUTS ..................................................................................................................... 15 5.3 OUTPUT PIN FUNCTION .............................................................................................................................. 15 5.3.1 Output function: Active .................................................................................................................... 15 5.3.2 Output function: Latch (for tLATCH) .................................................................................................... 15 5.3.3 Output function: Toggle ................................................................................................................... 16 5.4 PROXIMITY THRESHOLD ............................................................................................................................ 16 5.5 TOUCH THRESHOLD .................................................................................................................................. 16 5.6 POWER MODES......................................................................................................................................... 17 5.7 BASE VALUES ........................................................................................................................................... 18 5.8 MULTIPLIERS ............................................................................................................................................ 18 5.9 CHARGE TRANSFER .................................................................................................................................. 18 5.10 ATI TARGET COUNTS .............................................................................................................................. 18 5.11 NOISE DETECT ........................................................................................................................................ 18 5.12 ENABLE PARTIAL ATI .............................................................................................................................. 18 5.13 FILTERS USED BY THE IQS227AS/B ........................................................................................................ 18 5.13.1 Long Term Average (LTA) ............................................................................................................ 18 5.13.2 IIR Raw Data filter ......................................................................................................................... 19 6 DATA STREAMING MODE .......................................................................................................................... 19 6.1 EVENT MODE ............................................................................................................................................ 21 6.2 I2C ........................................................................................................................................................... 21 7 AUTO TUNING IMPLEMENTATION (ATI)................................................................................................... 21 7.1 AUTOMATIC ATI ........................................................................................................................................ 21 7.2 IQS227AS/B NOISE IMMUNITY .................................................................................................................. 22 8 ELECTRICAL SPECIFICATIONS ................................................................................................................ 23 8.1 ABSOLUTE MAXIMUM SPECIFICATIONS ....................................................................................................... 23 8.2 GENERAL CHARACTERISTICS ..................................................................................................................... 23 Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS227AS/B Datasheet Revision 1.40 Page 2 of 37 October 2021 IQ Switch® ProxSense® Series Azoteq 8.3 OUTPUT CHARACTERISTICS ....................................................................................................................... 24 8.4 PACKAGING INFORMATION ......................................................................................................................... 25 8.4.1 TSOT23-6 ........................................................................................................................................ 25 8.4.2 WLCSP-8......................................................................................................................................... 26 8.4.3 DFN-6 .............................................................................................................................................. 27 8.5 PACKAGE MSL ......................................................................................................................................... 28 9 DATASHEET AND PART-NUMBER INFORMATION ................................................................................. 29 9.1 ORDERING INFORMATION........................................................................................................................... 29 9.2 DEVICE MARKING – TOP ............................................................................................................................ 30 9.2.1 TSOT23-6 Packaging Markings ...................................................................................................... 30 9.2.2 WLCSP-8 Package Markings .......................................................................................................... 31 9.2.3 DFN-6 Package Markings ............................................................................................................... 31 9.3 DEVICE MARKING - BOTTOM ...................................................................................................................... 31 9.4 TAPE & REEL SPECIFICATION .................................................................................................................... 32 APPENDIX A. MEMORY MAP ........................................................................................................................ 33 APPENDIX B. CONTACT INFORMATION ..................................................................................................... 37 Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS227AS/B Datasheet Revision 1.40 Page 3 of 37 October 2021 IQ Switch® ProxSense® Series Azoteq List of Abbreviations ATI Automatic Tuning Implementation BP Boost Power Mode CS Counts (Number of Charge Transfers) Cs Internal Reference Capacitor EMI Electromagnetic Interference ESD Electro-Static Discharge FTB/EFT (Electrical) Fast Transient Bursts GND Ground HC Halt Charge LP Low Power Mode LTA Long Term Average ND Noise Detect THR Threshold Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS227AS/B Datasheet Revision 1.40 Page 4 of 37 October 2021 IQ Switch® ProxSense® Series Azoteq 1 Overview The IQS227AS/B is a single channel capacitive proximity and touch controller with an internal voltage regular and reference capacitor (Cs). The IQS227AS/B devices have dedicated pin(s) for the connection of sense electrodes (Cx) and output pins for proximity events on POUT and touch event on TOUT. The output pins can be configured for various output methods including a serial data streaming option on TOUT (1-wire protocol) or debug I2C. Device configuration is determined by one time programmable (OTP) options. The devices automatically track slow varying environmental changes via various filters, detect noise and has an Automatic Tuning Implementation (ATI) to tune the device sense electrode(s). The IQS227AS/B is built on ProxSense® new low voltage platform ideal for battery application (down to 1.8V). 1.1 Applicability All specifications, except where specifically mentioned otherwise, provided by this datasheet are applicable to the following ranges: > Temperature: • IQS227AS: -20°C to +85°C • IQS227B: -40°C to +85°C > Supply voltage (VDDHI): 1.8V to 3.6V 1.2 Analogue Functionality The analogue circuitry measures the capacitance of a sense electrode attached to the Cx pin through a charge transfer process that is periodically initiated by the digital circuitry. The measuring process is referred to a conversion and consists of the discharging of reference capacitor and Cx, the charging of Cx and then a series of charge transfers from Cx to Cs until a trip voltage is reached. The number of charge transfers required to reach the trip voltage is referred to as the Counts (CS). Copyright © Azoteq (Pty) Ltd 2021 All rights reserved The capacitance measurement circuitry makes use of an internal C s and voltage reference (VREF). The analogue circuitry functionality for: further provides > Power on reset (POR) detection. > Reset detection. > Detection of a watch dog timer (WDT) IQS227AS/B Datasheet Revision 1.40 Page 5 of 37 October 2021 Azoteq IQ Switch® ProxSense® Series 2 Packaging and Pin-out 2.1 IQS227AS/B The IQS227AS is available in a TSOT23-6 package, the IQS227B is available in TSOT23-6 or WLCSP-8 package 2.1.1 TSOT23-6 Pin-out TOUT 1 227AS/B 6 Cx GND 2 5 VDDHI POUT 3 4 VREG Figure 2.1: Pin-out of IQS227AS/B in TSOT23-6 package. 22-Bxx Table 2.1:Pin-out description. IC NAME Batch code IQS227AS/B 227Bxx Pin Name Type Function 1 TOUT 2 GND Ground GND Reference 3 POUT Digital Out Proximity Output 4 VREG Analogue Output 5 VDDHI Supply Input 6 CX IC Digital NAME Out Batch Touch Output 227Axx code Internal Regulator Pin Supply Voltage Input ICAnalogue NAMEI/O Sense Electrode Batch code 22-Axx IC NAME Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS227AS/B Datasheet Revision 1.40 Batch code Page 6 of 37 October 2021 Azoteq IQ Switch® ProxSense® Series 2.1.2 WLCSP-8 Pin-out 1 2 3 4 IQS227 8 7 6 5 Figure 2.2 IQS227B 8-pin WLCSP Table 2.2 8 -pin WLCSP Pin-out Description IQS227B 8-pin WLCSP Pin Name Type Function 1 Cx Sense electrode Connect to conductive area intended for sensor 2 TOUT Digital Out Touch Output 3 VREG Regulator output Requires external capacitor 4 VSS Signal GND 5 INPUT Digital Input Floating input during runtime. Recommended: Connect to POUT 6 POUT Digital Out Proximity Output 7 VDDHI Supply Input Supply Voltage Input Configuration pin Connection for OTP programming. Floating input during runtime. Recommended: Connect to TOUT pin. Programming can still be performed using this pin, provided a diode is used. (See AZD026 – Configuration Tools Overview) 8 PGM Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS227AS/B Datasheet Revision 1.40 Page 7 of 37 October 2021 Azoteq IQ Switch® ProxSense® Series 2.1.3 DFN-6 Pin-out POUT 3 TOUT 1 5 GND 2 4 POUT 3 6 Cx TOUT 1 5 VDDHI GND 2 4 VREG POUT 3 IQS228 GND 2 6 IQS227 IQS211 TOUT 1 Figure 2.3: Pin-out of IQS227B in DFN-6 package. Table 2.3:Pin-out description. 22-Bxx IQS227B 6-pin DFN Pin Name IC NAME 1 TOUT 2 GND 3 POUT 4 ICVREG NAME Type 227Bxx Ground Digital Out Digital Out Analogue Output Function Batch code Touch Output GND Reference Proximity Output Batch code Internal Regulator Pin 5 VDDHI Supply Input Supply Voltage Input 6 CX Analogue I/O Sense Electrode 227Dxx IC NAME Batch code 22-Dxx IC NAME Copyright © Azoteq (Pty) Ltd 2021 All rights reserved Batch code IQS227AS/B Datasheet Revision 1.40 Page 8 of 37 October 2021 6 5 4 IQ Switch® ProxSense® Series Azoteq 2.2 Schematic 2.2.1 TSOT23-6 Refer to AZD008 for touch key designs Figure 2.4: Typical application schematic of IQS227AS/B. 100pF capacitors are optional for added RF immunity. Place all decoupling capacitors (on VDDHI and VREG) as close to the IC as possible. Where a system level ESD strike is found to cause the IC to go into ESD induced latch-up, it is suggested that the supply current to the IQS227 IC is limited by means of a series resistor that could limit the maximum supply current to the IC to > This section describes the individual user programmable options of the IQS227AS/B in more detail. > User programmable options are programmed to One Time Programmable (OTP) fuse registers (refer to Section 3). HIGH=Logical ‘1’ and LOW=Logical ‘0’. The following sections are explained with POUT and TOUT taken as ‘Active LOW’. The default is always where bits are set to 0. Refer to section 0 for the sourcing and sinking capabilities POUT and TOUT. These pins are sourced from VDDHI and will be turned HIGH (when active high) for a minimum time of t HIGH, and LOW for a minimum time of tLOW (when active low). Note: Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS227AS/B Datasheet Revision 1.40 Page 14 of 37 October 2021 IQ Switch® ProxSense® Series Azoteq 5.1 Proximity / Touch Sensor Configuration: Bank0 bit5 The IQS227AS/B provides a Proximity output on POUT and a Touch output on TOUT, and does not need to be configured. LOGIC: Output logic select Bit Selection 0 Active Low 1 Active High 5.2 Logic select for outputs 5.3 Output pin function The logic used by the device can be selected as active HIGH or active LOW. The output pins, POUT and TOUT, will function based on this selection. The I/O’s are push pull in both directions and does not require a pull-up resistor. When configured as Active High, the I/O’s will remain high at POR until ATI has been completed. ATI times will vary based on the capacitive load on the sensor, but typically do not exceed 500ms. Various options for the function of the output pin(s) are available. These are selected as follow: Configuration: Bank0 bit7-6 FUNC1:FUNC0 OUTPUT Pins’ functions Bit Selection 00 POUT active, TOUT active 01 POUT latch, TOUT active 10 POUT active, TOUT toggle 11 POUT latch, TOUT toggle 5.3.1 Output function: Active With a Proximity or Touch event, the output pin will change to LOW and stay LOW for as long as the event remains (see Figure 5.1 Also refer to the use of tHALT section 5.13.1 that may cause the termination of the event. User Actuation 1 0 Output Pin 1 0 Figure 5.1: Active Mode Output Configuration 5.3.2 Output function: Latch (for tLATCH) With a Proximity or Touch event, the output pin will latch LOW for tLATCH seconds (4 seconds). When the event terminates prior to tLATCH the output pin will remain LOW. Copyright © Azoteq (Pty) Ltd 2021 All rights reserved When the event remains active longer than tLATCH the output pin will remain LOW as long as the event remains active (see Figure 5.2) When a subsequent event is made before the latch time (4 seconds) has passed, the timer will reset and the output will remain low for another duration of tLATCH seconds (4 seconds). For more details see Figure 5.2. IQS227AS/B Datasheet Revision 1.40 Page 15 of 37 October 2021 Azoteq IQ Switch® ProxSense® Series User Actuation 1 0 tLATCH tLATCH Output Pin tLATCH + time that User Actuation stays active 1 0 Figure 5.2: Latch Mode Output Configuration 5.3.3 Output function: Toggle The output pin will toggle with every Proximity or Touch event occurring. Thus when an event occurs and the output is LOW the output will become HIGH and when the output is HIGH the output will become LOW (see Figure 5.3) User Actuation 1 0 Output Pin 1 0 Figure 5.3: Toggle Mode Output Configuration Configuration: Bank0 bit1-0 5.4 Proximity Threshold The IQS227AS/B has 4 proximity threshold settings. The proximity threshold is selected by the designer to obtain the desired sensitivity and noise immunity. The proximity event is triggered based on the selected proximity threshold; the Counts (CS) and the LTA (Long Term Average). The threshold is expressed in terms of counts; the same as CS (refer to 0) PTHR =< LTA-CS Where LTA is the Long Term Average (refer to PTHR1:PTHR0 Proximity Thresholds Bit Selection 00 4 01 2 (Most sensitive) 10 8 11 16 (Least sensitive) A proximity event is identified when for at least 6 consecutive samples the following equation holds: identified when for at least 3 consecutive samples the following equation holds: 5.13.1) TTHR =< LTA-CS 5.5 Touch Threshold The IQS227AS/B has 8 touch threshold settings. The touch threshold is selected by the designer to obtain the desired touch sensitivity. The touch threshold is expressed as a fraction of the LTA as follows: 𝑇𝑇𝐻𝑅 = 𝑥⁄256 × 𝐿𝑇𝐴 With lower average counts (therefore lower LTA) values the touch threshold will be lower and vice versa. The touch event is triggered based on T TH, Counts (CS) and LTA. A touch event is Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS227AS/B Datasheet Revision 1.40 Page 16 of 37 October 2021 Azoteq IQ Switch® ProxSense® Series Configuration: Bank0 bit4-2 TTHR2:TTHR0: Touch Thresholds Bit Selection 000 72/256 001 8/256 (Most sensitive) 010 24/256 011 48/256 100 96/256 101 128/256 110 160/256 111 192/256 (Least sensitive) 5.6 Power Modes The IQS227AS/B has four power modes specifically designed to reduce current consumption for battery applications. The power modes are basically implemented around the occurrence of charge cycle every tSAMPLE seconds (refer to Table 5.1). The fewer charge transfer cycles that need to occur per second the lower the power consumption (but decreased response time). During Boost Power Mode (BP), charge cycles are initiated approximately every 9ms. While in any power mode the device will zoom to BP whenever an existing count sample (CS) indicates a possible proximity or touch event. The device will remain in BP for tZOOM seconds and then return to the selected power mode. The Zoom function allows reliable detection of events with counts being produced at the BP rate. Table 5.1: Power Mode configuration: Bank2 bit1-0 Charge Cycle Duration = tCHARGE Bit Power Mode timing tSAMPLE (ms) 00 tBP (default) BP (9ms) 01 tNP 128 10 tLP1 256 11 tLP2 512 Zoom to Boost Mode after proximity detected CX tSAMPLE tSAMPLE Figure 5.4: LP Modes: Charge cycles Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS227AS/B Datasheet Revision 1.40 Page 17 of 37 October 2021 IQ Switch® ProxSense® Series Configuration: Bank2 bit3 5.7 Base Values The sensitivity of the IQS227AS/B can be changed by adjusting the base value of the ATI algorithm, and as a result changing the compensation required to reach the target. 𝑆𝑒𝑛𝑠𝑖𝑡𝑖𝑣𝑖𝑡𝑦 = Azoteq Target: ATI Target Counts Bit Selection 0 1024 1 512 5.11 Noise Detect 𝑇𝐴𝑅𝐺𝐸𝑇 𝐵𝐴𝑆𝐸 ND: RF Noise Detection The target of the IQS227AS/B is fixed at 1000 counts. Configuration: Bank1 bit2-0 BASE: Base Value Select Bit Selection 000 200 001 50 010 75 011 100 100 150 101 250 110 300 111 500 The IQS227AS/B has RF Noise Detect (ND) functionality. If ND function is enabled, the IQS227AS/B is able to detect RF Noise on the TOUT pin. Further details on the working of this can be found in the Application Notes: AZD015 and AZD015b. In extremely noise environments, and close proximity to RF noise sources, the noise detect of the IQS227AS/B can be enable to block false triggers. Proper layout guidelines should always be used before the need to use ND. Configuration: Bank2 bit4 5.8 Multipliers When using partial ATI, the base value is set up using the multipliers. Compensation will still be added automatically to reach the target. ND: Noise Detect Bit Selection 0 Disabled 1 Enabled 5.12 Enable Partial ATI The charge transfer frequency of the IQS227AS/B is adjustable. Changing the transfer frequency will affect sensitivity and response rate. Two options are available: In some applications the startup time of the IQS227AS/B may be required to be decreased. This is possible by enabling partial ATI, if the multipliers required can be determined, and the compensation alone is adequate to account for environmental change. Configuration: Bank2 bit6 Configuration: Bank2 bit2 TRANS: Charge Transfer Frequency Bit Selection 0 512kHz 1 250kHz ATI: Partial ATI Bit Selection 0 Disabled 1 Enabled 5.10 ATI Target Counts 5.13 Filters used by the IQS227AS/B The target of the ATI algorithm can be adjusted between 1024 (default) and 512 counts. When less sensitivity is required, the lower counts will also increase response rate. The IQS227AS/B devices employ various signal processing functions that includes the execution of various filters as described below. 5.9 Charge Transfer 5.13.1 Long Term Average (LTA) Capacitive touch devices detect changes in capacitance that are not always related to the Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS227AS/B Datasheet Revision 1.40 Page 18 of 37 October 2021 IQ Switch® ProxSense® Series Azoteq intended proximity or touch of a human. This is a result of changes in the environment of the sense plate and other factors. These changes need to be compensated for in various manners in order to reliably detect touch events and especially to detect proximity events. One mechanism the IQS227AS/B employs is the use of a Long Term Averaging filter (IIR type filter) which tracks slow changes in the environment (expressed as changes in the counts). The result of this filter is a Long Term Average (LTA) value that forms a dynamic reference used for various functions such as identification of proximity and touch events. Refer to Application note “AZD024 - Graphical Representation of the IIR Filter” for detail regarding the execution of the LTA filter. The LTA is calculated from the counts (CS). The filter only executes while no proximity or touch event is detected to ensure compensation only for environmental changes. However there may be instances where sudden changes in the environment or changes in the environment while a proximity or touch event has been detected cause the counts to drift away from the LTA. To compensate for these situations a Halt Timer (tHALT) has been defined. In order to compensate for noise the IQS227AS/B uses an IIR filter on the raw data to minimize result of noise in the counts. This filter is implemented on all of the IQS227AS/B devices, and cannot be disabled. The Halt Timer is started when a proximity or touch event occurs and when it expires the LTA filter is recalibrated. Recalibration causes LTA < CS, thus the disappearance of proximity or touch events (refer to 5.4 and 5.5). The designer needs to select a Halt Timer value to best accommodate the required application. Configuration: Bank1 bit7-6 tHALT1:tHATL0: Halt time of Long Term Average Bit Selection 00 20 seconds 01 40 seconds 10 NEVER 11 ALWAYS (Proximity on 40 seconds) Notes: > The “NEVER” option indicates that the execution of the filters will never be halted. > With the ‘ALWAYS’ option and the detection of a proximity event the execution of the filter will be halted for only 40 seconds and with the detection of a touch event the execution of the filter will be halted as long as the touch condition applies. Copyright © Azoteq (Pty) Ltd 2021 All rights reserved 5.13.2 IIR Raw Data filter The extreme sensitivity of the IQS227AS/B makes it susceptible to external noise sources. This causes a decreased signal to noise (S/N) ratio, which could potentially cause false event detections. Noise can also couple into the device as a result of poor PCB, sense electrode design and other factors influencing capacitive sensing devices. 6 Data Streaming Mode The IQS227AS/B has the capability to stream data to a MCU. This provides the designer with the capability to obtain the parameters within the device in order to aid design into applications. Data streaming may further be used by an MCU to control events or further process results obtained from the IQS227AS/B devices. Data streaming is performed as a 1wire data protocol on TOUT, OR set to I 2C streaming (SDA on POUT, SCL on TOUT). Data Streaming can be enabled as indicated below: Configuration: Bank2 bit7 COMMS: Data Streaming Bit Selection 0 Disabled 1 Enabled Configuration: Bank2 bit5 STREAMING: Data streaming mode Bit Selection 0 1-Wire 1 I2C Data streaming is initiated by the IQS227AS/B. When data streaming is enabled data is sent following each charge. Figure 6.1 illustrates the communication protocol for initialising and sending data with the 1 wire communication protocol. IQS227AS/B Datasheet Revision 1.40 Page 19 of 37 October 2021 Azoteq IQ Switch® ProxSense® Series 1. Communication is initiated by a START bit. Bit defined as a low condition for tSTART. 2. Following the START bit, is a synchronisation byte (TINIT = 0xAA). This byte is used by the MCU for clock synchronisation. 3. Following TINIT the data bytes will be sent. With short data streaming mode TOUT /OUT B1 tINIT tDATA B2 B3 enabled, 5 bytes of data will be sent, otherwise 8 bytes will be sent after each charge cycle. 4. Each byte sent will be preceded by a START bit and a STOP bit will follow every byte. 5. STOP bit indicated by taking pin 1 high. The STOP bit does not have a defined period. B4 B5 B6 B7 B8 tSTOP Stop – Start Start Stop – Start Figure 6.1: 1-wire data streaming mode The following table defines the data streamed from the IQS227AS/B devices during the 1-wire streaming protocol. Copyright © Azoteq (Pty) Ltd 2021 All rights reserved IQS227AS/B Datasheet Revision 1.40 Page 20 of 37 October 2021 Azoteq IQ Switch® ProxSense® Series Table 6.1: Byte Definitions for 1-Wire Data Streaming Mode Byte (B) Bit 0 Value 7:0 CS High byte 2 15:8 CS Low byte 3 23:16 LTA High byte 4 31:24 LTA Low byte 5 Sys Flags 39 38 37 36 35 34 33 32 ~ ~ Active High Filter Halt LP active ATI Busy Noise Found In Zoom 47 Touch 46 45 44 43 42 41 40 Proximity Multipliers Multipliers Multipliers Multipliers Multipliers Multipliers 6 7 55:48 Compensation 8 63:56 Counter Bit 0 1 Selection 1-Wire Protocol I2C Streaming The Memory Map for the IQS227AS/B can be found in Appendix A. AA 1 Configuration: Bank2 bit7: Streaming Mode The IQS227AS/B can communicate on an I 2C compatible bus structure. Note that 4.7kΩ pullup resistors should be placed on SDA and SCL. The Control byte indicates the 7-bit device address (0x44H) and the Read/Write indicator bit. 7 Auto Tuning Implementation (ATI) ATI is a sophisticated technology implemented in the latest generation ProxSense ® devices that optimises the performance of the sensor in a wide range of applications and environmental conditions (refer to application note AZD0027 Auto Tuning Implementation). ATI makes adjustments through external reference capacitors (as required by most other solutions) to obtain optimum performance. ATI adjusts internal circuitry according to two parameters, the ATI multiplier and the ATI compensation. The ATI multiplier can be viewed as a course adjustment and the ATI compensation as a fine adjustment. The IQS227AS/B has Event Mode implemented during 1-wire communication. This allows the MCU to monitor the POUT pin for status changes (proximity or touch made or released events) instead of capturing data continuously. Upon a status change, the IQS227AS/B will pull the POUT pin for low to indicate to the MCU to read data. The POUT pin will stay low for 1.6ms. The adjustment of the ATI parameters will result in variations in the counts and sensitivity. Sensitivity can be observed as the change in current sample as the result of a fixed change in sensed capacitance. The ATI parameters have been chosen to provide significant overlap. It may therefore be possible to select various combinations of ATI multiplier and ATI compensation settings to obtain the same count value. The sensitivity of the various options may however be different for the same count value. 6.2 I2C 7.1 Automatic ATI 6.1 Event Mode The IQS227AS/B also allows for I2C streaming for debugging. Data Streaming can be changed from 1-wire protocol to I2C as shown below: Copyright © Azoteq (Pty) Ltd 2021 All rights reserved The IQS227AS/B implements an automatic ATI algorithm. This algorithm automatically adjusts the ATI parameters to optimise the sensing electrodes connection to the device. IQS227AS/B Datasheet Revision 1.40 Page 21 of 37 October 2021 IQ Switch® ProxSense® Series The device will execute the ATI algorithm whenever the device starts-up and when the counts are not within a predetermined range. While the Automatic ATI algorithm is in progress this condition will be indicated in the streaming data and proximity and touch events cannot be detected. The device will only briefly remain in this condition and it will be entered only when relatively large shifts in the counts has been detected. The automatic ATI function aims to maintain a constant count value, regardless of the capacitance of the sense electrode (within the maximum range of the device). The effects of auto-ATI on the application are the following: > Automatic adjustment of the device configuration and processing parameters for a wide range of PCB and application designs to maintain an optimal configuration for proximity and touch detection. > Automatic tuning of the sense electrode at start-up to optimise the sensitivity of the application. > Automatic re-tuning when the device detects changes in the sensing electrodes capacitance to accommodate a large range of changes in the environment of the application that influences the sensing electrode. > Re-tuning only occurs during device operation when a relatively large sensitivity reduction is detected. This is to ensure smooth operation of the device during operation. > Re-tuning may temporarily influence the normal functioning of the device, but in most instances the effect will be hardly noticeable. > Shortly after the completion of the re-tuning process the sensitivity of a Proximity detection may be reduced slightly for a few seconds as internal filters stabilises. Automatic ATI can effectively due to: be implemented so > Excellent system signal to noise ratio (SNR). > Effective digital signal processing to remove AC and other noise. Copyright © Azoteq (Pty) Ltd 2021 All rights reserved Azoteq > The very stable core of the devices. > Built in capability to accommodate a large range of sensing electrode capacitances. 7.2 IQS227AS/B Noise Immunity The IQS227AS/B has advanced immunity to RF noise sources such as GSM cellular telephones, DECT, Bluetooth and WIFI devices. Design guidelines should however be followed to ensure the best noise immunity. The design of capacitive sensing applications can encompass a large range of situations but as a summary the following should be noted to improve a design: > A ground plane should be placed under the IC, except under the Cx line. > All the tracks on the PCB must be kept as short as possible. > The capacitor between VDDHI and GND as well as between VREG and GND, must be placed as close as possible to the IC. > A 100pF capacitor can be placed in parallel with the 1uF capacitor between VDDHI and GND. Another 100pF capacitor can be placed in parallel with the 1uF capacitor between VREG and GND. > When the device is too sensitive for a specific application a parasitic capacitor (typically up to 20pF) can be added between the Cx line and ground. > Proper sense electrode and button design principles must be followed. > Unintentional coupling of sense electrode to ground and other circuitry must be limited by increasing the distance to these sources or making use of the driven shield. > In some instances, a ground plane some distance from the device and sense electrode may provide significant shielding from undesired interference. > When then the capacitance between the sense electrode and ground becomes too large the sensitivity of the device may be influenced. Note: ND input enable is a legacy input and is not recommended for use in new designs. The input has been desensitized by default and is not tested to trigger at a specific RF input power level IQS227AS/B Datasheet Revision 1.40 Page 22 of 37 October 2021 Azoteq IQ Switch® ProxSense® Series 8 Electrical Specifications 8.1 Absolute Maximum Specifications Exceeding these maximum specifications may cause damage to the device. IQS227AS IQS227B Operating temperature -20°C to 85°C -40°C to 85°C 3.6V VDDHI + 0.3V 1.7V VSS - 0.3V 100V/s 8kV Supply Voltage (VDDHI – VSS) Maximum pin voltage (TOUT, POUT) Pin voltage (Cx) Minimum pin voltage (VDDHI, VREG, TOUT, POUT, Cx) Minimum power-on slope HBM ESD protection (VDDHI, VREG, VSS, TOUT, POUT, Cx) 8.2 General Characteristics The IQS227AS/B devices are rated for supply voltages between 1.8V and 3.6V. Table 8.1: IQS227AS/B General Operating Conditions (Self) DESCRIPTION Conditions Supply voltage PARAMETER MIN TYP MAX UNIT VDDHI 1.8 3.3 3.6 V Internal regulator output 1.8 ≤ VDDHI ≤ 3.6 VREG 1.64 1.7 1.75 V Boost operating current 1.8 ≤ VDDHI ≤ 3.6 IIQS227AS/B BP 119 128 135 μA Normal operating current 1.8 ≤ VDDHI ≤ 3.6 IIQS227AS/B NP 4.7 6 7.6 μA Low power operating current 1.8 ≤ VDDHI ≤ 3.6 IIQS227AS/B LP1 2.8 3.5 4.7 μA Low power operating current 1.8 ≤ VDDHI ≤ 3.6 IIQS227AS/B LP2 1.75